Journal articles: 'Casting waxes'

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Mäsiar, H., L. Repka, P. Lipták, and O. Híreš. "Investigate the Possibility of Tekcast Methods Used for Casting Polymeric Resin Materials." Archives of Foundry Engineering 14, no. 2 (June 1, 2014): 119–22. http://dx.doi.org/10.2478/afe-2014-0049.

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Abstract Contribution gives an overview of knowledge about the method of centrifugal casting with orientate on Tekcast system. Company Tekcast Industries has developed a device for centrifugal casting, extending the area of production of castings or prototyping of metal or plastic. Materials suitable for the centrifugal casting with flexible operating parameters may include non-ferrous metal alloy based on zinc or aluminum or non-metallic materials such as polyester resins, polyurethane resins, epoxy resins, waxes and the like. The casting process is particularly suitable for a wide range of commercial castings and decorative objects.

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Masato, Davide, Marco Sorgato, and Giovanni Lucchetta. "Prototyping and modeling of the centrifugal casting process for paraffin waxes." Materials and Manufacturing Processes 32, no. 16 (April 12, 2017): 1823–30. http://dx.doi.org/10.1080/10426914.2017.1317791.

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Ozyegin, L. S., R. Tuncer, and E. Avci. "Hardness, Behavior and Metal Surface Evaluation of Recasting Non-Precious Dental Alloys." Key Engineering Materials 330-332 (February 2007): 1425–28. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.1425.

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Recasting of economic alloys can change several properties. The number of recasting was found to have negligible effect on surface texture and on the amount of corrosion products released. The methods and equipments utilized in the casting of an alloy are important on the quality of casting. Carbon incorporated in a noble or economic alloy during casting is known to affect the mechanical values of the metal. In the present study we aimed to investigate the change in structure and metal hardness due to recasting. Materials and method: The effect of recasting, up to four times of a non precious “Finalloy” commercial dental alloy on their Rocwell C hardness behavior and their microstructures was inspected. Using “Kerr casting waxes” patterns were prepared similar to the samples from “Finalloy”. The investments were pre-heated to phase at temperatures between 900°C and 1000°C. The alloy was melted by an acetylene-oxygen flame in a silicate crucible and four groups were compared: New alloy and alloys casted two, three, and four times (n = 7). After casting, Brinell harnesses were recorded. Values of Rocwell C strength, for each specimen group were analyzed by one-way analysis of variance, followed by the Student- Newman-Keuls multiple range test. A metal microscope was used to evaluate the surface morphology of the samples before hardness tests. 1st Casting :30.65 ± 0.3 kgf, 2nd Casting: 31.33 ± 0.4 kgf, 3rd Casting:34.80 ± 0.3 kgf, 4th Casting: 35.5 ± 28 kgf represents the Rocwell hardness of the castings. The results showed that hardness, increased with repeated castings. The experimental data indicates that increasing the number of successive recasting of “Finalloy” enhances the Rocwell C hardness, thus, after remelting and recasting, the biological properties decreases. Microscope study: Increase of the carbon content on the gren bounders of a cobalt-chromium alloy causes a considerable change in its microstructure. The hardness and yield point for 0.05 %, 0.1 % and 0.2 % tensile strength and elongation were determined for these test-pieces. The results showed that hardness, yield points and tensile strength increased with increased carbon content, whereas the elongation lessened. We determined that carbon concentrated at gren bounders. The clinical importance of the study is that recasting affected the properties of the metal, for best biological results with dental alloys always new metals must be used.

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Ito, Michio, Toshio Yamagishi, Yoshiki Oshida, and Carlos A. Munoz. "Effect of selected physical properties of waxes on investments and casting shrinkage." Journal of Prosthetic Dentistry 75, no. 2 (February 1996): 211–16. http://dx.doi.org/10.1016/s0022-3913(96)90101-8.

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Wongpreedee, Kageeporn, Adiruj Peerawat, Bongkot Phichaikamjornwut, and Duangkhae Bootkul. "Lost Wax Casting Conditions with Tourmaline In Situ." Key Engineering Materials 737 (June 2017): 595–98. http://dx.doi.org/10.4028/www.scientific.net/kem.737.595.

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The technique of stone-in-place casting has been established in jewelry production for three decades. However, the process is not widely used since it is limited to precious stones with high hardness and high stability at high temperature. This experiment tested tourmaline, which is a semi-precious gemstone having less hardness and less stability compared with precious stones. The objective was to achieve the conditions of a lost-wax casting process with tourmaline placed in waxes in the casting process. The experiment was divided into two parts. The first part was to understand the tolerance of tourmaline under the heating conditions. Natural tourmaline stones were investigated and compared inclusions tested at a temperature of 700°C. Tourmaline with ion-implantation was also heated to 700°C for comparison. The second part was to test tourmaline in-place casting with tree conditions of flask casting at 550°C, 625°C, and 700°C. The results showed that stones were able to tolerate as much as at 700°C. The inclusion growth of ion-implantation under heating to 700°C also observed the growth of inclusion in the same way as untreated tourmaline. The casting condition at 550°C showed better results. The highest probability of stones breaking after casting occurred in bezel settings.

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Michalakis, Konstantinos X., Vassiliki Kapsampeli, Aikaterini Kitsou, Yvone Kirmanidou, Anna Fotiou, Argirios L. Pissiotis, Pasquale Lino Calvani, Hiroshi Hirayama, and Yukio Kudara. "Marginal adaptation of four inlay casting waxes on stone, titanium, and zirconia dies." Journal of Prosthetic Dentistry 112, no. 1 (July 2014): 70–78. http://dx.doi.org/10.1016/j.prosdent.2014.01.009.

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Tewo, Robert K., Hilary L. Rutto, Walter Focke, Tumisang Seodigeng, and Lawrence K. Koech. "Formulations, development and characterization techniques of investment casting patterns." Reviews in Chemical Engineering 35, no. 3 (March 26, 2019): 335–49. http://dx.doi.org/10.1515/revce-2017-0068.

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Abstract Conventionally, unfilled wax has been used as a universal pattern material for the investment casting process. With increase in demand for accurate dimensions and complex shapes, various materials have been blended with wax to develop more suitable patterns for investment casting in order to overcome performance limitations exhibited by unfilled wax. The present article initially reviews various investigations on the development of investment casting patterns by exploring pattern materials, type of waxes and their limitations, the effect of filler materials and various additives on unfilled wax, wax blends for pattern materials, plastics and polymers for pattern materials and 3D-printed patterns. The superiority of filled and polymer patterns in terms of dimensional accuracy, pattern strength, surface and flow properties over unfilled wax is also discussed. The present use of 3D patterns following their versatility in the manufacturing sector to revolutionize the investment casting process is also emphasized. Various studies on wax characterization such as physical (surface and dimensions), thermal (thermogravimetric analysis and differential scanning calorimetry), mechanical (thermomechanical analysis, tensile stress testing, dynamic mechanical analysis) and rheological (viscosity and shearing properties) are also discussed.

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Żymankowska-Kumon, Sylwia, and Joana Kolczyk-Tylka. "Identification of Gas Products from Pyrolysis Process of Waxes Used in Lost-Wax Casting Technology." Journal of Casting & Materials Engineering 2, no. 3 (2018): 53. http://dx.doi.org/10.7494/jcme.2018.2.3.53.

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Stirbescu, Nicolae Mihail, Rodica Mariana Ion, Adrian Radu, Sofia Teodorescu, Ioan Alin Bucurica, Raluca Maria Stirbescu, Maria Geba, and Ioana Daniela Dulama. "Complex Analytical Investigations of Old Wax - sealed Romanian Paper Documents." Revista de Chimie 69, no. 7 (August 15, 2018): 1608–11. http://dx.doi.org/10.37358/rc.18.7.6380.

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Waxes as a component of seals, are recognized in our history as adhesives, for surface coating purposes, modeling or casting materials and also in conservation practice. The waxes with mineral, vegetable and animal origin should be connected to modern methods of analysis, due to their complex composition: long chain hydrocarbons, acids, alcohols, esters. They support many mechanical damages in library and archive collections: cracking, pieces lost by an excessive handling of documents. In this paper the compositional analyses of some wax seals belonging to some paper samples have been achieved by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) - for molecular structural information of wax materials, by gas chromatography / mass spectrometry (GC/MS) - for evidence of some compounds resulted from degraded wax seal, and by optical microscopy (OM) and scanning electron microscopy (SEM) - for visualization of the damaging effect on the wax seal. All these analytical investigations have been achieved for wax seals detached from the paper samples recovered from two disaffected pulp and paper factories - Letea and Busteni (Romania) belonging to Romanian industrial patrimony.

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Sandhu, Er Charanjeet singh. "Investigation Of Optimize Wax Pattern In The Investment Casting By Using The Different Form Of Waxes." IOSR Journal of Mechanical and Civil Engineering 3, no. 4 (2012): 01–06. http://dx.doi.org/10.9790/1684-0340106.

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Kissi, Samuel Baah, Peggy Ama Fening, and Dickson Adom. "Beeswax in Asante Castings: The Then, Now and the Way Forward." Journal of Arts and Humanities 5, no. 10 (October 20, 2016): 07. http://dx.doi.org/10.18533/journal.v5i10.984.

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<p>Beeswax used for Asante casting by Krofofrom artisans and the Asantehene gild of metalsmiths in the 1700`s are extracted naturally without further chemical treatment to enhance their workability. Although modelling with this wax is very effective, mass production technique now adopted by local artisans and the inflow of machine made artefacts due to globalization has crippled the sale of locally manufactured artefacts. This research dives into various ways of manipulating the natural beeswax using conventional waxes to help achieve complex and competitive designs suitable for the international feed. Qualitative research design approach was used and the descriptive and experimental research methodologies were employed. A comparative analysis was conducted on the production processes employed in the 1700`s and those practiced by various cultures in Africa and experiment was conducted on beeswax to ascertain a suitable wax formulation for the production of complex shapes and sizes using simple Jewellery technique less employed by local metal artisans for casting. It was found that the addition of various additives to the beeswax improved its workability and also the use of Plaster of Paris in wax modelling should be adapted as used in this research for traditional mass production for maximum yield and less stress.</p>

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Matteini, Mauro, José Delgado Rodrigues, Rute Fontinha, and A. Elena Charola. "Conservation and Restoration of the Don José I Monument in Lisbon, Portugal. Part II: Metal Components." Restoration of Buildings and Monuments 22, no. 2-3 (December 1, 2016): 81–87. http://dx.doi.org/10.1515/rbm-2016-5678.

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Abstract The equestrian statue of D. José I, in Lisbon, is a masterpiece of the sculptor Joaquim Machado de Castro. It weights over thirty eight tons and was made in a single casting by Bartolomeu da Costa in a copper alloy (brass). After over two centuries exposure, the statue presented an unappealing heterogeneous appearance and showed some deterioration features that required attention. Preliminary studies showed that the deterioration phenomena were typical of copper alloys exposed to outdoor urban environments. The proximity of the seacoast also contributed to some specific decay mechanisms. The highly contrasting patterns of the superficial patinas consisted of black dense deposits covering an original cuprite layer side by side with the common green deposits of basic copper sulfates, hydroxides and chlorides. The highly corrosive nantokite was present in sheltered areas, where chlorides are able to accumulate. The conservation intervention included cleaning, mostly carried out with low pressure jets of round glass beads. Onsite tests were made to select the cleaning levels required to match the areas of black and green patinas. A reddish brown cuprite layer was found underneath most of the areas with black dense deposits, while it could only be perceived by transparency on the green covered areas. When a high contrast remained between the two areas, these were mitigated with the application of water colors during the final protection phase. Nantokite active areas were passivated with sodium oxalate after the entire statue was first washed with clean water and treated with lime water to leave an alkaline reserve to slow down the eventual corrosion process, and the sculpture rinsed with ethanol to accelerate its drying. The final protection was made with Paraloid B44 and microcrystalline waxes.

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Seoane Pérez, Helena. "Morgana despierta nuestra conciencia." Revista Internacional de Culturas y Literaturas, no. 20 (2017): 130–44. http://dx.doi.org/10.12795/ricl.2017.i20.10.

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La escritora gallega Begoña Caamaño en su libro Morgana en Esmelle analiza el tema de la sororidad, un término aún no aceptado por la Real Academia Española, o hermanamiento femenino o de solidaridad entre mujeres. A través de este personaje femenino tan castigado durante casi toda su historia, busca el cambio que debemos realizar para conseguir que el sistema patriarcal acabe sus días y dé paso a la hermandad entre hombres y mujeres. Asimismo, planea por la obra un sentimiento de culpabilidad en todos los personajes, de tal manera que el arrepentimiento, el castigo y el remordimiento los acompañan durante su viaje de iniciación. Cabe agregar la voz de la autora, una voz pesimista y alentadora simultáneamente, que se sirve de Morgana para señalar el costumbrismo social anclado en unos arquetipos antiguos y obsoletos.

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Chen, Liang, Shao Lin Xu, Guo Hua Zhang, and Zhong Wu Xia. "The Emissivity of the Casting Surface." Applied Mechanics and Materials 157-158 (February 2012): 1384–87. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.1384.

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According to electromagnetic waves theories, emissivity modeling of a layered casting surface has been developed to elucidate the different emissivity during the growth of oxide film. Through test detection a angle where p-polarized emissivity assumes a peak value is between 60°-80°. Emissivity stabilized when the growth of oxide film is enough. The conclusion provides an important theory for the design the temperature measurement equipment on the surface of casting.

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Nikitenko, I., O. Starik, and M. Kutsevol. "RESULTS OF A PETROGRAPHIC STUDY OF THE BRONZE AGE CASTING MOLDS FINDS." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 2 (89) (2020): 28–35. http://dx.doi.org/10.17721/1728-2713.89.04.

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The present article is devoted to the mineralogical and petrographic research of raw materials of the collection of casting molds of the Bronze Age, found by the expedition of Dnipropetrovsk National Historical Museum named after D.I. Yavornytskyi during the excavations of the archaeological monument of Tokivske-1, located near the village Tokivske of Apostolove Rayon, Dnipropetrovsk Oblast. The finding of casting molds is of great importance, since it can be the evidence of bronze foundry production existence in the territory of the monument, which until now was regarded only as a megalithic place of worship. Provenance determination of the raw materials of casting molds can help to identify the role of Tokivske-1 in the system of metalworking cells of the Sabatynivska culture time (XVI–XIII centuries BC) and to establish its links with the ancient centers of mining of stone raw materials. According to previous petrographic studies, it is known that stone molds were made mainly of talc-chlorite-tremolite schists, since this material was easily processed and could withstand more castings than clay molds. Because of this, stone casting molds were highly valued, as well as bronze wares and ingots, and were transported over long distances. The purpose of the study was to establish links between the archaeological monument of Tokivske-1 and known mining and metallurgical centers of the Bronze Age, on the basis of mineralogical and petrographic research of raw materials of casting molds. As a result of the study of samples in thin sections and by X-ray diffraction analysis, it was established that the stone molds were mainly made of tremolite-chlorite-anthophyllite meta-ultrabazites. The determination of the origin of the rocks from which the casting molds were made was carried out by comparing their mineralogical and petrographic features with the features of similar rocks that form natural outcrops, as described in geological survey reports and literary data, and as observed by us in rock samples from natural outcrops in the Middle Dnipro and the Azov Sea areas. It was ascertained that the rocks from which all the casting molds of the collection were made do not form natural outcrops in the Middle Dnipro area and are not characteristic of the Kryvyi Rih area, which is considered to be the main center of raw materials extraction for the stone foundry forms of the Late Bronze Age on the territory of Ukraine. It was established that such rocks are more characteristic of the Western Azov Sea area, but one can not exclude another source of raw materials of the mold collection, in particular the Southern Urals, where bronze metallurgy was significantly developed and similar stone matrices were used. The obtained results suggest revision of established ideas on sources of supply of stone raw materials during the late Bronze Age.

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Lee, Joo Sung, Hyun Wook Jung, Hyun-Seob Song, Kwan-Young Lee, and Jae Chun Hyun. "Kinematic waves and draw resonance in film casting process." Journal of Non-Newtonian Fluid Mechanics 101, no. 1-3 (November 2001): 43–54. http://dx.doi.org/10.1016/s0377-0257(01)00155-0.

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Kluwick, Alfred, and Stefan Scheichl. "Asymptotic analysis of surface waves in continuous strip casting processes." Fluid Dynamics Research 27, no. 3 (September 2000): 163–81. http://dx.doi.org/10.1016/s0169-5983(00)00002-2.

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Rodríguez-González, P., P. E. Robles Valero, A. I. Fernández-Abia, M. A. Castro-Sastre, and J. Barreiro García. "Application of Vacuum Techniques in Shell Moulds Produced by Additive Manufacturing." Metals 10, no. 8 (August 12, 2020): 1090. http://dx.doi.org/10.3390/met10081090.

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This research shows the feasibility of the additive manufacturing technique (AM), Binder Jetting (BJ), for the production of shell moulds, which are filled by vacuum suction in the field of aluminium parts production. In addition, this study compares the gravity pouring technique and highlights the advantages of using vacuum techniques in AM moulds. A numerical simulation was carried out to study the behaviour of the liquid metal inside the moulds and the cooling rate of parts was analysed. The results show that in the gravity-pouring mould, the velocity in the gate causes moderate turbulence with small waves. However, vacuum suction keeps the velocity constant by eliminating waves and the filling process is homogeneous. Regarding dimensional accuracy, the staircase effect on the surface of the 3D moulds was the most critical aspect. The vacuum provides very homogeneous values of roughness across the entire surface of the part. Similarly, 3D scanning of castings revealed more accurate dimensions thanks to the help of vacuum forces. Finally, the microstructure of the cross section of the moulded parts shows that the porosity decreases with the vacuum filled. In both cases, the origin of the pores corresponds to gas entrapment and shrinkage during the filling process, the binder vaporization and nucleation points creation, leading to pores by shrinkage, gas entrapment or a mixture of both. This is the first study that uses vacuum filling techniques in moulds created by BJ, demonstrating the feasibility and advantages of AM using vacuum techniques, as an alternative to traditional casting.

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Diwan, Randa, Yousef Talic, Noura Omar, and Walid Sadig. "Pattern waxes and inaccuracies in fixed and removable partial denture castings." Journal of Prosthetic Dentistry 77, no. 5 (May 1997): 553–55. http://dx.doi.org/10.1016/s0022-3913(97)70152-5.

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Blanco, German, Carlos A. Flores, and Alfonso Flores-Lagunes. "The Effects of Job Corps Training on Wages of Adolescents and Young Adults." American Economic Review 103, no. 3 (May 1, 2013): 418–22. http://dx.doi.org/10.1257/aer.103.3.418.

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Previous evaluations of Job Corps document disparate effects on the earnings of adolescents (aged 16-19) and young adults (aged 20-24). These are conjectured to be due to differential human capital accumulation within the program between these groups. If correct, the effect of the program on wages should be larger than that on earnings, since wages more accurately reflect human capital. We estimate bounds on average and quantile treatment effects of Job Corps on wages and find that the relative effects on both outcomes are similar, casting some doubt on the conjecture that human capital is driving the disparate effects.

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Crha, Jan, J. Havlíček, Jiri Molínek, and Petr Kozelský. "Acoustic Emission Monitoring during Solidification Processes." Advanced Materials Research 13-14 (February 2006): 299–304. http://dx.doi.org/10.4028/www.scientific.net/amr.13-14.299.

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The paper summarizes the experiences acquired from on-line acoustic emission monitoring (herafter AE) of heavy castings during their manufacturing (solidification and following cooling in the mould). They are usually monitored elastic waves generated above all by stress changes in the solid state. In order to exactly determine plastic-elastic transition state the investigation was focused on raising the sensitivity of detection. The suitable experimental technique is discussed in the first part of this article. The main problem of the measurement by high temperatures was solved by using waveguides. It is very important in this case to select useful signal sources from mechanical and electromagnetical disturbances. Some laboratory experiments were done for studying the signal origin in the first state of solidification. The results from on-line monitoring of two types cast rolls during manufacturing were compared. Each type of casting has its typical AE histogram. For the quality evaluation ( in our case) is significant the time period of approximate 5 days after pouring . The time delayed stress induced cracking generates high level AE signal in this time period and the presence of such signal indicates defective product. The study of high temperature tensile tests, structural phase transformation and solidification processes using AE is very important for analysis of AE sources. The use of the laboratory results for the AE source analysis on real products will be subject to futher research.

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Yesil, Mehmet Ali, Korkut Yegin, Mustafa Culha, and Esen Efeoglu. "Thin Films Prepared from Nanometer Size TiO2Absorbs Millimeter Waves." International Journal of Photoenergy 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/494636.

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Absorption of average 10 nm size TiO2nanoparticles deposited on glass surfaces as a thin film using convective assembly technique and drop-casting is studied in the millimeter wave range from 26 GHz to 40 GHz. The millimeter wave responses of the fabricated samples were obtained using a vector network analyzer. Reflection properties of the prepared samples were also measured. Absorption and reflection of TiO2nanoparticles were more pronounced between 35 GHz and 40 GHz compared to glass-only sample.

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Mughal, Aquib, Ritu Batra, Manjit Kumar, Ajay Bansal, and Himani Jain. "Prosthodontic Rehabilitation of Edentulous Patient with Implant Supported Hybrid Prosthesis: A Case Report." Dental Journal of Advance Studies 6, no. 02/03 (December 2018): 122–25. http://dx.doi.org/10.1055/s-0038-1677630.

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AbstractA hybrid denture is fabricated over a metal framework that is retained by screws into the implants. The anterior part of a hybrid denture is fixed on implants and the posterior part of the denture is cantilevered. This case report presents the fabrication of a maxillary implant retained hybrid prosthesis. Four implants were placed in the maxillary arch. Framework was waxed, castable abutments were used, after-casting denture teeth were waxed to the hybrid framework, and a final try-in was done to verify and correct maxillomandibular relations before processing. The prosthesis was inserted after verifying fit of the framework.

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Lee, Jun Youn, Soon Bok Lee, and Jae Kyung Yi. "Ultrasonic Transmission Characteristics of Continuous Casting Slab for Medium Carbon Steel." Key Engineering Materials 297-300 (November 2005): 2201–6. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2201.

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Until now, surface defects of continuous casting slab have been removed by the enforced surface scarfing to produce high quality steel materials. An evaluation technique for surface and internal defects of slab is required to enhance the production of medium carbon steels and acquire defect-map. Accordingly as a preliminary step, longitudinal wave testing and Rayleigh wave testing were carried out on slab specimens of medium carbon steel to get basic transmission characteristics of ultrasonic waves. This research provides as basic data for on-line defect estimation using a laser ultrasonic or EMAT in non-contact ultrasonic detecting techniques in future.

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Kamal, Manish, and Yogeshwar Sahai. "Modeling of Melt Flow and Surface Standing Waves in a Continuous Casting Mold." steel research international 76, no. 1 (January 2005): 44–52. http://dx.doi.org/10.1002/srin.200505971.

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Matsumoto, Wilson, Paula Pastana Beraldo, Rossana Pereira de Almeida, Ana Paula Macedo, Beatriz Roque Kubata, and Takami Hirono Hotta. "Evaluation of Marginal Misfit of Metal Frameworks Welded by Gas-Torch, Laser, and Tungsten Inert Gas Methods." International Journal of Dentistry 2018 (October 30, 2018): 1–6. http://dx.doi.org/10.1155/2018/9828929.

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Purpose. The objective of this study was to evaluate the marginal fit and the flexural resistance of nickel-chromium frameworks welded by different techniques, gas-torch, laser, and tungsten inert gas (TIG), compared with that of frameworks made via one-piece casting. Methods. To evaluate the marginal fit, a master model was fabricated simulating four implants. Transfers and replicas were used to transfer the positions of the implants to the model, using a silicone matrix. The bars were waxed up and casted. Three assessments of misfit were performed for each implant using a stereomicroscope before and after welding in two predetermined regions, totaling six readings for each implant. To evaluate the flexural resistance, one group was made casting the specimens in one piece. Other 3 groups using gas-torch, laser, and TIG welding techniques were made after sectioned transversally. The data showed normal distribution and two-way ANOVA for marginal fit and one-way ANOVA for flexural resistance, and Tukey’s posttest (α=0.05) was performed. Results. For the marginal fit, the three welding methods presented similar results and were different from one-piece casting. For the flexural resistance, significant differences were observed among the studied groups (p<0.001), and the one-piece group presented higher resistance compared to the three welding techniques. Conclusions. Within the limits of this study, the three welding techniques yielded similar misfit results, and the laser and TIG techniques presented similar flexural resistance but lower than gas-torch and one-piece casting.

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Montero, J. C., I. J. Mirón, J. J. Criado-Álvarez, C. Linares, and J. Díaz. "Mortality from cold waves in Castile — La Mancha, Spain." Science of The Total Environment 408, no. 23 (November 2010): 5768–74. http://dx.doi.org/10.1016/j.scitotenv.2010.07.086.

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Gołaszewski, Jacek, Tomasz Ponikiewski, Grzegorz Cygan, and Małgorzata Gołaszewska. "Laser System for Testing Early Shrinkage of Concrete Elements in Conjuction with the Deterioration of the Setting Time." Transactions of the VŠB – Technical University of Ostrava, Civil Engineering Series. 16, no. 2 (December 1, 2016): 25–34. http://dx.doi.org/10.1515/tvsb-2016-0011.

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Abstract The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting.

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MITA, Ikuo, and Hajime MIYASAKA. "Anodic oxidation of ADC 12 aluminum alloy die castings by pulse waves." Journal of the Metal Finishing Society of Japan 39, no. 6 (1988): 323–29. http://dx.doi.org/10.4139/sfj1950.39.323.

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Tszeng, T. C., and Y. L. Chu. "A Study of Wave Formation in Shot Sleeve of a Die Casting Machine." Journal of Engineering for Industry 116, no. 2 (May 1, 1994): 175–82. http://dx.doi.org/10.1115/1.2901928.

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The objective of this study was to find the optimum process variables for minimizing the amount of air entrapped within the shot sleeve during the slow shot phase of the injection process. To achieve this objective, the relations between process variables (e.g., plunger speed/acceleration, initial filling percentage, sleeve diameter, etc.) and the wave formation within the shot sleeve of a die casting machine have to be determined. For this purpose, a mathematical model has been developed to study the transient wave formation in shot sleeve. The model based on the theory of waves of finite amplitude can predict the critical plunger speed and the profile of wave front, which in turn affect the degree of air entrapment. The optimum plunger speeds for minimum air entrapment are thus determined based on the predicted profile of wave front. Good agreement with the results from water analogue experiments is found.

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Costa, Elza Maria Valadares da, Maximiliano Piero Neisser, and Marco Antônio Bottino. "Multiple-unit implant frames: one-piece casting vs. laser welding and brazing." Journal of Applied Oral Science 12, no. 3 (September 2004): 227–31. http://dx.doi.org/10.1590/s1678-77572004000300013.

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The linear distortion of prostheses over implants, one-piece casting and cast in sections followed by laser welding by laser and brazing was evaluated in an edentulous mandibular model with five parallel abutments, with a distance of 10mm from center to center. Seventy five gold cylinders were tightened with screws on the abutments with 10Ncm torque. The cylinder/analogue assemblies were measured by microscopic examination (0.001mm accuracy) and the obtained results were compared with the GC (control group). Fifteen metal frames were waxed and cast in a gold alloy (Stabilor, Degussa Hulls, Brazil) and divided into three groups with five elements each, as followed: GM (one-piece casting), GB (section and brazing) and GL (section and laser welding). In all groups, measurements were taken at the right, left, buccal and lingual sides of the cylinder/analogue interface and the results were submitted to analysis of variance (ANOVA) and to the Tukey test (5%). The smallest amount of distortion was seen in the laser group (GL with a mean value of 13.58), followed by the brazing group (GB with a mean value of 24.33) and one-piece (GM with a mean value of 40.00). The greatest distortion was found in the one-piece group (GM).

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Pola, Annalisa, Alberto Arrighini, and Roberto Roberti. "Effect of Ultrasounds Treatment on Alloys for Semisolid Application." Solid State Phenomena 141-143 (July 2008): 481–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.481.

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Semisolid metallic alloys are commercially produced by means of mechanical or electromagnetic stirring. Among the mechanical devices, the rotating pin immersed in a solidifying alloy seems to be easier to manage in industrial practice although it can induce some porosity, depending on the shape of the pin. As known, ultrasounds are mechanical waves which, when applied to liquid metals, increase the number of solidification nuclei, so that the cast products show superior mechanical performances, as a consequence of the finer grain structure. In this paper the use of ultrasound waves applied to different alloys during solidification was studied in order to obtain feedstock for semisolid die-casting application. A dedicated ultrasound power unit, together with a proper sonicator pin, was designed and manufactured by the authors and, subsequently, the effect of the ultrasonic treatment on the microstructure of A356 aluminum alloy and ZA27 zinc alloy was investigated. All the produced samples were characterized by metallographic analyses to measure the globule size and shape factor, which are main criteria for thixo-microstructure assessment. The results were compared to those obtained with traditional mechanical stirring, showing the higher capability of ultrasound treatment in producing better semisolid microstructure. An optimized combination of process parameters seems to be necessary to get a reasonable thixotropic structure in treating ZA27 alloy. Less severe production conditions are needed in the case of aluminum alloy, revealing the potentiality of ultrasounds as an alternative treatment to traditional mechanical stirring, with the further advantage of alloy degassing and grain refinement, without the use of expensive addictions (TiB2). Trials were finally performed on a continuous casting pilot plant in combination with electromagnetic stirring to produce semisolid billets.

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Kamal, Manish, and Yogeshwar Sahai. "A Simple Innovation in Continuous Casting Mold Technology for Fluid Flow and Surface Standing Waves Control." ISIJ International 46, no. 12 (2006): 1823–32. http://dx.doi.org/10.2355/isijinternational.46.1823.

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Somashekarappa, H., Y. Prakash, K. Hemalatha, T. Demappa, and R. Somashekar. "Preparation and Characterization of HPMC/PVP Blend Films Plasticized with Sorbitol." Indian Journal of Materials Science 2013 (December 12, 2013): 1–7. http://dx.doi.org/10.1155/2013/307514.

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The aim of this present work is to investigate the effect of plasticizers like Sorbitol on microstructural and mechanical properties of hydroxypropyl methylcellulose (HPMC) and Polyvinylpyrrolidone (PVP) blend films. The pure blend and plasticized blend films were prepared by solution casting method and investigated using wide angle X-ray scattering (WAXS) method. WAXS analysis confirms that the plasticizers can enter into macromolecular blend structure and destroy the crystallinity of the films. FTIR spectra show that there are a shift and decrease in the intensity of the peaks confirming the interaction of plasticizer with the blend. Mechanical properties like tensile strength and Young’s Modulus decrease up to 0.6% of Sorbitol content in the films. Percentage of elongation at break increases suggesting that the plasticized films are more flexible than pure blend films. These films are suitable to be used as environmental friendly and biodegradable packaging films.

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Chankitmunkong, Suwaree, Dmitry G. Eskin, and Chaowalit Limmaneevichitr. "Structure Modification upon Ultrasonic Processing of an AA4032 Piston Alloy: Comparison of Permanent Mold and Direct-Chill Casting." Metallurgical and Materials Transactions A 51, no. 2 (December 9, 2019): 818–29. http://dx.doi.org/10.1007/s11661-019-05575-5.

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AbstractPiston Al-Si alloys have very complex compositions and multi-phase heterogeneous structure, so it is necessary to control the formation of primary and eutectic compounds. In this study, the ultrasonic melt processing (USP) of a eutectic Al-Si piston alloy (AA4032-type) was performed in a permanent mold and during direct-chill (DC) casting to study its effects on the structure refinement and modification. The principal difference between these two ways of casting is that in the permanent mold the solidification front progressively moves towards the ultrasound source, while in the DC casting the position of the solidification front is fixed in space. The results showed that the USP can successfully refine primary Si, Fe-containing intermetallics and aluminum grains. Refinement of primary Si was accompanied by the increase in its amount, which was attributed to both enhanced heterogeneous nucleation and fragmentation. The refinement of Fe-containing intermetallics and Al grains resulted from the fragmentation mechanism and were more pronounced when USP was applied below the liquidus temperature in the permanent mold. However, the eutectic phases coarsened upon USP, and this effect was most pronounced when USP was applied to the semi-solid material. This was related to the strong attenuation of acoustic waves, which effectively heats the semi-solid material and induces corresponding coarsening of the phases. Acoustic streaming induced by an oscillating sonotrode affected the depth of the sump while simultaneously decreasing the macrosegregation, which reflects the dominant role of the melt flow directed against natural convection. The results demonstrated the importance of the solidification stage at which the USP was applied and the specifics of the USP mechanisms acting at the different stages of solidification.

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Safonov, V. M., V. G. Borisevich, V. V. Kislitsa, and D. V. Morov. "Physical simulation of liquid steel motion in a thin-slab continuous caster mold." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 75, no. 4 (May 18, 2019): 454–59. http://dx.doi.org/10.32339/0135-5910-2019-4-454-459.

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Industrial experience of steel casting at the thin-slab continuous caster (CC) revealed processes, having negative effect on the quality of internal structure and surface of CC thin slab. The main problems are as follows: flat streams of liquid steel, flowing through submerged snorkel into restricted dead volume, form circulating flows of extremely high velocity in both liquid core and on the slab surface. This circumstance makes specific requirements to the design and parameters of the submerged snorkel to supply the metal into the thin-slab CC mold. Despite the more than 25 years’ experience of the snorkel form and geometric parameters development, there is no single opinion on its optimal design. Results of physical simulation of the liquid motion processes in a thinslab Caster mold presented (for slab maximum width 1800 mm, thickness – 90 mm) of JSC “Vyksa Steel-works” casting and rolling complex. Description of the physical model facility quoted, as well as description of the experiment methodology and its results. The speed was measured and structure of liquid steel flows revealed in depth and sub-surface layers, as well as in slag-forming mixture at the mold surface. The comparison of two principally different variants of liquid steel feeding into the mold made. The two variants were as follows: by a flat down-directed stream with a narrow central divider (direct-flow submerged snorkel) and by four streams , two of them directed down under an angle relating the vertical axe, and the other (about 20% of total liquid consumption) – directed upward to the bath mirror (the snorkel of “hammer” type). It was determined, that steel casting with technological speed through the direct-flow snorkel was most effective into the slab of 1400 mm width and less, since in this case the sub-surface flows speed did not resulted in the intensive waves formation, constant whirls formation and slag particles dragging into deep layers of the slab. For steel casting into slab of width more than 1400 mm, it is reasonable to use a snorkel of the “hammer” type, which enables to create a favorable stable structure of circulation and decrease the tendency of slag particles dragging in the deep layers of the slab.

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Solonenko, L. I. "Some features of drying casting forms and cores in the field of standing waves of microwave radiation." Metal and Casting of Ukraine 28, no. 1 (May 10, 2020): 69–78. http://dx.doi.org/10.15407/steelcast2020.01.069.

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Chang, Yaw Jen, Yun Wei Chung, Ting An Chou, and Min Fen Huang. "Valve-Less Diaphragm Micropump with Electromagnetic Actuation." Advanced Materials Research 647 (January 2013): 929–34. http://dx.doi.org/10.4028/www.scientific.net/amr.647.929.

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In this paper, a micropump with electromagnetic actuation is presented. The micropump mainly consists of coil actuators and a PDMS micropump layer. The microcoil was fabricated using the printed circuit board (PCB) with the conventional PCB treatment and the PDMS layer was formed by casting technique. A control circuit was designed using microcontroller to produce square waves to control coil actuator. Due to the simple fabrication process, the micropump can be incorporated in a disposable PDMS lab-on-a-chip device as a fluid actuation component. However, the coil actuator is reusable. In addition, the control circuit makes the micropump portable. The experiment results show that this proposed micropump is capable of delivering a flow rate of 470 μL/min using one coil actuator.

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Morey, Erica F. "Dimensional accuracy of small gold alloy castings. Part 1. A brief history and the behaviour of inlay waxes." Australian Dental Journal 36, no. 4 (August 1991): 302–9. http://dx.doi.org/10.1111/j.1834-7819.1991.tb00727.x.

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Wang, Chunhe, Fengchun Jiang, Shuaiqi Shao, Tianmiao Yu, and Chunhuan Guo. "Acoustic Properties of 316L Stainless Steel Hollow Sphere Composites Fabricated by Pressure Casting." Metals 10, no. 8 (August 3, 2020): 1047. http://dx.doi.org/10.3390/met10081047.

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In this study, we prepared metal hollow sphere composites (MHSCs) using metal hollow spheres (MHSs) by pressure casting under vacuum conditions, and investigated the acoustic properties. The density of the MHSCs was measured using the mass to volume ratio, the microstructure of the MHSCs was observed using a scanning electron microscope, and the acoustic properties of the MHSCs were tested using an impedance tube. The measured MHSCs showed that the densities of the MHSCs with the random distribution of MHSs with diameter ~3.28 mm (1.74 g/cm3 to 1.77 g/cm3) (MHSC-3.28) were nearly equal to that of the MHSCs with the random distribution of MHSs with diameter ~5.76 mm (1.74 g/cm3 to 1.76 g/cm3) (MHSC-5.76), and lower than that of the MHSCs with the layered structure of MHSs with diameter ~3.28 mm (1.93 g/cm3 to 1.97 g/cm3) (MHSC-LS). Microstructural observations confirmed that the interface region between the MHSs and matrix demonstrated a simple physical combination pattern with pores. The acoustic properties of the MHSCs showed that the sound absorption coefficient of MHSC-LS was lower than that of MHSC-3.28 and higher than that of MHSC-5.76 at off-resonance. The sound absorption coefficient peak value of MHSC-3.28 was higher than that of MHSC-LS, and lower than that of MHSC-5.76 at resonance. The sound transmission loss of MHSC-3.28 was lower than that of MHSC-5.76, which shows the rules are independent from the resonance. The sound transmission loss of MHSC-LS was higher than that of MHSC-5.76 at resonance, but lower than that of MHSC-3.28 at off-resonance. In addition, we discuss the propagation mechanism of the sound waves in the MHSC, which is mainly determined by the distribution of the MHSs in the MHSC.

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41

Roberts, Lois. "Steve Striffler, In the Shadows of State and Capital: The United Fruit Company, Popular Struggle, and Agrarian Restructuring in Ecuador, 1900–1995. Durham and London: Duke University Press, 2002. 242 pp. $64.95 cloth; $19.95 paper." International Labor and Working-Class History 65 (April 2004): 216–19. http://dx.doi.org/10.1017/s0147547904380130.

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Ecuadorianists have long awaited a book on the country's banana industry, and Steve Striffler has made an excellent beginning with this prize-winning research on the United Fruit (UF) company's Tenguel estate. He wanted his study of the workers' struggle for better wages and land to go beyond previous works that tended to focus on leading capitalistic actors. Casting his work in Marxian terms, Striffler finds that worker power—at Tenguel, at other banana producing regions in Ecuador, and across Latin America—played a decisive role in undermining foreign-owned enclaves. Striffler argues that “class struggle” best explains the emergence of the “contract farming” system that transformed agrarian landscapes. Although Ecuadorian worker efforts did not ultimately improve their lives, Striffler finds that struggles at least provided a base for subsequent popular organizations.

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Pola, Annalisa, Aldo Attanasio, Elisabetta Ceretti, and Giovina Marina La Vecchia. "Thixoforging of Ultrasound Treated 6060 Aluminum Alloy." Key Engineering Materials 554-557 (June 2013): 572–81. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.572.

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In the last years researches on thixotropic materials have been developed in order to introduce this new technology in manufacturing processes. For instance, when considering high pressure die-casting, several applications are present in literature mainly related to low melting point alloys (Al and Mg) because of the limited die life experienced when casting higher melting materials. In this case, semi-solid metal forming allows to work at lower temperature with subsequent increase in die life and reduction in production costs, combined with lower porosity level in the casting. On the other hand, in the case of conventional forging, semi-solid processing needs higher performance materials and/or coatings for the mould because of the working temperatures; however, the advantages of obtaining near net shape part in a single step, with reduced machining and finishing costs, make the semi-solid technology competitive. The present paper deals with the thixoforging of aluminum 6061 alloy, whose semi-solid feedstock material was obtained by ultrasound treatment. The application of ultrasonic waves to liquid or solidifying alloys has been already demonstrated to be an effective technique for the obtainment of globular microstructure. Along with a refining effect, ultrasound can also produce a series of beneficial effects, such as hydrogen degassing or oxide and non-metallic inclusion removal, which all improve mechanical properties of the component. The aim of this research was to investigate the influence of process parameters on final forged part quality. The solid fraction percentage as a function of temperature was measured by differential scanning calorimetric analysis. The geometry of the die was properly designed and optimized by FEM simulation in order to be suitable for forging semi-solid material, allowing a comparison with conventional forging process. 14 K-type thermocouples were used for monitoring the temperature of top and bottom dies; an instrumented 100 ton press was also equipped with load cells to acquire the forging force. A deep metallurgical analysis of the forged parts was performed in order to evaluate their mechanical properties and quality.

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Eron’ko, S. P., E. A. Ponamareva, and E. S. Tsykhmistro. "Development of vibration system for decreasing of intensity of steel ladle outlet channel tightening." Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 77, no. 2 (February 25, 2021): 165–74. http://dx.doi.org/10.32339/0135-5910-2021-2-165-174.

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The problem of tightening of outlet channel of steel ladle still remains relevant at present. A review of scientific and technical studies, aimed at elaboration of methods to keep the channel flow section constant presented. An analysis of deposition forming mechanisms on walls of outlet channel of steel ladle was done. To prevent their formation it was proposed to apply a vibration impact on the ladle shutter. Using simulation studies and specially elaborated methodology, the degree of influence and frequency of amplitude oscillations, acting along the ladle channel, on increasing speed of layer thickness formation on its walls and number of tearing off hard particles was established. To evaluate intensity of elastic waves absorption by the refractories of ladle shutter during vibration impact on it, a natural experiment was done. As a result of the experiment an initial information was obtained for determining parameters of oscillation process to guarantee effective functioning of the proposed casting facility. A necessity was established to account tenfold decrease of vibration acceleration during propagation of elastic wave along the casting channel from the lower end of collector nuzzle to the upper end of the ladle casting nozzle. Results of the complex studies became base of technical solution at elaboration of design of the ladle shutter. The elaborated shutter is equipped by a system of exciting vertically-directed oscillations, promoting decreasing intensity of hard particles sticking on the walls of the outlet channel. The design of the perfected ladle shutter and general view of its test model shown, which is equipped with the vertically-directed oscillations exciting system. Depending on capacity of the steel ladles, which can be from 100 to 300 t, their shutters can be equipped with one or several pneumatic plunger vibrators. Each of the plunger having the mass of 0.8 kg, can develop an impact force up to 300 N when supplying into its working cavity compressed air of 0.2 MPa pressure at flow rate 150 l/min. Industrial tests of the modernized shutter in a foundry shop of Yasinovatsky machine-building plant were done.

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Welzel, Mario, Tobias Kreklow, Torsten Schlurmann, and Arndt Hildebrandt. "EXCITATION AND DYNAMIC RESPONSES OF JACKET STRUCTURES IN REGULAR WAVES FOR OFFSHORE INSTALLATION." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 12. http://dx.doi.org/10.9753/icce.v35.management.12.

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The worldâ€™s energy supply needs to scope two aims: Securing an ongoing growth in energy demand while gradually shifting to exploitation of renewable energy resources. Since onshore and near shore areas to harvest energy from wind are running short, the focus is laid on concepts for deep water regions ranging from 30 up to 50m with over 6MW. The presented work is a part of the research project HyConCast which progresses the development of a novel, hybrid support structure for offshore wind turbines. Thereby the concept addresses to develop and deploy hybrid offshore wind farm support structures which are based on the advantages of combined ductile iron casting knots and precast concrete pipes. The overall objective of the project is to assess the feasibility and general applicability under design load cases stemming from environmental, eco-logical and economical dimensions. With respect to the distinctly higher total weight of the hybrid structure compared to common steal structures, the results of its so far not understood excitation and dynamic motion response in regular waves during floating installation are researched and discussed in the following article.

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Olhero, Susana M. H., and José Maria F. Ferreira. "Effect of the Consolidation Technique on the Sintering Ability and Thermal Properties of AlN Processed from Aqueous Suspensions." Materials Science Forum 514-516 (May 2006): 1531–35. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1531.

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In this work, two different consolidation techniques were used to obtain AlN samples: slip casting and dry pressing of granules obtained from aqueous suspensions by freeze granulation. The green samples were sintered at a temperature (1750°C) lower than those usually used (>1800°C), using CaF2 and YF3 as sintering aids. The microstructural features were analysed by scanning electron microscopy (SEM) and the crystalline phases formed were identified by X-ray (XRD). Full dense AlN-based ceramics were obtained from both consolidation techniques; however the thermal conductivity values were quite different. The presence of carbon in the samples derived from the freeze granulated powder containing organic processing additives de-waxed in an inert atmosphere revealed to be helpful in the cleaning of oxygen present at the grain boundaries and consequently, for enhancing the thermal conductivity.

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Stachowicz, M. "Effect of Sand Base Grade and Density of Moulding Sands with Sodium Silicate on Effectiveness of Absorbing Microwaves." Archives of Foundry Engineering 16, no. 3 (September 1, 2016): 103–8. http://dx.doi.org/10.1515/afe-2016-0059.

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Abstract In the paper, presented is a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened moulding sands prepared of three kinds of high-silica base and a selected grade of sodium silicate. Measurements of power loss of microwave radiation (Pin) expressed by a total of absorbed power (Pabs), output power (Pout) and reflected power (Pref) were carried-out on a stand of semiautomatic microwave slot line. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological and economical importance for manufacture of high-quality casting moulds and cores of various shapes and sizes. It was found that relative density influences parameters of power output and power reflected from samples of moulding sand placed in a waveguide. Absorption expressed by the parameter Pabs is not related to granularity of high-silica base: fine, medium and coarse. It was found that the semiautomatic microwave slot line supports evaluation of effectiveness of microwave absorption on the grounds of power loss measurements and enables statistic description of influence of relative density of the sandmix on penetration of electromagnetic waves in unhardened moulding sands.

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Park, Youn Jung, and Cheol Min Park. "Anisotropic Deformation Behavior of the Oriented Nanostructure of a Semicrystalline Terblock Copolymer with Multi-Scale Orderings." Materials Science Forum 449-452 (March 2004): 1225–28. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.1225.

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A highly oriented nanostructure of poly(styrene)-b-(ethylene-alt-propylene)-b-(ethylene) (PS/PEP/PE) semicrystalline terblock copolymer was deformed under tensile loading. Roll casting process oriented the microdomains of the terpolymer. Hexagonally ordered PS cylinders subsequently guided the crystallization of the PE block occurring in between the PS cylinders, resulting in the molecular chain orientation of the PE blocks perpendicular to the PS cylinder axis. The structure change of the terblock copolymer under deformation was monitored using Simultaneous Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS). The samples with the load parallel and perpendicular to the cylindrical axis of the PS show their mechanical failures at the strain of approximate 100 % and 210%, respectively. The anisotropic mechanical behavior was interpreted by interplay of the different types of the nano scale domains

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Remiš, Tomáš, Petr Bělský, Tomáš Kovářík, Jaroslav Kadlec, Mina Ghafouri Azar, Rostislav Medlín, Veronika Vavruňková, Kalim Deshmukh, and Kishor Kumar Sadasivuni. "Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites." Polymers 13, no. 9 (April 28, 2021): 1426. http://dx.doi.org/10.3390/polym13091426.

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In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

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Castilio, Daniela, Ana Paula Ribeiro do Vale Pedreira, Paulo Henrique Orlato Rossetti, Leylha Maria Nunes Rossetti, and Wellington Cardoso Bonachela. "The influence of screw type, alloy and cylinder position on the marginal fit of implant frameworks before and after laser welding." Journal of Applied Oral Science 14, no. 2 (April 2006): 77–81. http://dx.doi.org/10.1590/s1678-77572006000200003.

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Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. OBJECTIVES: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. METHODS: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected prosthetic components. Five specimens were one-piece cast in titanium and five in cobalt-chromium alloy. On each specimen, tests were conducted with hexagonal titanium and slotted gold screws separately, performing a total of thirty tested screws. Measurements at the interfaces were performed using an optical microscope with 5mm accuracy. After sectioning, specimens were laser welded and new measurements were obtained. Data were submitted to a four-way ANOVA and Tukey's multiple comparisons test (alpha=0.05). RESULTS: Slotted and hexagonal screws did not present significant differences regarding to the fit of cylinders cast in titanium, either in one-piece casting framework or after laser welding. When slotted and hexagonal screws were tested on the cobalt-chromium specimens, statistically significant differences were found for the one-piece casting condition, with the slotted screws presenting better fit (24.13µm) than the hexagonal screws (27.93 µm). Besides, no statistically significant differences were found after laser welding. CONCLUSIONS: 1) The use of different metal alloys do exert influence on the marginal fit, 2) The slotted and hexagonal screws play the exclusive role of fixing the prosthesis, and did not improve the fit of cylinders, and 3) cylinder position did not affect marginal fit values.

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Madhu, B. J., Mohammed Irfan, A. Manjunath, N. P. Divya, S. S. Mahesh, and B. Shruthi. "Influence of Zinc Oxide Nanoparticles on the Optical, Dielectric and Electromagnetic Interference Shielding Performance of Polystyrene Films." International Journal of Surface Engineering and Interdisciplinary Materials Science 8, no. 1 (January 2020): 13–24. http://dx.doi.org/10.4018/ijseims.2020010102.

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In the present work, Zinc oxide (ZnO) nanoparticles are synthesized using solvothermal technique. Polystyrene-ZnO (PS/ZnO) nanocomposite films are synthesized by solution casting procedure. PS/ZnO films are analyzed by XRD, FTIR and UV-Vis spectroscopic techniques. The addition of ZnO into the PS film is found to decrease the optical band gap (OBG) from 4.07 eV to 1.86 eV. Frequency dependence of dielectric constant (ε′), loss tangent (tanδ), ac conductivity (σac) and electromagnetic (EM) interference shielding effectiveness (SE) studies have been undertaken on the pure PS and PS/ZnO films. Insertion of ZnO into pure PS polymer matrix is found to enhance ε′, tanδ, σac, and SE considerably. The ε′ and tanδ were reduced with an enhancement in the frequency. σac of PS/ZnO nanocomposites was enhanced with rise in frequency and electrical conduction process in PS/ZnO film is in agreement with an electron-hopping model. EM interference SE is reduced with rise in the frequency. PS/ZnO films were proven as a favorable functional substance for the absorbing of EM waves at lower frequencies.

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Journal articles on the topic 'Casting waxes'

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