Dissertations / Theses on the topic 'Titanium sheet'

This work was motivated by the industrial and academic needs for process development of automated keyhole plasma arc welding (K-PA W) in thin Ti- 6AI-4V sheet and the control required for the process to be suitable for aerospace components. K-PAW, is a high energy density precision welding process which is a lowcost alternative to laser and electron beam welding. It is potentially capable of fabricating high integrity titanium alloy welds in aero-engine thin panel structures. However, the process has always represented a challenge owing to the complexity of welding torch configurations and the associated large number of process parameters to take into consideration. Three types of weld joint, which represent the welding fabrications in a simplified aero-engine casing component, were manufactured in the work: flat bead-on-plate, flat Tjoint and curved T -joint. A new welding procedure was developed to produce thin sheet T-joints by K-PAW, which has overcome the difficulty of operating the structurally complicated welding torch in limited space. An analytical model was experimentally validated and was employed to identify the process parametric envelopes for valid keyhole welding modes from the numerous possible parameter combinations. Weld joints were characterised in tenns of thermal history, micro-hardness and metallurgical microstructure. Distortion and residual stresses are maJor concerns associated with fusion welding fabrication. While distortions can lead to geometrical inaccuracy, paIticularly in the thin panel stl11ctures, residual stresses can combine with applied stresses to reduce the life of components. In this thesis, the out-of-plane l distortions of welded thin Ti-6AI-4V bead-on-plate and T-joint welds were measured using contact and non-contact coordinate-measuring techniques, from which the effects of welding sequence on the distortions can also be identified. Residual stress distributions in the welded sheet were detennined by synchrotron X-ray and neutron diffraction techniques. The use of synchrotron X-ray methods is relatively newly developed as titanium alloys respond weakly to neutron beams. These not only have provided improved understanding of residual stresses in thin sheet welds but also have greatly contributed to validation of finite element (FE) modelling work undertaken by other researchers.

Mechanical fasteners are used extensively in the joining of two or more metal plates or sheets. Riveted joints have been the joints of choice mainly for the Aerospace Industry. However for this research, Friction Hydro Pillar Processing has been used to develop and characterise a new riveting technique termed Friction Hydro Pillar Riveting (FHPR). Two overlapping 3.17 mm Ti-6Al-4V sheets were joined together using Ø6 mm rivet which was friction processed. This research has focussed on the initial development of Friction Hydro Pillar Riveting thereby establishing a basic understanding of the influences of main process parameters, rotational speed and axial force - and also joint configurations. The results showed that with a decrease in the bottom hole chamfer angle, there was resulting overall increase in the rivet joint pull off strength. From the best performing joint configuration in pull off tests, shear tests were conducted whilst a blind hole FHPR joint was also done and tested in pull off and shear strength. The shear test fracture surfaces exhibited ductile failure. The microstructure of the joints was thus evaluated. From parent material, heat affected zone and to weld zone there was a variation in the microstructure analysed. The hardness profiles showed increased hardness in the weld zone which partly explained the shear results. The hardness increase was mainly due to grain refinement in the weld zone by the Friction Hydro Pillar Riveting process.

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Osteoarthritis (OA), also known as degenerative joint disease is a progressive disorder of the joints caused by gradual loss of cartilage and resulting in the development of bony spurs and cysts at the margins of the joints. The degradation of the musculoskeletal system, which is mainly caused by joint injury, obesity (leading to musculoskeletal fatigue) and aging can also lead to osteoarthritis. The hands, feet, spine, and large weight-bearing joints, such as the hips and knees are commonly affected. The only medical solution to severe cases of osteoarthritis is the surgical reconstruction or replacement of a malformed or degenerated joint, better known as arthroplasty. Arthroplasty makes use of biomedical implants and replacements to restore functionality of the joints. Biomedical engineering in arthroplasty is an ever increasing field of interest as a result of its innovative improvements to surgical quality. Certain cases of partial osteoarthritis require less surgical action. Partial knee replacement surgery, also known as unicondylar (or unicompartmental) knee arthroplasty involves a covering which is placed over the affected area to resurface the affected bone and protect the patient from further degeneration. Advantages of partial replacement include faster recovery time and less post-operative pain. The biomedical implants used for these operations consist of a standardized implant that is fit onto the bone by modifying (cutting away) the outer structure of the bone. The result is known to cause post-operative discomfort among some patients. The problem with these standard designs includes the requirement of the removal of unaffected (healthy) bone matter, leading to induced trauma and pain for patients during the recovery phase of the operations. A preferred alternative to the standard design would be to create a custom implant for every patient, reducing the need to remove parts of unaffected bone matter. The implementation of this proposed method tends toward Minimally Invasive Surgery (MIS). MIS is normally preferred as it reduces the risk of various negative consequences of normal arthroplasty such as nerve or tendon damage during surgery. It could be argued that the proposed method may cause less damage to the fragile tendon, bloodflow, and nerve networks of the knee. Increasing material costs of metal products introduce great interest in more cost efficient forming processes to reduce the loss of redundant blank material. Incremental Sheet Forming (ISF), a relatively new class of forming process, has the potential to meet the need for this more efficient forming process. The ISF process is highly flexible, can be developed in normal milling machines, and can reduce production cost by up to 90% in comparison to processes such as stamping. The ISF process is a non-patented process, as the existing patents are referred to the designed machines and not the process. The availability of the ISF process contributes greatly to its attractiveness. ISF can be implemented in any facility that has access to a three- or more-axis CNC machine. The advantage of ISF implemented in CNC machines is that CNC technology has already reached a mature stage in development, contributing to the accuracy and methodology (such as feed rate or angular velocity of the tool) of the ISF process. The forming of valuable lightweight materials is well covered by ISF processes. A variety of studies contribute to research on the forming of titanium and titanium based alloys as part of ISF of lightweight materials. The ISF process utilizes the functionality of commercial CNC machines, improving the process availability of many manufacturing companies. The ISF process offers fast setup times and flexibility of the forming process. The purpose of this project is to define a process chain for creating a customized biomedical implant as well as determining the validity of the process chain by applying each step. The design and development procedure of a titanium based biomedical arthroplasty implant using innovative Incremental Sheet Forming (ISF) techniques will be documented, as well as an investigation of the financial cost and potential gain that this implant can offer.
AFRIKAANSE OPSOMMING: Osteoartritis is 'n gewrig siekte wat degeneratiewe newe-effekte behels in die gewrigte. Hierdie siekte lei to die geleidelike verlies van kraakbeen en lei tot die onreelmatige ontwikkeling van abnormale beengroei. Osteoartritis kan ook deur beserings in die gewrig veroorsaak word. Die hande, voete, ruggraat, en enige groter gewigdraende gewrigte, soos die heupe en knieë kan geaffekteer word. Die enigste mediese oplossing tot ernstige gevalle van die siekte is chirurgiese rekonstruksie of vervanging van die gewrig, meer bekend as artroplastie. Artroplastie maak gebruik van biomediese implantate om funksionaliteit van die gewrig te herstel. Biomediese ingenieurswese in artroplastie is 'n toenemende navorsingsveld as gevolg van die innoverende aspekte om chirurgiese kwaliteit te verhoog. Sekere gevalle van gedeeltelike osteoartritis vereis veel minder chirurgiese behandeling. Gedeeltelike knie vervanging chirurgie, meer bekend as unikompartementele knie artroplastie, behels 'n bedekking wat slegs die geaffekteerde been bedek, om die pasiënt van verdere degenerasie te beskerm. Voordele van gedeeltelike vervanging sluit vinniger herstel tyd en minder pyn in. Die biomediese implantate wat gebruik word vir hieride operasies bestaan uit standaard ontwerpe wat aan die been gepas word deur die wysiging (of wegsny) van die buitenste beenstruktuur. Die nagevolg van hierdie chirurgie is lang herstel periodes en kan ongemaklikheid in die knie veroorsaak. Die probleem met die bogenoemde standaard is dat die prosedure die verweidering van selfs ongeaffekteerde (of gesonde) been in sluit, wat lei tot verdere kniepyn en ongemak vir pasiënte lei tydens die herstelperiode. 'n Verkiesde alternatief tot die standaard ontwerpe is om 'n persoonlikke implantaat vir elke pasiënt te skep, en so kan die behoefte om dele van ongeaffekteerde been te behou moontlik wees. Die toepassing van die voorgestelde metode neig na Minimale Skade Chirurgie (MSC). MSC word gewoonlik verkies om die risiko van verskeie negatiewe nagevolge te verminder, en skade aan die tendon, bloed- en senunetwerke van die knie te beperk. Die toenemende materiaalkoste vand metal produkte lei tot 'n groot belangstelling in meer koste besparing vormings prosesse, om sodoende die verlies van oortollige materiaalverlies te verminder. Inkrementele Plaat Vervorming (IPV), 'n relatiewe nuwe klas van vervorming, is 'n waardige kanidaat om hierdie doel te bereik. Die IPV proses is baie toepaslik, en kan deur die gebruik van Rekenaar Numeriese Kontrole (RNK) masjienerie toegepas word. Verder sal dit vervaardigingskoste kan verlaag met soveel as 90% in vergelyking met ander prosese soos die stempel metode. Die beskikbaarheid van die IPV proses dra grootliks by tot die proses se aantreklikheid in die industrie. IPV kan geimplementeer word in enige fasiliteit wat toegang tot 'n drie-as RNK masjien het. Die voordeel van dit is die feit dat RNK masjienerie klaar ontwikkel en volwasse is, wat kan bydra tot goeie akkuraatheid in die vormingsproses. Die vervaardiging van laegewig materiale soos titaan of aluminium is gedokumenteer. 'n Verskeidenheid van studies dra waarde tot navorsing van die vormingsproses van titaan as deel hiervan. Die IPV proses bied vinnige opstel tye en goeie buigsaamheid met die vormingsproses, veral met behulp van 'n vyf-as masjien. Die doel van hierdie projek is om 'n proses ketting te ontwerp. Die proses ketting, wat uit vele stappe bestaan, sal die ontwerp en vervaardigingsproses van 'n persoonlike biomediese knie implantaat bevestig deur middel van die IPV vormings tegniek. Validasie van die proses ketting sal dus plaasvind deur die stappe van die voorgestelde proses ketting uit te voer. 'n Finale ondersoek sal die finansiele en regalutoriese aspekte van die projek aanspreek.

O objetivo deste trabalho é fabricar próteses cranianas personalizados de baixo custo, em chapa de titânio puro. A fabricação antecipada do implante de acordo com as características do paciente permite ao cirurgião estudar e planejar a cirurgia com maiores possibilidades de atingir o resultado esperado, a personalização contribui para o resultado estético e funcional do implante, já que considera a anatomia de cada paciente, o custo baixo permite que um maior número de pessoas possam ser beneficiadas. Os experimentos práticos iniciam-se com aquisição de imagens tomográficas computadorizadas de um crânio defeituoso, reconstruiu-se digitalmente em CAD o crânio com defeito e também a reparadora (implante). A fabricação do implante em chapa de titânio puro grau 2 foi realizada por estampagem incremental, processo de baixo custo e que permite a fabricação customizada de peças. Foram comparadas as dimensões entre o modelo CAD e o modelo físico do implante. A partir da imagem tomográfica também foi gerado o modelo CAD do crânio fraturado e foi feita a usinagem do mesmo em madeira para a realização do teste funcional do implante onde foi comprovada a funcionalidade do mesmo, indicando a eficiência dos recursos e parâmetros utilizados. A ferramenta utilizada para a estampagem incremental foi fabricada em aço SAE 4340 com ponta intercambiável de titânio puro e o lubrificante utilizado no processo foi a base de gordura animal para evitar a contaminação da prótese. Foi feito o tratamento térmico de alivio de tensões na prótese estampada para manter as dimensões geométricas após o corte da prótese, melhoria na rugosidade superficial e biocompatibilidade do titânio. Após o tratamento térmico foram feitas análises na rugosidade e teste de molhabilidade no implante, onde os resultados mostraram que a prótese tratada termicamente muda as características biomecânicas. Para analise da geometria do implante foi feito uma varredura por escâner e comparação com o modelo CAD da prótese.
The work main objective is manufacture custom cranial implants with low cost, in titanium pure sheet. The prior implant fabrication according with the characteristics of the patient allow surgeon to study and planning surgeries with greater possibilities to achieve expected results. The customization helps for esthetic and functional results of implant, because regards the anatomy of each patient, the low cost allow the most people receive benefits. Practical experiments began with acquisition of computed tomographic images of a defective cranium, rebuilt the implant and this cranium in CAD images. Implant manufacture in titanium sheet pure grade 2, was performed with incremental forming, this process have low cost and enables to produce custom pieces. The implant dimensions been compared between the CAD Model and Physic Model. Starting with the tomographic image was generate the CAD Model of fractured cranium, and was make a machining the same in wood for realization of functional implant test, which was confirmed the same functionality, indicating resource efficiency and the parameters used. The tool used for sheet forming been manufactured in SAE 4340 steel with interchangeable point of pure titanium, and the lubricant used in the process has been the basis animal grease to avoid the implant contamination. Heat treatment was done to reduce the relief of stresses at the implant formed to maintain the geometric dimensions after the implant cut, superficial roughness better and titanium biocompatibility. After heat treatment, the average roughness analyzes performed and wettability test in the implant, witch results shows the treated prosthesis changes the biomechanical characteristics. For analysis of the implant geometry, was used a scanner and compared with the CAD model of the prosthesis.

Este trabalho apresenta um estudo sobre o uso do processo de estampagem incremental empregando chapas de titânio comercialmente puro. O modelo do componente empregado como foco do trabalho foi um implante craniano a base de titânio. Este tipo de implante é usado, por exemplo, em casos de acidentes em que a camada óssea do crânio foi perdida. Com auxílio de um sistema computacional CAD (Computer Aided Design), foi desenvolvido um modelo 3D, a partir de imagens de tomografia computadorizada. Foram determinadas as características mecânicas e biomédicas das chapas de titânio F67 - grau 2 e, através de software CAM, foi possível gerar as trajetórias de ferramenta, utilizadas na usinagem do molde e na estampagem da chapa. Os testes práticos demostraram que a estampagem incremental proporcionou maiores deformações do que a estampagem convencional e qual a estratégia de usinagem que proporcionou a maior homogeneidade na distribuição de espessura e conformidade dimensional das chapas estampadas.
This work present a research about the incremental sheet forming process, using commercially pure titanium sheets. The model of component used like focus on work was a titanium cranial implant. This kind of implant is used, e.g., in cases of accidents where skull bone was lost. With aided of a CAD computacional system (Computer Aided Design), was development a 3D model, with images of computadorized tomography. It was determined the mechanical and biomedical properties of the F67 grade 2 titanium sheet and, through CAM software, it was possible development the tool path, used in the milling mold and sheet forming. The pratical tests showed the incremental forming provided greater than convencional forming and which the tool movement strategy that provided better homogeneity in the thickness distribution and dimensional conformity of the forming sheets.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.
Includes bibliographical references (leaf 77).
The ability to apply Yttria patterns on titanium sheets is required on a secondary manufacturing operation. The freedom to create 2 dimensional patterns as well as 3 dimensional ones by using Three Dimensional Printing allows for the application of Yttria patterns onto these sheets without the use of any type of screens. Two methods for creating these patterns were identified and studied. The first approach consists of selectively printing binder on top of spread layer of powder. A second layer of powder is spread while the binder is still wet. The binder will then dry fixing the Yttria powder to the sheet on the selected positions. Sheets were printed using different particle sizes. Results show that patterns can be applied with good edge definition and uniform thickness using powder ranging from -53[mu]m down to -20[mu]m. The sheets were tested successfully in the secondary operation. And alternative approach consists of mixing the binder and the ceramic powder to create a slurry. The slurry will then be selectively printed onto the sheet using Three Dimensional Printing. A formulation for a -20 [mu]m Yttria powder slurry was developed using Poly Acrylic Acid as dispersant and Polyethylene Glycol as binder. Slurries with 20 volume fraction and less were dispersed and jetted through a 102 [mu]m nozzle. These slurries adhered well to the titanium sheet as they were printed. The formulation was tested successfully in the secondary operation. Following the High-Risk Approach patterns without deflection were printed. For a 102 [mu]m nozzle the best flow rate was determined, as well as the optimal line spacing. The best procedure to print a certain area was to print a first round of lines, dry them and then print lines in between the first set. The average roughness of the layer printed was 14 [mu]m. In order to allow future printing of slurries with a nozzle size of 102 [mu]m and deflection, the design of a print head to accommodate these slurries was also investigated.
by Gabriel Fernandez.
S.M.

Objectives: The present work was under taken to compare osseointegration of immediately and delayed restored implants in a sheep model, and to compare methods of assessing osseointegration. Methods: Twenty wide-platform implants were placed in the posterior mandibles of 10 sheep, 3 months after premolar extractions. Ten were control implants placed and restored after 3 months of submerged healing. Ten were test implants placed contralaterally and immediately restored. Animals were sacrificed after a further 3 months of healing. At each experimental stage implant stability was measured with resonance frequency analysis (RFA) and standardized radiographs were taken. Tissue blocks with the implants were embedded in acrylic resin. The specimens were analysed by three-dimensional micro tomogram (micro-CT) images. Ground sections of the tissue blocks were then prepared for light microscopy and quantitative morphometry. Morphometric parameters computed by both methods were mean percent bone-to-implant contact (BIC) and mean percent bone density (BD). Radiographic, stability and morphometric measurements were compared statistically. Results: The survival rate was 60% (controls) versus 40% (test) (p=0.28). Mean crestal bone levels after three months restoration did not differ significantly between control (5.54 � 0.92) and test groups (4.35 � 1.61) (p=0.56). All surviving implants were stable at stage three and RFA values in implant stability quotient (ISQ) did not differ significantly between the two groups (test 82.3 � 3.9 versus control 78.8 � 4.3, p=0.36). No correlation was found between crestal bone loss and RFA (Spearman�s rho =-0.27, p=0.46). Histomorphometric analysis found no statistical difference (%BIC test 65.65 � 12.7%, control 53.36 � 6.41%, p=0.18; and %BD test 54.84 � 8.45%, control 64.69 � 13.57%, p=0.11). A similar trend was observed for mean micro-CT (%BIC test 65.72 � 72, control 50.84 � 4.19, p=0.11). Histology revealed high density inflammatory infiltrates beneath the sulcular and pocket epithelium. No significant difference was found between histomorphometric (HMA) and microCT analysis (%BIC p=0.08, %BD p=0.08). A statistically significant correlation was observed between HMA and microCT for %BIC (Spearman�s rho = 0.89, p=0.02) but not %BD (Spearman�s rho = 0.51, p=0.30). Conclusions: The results suggest that the sheep mandibular model has limited potential for evaluation of implants designed for poor quality bone and for the assessment of implant loading protocols. This thesis does highlight the potential for the use of this model in peri-implantitis studies. The results suggest that morphometric variables determined by HMA and microCT analysis are comparable, however further studies are required to standardize the microCT protocol to reduce metal artifacts and enhance bone-implant contrast.

Thesis (M.S.)--University of Akron, Dept. of Biomedical Engineering, 2006.
"December, 2006." Title from electronic thesis title page (viewed 06/27/2007) Co-Advisors, Glen O. Njus, Daniel B. Sheffer; Faculty Reader, Mary C. Verstraete; Department Chair, Daniel B. Sheffer; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Caracterisation generale de la superplasticite et du procede de mise en forme des toles par pression gazeuse. Presentation d'une modelisation numerique permettant une meilleure maitrise de ce procede de fabrication notamment utilise dans l'industrie aeronautique pour le formage de pieces de structures en toles d'alliages de titane ou d'aluminium

Etude de certains aspects et parametres lies au traitement de conversion par phosphatation des toles d'aciers galvanises et electrozingues: temperature, composition, ph des bains. . . Caracterisation de la couche de conversion et examen de l'influence du vieillissement du bain de degraissage et du traitement final de passivation par des solutions de ticl::(3)

This thesis deals with the design and elaboration process of a project documentation of a sports centre. The designed sports centre building is situated in the southern part of the town of Polička, in the area determined for sports and free time activities complexes and areas. It is a two-floor, non-cellar, flat-roof building. It is based on plain concrete strip foundations and reinforced concrete foundation footing. The bearing, peripheral and partition walls are designed from POROTHERM hollow clay blocks. Reinforced concrete columns are designated in open disposition areas. The ceiling construction is made from SPIROLL pre-stressed concrete floor slabs and point-supported reinforced concrete slabs. The peripheral walls of the first aboveground floor are insulated with external thermal insulation system with a protective gabion facade. The peripheral wall thermal insulation in a bowling restaurant and gym halls extension is designed from a ventilated facade with CEMBRIT METRO facade cladding panels. The building is functionally divided into two main parts with a shared entrance. The sports centre with gyms and other sports facilities form the first part. Three squash courts, a mini-football piste, a special room for spinning and alpinning, a room for group exercising and cloakrooms with sanitary facilities are designed within one part of the sports centre. A restaurant with a bowling area and a kitchen with storerooms and other facilities for employees form the second part. The designed complex is barrier-free. There is aimed to be a car park for fifty cars, four motorbikes and a bus in front of the building. Three parking places are for disabled people.

碩士
國立高雄應用科技大學
模具工程系碩士班
101
The shearing and drawing processes of sheet metals are common techniques to produce metal components. The processes involve complex forming behaviors. It is difficult to predict the forming limit of sheet metals. Therefore, it is widely interested in developing methods which are able to accurately predict the facture. This study used a finite element package, DEFORM, to simulate micro shearing and micro drawing processes of pure titanium sheets. By comparing the simulated results with experimental ones, the critical values were estimated for three damage criteria which are Normalized Cockcroft and Latham, Rice and Tracey, and Ayada criteria. This study used titanium sheets with different thicknesses of 0.05 mm, 0.1 mm and 0.25 mm in the experiments and simulations of micro shearing and micro drawing processes. The sections of the sheared sheets were examined by an optical scope and analyzed by imaging software. The ratio of burnished land to thickness was used as a reference for estimating the critical values of the damage criteria. In the case of the micro drawing process, the stroke at the fracture was employed to estimate the critical values. The results show that the used damage criteria are able to predict the fracture profiles in the micro shearing processes and the fracture locations in the micro drawing processes. However, their critical values vary with the thickness of the sheet and the type of the forming process. The results imply that the facture is highly associated with the initial conditions of materials and the path of deformation.

碩士
國立虎尾科技大學
機械與電腦輔助工程系碩士班在職專班
102
Forging industry for Taiwan''s economic development plays a pivotal role, ranging from marine spindle, small screws and nuts can utilize forging technology to produce. The biggest problem is that the industry experience, and ways to solve the problem with the test, this approach is quite time-consuming and cost, but more often because of the human factor, the experience can not lead to faults caused by inheritance and it makes the experience can not continue. In this paper, through the test with computer-aided simulation for verification to complete the process improvement. This thesis investigate hernia surgical instruments with titanium nail shape forging piece of molding analysis, improvements to the current process, the students want to theories of plastic molding as a basis for further in forging trip ways to improve the cost of this product, so that the process be improved to improve efficiency . In this paper, first by modeling the finished product reuse Deform-3D analysis software to simulate the results of further tests with real comparison.In this paper, blank flow generated simulation deformation, stress , strain and stress distribution resulting from the mold , wear and other conditions, In this paper, blank flow generated simulation deformation, stress, strain and stress distribution resulting from the mold, wear and other conditions, discussion and research. From the simulation results, when the upper die proceeds 20%, the maximum stress in the middle of the forging surface edge portion, when the upper die proceeds 40%, the relative roles of the titanium sheet and the staple forming molds and more significantly, the maximum stress distribution molding the intermediate material turning part, as this range is applied to the mold at a position on the material. When 60% of the forward mode, the maximum stress in the material in the middle portion, when the pressure is continuously applied to the mold material to allow the material in the mold cavity is filled last. 80% when the upper die advances, the maximum stress in the material or the distribution of the intermediate portion, then the mold material continues to put pressure on the material in the mold cavity is filled last. When the upper mold 100% advancing, the material has completely filled the mold cavity, the maximum average stress distribution material of the intermediate section. Data results after the Deform-3D simulation for comparison, data analysis and simulation of the resulting titanium screw shaped piece dimensions are in line with the planned surface tolerances, the accuracy rate of 95%, can be seen after Deform-3D simulation , a high reference value. So simulation analysis can be applied to the design and development process actually, thus shortening development time reduce the cost of failure.

碩士
國立清華大學
材料科學工程學系
100
In this study, titanium oxynitride sheets were obtained by nitration using hydroxo titanate with as prepared by hydrothermal method as the precursor under ammonia atmosphere at different temperature. Titanium oxynitride sheets would be used in supercapacitors due to its high conductivity, chemical stability and multi oxidation states. Among these sheets, N64 show excellent capacitance (5 mVs-1, 572.7 Fg-1). This is a cost-effective and simple preparation for a single-material supercapacitor, thereby eliminating the concern for a junction. The titanium oxynitride sheets, composed of mesoporous nanofibers with high porosity and multi-oxidation state of the center metal, exhibit both electric double-layer and pseudocapacitance significantly. These results demonstrate that this material can be a promising electrode material for supercapacitors for energy storage. In addition, a supercapacitor device of two electrodes system was successfully prepared by assembling two FSM of N64 which were sandwiched within PVA/H2SO4. It shown that N64 is a typical behavior of supercapacitor with large working window. This suggests that N64 may play a potential role in electrode material for further electrochemical applications.

碩士
國立虎尾科技大學
創意工程與精密科技研究所
98
In this paper, the finite element method is employed in conjunction with the abductive network to predict the optimum blank contour of a rectangular cup in deep drawing of pure titanium. The height fluctuation behavior of the drawn cup is caused primarily by the unsuitable shape of blank. Different cup heights combined with various aspect ratios of the rectangular cup are taken into account as the process parameters in this study. A finite element-based code is utilized to investigate the material flow characteristics under different process parameters, and the abductive network is then employed to synthesize the data sets obtained from numerical simulations, thus establishing a predictive model. From this model, an optimal blank contour for producing a rectangular cup can be found. Experiments were carried out with pure titanium sheet blanks for some cases, and the results of experiments show good agreement with the FEM calculations.