Academic literature on the topic 'Vytvrzování'

<p><span style="vertical-align: inherit;"><span style="vertical-align: inherit;">Jednou z dnešních pokročilých cest tepelné úpravy ocelí s vysokou pevností je proces Q &amp; P, který poskytuje vysokou pevnost v kombinaci s dobrou tažností. </span><span style="vertical-align: inherit;">Výsledná mikrostruktura je kombinací martenzitu a malých frakcí bainitu a zadrženého austenitu. </span><span style="vertical-align: inherit;">Zadržený austenit má podobu tenkých jehel, které přiléhají k martenzitovým lištám. </span><span style="vertical-align: inherit;">Použití tohoto způsobu v průmyslové praxi je komplikované potřebou udržení při rozdělovací teplotě, když se zadaný austenit stabilizuje migrací uhlíku z super-nasyceného martenzitu. </span><span style="vertical-align: inherit;">Inženýři proto hledají procesní cesty, při nichž přerušení chladicího procesu při určité teplotě a udržení při této teplotě nepředstavují technologické problémy. </span></span></p><span style="vertical-align: inherit;"><span style="vertical-align: inherit;">Jednou z dostupných možností je vytvrzování lisováním, které se často zabývá ošetřením částí těla vozidla. </span><span style="vertical-align: inherit;">Ocel 42SiCr, která je legována manganem, křemíkem a chrómem, byla Q &amp; P zpracována za použití experimentálních sekvencí s různými teplotami kalení a dělení. </span><span style="vertical-align: inherit;">Doba namáčení a teplota a rychlost chlazení byly shodné s parametry používanými v reálných procesech. </span><span style="vertical-align: inherit;">Správně zvolené parametry vedly k martensiticko-bainitickým mikrostrukturám s částí zadrženého austenitu, maximální pevností přibližně 2000 MPa a </span><span style="vertical-align: inherit;">protažením </span><span style="vertical-align: inherit;">A </span></span>_{<span style="vertical-align: inherit;"><span style="vertical-align: inherit;">20</span></span>}<span style="vertical-align: inherit;"><span style="vertical-align: inherit;"> více než 10%.</span></span>

The work deals with the determination of optimal curing temperature by powder coating. The thesis includes a literary study of powder coating. In the experimental part of the thesis will be performed pre-treatment and coated several test samples. It will be carried out verification of the properties of powdered coating

The bachelor thesis submitted deals with properties of electro-insulating lacquer hardenable by ultraviolent radiation and temperature. Within the theoretical part a summary of electro-insulating lacquers used in electrotechnics has been elaborated. Chemical changes that take place in this material group have been described during hardening process. A method of dielectric relaxation spectroscopy specifically focused on mathematic and physical description of polarisation and conductive mechanisms taking place in the structure of the given material has been closely studied. In the experimental part a workplace for hardening and long-term exposition of lacquered samples during simultaneous effect of various climatic elements has been designed and built. The selected electric and mechanical properties have been monitored on three sets of experimental samples prepared by means of different methodical procedures. The results gained have been mathematically evaluated and physically interpreted in term of methodical procedure of hardening and different temperature of measurement.

The thesis deals with the comparison and selection of a suitable system of curing powder coatings. The work includes a literature review focused on the issue of powder coating. In the experimental part of the work will be carried out techno-economic analysis of the suitability of each technology for curing parts in a conventional and catalytic infrared oven.

The aim of this thesis is influence of precipitation hardening regime, specifically quench rate, on mechanical properties of aluminium alloy A356 (AlSi7Mg0.3). Samples were after solution treatment quenched into water with different temperatures and age hardened. Tensile strength tests, hardness tests and microstructure observations were done after heat tretment.

his thesis deals with preparation of transparent ceramic sheets made out of sub-µm alumina powder. Green bodies are prepared by ultraviolet (UV) curing of UV curable resin containing ceramic powder followed by debinding of organic parts at elevated temperature. High relative density of green bodies is essential for reduction of shrinkage during subsequent sintering process. Therefore high solids loading dispersions containing > 57 vol% ceramic particles are used. To reach transparent behaviour, porosity within the sheets must be reduced completely. Therefore hot isostatic pressing (HIP) is used as a final operation. Finally, light transmission and hardness measurements are presented. Possibilities of making high resolution microstructures using maskless lithography and some suggestions for use of the UV curing technique for production of complex-shaped 3D structures are briefly mentioned.

Diplomová práce je zaměřena na přípravu koloidních suspenzí, vytvrditelných UV zářením, jenž jsou určeny k 3D tisku komplexních keramických vláknových struktur. Rovněž jsou v práci představeny techniky následného tvarování vytisknutých a vytvrzených struktur. Z hydroxyapatitu ve formě prášku a komponent, vytvrditelných UV zářením, byly vytvořeny pasty, určené k 3D tisku komplexních keramických vláknových struktur a multivrstev. U takto vytisknutých a vytvrzených struktur bylo navíc dosaženo zlepšení kvality povrchu a soudržnosti vláken. Pro výrobu past, určených k 3D tisku, s vhodnými reologickými vlastnostmi je nezbytné důkladné pochopení interakcí mezi částicemi, surfaktantem a monomerní/oligomerní směsí. Za použití lineárních a zesíťujících oligomerů jako disperzního média vznikají po tisku a UV vytvrzení velmi flexibilní vláknové mřížky, které lze dále tvarovat a takto vytvářet rozmanité struktury. Tyto struktury jsou následně slinuty, bez významných vad na povrchu či delaminace vrstev, za vzniku složitých keramických těles. Vysoké kvality povrchu je dosaženo UV vytvrzením vytisknutých struktur v argonové atmosféře, která brání kyslíkové inhibici radikálů v blízkosti povrchu vláken. Výhody kombinace 3D tisku s UV vytvrzováním jsou demonstrovány v této práci za užití dvouvrstvých flexibilních struktur, určených k následným metodám 3D tvarování. Takto vytvořených složitých 3D struktur je jen velmi obtížné, ne-li nemožné, dosáhnout pouze užitím přímého 3D tisku. Na základě této práce může být v budoucnu odvozena univerzální teorie k přípravě past, určených k 3D tisku komplexních keramických struktur pro různé aplikace.

The thesis deals with the influence of the curing process on varnish quality of paint powder coating. The thesis includes a literary study focused on the issue of powder coating. In the experimental part of the work will be done curing of two different materials in three technically different kilns and compare the effect of firing.

This thesis deals with relationship between tensile strength and hardness of aluminium alloys. The introduction provides an overview of aluminum aloys and their properties. In the following section there is an analysis of the processing of aluminum alloys. A large part is devoted to the course of precipitation hardening. The second part of the thesis contains a practical part, which describes the methodology of measuring hardness and tensile strength. The measurement process is described below. At the end, the measured data are processed into various graphs and their results are evaluated.

In the presented dissertation thesis, I closely focused on corrosion resistance of non-ferrous metals. For full understanding of the possibilities for increasing corrosion resistance, it was vital to initially recognize the influences to the corrosion system of the samples and their surrounding environment. For this purpose, I focused on heat treatment, corrosion, and protective coatings, in the theoretical part of the thesis. For the subsequent research, it was necessary to define several constant variables, first. For this purpose, I have chosen a group of magnesium alloys, namely AZ91 Alloy and 3.5 % NaCl Electrolyte. AZ91 Alloy is of heterogenous structure formed by a solid solution of aluminum in magnesium, intermetallic phase in Mg17Al12, and their eutectic. Local microcells tend to occur in these heterogenities, which leads to faster corrosion. In order to increase corrosion resistance of the alloy, I used a combination of heat treatment and protective phosphate coating. For creating of the desired structure, which further affects compact coating formation, I selected a process involving solution heating with precipitation hardening T6. Secondary goals of the thesis involved optimization of standard technical procedures for the sake of increasing efficiency. With regard to this goal, I introduced optimized heat treatment T6 using accelerated cooling of a sample in water and liquid nitrogen. A modification besides the standard phosphating procedure was carried out with no activation step. For evaluation of corrosion resistance of the samples, I conducted water immersion tests using electrochemical methods; such as potenciodynamic curves combined with electrochemical impedance spectroscopy. In order to streamline the evaluation of the corrosion surface in technical practice, I used automatic detection. Substantial improvement of corrosion resistance of the above mentioned system, compared to heat-untreated samples, was proven through electrochemical methods. Due to accelerated cooling, a more homogeneous structure was achieved, which could be further utilized to create more uniform protective coating. For some phosphate coating, specifically manganese phosphate coating, I identified certain modifications that were in line with the set goals; i.e. skipping the activation phase, and using automatic detection for evaluation of uniform corrosion on the samples.

This diploma thesis is focused on the description and summary of existing knowledge about vibro-pressed concrete products with treated surface with protective coating, that is hardering by ultravioled and infrared radiation. The theoretical part describes the production of vibro-presses products, possible wayt of finishing the surface including the description of the most commonly used materials and the methods of application and hardering of protrctive coating on the surface. Another point of the theoretical part is creating of lime efflorescence on the concrete surface and their subsequent disappearance. The experimental part of the thesis is ficused on obtaining information about the properties of the modified pavements by these techologies and comparing the acquired properties with the charakteristice of the reference pavements that do not have any protective coating on their surface.