|
|
Mechanical response during dynamic loading of layers prepared by cold spray technology
Šprincl, Jan ; Válka, Libor (referee) ; Řehořek, Lukáš (advisor)
Cold spray is a relatively modern technology that falls into the additive category. It is a coating method that doesn´t cause the input material to melt. This brings many advantages, including the minimization of changes to the original structure, the absence of a heat-affected zone, and the possibility of combining different types of materials. This work mainly focuses on the deposition of Ti6Al4V titanium powder, along with other materials to supplement or modify the spray, improve its efficiency, and enhance its mechanical properties. Ballistic tests, three-point bending tests, indentation methods, optical analysis using light and electron microscopy, X-ray diffraction, differential scanning calorimetry, and the influence of thermal treatment on the structure were used to evaluate the properties. Thermal treatment led to the formation of completely new phases in the structure, resulting in a significant increase in the coating's hardness along with a reduction in its porosity. Highly hard phases based on TiC and Ti5Si3 were formed in a tough matrix composed of varying ratios of Ni-Ti and associated elements – V, Al, Si. Finally, proposals for potential future development of this material are described. Preconditions for specific improvements in the methods and procedures used in this work are laid out, with a very promising outlook for the future of this material and its potential implementation in real ballistic protection, typically in the military industry.
|
|
|
Deposition of MMC-type composite coatings on steel substrates using the Cold Spray method
Šesták, Stanislav ; Doubrava, Marek (referee) ; Řehořek, Lukáš (advisor)
The Cold Spray method is a modern coating method characterized by several interesting advantages and drawbacks. One of the most significant drawbacks is the difficult manufacturing of materials with limited ductility. This work is dedicated to this issue, and its main objective is the development of tribological coatings for high-temperature applications on steel substrates. Extensive research focused on the nature of the chosen deposition method and its specifics in the context of materials with limited ductility is provided and concluded by a set of methodical approaches of deposition, which are verified in the experimental part of this work. The experimental part focused on processing Ni-B4C and Ni-SiC composite coatings, in which the reinforcement particle volume fraction was chosen as 20 and 40 %. All coatings were deposited on 42CrMo4 steel substrates. The analysis of the coatings consisted of microstructure evaluation (using optical and electron microscopy) hardness testing and adhesion testing. The Ni-SiC coating consisting of 40 vol.% SiC particles showed the best properties; compared to other coatings it offered the highest microstructural quality and microhardness values. This coating was found suitable for the chosen application, and further suggestions on improving the quality of this coating were provided in this work’s conclusion.
|
guest ::
