This paper presents numerical studies of powder compaction in cold uniaxial pressing. The powder compaction in this work is considered as an initial stage of a hot pressing process so it is realized with relatively low pressure (up to 50 MPa). Hence the attention has been focused on the densification mechanisms at this range of pressure and models suitable for these conditions. The discrete element method employing spherical particles has been used in the numerical studies. Numerical simulations have been performed for two different contact models-the elastic Hertz-Mindlin-Deresiewicz model and the plastic Storåk-ers model. Numerical results have been compared with the results of laboratory tests of the die compaction of the NiAl powder. Comparisons have shown that the discrete element method is capable to represent properly the densification mechanisms by the particle rearrangement and particle deformation.
Abstract. Functionally graded materials (FGMs) belong to a new, continuously developing group of materials, finding application in various branches of industry. The idea of freely designing their construction profile, restricted only by the available manufacturing techniques, enables obtaining materials with composition and structure gradients having unprecedented properties. In this paper, selected results of works carried out by the authors and relating to the application of the developed metal-ceramic composites were presented in order to manufacture functionally graded materials for target purposes. Gradient structures with various construction profiles that can play different roles were produced on the basis on the following material pairs: Cr-Al2O3, NiAl-Al2O3 and Cu-AlN. Manufacturing conditions, microstructure characteristics and selected properties, crucial from the point of view of future applications, were presented.
The paper presents the results of research on the production by means of arc spraying of composite coatings from the Fe-Al system with participation of in-situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum and steel. The aim of the research is to create protective coatings with a composite structure with a significant participation of FexAly as an intermetallic phases reinforcement. The synthesis of intermetallic phases takes place during the (in-situ) spraying process. Currently most coatings involving intermetallic phases are manufactured by different thermal spraying methods using coating materials in the form of prefabricated powders containing intermetallic phases. The obtained results showed the local occurrence of intermetallic phases from the Fe-Al system, and the dominant components of the structure have two phases, aluminum solid solutions in iron and iron in aluminum. The participation of intermetallic phases in the coating is relatively low, but its effect on the properties of the coating material is significant.
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