(Data obrony: 2007-09) Madej, Marcin Wydział Inżynierii Metali i Informatyki Przemysłowej
The research work presented in the doctoral dissertation concerned 3 types of infiltrated composites i.e. M3/2 grade high speed steel (M3/2 HSS)-copper containing 7.5% Cu and 0.3% graphite, M3/2 HSS-iron-copper containing either 20 or 50% Fe, and M3/2 HSS-WC-copper containing either 10 or 30% WC. Fourteen HSS-based PM composites were manufactured by infiltrating both green compacts and pre-sintered porous skeletons with copper. The infiltration process comprised two stages, i.e. the production of porous bodies and the subsequent infiltration. The main objective of the research work was to evaluate the combined effects of powder characteristics and production process parameters on the properties of green pre-forms for infiltration, the infiltration itself and on the final microstructure and properties of the composites. Prior to infiltration both the green compacts and porous pre-sintered bodies were tested for density and porosity, and subjected to dilatometric measurements and fractographic studies in order to observe the morphology of capillaries. The infiltrated composites were tested for density, porosity, degree of pore filling with the infiltration metal, hardness, microhardness, transverse rupture strength, resistance to sliding wear, sliding coefficient, and resistance to oxidation at elevated temperatures. They were also subjected to microstructural studies by means of light microscopy and X-ray diffraction phase analysis. Basing on the experimental data it was possible to establish the effects of the number and type of starting components and the production route of the porous pre-forms on the final density, microstructure and properties of the infiltrated composites.
