Wear Analysis of Functionally Gradient Composite Materials by FE Modelling of Microhardness Measurements and Wear Tests

Rollers of three different material structures were examined: rollers consisting of pure EP resin; homogeneous EP/SiC composite rollers containing 5 vol.% SiC; and EP/SiC composite rollers with functionally gradient (FG) material structure. Wear tests were performed on the rollers. The wear tests showed that rollers of gradient structure are the most wear-resistant of all. Microhardness measurements were performed on the materials of the three different rollers. SEM images were made of the surface of wear traces. In order to get to know better the effect of SiC reinforcement particles on the wear mechanism, microhardness measurements were simulated by 3D FE micro-models. The SEM images and the FE models were used to explain the excellent wear behavior of the tread of rollers with gradient material distribution.

Non-Electrolytic Deposition of Silver on Tungsten Powders for Functionally Gradient Composite Powder

The research conducted was focused primarily on the development of a process for obtaining silver-coated tungsten powders for applications related to electrical-conducting devices. Particles of high strength material when coated with silver offer a means of obtaining desirable electrical properties and high strength. The coating process employed aqueous ammoniacal silvernitrate electrolytes with a formaldehyde solution as the reductant. Modifying additives were also applied. The reduction and subsequent deposition of silver occurred selectively on the surface of the tungsten particles. The morphologies of the coated particles were assessed by SEM imaging. The silver was uniformed coated on tungsten powder and its thickness was estimated to be approximately 100nm on the basis of a mass account.