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The utilization of silicon based polymers as a source of amorphous non oxide ceramics obtained upon pyrolytic treatment of them is increasingly gaining attention in research and is currently expanding into the field of commercial products. This work is focused on the near net shaped fabrication mechanical and tribological properties of a polymer derived Si/C/N system. Small sub millimetre thick ceramic test discs and bars were fabricated by casting of polysilazane and/or polycarbosilane precursor mixtures into elastomeric polydimethylsiloxane forms thermal cross linking and subsequent pyrolysis. Additional carbon was introduced on the molecular level using triphenylvinylsilane as the precursor its cross linking with the polymers via hydrosilylation prohibits phase separation of graphite within the amorphous matrix. The characteristic strength of nearly 700. MPa along with stable low friction coefficients in sliding against similar polymer derived ceramics testifies to their potential in micro electro mechanical system applications. © 2012 Elsevier Ltd.

A modified Shell four-ball apparatus was used to determine failure mechanisms and estimate time to failure of hybrid ball bearings using silicon nitride and zirconia balls. The machine was set up to hold a hybrid bearing containing three ceramic balls, instead of the usual 14 in order to increase contact pressure. Five kinds of silicon nitride ceramics, which differed in terms of surface roughness, porosity as well as the amount and chemical composition of additives were investigated. The goal of this study was to establish a quality criterion for silicon nitride for industrial use in hybrid ball bearings. Lifetime and failure mechanisms varied between the five bearings with silicon nitride balls and a dependance was found on the porosity and chemical composition of the materials, whereas surface roughness did not seem to influence their performance.