Identification of materials and coatings to minimise/eliminate Wankel rotary engine's apex seal/trochoid wear chatter

A well-known problem is existing in Wankel rotary engine that leads the engine to seize before it achieves operational loading conditions. Existing research literature shows one of the primary indications to cause engine seizure are the chatter marks. The present study focuses on performing bench testing to rank the combinations of chosen materials and coatings resulting in lowest friction and reduced chatter. A total combination of 11 materials and coatings were analysed and tested. It was found that titankote with PVD coating and nikasil coating with diamond particles on A-2 tool steel performed the best, resulting in no wear, scuffing or chattering, with an increased surface smoothness. The lowest coefficient of friction measured was 0.06 with HTCS-150 hard trochoid and C-Lee Cook apex seals. The maximum average face wear reduction obtained was 15 μm on titankote with PVD coated trochoid and 18 μm on ceramic apex seal.