Development of ceramic electrodes for spark plugs: Materials selection

Wear resistance and durability are a challenge for current spark plug metal electrodes (e.g. Pt–Rh electrodes) due to increasing requirements (e.g. in terms of ignition voltage or temperature). Therefore, new attempts are being made to replace conventional materials with superior ones. The demand is: low life
cycle costs and an acceptable durability. Therefore, high melting temperature, high thermal conductivity, good thermal shock resistance and high corrosion/oxidation resistance must be provided by the new
materials. This work gives an overview on ceramic material groups which could be appropriate for spark plugs electrodes in large gas engines. Initial investigations were carried out to reduce the number of possible materials. Three large groups of ceramics (high entropy ceramics, oxides and MAX-phases) could already be excluded during the literature study. Sample materials from the groups of silicides, carbides, nitrides and borides was selected for preliminary experiments investigating functional as well as mechanical behaviour. Investigations into borides showed a poor performance in terms of wear, the others seem to be promising candidates for the application as spark plug electrodes in large gas engines.