Developing High Dielectric Strength Alumina for Spark Plugs

Engine downsizing and widely adopted Gasoline Turbo Direct injection (GTDi) technology has led to harsher application condition for spark plugs, which demand insulators with higher dielectric strength to meet the new challenges in modern engine platform. To improve conventional alumina insulators, the influences of material properties, such as porosity, grain size, glass chemistry and surface finish, on dielectric strength performance are studied. It is also found that, the manufacturing process can greatly impact the final performance. Hence, the effort in optimizing process variables will be discussed and the performance of resultant Autolite HD⁹⁵ ceramic will be reviewed against those of several leading manufacturers.