Sintered ceramic body for a spark plug

摘要

In a spark plug insulator made of a sintered ceramic body, including aluminum nitride (AlN) or aluminum oxynitride (AlON) ceramic powder having an average grain size of 1.5 mu m in which the oxygen content of the aluminum nitride or the aluminum oxynitride powder is less than 2 percent by weight. Magnesium (Mg) is also present in an amount in the range from 0.01 wt. % to 5.0 wt. % where the amount of the magnesium (Mg) is calculated by converting the magnesium (Mg) to its oxidized compound (MgO). Also included is a sintering additive present in an amount up to 10 wt. % selected from the group consisting of rare earth metal compounds in which the weight percentage of the sintering additive is calculated by converting the sintering additive to its oxidized compound. The rare earth metal compound is selected from the group of yttrium oxide (Y2O3) calcium oxide (CaO), barium oxide (BaO), strontium oxide (SrO), scandium oxide (Sc2O2), europium oxide (Eu2O3) and lanthanum oxide (La2O3).