CORUNDUM INSULATOR FOR SPARK PLUG Russian patent published in 1997 - IPC

FIELD: devices for fuel ignition in engines. SUBSTANCE: insulator is made from Al2O3 as base, SiO2 as glass-producing oxide and metal oxides as mineral doping. Ratio of weights of components is in range of 93-95 % of Al2O3, 2-3 % of SiO2, rest is mineral doping of MnO and Cr2O3. Best results are achieved using following ratio of weights: 93.90 % of Al2O3, 2.76 % of SiO2, 2.85 % of MnO, 0.49 % of Cr2O3. EFFECT: increased density and decreased coefficient of thermal extension. 3 cl