Abstract: A contact glass composition for use in resistor-type spark plugs is described. The contact glass composition is a mixture of: (a) at least one metal; (b) graphite; and (c) silicon. Additionally, borosilicate glass, barium borate glass, magnesium aluminum silicate, ball clay, and aluminum may also be included in the contact glass composition.

Abstract: An oxygen sensor utilizes a chrome oxide compensating resistor (5) in series with a titania sensing resistor (3). The chrome oxide resistor (5) not only compensates for the effects of temperature on the titania sensing (3) resistor, but since it exhibits (p) type behavior while the titania exhibits (n) type behavior in the presence of gaseous oxygen, the sensitivity of the sensor is increased. The resistors (3, 5) can be applied as a film to a substrate (7) or they can be formed as discrete chips. Substantial quantities of alumina and glass can be added to the chrome oxide without affecting oxygen sensitivity although the electrical resistance rises substantially.

Abstract: An oxygen sensor (1) for detecting the oxygen content of an internal combustion engine exhaust gas system includes a generally cylindrical hollow insulator (3) having a first resistive element (17), preferably of titania, and a second resistive element (19) preferably of zirconia or chromia, adjacent the closed end (9) thereof, grooves (23) adjacent the open end (7) thereof, and an intermediate portion (11) having a shoulder (13), with electrically conductive film leads (29) passing over the surface of the insulator (3) between the resistive elements (17 and 19) and the grooves (23), with a dielectric coating (33) over the conductive film leads (29) in the area of a metal shell (31) to insulate the film leads (29) from the shell (31).