Method of manufacturing a semiconductor body for a low voltage type spark plug.

摘要

A low-voltage type spark plug including; a centre electrode (2) having a firing-tip(21) mounted within a tubular insulator (4) which in turn is placed within a metallic shell (1); a ground electrode (11) in electrical contact with said metallic shell (1) and defining with said firing-tip (21) of the centre electrode (2), a spark-gap (10); a semi-conductor body (3), a surface (31) of which is mounted adjacent the spark-gap in electrical contact with both the centre and ground electrodes (2, 11), characterised in that said semi-conductor body (3) is formed from silicon carbide particles of average diameter less than 5 microns and alumina particles of average diameter less than 1 micron in a ratio by weight in the range 65:35 to 80:20 inclusive and in that the silicon carbide and the alumina particles have been mixed with a suitable amount of binder and hot press sintered at a temperature greater than or equal to 1800 degrees Celsius and pressure greater than or equal to 200 kgf/cm<2>.