Spark plug and producing method therefor

摘要

In a spark plug, a complex chromate coat 42 that contains a chromium component and a phosphorus component as cationic components, at least 90 wt% of the chromium component being trivalent chromium and the phosphorus component being present in an amount of 1 to 15 wt% as calculated for PO4, is formed on the surface of the galvanized main metal shell 1 of a spark plug. If a silicon component is substituted for the phosphorus component, it may be present in an amount of 5 to 75 wt% as calculated for SiO2. <IMAGE>