Development of Zinc Phosphating Conversion Process at Normal Temperature

A new process for phosphate conversion (“normal-temperature zinc phosphate conversion process”) has been developed and applied for the paint pretreatment processes of auto parts etc. The conventional zinc phosphate conversion process was generally performed in a bath heated to 40°C or more. Such a heated bath high temperature bath. However posed problems such (1) difficult process control and (2) large energy consumption. We determined the zinc phosphate conversion reaction to be an electrochemical reaction and then developed a new chemical conversion treatment which can be automatically controlled at normal temperature.