Lubricating Mechanism of Different Structure Phosphates as Extreme-Pressure Additive

Three kinds of phosphates commonly used in lubricant as extreme-pressure additive in metal working were evaluated using an Optimol SRV tribometer at elevated temperature. The wear scar was investigated using scanning electron microscopy and energy dispersive spectrum. Based on thermogravimetric analysis of the three additives, it indicates that the reactivity and thermal stability of phosphates determined the lubrication performance, i.e. anti-wear and extreme pressure. The stamping lubrication performance of the phosphates was evaluated on an ERICHSEN sheet metal forming machine. And the efficient use of the three phosphates as extreme pressure agent were discussed.