The effects of processing bath parameters on the quality and performance of zinc phosphate stearate coatings

In cold metal-forging processes, low-friction coatings often provide the ma in part of the lubrication. Tn many cases, zinc phosphate stearate (ZPS) co atings are used. Many parameters affect the coatings' quality and performan ce. In this paper the typical Brinell indentation test: is used to answer t wo industrial requirements: first, to reveal the sensitivity of the coating with regard to the ageing of the processing baths and phosphating time and , second, to make clear the correlation between the bulk propertiesof the c oated surface and the tribological performance of the ZPS coatings. It is s hown that a single configuration of the Brinell indentation test and a stat istical analysis of the measurements provides answers to these questions. ( C) 1999 Elsevier Science S.A. All rights reserved.