Wear Characteristics of Sputtered versus Electroplated Chromium on Aluminum.

摘要

The wear characteristics of sputtered chromium coatings on aluminum 7075 substrates were investigated and compared with electroplated chromium coatings. Both types of coatings were tested on a LFW-1 machine of the flat-on-cylinder variety under oscillating contact conditions. The structural characteristics of each type of chromium coatings have a definite relationship to the type of wear observed. The electroplated coated rings exhibited negligible wear during the initial cycle but eventually failed catastrophically by flaking and shearing of the deposits owing to its residual stress and cracked microstructure. The sputtered coatings, on the other hand, were found to be devoid of the residual stresses and cracked microstructure prevalent for the electroplated coatings. A conical-or columnar- shaped microstructure was exhibited. A uniform wear rate and lower overall wear of the sputtered coating was attributed to this microstructure and absence of gross defects. Evidence of abrasion and localized plastic flow on the sputtered wear surface was noted. (Author)