Laser cladding of metal matrix composites reinforced by cermet inclusions for dry friction applications at ambient and elevated temperatures

摘要

Metal matrix (CuSn, Stellite + CuSn, stainless steel + CuSn) composite coatings reinforced by conventional or nanostructured cermet inclusions (WC-Co, WC-Co-BN) are deposited by laser cladding. A particular focus is on minimising the heating of particles-in-flight by laser radiation. Coating microstructure, composition and element-distribution are analysed. Dry friction coefficient at ambient and elevated (450 degrees C) temperatures is measured using reciprocated plate-on-plate test. Evolution of the friction coefficient during testing and its average value over a whole series of measurements versus coating composition are analysed and discussed as well as an eventual influence of cermet nanostructuring. Stellite + CuSn based coatings with nanostructured cermet inclusions are found promising for dry friction conditions at ambient temperature. In particular, their high performance is evident at the initial stage of friction tests when the accumulated debris quantity is limited. Evolution of the friction coefficient for ambient and elevated temperatures has qualitatively different characters. Conventional WC-Co-Cr coating deposited by detonation spraying is used for comparison. (C) 2015 Elsevier B.V. All rights reserved.