Friction behaviour of plasma-sprayed stainless steel coatings doped with graphite particles

Abstract

The objective of this study is to achieve, by atmospheric plasma spraying (APS) on aluminium alloy substrates, a coating exhibiting a higher superficial hardness and an improved tribological behaviour in dry friction compared with that of the aluminium alloy. A new process has been developed to incorporate graphite particles in a stainless steel coating during its formation. A special injection system has been developed to deposit graphite particles (2–12 μm in diameter) at the surface close to the spot sprayed with stainless steel in order to incorporate them within the forming coating. Tribological tests have been carried out on a pin-on-disc tribometer. The friction coefficient evolution of this composite coating is compared with that of commonly used stainless steel coatings. Tribological behaviour has been characterized for different test conditions. The dry friction coefficient of this coating against a 100C6 steel pin is reduced by a factor of between 1.5 and 4 compared with that obtained with plasma-sprayed stainless steel, depending on the experimental conditions.