Mechanical and tribological characterisation of electrodeposited AuCuCd

Abstract

Tribological properties are critical for the functional performance of AuCuCd electrodeposited alloys, that are widely used both in jewellery and electric/electronic applications. In this paper, we report on mechanical and tribological characterisation of 14, 18 and 23 kt electrodeposited AuCuCd thick layers. The coatings were deposited from a free-cyanide bath under operating conditions ensuring high compositional homogeneity. Composition, crystal structure and surface roughness of the samples were studied by energy dispersive spectroscopy (EDX), X-ray diffraction (XRD) and laser interferometry. Mechanical properties (Young’s modulus, hardness, plasticity index, strain-rate sensitivity, crack-arrest fracture toughness) were measured. Unlubricated sliding tests against PVD coated tool steel were carried out in order to study both the early stages of sliding and the load dependence of the wear behaviour. Two main wear modes were identified: (i) microploughing at low loads and (ii) adhesive failure at high loads, and correlations with mechanical properties of coated systems were proposed.