Three-body abrasion of high-speed laser-clad tungsten carbide reinforced Ni-based composite coatings to replace hard chrome

Abstract

Hard chrome is an electroplating process that increases the durability, hardness, wear, and corrosion resistance of metal components in various machinery and equipment. However, the method is being banned due to harmful health and environmental effects. In this paper, high-speed laser cladding was employed to develop alternative coatings for hard chrome. The fabricated coatings, relatively low in thickness (~0.2 mm), were based on self-fluxing NiBSi alloy reinforced with small (~25-50 µm) spherical and angular fused tungsten carbides (WC/W2C) on moderately hard (~450 HV) quenched and tempered steel. Obtained coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and optical surface profilometry. Mechanical and wear properties were tested by the Vickers microhardness method and low-stress three-body dry-sand rubber wheel abrasion test (RWAT). The results demonstrated that coatings reinforced with spherical WC/W2C with bulk hardness up to ~1000 HV1 exhibited wear resistance better than hard-chrome plated coating. Better wear resistance was attributed to the high-volume fraction (~43 vol.%) of very hard (~3100 HV0.1) and high fracture toughness spherical carbide reinforcements. Consequently, the developed coating is a good alternative to hard chrome in a low-stress three-body abrasion tribosystem.