Tribological Behavior of Laser-Cladding Ni60 and Co-Cr-W Coatings at Elevated Temperature
Nickel base Ni60 and cobalt base Co-Cr-W coatings were prepared on substrate of refractory alloy steel 4Cr14NiW2Mo by laser-cladding technology. A 2 kW transverse-flowing CO2 laser device was used for cladding alloy powder. Another Co-Cr-W coating was formed by bead welding. Under room temperature, 250 oC.and 420 oC, reciprocate sliding wear tests with a ball-on-flat contact for three coatings have been carried out. For the laser cladding coating, a good metallurgical bonding with the substrate was obtained. Different tribological behaviors of three coatings were observed. For the two Co-Cr-W coatings, the friction coefficients decreased with the increase of test temperature, and larger spot-like stripping pit and wider ploughing trenches in the wear scars were presented. The wear mechanism was the combination of abrasive wear, delamination and oxidation wear. For the Ni60 laser cladding layer, the friction coefficient hardly changed with the elevated temperature, and the wear mechanism mainly performed as abrasive wear due to its high oxidation resistance. The wear tests showed that the Ni60 clad coating had provided excellent wear resistance than Co-Cr-W layers under high temperature reciprocating sliding wear condition.
Yu Zhou, Shan-Tung Tu and Xishan Xie
Z. B. Cai et al., "Tribological Behavior of Laser-Cladding Ni60 and Co-Cr-W Coatings at Elevated Temperature", Key Engineering Materials, Vols. 353-358, pp. 878-881, 2007