Effect of Heat-Treatment Temperature on the Tribological Properties of WC-12Co-Reinforced Ni-Based Coating

Abstract

WC-12Co-reinforced Ni-based coatings were fabricated on Inconel 718 substrates using a high-velocity air-fuel (HVAF) technique. The as-fabricated coatings were heat-treated at a temperature of 970 °C, 1000 °C, 1030 °C, or 1070 °C. The microstructure, mechanical properties, and tribological behaviors of the heat-treated coatings were investigated systematically. The results showed that the heat treatment could reduce the porosity of the coating and promote the metallurgical bonding of the interface between the coating and the substrate. As the heat treatment temperature increased from 970 °C to 1000 °C, the hardness and toughness of the coating increased gradually. After being heat-treated at 1000 °C, the coating possessed the best comprehensive mechanical properties and the best tribological properties at both room temperature and 580 °C. The wear rates of the as-fabricated coatings were 2.63 × 10−6 mm3 N−1 m−1 at room temperature and 3.96 × 10−5 mm3 N−1 m−1 at 580 °C, respectively. Also, the wear mechanisms were fatigue wear as well as abrasive wear accompanied by mild adhesive wear, respectively. However, the wear rates of the coating heat-treated at 1000 °C were 1.04 × 10−6 mm3 N−1 m−1 at room temperature and 3.87 × 10−5 mm3 N−1 m−1 at 580 °C, respectively. The wear mechanisms of the heat-treated coatings at room temperature were mainly fatigue wear and abrasive wear, while the wear mechanisms at 580 °C were mainly abrasive wear accompanied by mild adhesive wear. With the increase of heat treatment temperature above 1000 °C, the mechanical properties and tribological properties of the coating deteriorated gradually.