Microstructure, mechanical properties, and tribological properties of laser assisted cold sprayed CuCrZr coatings: Influences of laser power and laser position

CuCrZr has good conductivity, thermal conductivity and high strength and is widely used in the production of continuous casting mold. In this study, for the first time, high-performance CuCrZr coatings were successfully deposited on the surface of CuCrZr mold by laser assisted cold spray (LACS) method as a preliminary trial to validate LACS a repair technique of worn mold surfaces. This study systematically characterizes the microstructure, microhardness, bonding strength, electrical conductivity, wear performance, and thermal shock performance of CS, concentric LACS and eccentric LACS coatings. The results show that compared to CS, LACS shows great improvements in coating density, bond strength, friction and wear performance, and electrical conductivity, thus exhibiting significant prospects in the repair of mold. In particular, eccentric LACS CuCrZr coatings feature higher bonding strength and deposition efficiency, while concentric LACS coatings have better wear, hardness, and electrical conductivity. The best overall coating performance is achieved at eccentric LACS-4 kW-5.5 mm CuCrZr coating which exhibits a porosity of 0.49 %, a grain size of 1.06 µm, a microhardness of 200 HV _0.3 , a bond strength of 205 MPa (on CuCrZr substrates), a friction coefficient of 0.48 and a wear rate of 1.55 × 10 ^-5 mm ³ /N·m (counterbody: GCr15 balls, 15 N load), an electrical conductivity of 63.50 % IACS, and a thermal shock resistance of > 120 cycles under 650 ℃. The mechanisms associated with microstructural formation and mechanical performances of LACS coatings are also analyzed. There was no obvious phase change within the coating, while a heat affected zone is formed at the coating-substrate interface with the formation of Cu _xZr _y phases and slight oxides. The grain characteristics of LACS coatings include deformed grains, recovered grains, recrystallized grains. The wear mechanisms of LACS coatings are combined adhesive wear and abrasive wear.