Thermal expansion control of composite coatings on 42CrMo by laser cladding

The laser cladding technology is a rapidly developing coating technology and is used nowadays because of its industrial advantages. Its large-scale application, however, has been limited by the crack in the laser cladding coating due to the thermal expansion mismatch between coating materials and substrate. This paper presents a new method for controlling laser cladding coatings' thermal expansion coefficient with ZrW2O8 addition on NiCrBSi powder particles. The effects of ZrW2O8 on the microhardness, friction properties, and thermal expansion properties of the cladding coatings were also explored. The result indicates that no visible cracks are forming in the composite cladding coatings. The cladding coatings' thermal expansion coefficient is lower than that of the substrate at the test temperature between 30 °C and 500 °C. The cracks were effectively controlled by using ZrW2O8/NiCrBSi low-expansion composite materials during laser cladding processing.