Laser cladding offers several advantages, including rapid cooling (up to 10^6 K/s), low coating dilution (typically less than 5%), low heat input and distortion, a wide range of powder selection, a large range of cladding layer thicknesses (0.2~2.0 mm per single pass), selective cladding capability, low material consumption, and ease of automation.
Laser cladding is a rapid solidification process that easily produces fine-grained structures or generates new phases, resulting in a dense coating with a strong metallurgical bond to the substrate. For example, the (CrFeNiAl)100–xMox high-entropy alloy coating consists of a body-centered cubic (BCC) phase and a B2 phase, achieving a hardness of up to HV0.2 636.6. Ultra-high-speed laser cladding (EHLA) technology can further refine the microstructure and promote uniform composition, thereby improving the coating's wear resistance, corrosion resistance, and high-temperature resistance.
Evaluating the quality of laser cladding layers requires a macroscopic examination of the cladding channel shape, surface roughness, cracks, porosity, and dilution rate, as well as a microscopic examination of the microstructure. Common defects include porosity, cracks, deformation, and surface roughness. By optimizing process parameters such as laser power, scanning speed, and powder feed rate, or by employing external field-assisted techniques, defects such as cracks and porosity can be effectively reduced.