Microstructure and Properties of Cu-Ni-W-Si Gradient Coating on Copper Alloy by Laser Cladding.

Area of Science:

• Materials Science
• Surface Engineering
• Metallurgy

Background:

• Copper alloys are widely used but often require enhanced surface properties for demanding applications.
• Improving surface hardness and wear resistance is crucial for extending the service life of copper alloy components.
• Laser cladding offers a viable method for fabricating advanced coatings with tailored properties.

Purpose of the Study:

• To fabricate a Cu-Ni-W-Si gradient coating on a Cu-Cr-Zr alloy substrate using laser cladding.
• To optimize the laser cladding process parameters for enhanced coating performance.
• To evaluate the microhardness, microstructure, and wear resistance of the developed gradient coating.

Main Methods:

• Coaxial powder-feeding laser cladding technology was employed to deposit the Cu-Ni-W-Si gradient coating.
• Orthogonal experiments were conducted to optimize laser cladding parameters (power, speed, step) for both bottom and top layers.
• Surface morphology, microstructure, phase composition, microhardness, and friction/wear performance were analyzed.

Main Results:

• Optimized laser cladding parameters yielded a gradient coating with a hardness of 417 HV, 5.8 times that of the substrate.
• The coating demonstrated a significantly reduced wear rate, achieving 49.1% of the substrate's wear rate.
• Microstructural analysis revealed a favorable gradient metallurgical bond and dispersed WSi2 high-hardness phases.

Conclusions:

• The fabricated Cu-Ni-W-Si gradient coating effectively enhances the surface hardness and wear resistance of Cu-Cr-Zr alloy substrates.
• The optimized laser cladding process and resulting microstructure, including WSi2 phases, are responsible for the superior performance.
• This advanced coating technology shows promise for improving the durability of copper alloy components in wear-intensive applications.