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The laser cladding stellite F alloy on valve face by 2 KW CO2 laser equipment was investigated. The powder mixture paste was precoated on valve face in experiments of laser cladding process. The laser cladding process, the microstructure of laser cladding layer, the chemical composition distribution and the microhardness distribution in laser cladding layer were examined by metallurgical microscope and scanning electric microscope, and the 1000-hours engine endurance test was conducted in WD615.68 high-performance test engine. The results show that the cladding layer on valve face which possesses fine crystalline grain, close microstructure and low dilutability has been obtained by laser cladding stellite F alloy. The microhardness of the laser cladded layer is above l600 kg/mm2, HV0.2 100 higher than microhardness of bead welding layer at same depth.

The latest developments of material surface engineering to reduce the friction and wear of the piston ring in recent decade have been summarized. This paper analyzes the severe operating conditions of the piston ring in engine in detail. Based on the theoretical analysis, the essential technique requirements for piston ring wear resistant coatings are proposed. The state of research and application, the process features and furture development tendency of main material surface engineerings such as plasma spray, neckel-based plating and vapor deposition are investigated. The results show that material surface engineering will play more and more important role in the piston ring and other components in high performance engine in the near furture. Particularly the nickel-based plating and physical vapor deposition are more powerful and flexible in pratical application for the piston ring.