Chemical Activation Induces The Growth Of Metal Layer On Carbide Ceramic Powder’s Surface And Its Applications

The foundation of laser cladding technology is the preparation of feeding powder withexcellent performance. Electroless plating is an advanced method for producing metal-coatedcomposite powder which wetting ceramic powder. The metal amount is controllable, and thecomposite powder disperses well. It effectively solves the problems of reunion and mixeduneven with traditional preparation method, and lays the foundations for the preparation ofexcellent performance coating. Different from traditional ceramic powder catalytic activationmechanism, this paper uses chemical activation pretreatment to induce carbide ceramic powder’ssurface to born defective chemical surface by themselves for the growth of metal layer duringlow temperature ultrasonic-assisted electroless plating, which shortens the production process,reduces the production cost, and improves the quality of the composite powder.Different metal-coated carbide ceramic composite powders (WC-Ni、WC-Ag、SiC-Ni) havebeen synthesized by ultrasonic-assisted electroless plating process with chemical activationpretreatment at low temperature. Carbide ceramic powder itself has a certain surface catalyticactivity, and the catalytic activity of WC ceramic powder is strong enough to catalyze platingreaction without chemical activation pretreatment because of the unique surface electronicstructure. After chemical activation pretreatment, the fresh surface defects with special surfaceelectronic structure further enhance its surface catalytic activity, which not only improves theuniformity of the coating, but also strengthens the combination of the two phases. Metal particlesNi (Ag) nucleate along the defect, then carbide ceramic powder is paved with metal particleswith the three-dimensional growth step by step, finally, carbide ceramic-metal composite powderwith the core-shell structure is successfully prepared.The coating layer on the surface of45steel substrate is prepared by CO2laser claddingtechnology with the WC-Ni micro composite powder, which obtains the dendrite shape claddinglayer organization with uniform distribution of WC particles. The coating layer binds with thesteel substrate firmly, which belongs to the metallurgical combination. The microhardness of thecoating is improved significantly, the highest reaches1200HV. The wear rate of the coating is95.8%lower than sample matrix. After laser cladding, the plastic deformation and adhesive wearresistance are improved, and the abrasion characteristic of composite coating is mainly forabrasive wear.