Research on the Characterization of Ag+Cu+B83 Composite Coatings on the Surface of Tin Bronze by Electro-spark Deposition

The composite coatings of the tin bronze surface that was formed by alternately Electro-spark deposition (ESD) applying the soft anti-friction material of silver, copper, and babbit B83. The analysis of deposition on mass, roughness, cross-section morphology, surface morphology, thickness, elemental composition, and microhardness of the coatings were investigated by electronic scales, 3D optical profilometers, metallographic microscope, scanning electron microscopy (SEM), energy dispersion spectrum (EDS) and Vickers microhardness tester. The results show that the optimal process parameters of ESD are as follows: voltage is 60V/60V/30V, capacitance is 150μF/150μF/90μF and productive capacity is 3(min/cm2) /3(min/cm2) /4(min/cm2), respectively. Under the optimal parameters, the unit coating mass of the substrate is 54.4 mg/cm2, and the surface roughness of the coating is 32.3μm. The coatings are dense, metallurgical fusion with the substrate, and under the optimal parameters, the thickness of the coatings is about 100 μm. The elemental composition of the three characteristic regions (smooth surface, rough surface, and pore) on the surface of the composite coating varies significantly due to the different production modes. The hardness distribution from the coating surface to the substrate increases first, then decreases, and then increases gradually. The surface microhardness of the composite coatings is 29 HV0.01, which is about 82% lower than that of the tin bronze substrate (161 HV0.01).