Metallographic Preparation Technology of Porous Nickel-Graphite Thermal Spraying Coating

Because the hardness and toughness of metal skeleton, lubricating phase and pore in the nickel-graphite thermal spraying coating differ greatly, the surface defects of the metallographic sample such as pore enlargement, pulling out, scratch and water pollution were easy to appear, which led to the true micromorphology of the coating could not be reflect eventually. By means of improving and optimizing metallographic preparation parameters such as cutting sampling, inlaying and sample grinding, metallographic specimens of nickel-graphite thermal spraying coating were prepared. The results show that during the process of sample cutting added plastic sheet between the clamp and the sample, the sample were soaked in the anhydrous alcohol solution after cutting, special three times vacuum infiltration method inlaid sample, selecting the best polishing time and low recovery polishing cloth could truly show the pore morphology, quantity and distribution of each phase of the nickel-graphite thermal spraying coating.