多孔镍-石墨热喷涂涂层的金相制备技术

Metallographic Preparation Technology of Porous Nickel-Graphite Thermal Spraying Coating

由于镍-石墨热喷涂涂层中金属骨架、润滑相及孔隙各相的硬度和韧性差异较大,使得金相试样表面容易出现孔隙扩大、拔出、划痕、水污等制样缺陷,导致无法反映涂层的真实微观形貌。通过改进和优化切割取样、镶嵌、试样磨抛等金相制备参数,制备了镍-石墨热喷涂涂层金相试样。结果表明:试样切割取样过程中在夹具与试样之间加装塑料薄片,切割后试样浸没于无水酒精溶液清洗,特殊的3次真空浸渗方式镶嵌试样,选择最佳抛光时间和低回复性抛光布,能真实呈现镍-石墨热喷涂涂层各相的形貌、数量和分布。

Because the hardness and toughness of metal skeleton,lubricating phase and pore in the nickelgraphite 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.