金相制备工艺对纳米氧化锆涂层显微组织评定的影响

Effects of Metallographic Preparation Process on the Microstructure Evaluation of Nano-Zirconia Coating

为制备出能够表征所分析样品真实状态的金相试样,从而对涂层的显微组织作出准确评价,以纳米氧化锆涂层为研究对象,采用不同镶嵌方式制备金相样品,基于正交试验研究不同磨抛工艺参数对涂层显微组织评定的影响,并通过纳米CT法测量涂层的孔隙率,对其结果进行验证。结果表明:采用真空冷镶嵌方式可显著减少涂层颗粒的脱落,影响涂层孔隙率的因素从大到小排序依次为粗磨时研磨盘转数、粗磨时夹具转数、粗抛时间、研磨及粗抛时压力。优化后最佳磨抛工艺参数如下:研磨及粗抛时压力为15 N,粗磨时研磨盘转数为200 r/min,粗磨时夹具转数为50 r/min,粗抛时间为9 min。此工艺下涂层孔隙率为4.26%,显著减少了涂层颗粒的脱落,能够制备出反映涂层真实显微组织结构的金相样品,达到了准确评价涂层性能的目的。纳米CT法检测结果与本方法相符。

In order to prepare metallographic samples that accurately characterize the true state of the analyzed samples and evaluate the microstructure of the coating precisely,taking nano-zirconia coating as the research object,metallographic samples were prepared by using different inlaying methods.The influence of different grinding and polishing process parameters on the microstructure evaluation of the coatings based on orthogonal tests was investigated,and the results were verified by measuring the porosity of coatings through the nano-CT method.Results showed that the method of vacuum cold inlay could significantly reduce the phenomenon of coating particle detachment.The factors affecting the porosity of the coating in order of magnitude were the number of revolutions of the grinding disc during rough grinding,the number of fixture revolutions during rough grinding,the polishing time during rough polishing and the pressure during grinding and rough polishing.The optimized parameters for the grinding and polishing process were 15 N pressure for grinding and rough polishing,200 r/min for the grinding disc during rough grinding,50 r/min for the fixture during rough grinding,and 9 min for rough polishing.The porosity of the coating under this process was 4.26%,which significantly reduced the phenomenon of shedding of coating particles and allowed the preparation of metallographic samples that reflected the true microstructure of the coating,thereby achieving the goal of accurately evaluating the performance of the coating.The results obtained by the nano-CT method were consistent with the present method.