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涂覆预处理对SiC增强铁基堆焊层组织的影响

Effect of precoating on microstructure of SiC reinforced iron-based coating

  • 摘要: 采用PIRAC技术处理后SiC表面的涂覆层由Cr3Si,Cr7C3,Cr23C6等组成.通过等离子堆焊-后送粉技术制备SiC增强铁基合金复合涂层.结果表明,未预涂覆SiC颗粒在涂层表层完全分解,由于分解产物碳、硅扩散不均匀,影响了各区域的成分.上部出现大量初生多边形状碳化物,中部为树枝晶,底部为不规则胞状晶.预涂覆SiC颗粒分布在涂层表面上,没有发生明显溶解,原始形态保持完好.SiC颗粒与基体之间包括界面反应区和过渡区,界面反应区由(Fe,Cr)7C3,(Fe,Cr)23C6碳化物和α-(Fe,Cr)固溶体组成;过渡区为固溶较多Cr元素的α-(Fe,Cr)固溶体,耐蚀性较好,形貌难以显示.

     

    Abstract: The reaction layers consisting of Cr3Si,Cr7C3 and Cr23C6 were produced on SiC surface by PIRAC technology. The iron-based alloy coating reinforced by precoated SiC particles was prepared by plasma surfacing process with the back-feeding model. The results show that the non-precoated SiC particles dissolve completely in the coating. Massive primary polygonal carbides formed in the upper part,dendrites formed in the middle part and cellular grains generated in the bottom part. The precoated SiC particles distributed in the coating surface,retaining the original shape,and did not dissolve significantly. The region between SiC particles and the matrix could be divided into the interface reaction zone and the transition zone. The interface reaction zone consisted of α-(Fe,Cr) solid solution,massive (Fe,Cr)7C3 and (Fe,Cr)23C6 carbides. The transition zone consisted of the α-(Fe,Cr) solid solution with high Cr content,and it was difficult to expose the microstructure due to its excellent corrosion resistance.

     

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