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    CeO2添加量对粉末渗锌层耐磨性能和耐腐蚀性能的影响

    Effect of CeO2 Addition Amount on Wear Resistance and Corrosion Resistance of Powder Sherardizing Layers

    • 摘要: 在由锌粉、氯化铵粉和氧化铝粉组成的渗锌剂中添加质量分数分别为2%,4%,6%和8%的CeO2粉,采用粉末包埋渗锌法在440 ℃保温5 h条件下对Q235B钢板进行渗锌处理,研究了CeO2添加量对渗锌层显微组织、摩擦磨损性能和耐电化学腐蚀性能的影响。结果表明:不同CeO2添加量下的渗锌层均存在少量竖裂纹,随着CeO2添加量的增加,裂纹减少且变细,但当CeO2添加量超过4%(质量分数,下同)时,裂纹变多且变粗,4% CeO2添加量下的渗锌层结构最致密,裂纹最少且最细,质量最好;渗锌层表面主要为FeZn15相,CeO2添加量的增加使得FeZn8.87相和Fe3Zn10相的含量增加。随着CeO2添加量的增加,渗锌层的显微硬度增大,但过量的CeO2会导致硬度分布不均匀,4% CeO2添加量下的硬度分布最均匀。随着CeO2添加量的增加,渗锌层的平均摩擦因数和磨损质量损失均先减小后增加,磨损机制均以黏着磨损为主,同时存在轻微氧化磨损和磨粒磨损;4% CeO2添加量下的平均摩擦因数和磨损质量损失均最小,黏着磨损程度最轻,耐磨性能最好。随着CeO2添加量的增加,渗锌层的自腐蚀电流密度先增后减再增,电容弧半径先减后增再减,6% CeO2添加量下的自腐蚀电流密度最小,电容弧半径最大,耐腐蚀性能最好。

       

      Abstract: After adding 2%, 4%, 6% and 8% (mass fraction, below the same) CeO2 powder to the zincizing agent composed of zinc powder, ammonium chloride powder and aluminum oxide powder, Q235B steel plate was zincized by powder embedding zincizing method at 440 ℃ for 5 h. The effects of CeO2 addition amount on the microstructure, friction and wear properties and electrochemical corrosion resistance of the sherardizing layer were studied. The results show that there were a few vertical cracks in the sherardizing layer under different addition amounts of CeO2. With the increase of CeO2 addition amount, the number of cracks decreased and became finer, but when the CeO2 addition amount exceeded 4%, the cracks became more and coarser. The structure of the sherardizing layer with 4% CeO2 addition was the densest, the cracks were the least and the finest, and the quality was the best. The surface of the sherardizing layer was mainly FeZn15 phase, and the content of FeZn8.87 and Fe3Zn10 phases increased with the increase of CeO2 addition amount. With the increase of CeO2 addition amount, the microhardness of sherardizing layer increased, but the excessive CeO2 led to uneven distribution of hardness, and the hardness distribution under 4% CeO2 addition was the most uniform. With the increase of CeO2 addition amount, the average friction coefficient and wear mass loss of the sherardizing layer first decreased and then increased, and the wear mechanism was mainly adhesive wear, with slight oxidative wear and abrasive wear. The average friction coefficient and wear mass loss under 4% CeO2 addition were the smallest, and its degree of adhesive wear was the lightest, showing the best wear resistance. With the increase of CeO2 addition amount, the free-corrosion current density of sherardizing layer first increased and then decreased and then increased again, and the capacitive arc radius first decreased and then increased and then decreased. The free-corrosion current density under the addition of 6% CeO2 was the smallest and the capacitive arc radius was the largest, showing the best corrosion resistancee.

       

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