Cr元素含量对铜基原位复合材料耐蚀性的影响

Effects of Cr element content on corrosion resistance of in-situ copper matrix composites

采用选择腐蚀技术,提取了铜基原位复合材料中纤维相,并测定其电极电位。通过间歇式盐水喷雾试验和极化曲线测定,研究了Cu-15Fe、Cu-14Fe-1Cr、Cu-13Fe-2Cr、Cu-11Fe-4Cr四种原位复合材料在NaHSO3+NaCl混合介质中的腐蚀行为。同时用扫描电镜对腐蚀产物和腐蚀表面进行分析。结果表明,Cu-15Fe原位复合材料在NaHSO3+NaCl介质中,腐蚀电位EFe<ECu,故Cu基体为阴极,Fe相纤维为阳极。Cr元素的加入,使Fe-Cr相纤维为阴极,基体铜为阳极。随着Cr元素含量的增加,EFe-Cr正向移动,致钝电位负移,维钝电流密度降低,钝化区范围增大,EFe-Cr-ECu降低,材料的耐蚀性提高。

Selective etching technique was adopted to extract fibers from four in-situ copper matrix composites （Cu-15Fe, Cu-14Fe-Cr, Cu-13Fe-2Cr and Cu-11Fe-4Cr）. The electrode potential of the fibers was measured and the corrosion behaviors of composites in NaHSO3 ＋ NaCl solution were investigated. The results of salt spraying tests, polarization curves measurements and SEM observation show that matrix metal Cu is cathode and Fe fiber is anode due to Ere 〈 ECu for Cu-15Fe in-situ composite while Fe-Cr fiber is cathode and matrix metal Cu is anode because of the addition of Cr to the composites for the other composites. With the increase of Cr content, Erect shifts to the more positive level and passivation potential shifts to the more negative level and passive current density drops. Based on the above analysis, for composites with higher Cr content, the passivation region is enlarged and the difference between Erect and Eco becomes smaller thus its corrosion resistance is improved.