Al_2O_3基和Al_xTi_(1-x)N基复合涂层的电化学研究

Electrochemical study of Al_2O_3 based and Al_xTi_(1-x)N based composite coatings

采用动电位极化曲线和电化学阻抗谱方法,研究化学气相沉积方法制备的TiN/TiCN/TiAlCNO/Al_2O_3(简称Al_2O_3基)复合涂层,阴极电弧离子镀方法制备的Al_(0.55)Ti_(0.45)N/TiN(简称Al_(0.55)Ti_(0.45)N基)和Al_(0.67)Ti_(0.33)N/TiN(简称Al0.67Ti0.33N基)复合涂层在3.5%NaCl(质量分数)溶液中的电化学腐蚀行为。研究结果表明:Al_2O_3基、Al0.67Ti0.33N基和Al0.55Ti0.45N基复合涂层的孔隙率依次为0.34%,0.33%和0.02%,对基体的保护率依次为99.63%～99.91%,99.75%～99.93%和99.96%～99.99%;涂层合金耐腐蚀性能之间的差异实质上是涂层之间的差异;涂层耐腐蚀性能从高到低为Al0.55Ti0.45N(总厚度3.8μm),Al0.67Ti0.33N(总厚度6.3μm),Al_2O_3(总厚度15.1μm),其中总厚度最小的Al0.55Ti0.45N基涂层的耐腐蚀性能明显优于其他2种涂层的耐腐蚀性能;继续增大涂层厚度并不能进一步改善涂层对基体的保护效果和涂层的耐腐蚀性能。

Electrochemical corrosion behaviors of three composite coatings in3.5%NaCl(mass fraction)solution were studied by potentiodynamic polarization curve and electrochemical impedance spectroscopy.The coatings include TiN/TiCN/TiAlCNO/Al2O3(hereinafter referred to as Al2O3based)prepared by chemical vapor deposition and Al0.55Ti0.45N/TiN(Al0.55Ti0.45N based)and Al0.67Ti0.33N/TiN(Al0.67Ti0.33N based)by cathode arc evaporation ion plating.The results show that for Al2O3based,Al0.67Ti0.33N based and Al0.55Ti0.45N based composite coatings,the porosities are0.34%,0.33%and0.02%,respectively;the coating protection efficiencies for the substrate are99.63%-99.91%,99.75%-99.93%and99.96%-99.99%,respectively.The difference among the corrosion resistance of coated alloys is essentially caused by the kinds of coatings.The corrosion resistance of the coatings is ordered as:Al0.55Ti0.45N(total thickness3.8μm),Al0.67Ti0.33N(total thickness6.3μm),Al2O3(total thickness15.1μm).Compared with the other two coatings substantially higher corrosion resistance of Al0.55Ti0.45N based composite coating with the smallest thickness is observed.The protective effect of the coating on the substrate and the corrosion resistance of the coating cannot be further improved by increasing the coating thickness.