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采用扫描电镜(SEM)、X光电子能谱分析仪(XPS)等分析手段,研究了NiTi合金表面绝缘膜的结构及成分,从而探讨非阀金属NiTi合金表面微弧氧化陶瓷膜层的形成机制。结果表明,NiTi合金微弧氧化过程中的电流密度-时间曲线与纯钛形状基本一致,也可分为3个阶段,但其最大的电流密度为后者的13倍;NiTi合金表面的绝缘膜主要是通过电化学沉积形成的Al2O3及少量的TiO2、Ni2O3和磷酸盐薄膜,这一绝缘膜就相当于阀金属的阳极氧化膜,为NiTi合金进行微弧氧化处理提供了前提条件;NiTi合金表面的陶瓷膜层主要来源于电解液中的铝酸根离子和少量的基体Ni和Ti(包括固态的和溶解于电解液中离子态的),经反复的放电、熔融、喷射、冷却、凝固,发生一系列的电化学、等离子体化学和热化学反应最终形成表面粗糙多孔陶瓷膜层。
The structure and composition of the insulating film on the surface of NiTi alloy were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The formation mechanism of MAO film on the non-valve metal NiTi alloy surface was investigated. The results show that the current density-time curve during the micro-arc oxidation of NiTi alloy is basically the same as the shape of pure titanium and can be divided into three stages, but the maximum current density is 13 times that of NiTi alloy. The dielectric film on the surface of NiTi alloy Mainly formed by electrochemical deposition of Al2O3 and a small amount of TiO2, Ni2O3 and phosphate film, the insulating film is equivalent to the valve metal anodic oxide film for NiTi alloy micro-arc oxidation treatment provided the precondition; NiTi alloy surface Of the ceramic film mainly from the electrolyte of the aluminate ions and a small amount of matrix Ni and Ti (including solid and dissolved in the electrolyte in the ionic state), after repeated discharge, melting, jetting, cooling, solidification occurred A series of electrochemical, plasma chemical and thermochemical reactions eventually form a porous, porous, ceramic coating.