304不锈钢磁控溅射TiN_x薄膜不同偏压时的结构和耐蚀性能

Effect of Bias Voltage on Microstructure and Corrosion Resistance of Magnetron Sputtered Ti NxNanocrystalline Film on 304 Stainless Steel Substrate

基体偏压是影响磁控溅射TiNx薄膜结构和性能的关键因素,且TiNx薄膜的结构与其耐蚀性有极大的关系。利用直流反应磁控溅射技术,通过改变基体偏压在304不锈钢表面制备了具有结构缺陷和不同化学计量比的TiNx薄膜。采用原子力显微镜(AFM)、X射线衍射、场发射扫描电子显微镜、电化学技术研究了TiNx薄膜的表面形貌、相结构和耐蚀性与偏压的关系。结果表明:TiNx薄膜的表面结构与偏压明显相关,适当的偏压有利于获得细小、均匀、致密和光滑的TiNx薄膜;TiNx薄膜为B1-NaCl型面心立方结构,其择优取向为(111)面,增加偏压有利于获得符合化学计量比的TiNx薄膜;致密、光滑和符合化学计量比的TiNx薄膜具有更低的腐蚀倾向;不同化学计量比的TiNx薄膜的腐蚀均为局部剥离,且与该处高密度结构缺陷相关;减少TiNx薄膜的针孔等结构缺陷对于提高其耐蚀性极为重要。

TiNx films with structural defects and different stoichiometric ratios were prepared on AISI304 stainless steel by direct current reactive magnetron sputtering under different negative bias voltages. The effect of the bias voltage on the surface morphology,phase composition,microstructure and corrosion resistance of as-prepared TiNx nanocrystalline films was investigated with an atomic force microscope,an X-ray diffractometer,a field emission scanning electron microscope and an electrochemical test rig. Results showed that the surface microstructure of the TiNx films was strongly dependent on the bias voltage,and applying proper bias voltage was beneficial to obtaining the target films with fine,dense,uniform and smooth structure. Besides,as-prepared TiNx film possessed fcc structure of B1- Na Cl,and its preferential orientation was( 111) plane. Increasing bias voltages was favorable for acquiringTiNx films with stoichiometric ratio. Moreover,the as-fabricated TiNx films with compact and smooth structure as well as stoichiometric ratios exhibited good corrosion resistance. The TiNx films with different stoichiometric ratios were all dominated by local peeling off as they underwent corrosion,and their corrosion behavior was closely related to high density of structural defects. In addition,it was imperative to reduce the amount of through film pores or large structural defects in as-sputtered TiNx films so as to improve their corrosion resistance.