交/直流电源模式下BaTiO_3薄膜生长方式及微观结构研究

Synthesis and Microstructures of BaTiO_3 Coatings by AC/DC Micro-Arc Oxidation

Ba(OH)2电解液中,分别采用交/直流源微弧氧化法在Ti基体表面制备了钛酸钡薄膜,并分别研究了两种薄膜的生长方式及微观结构。结果表明:交、直流源模式下所得Ba Ti O3薄膜的晶体结构分别主要由六方相、四方相构成;交流模式下薄膜从试样边角向中心呈层片状生长,直流模式下薄膜生长则主要依靠缓慢移动的连续电弧在膜层较薄弱区域发生的放电击穿;交流源模式下所得薄膜表面较平整、致密性较好;两种电流源模式下所得膜层均分布着大小不一的微弧氧化孔洞,但直流源模式下所得薄膜中孔洞分布较少。

The BaTiO3 coatings were deposited in Ba（OH）2 solution by AC/DC micro-arc oxidation （MAO） on Tisubstrate.The influence of the growth conditions, including but not limited to the arc mode, scanning-speed of micro-arc and current density, on the microstructures of the coatings were investigated with X-ray diffraction, scanning electron mi- croscopy and metallurgical microscope. The results show that AC and DC modes of micro-arc significantly affect the growth mechanisms and microstructures of the BaTiO3 coatings. To be specific, with AC arc, the laminar islands of hexagonal- phased, porous BaTiO3coatings were grown from the substrate＇ s edges to the center; whereas with DC arc, highly non-uni- form tetragonal-phased, porous BaTiO3 coatings were deposited, possibly because of the localized discharge of the slowly- moving, continuous arc at the film＇s thinner spots. The BaTiO3 coatings synthesized by AC MAO have smoother and more compact surfaces but higher porosity than the films deposited by DC MAO.