Structural control and self-organization of the functional oxide films formed on titanium

1.自组织多孔阳极氧化物的形成在含磷酸二氢钠的热甘油溶液中，我们成功地在钛硅合金表面制备了自组织多孔阳极氧化膜。多孔膜形成的关键问题是抑制阳极氧化物的结晶，从而在阳极薄膜生长过程中诱导气体析出。在Nb和Al衬底上也制备了类似的多孔膜。铝表面多孔膜的大小取决于形成电压，与在酸性水溶液中形成的类似。2.形成具有优异介电性能的阻隔型阳极氧化物从衬底中引入外来物种有效地抑制了钛表面晶态阳极氧化物的形成。通过增加合金元素的含量，改变了阳极氧化前存在的空气形成膜的结构，使得非晶态氧化物的生长继续到更高的形成电压。3.钛合金电火花氧化硬化膜在含有铝酸盐和磷酸盐的碱性电解液中，对钛、Ti-6Al-4V和Ti-15V-3Al-3CR-3SN进行了电火花氧化。采用直流偏置交流高压阳极氧化技术制备了厚度约20μm的高晶态Al2TiO5基氧化物涂层。无论使用何种材料，均可获得硬度约为6 Gpa的涂层。涂层具有孔洞，与放电通道有关。根据火花氧化过程中的光学测量，估计放电区的温度为4500~5000℃。这样的高温使我们即使在室温下的水溶液中也能制备出高结晶度的涂层，其电解质物种的浓度也很高。

1.Formation of self-organized porous anodic oxideWe have successfully developed self-organized porous anodic oxide films on Ti-Si alloys in hot glycerol solution containing dibasic phosphate. The key issue for the formation of the porous films is suppression of the crystallization of anodic oxide, which induces gas evolution during anodic film growth. The similar porous films are also developed on niobium and aluminum substrates. The cell size of the porous films on aluminum is dependent upon the formation voltage, similar to those formed in acid aqueous solutions.2.Formation of barrier-type anodic oxide with excellent dielectric propertiesIncorporation of foreign species from substrate suppresses effectively the development of crystalline anodic oxide on titanium. By increasing alloying element content, the structure of the air-formed film present before anodizing is modified, such that growth of amorphous oxide continues to higher formation voltages. The compositional dependence of the dielectric properties of anodic oxides formed on a range of titanium alloys has been examined systematically.3.Hard coating of titanium alloys by spark anodizingSpark anodizing of titanium, Ti-6Al-4V and Ti-15V-3Al-3Cr-3Sn has been performed in alkarine electrolyte containing aluminate and phosphate. Highly crystalline Al2TiO5-based oxide coatings,〜20μm thick, have been developed by dc-biased ac anodizing to high voltages. Regardless of the materials used, the coatings with hardnes of 〜6GPa have been obtained. The coatings have porosity, associated with discharge channel. From optical measurements during spark anodizing, the temperature at the discharge region has been estimated to be 4500〜5000℃. Such high temperature allows us to develop the highly crystalline coatings with high concentration of electrolyte species even in an aqueous solution at ambient temperature.