Development of novel ceramic coatings with plasma electrolytic oxidation technique

本研究的目的是通过等离子体电解氧化（PEO）技术开发新型陶瓷涂层。本研究取得的主要成果如下：（1）具有磷灰石形成能力和光催化活性的新型氧化钛薄膜的开发为了提高骨与作为生物材料的钛合金之间的结合强度，我们对在体内形成具有高磷灰石形成能力的氧化钛薄膜提出了挑战。研究发现，以乙酸铵为电解质时，有利于氧化钛的结晶。因此可以获得高的磷灰石形成能力。我还发现，由二氧化钛组成的PEO膜具有相对较高的光催化活性，这意味着该材料可以通过使用紫外光轻松灭菌。磷灰石的形成是由于羟基芳香基团吸附在磷灰石（101）表面，将Ca^2+吸引到带负电荷的表面。 ...更多信息 f. (2)具有优良隔热性能的多孔氧化锆薄膜的研制喷气发动机涡轮机叶片用镍基单晶高温合金（SA），为了提高其耐热性，通常在SA表面涂覆ZrO_2。我挑战用PEO在SA上形成陶瓷涂层。在制备ZrO_2涂层之前，先用PEO在镀铝SA表面形成抗氧化Al_2O_3涂层。以K_2[ Zr（CO_3）_2（OH）_2]为电解液，采用PEO法在SA表面成功地制备了ZrO_2涂层。在结合强度和热屏蔽方面，涂层显示出与常规热障涂层相当的高性能。(3)含氮化硅颗粒的氧化物膜的制备我尝试用分散有氮化硅颗粒的电解液通过PEO在钛上制备含氮化硅颗粒的氧化物膜。我发现控制氮化硅含量的关键参数是每个周期的高压持续时间。持续时间的增加可由于火花放电而引起剧烈的局部对流，通过火花放电氮化硅颗粒被并入膜中。少

The aim of this study is to develop novel ceramic coating through the plasma electrolytic oxidation(PEO) technique. The results obtained in the study period are as follows;(1) Development of novel titanium oxide film with the apatite-forming ability as well as photocatalytic activityTo improve the bonding strength between bone and titanium alloy widely used as a biomaterial, we challenged to the formation of titanium oxide film which has high apatite-forming ability in vivo. I found that the crystallization of titanium oxide was promoted when ammonium acetate was chosen as an electrolyte of PEO. Then high apatite-forming ability can be consequently obtained. I also found that the PEO film consisted of titanium oxide had relatively high photocatalytic activity, which means that the material can be sterilized easily by using UV light. The apatite-forming ability is attributed to OH aromatic group absorbed on anatase(101) surface, which attracts Ca^<2+> to the negatively charged surface o … More f anatase.(2) Development of porous zirconia film with excellent heat shieldingNi-based single crystal superalloy(SA), which is utilized as a turbine blade of a jet engine, is usually coated with ZrO_2 in order to improve heat resistance. I challenged to form a ceramic coating on SA with PEO. Before making ZrO_2 coating, anti-oxidation Al_2O_3 coating was formed by using PEO on aluminum plated SA. The ZrO_2 coating on SA was successfully obtained by PEO with K_2[ Zr(CO_3)_2(OH)_2] as an electrolyte. In terms of adhesion strength and heat shielding, the coating showed high performance equivalent to the conventional thermal barrier coating.(3) Fabrication of oxide film containing silicon nitride particlesI tried to make oxide film containing silicon nitride particles on titanium by PEO with an electrolyte dispersed with silicon nitride particles. I found that the key parameter to control the content of silicon nitride is the duration of high voltage per cycle. The increase in the duration may cause vigorous local convection due to the spark discharge, by which silicon nitride particles are incorporated in the film. Less