ZHANG Yaping 1,2,3 , LIU Xiangdong 2,3 , LV Kai 2,3 , CHR Guangdong 2,3 , YAN Shufang 2,3
(1.School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot Inner Mongolia 010011, China; 2. Key Laboratory of Materials Processing & Control Engineering of Inner Mongolia Autonomous Region, Inner Mongolia University of Technology, Hohhot Inner Mongolia 010051, China; 3. Inner Mongolia Vocational College of
Chemical Engineering, Hohhot Inner Mongolia 010011, China)
Abstract: In Na2SiO3 electrolyte system contained a certain amount of CaCl2 or MgCl2, ceramic coating were prepared on the surface of Ti6Al4V alloy by micro-arc oxidation in this work. The effects of CaCl2/MgCl2 in the base electrolyte system on the formation and characteristics of coatings were investigated. The results show that the arc starting forward voltages increase from 350V to 358V with the increase of CaCl2 from 0.05 g/L to 0.35 g/L in the electrolyte. Similarly, for the increase of MgCl2 from 0.05 g/L to 0.35 g/L, the arc starting voltages increase from 330V to 369V. It is found by SEM that the amount of pores in the alloy surfaces decreases with the increase of CaCl2 in the electrolyte and many ceramic particles, 5μm in diameter, exist on the surfaces of the coatings. The surfaces of the coatings become looser. The amount of pores in the alloy surfaces also decreases with the increase of MgCl2 in the electrolyte. The results of EDS analysis indicate that there are Ti, Na, Al, Si, P and O in the coatings formed in the electrolytes containing CaCl2 or MgCl2. The amount of Ca element in the coatings formed in the electrolytes containing CaCl2 or MgCl2 increases slightly but there is not obvious variation in the amount of Ca element, comparing with that of the coatings formed in the base electrolyte. The results of XRD analysis show that anatase phase TiO2 in the coatings increases with the increase of CaCl2, but rutile phase TiO2 increases while CaCl2 is added to the electrolyte.
Keywords: Ti6Al4V, micro-arc oxidation, electrolyte, CaCl2, MgCl2, coating