标题：Influence of additives on microstructure and property of microarc oxidized Mg-Si-O coatings
作者：Y.K. Pan;C.Z. Chen;D.G. Wang
作者机构：[Pan, Y.K] Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jing Shi Road 更多
通讯作者地址：[Chen, CZ]Shandong Univ, Minist Educ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Dept Mat Sci, Jing Shi Rd 17923, Jinan 250061, Shandong, Peoples 更多
关键词：C. Corrosion;Magnesium alloy;Ceramic coating;Microarc oxidation;Additives
摘要：Ceramic coatings were fabricated on ZK60 magnesium alloy substrate by microarc oxidation (MAO) in Na_2SiO_3-KOH base electrolyte with four kinds of additives (i.e. KF, NH_4HF_2, C_3H_8O_3 and H_2O_2). The effects of these additives on microstructure and property of coatings were investigated. The surface morphology, phase composition and corrosion resistance of the ceramic coatings were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and simulation body fluid (SBF) immersion test respectively. It is found that different additives can change the spark discharge phenomenon during microarc oxidation. It is proved that both potassium fluoride (KF) and ammonium bifluoride (NH_4HF_2) promote discharge and accelerate reaction while the introduce of glycerol (C_3H_8O_3) leads to the refining of sparks and reduction of thermal effects. Results also demonstrate that the introduce of hydrogen peroxide (H_2O_2) contributes to the increase of coating surface roughness and enlargement of surface micropore size. XRD results indicate that the ceramic coatings are mainly composed of Mg_2SiO_4, MgSiO_3 and SiO_2. The introduce of H_2O_2 hinders the reaction between SiO_2 and MgO and creates favorable conditions for the formation of the MgO phase. The ceramic coatings formed in base electrolyte containing 7 g/L NH_4HF_2 and 5 mL/L C_3H_8O_3 exhibit the highest corrosion resistance.