Effect of TiO2 content on properties of Al2O3 thermal barrier coatings by plasma spraying
(1. School of Materials Science and Engineering, Shandong University, Ji’nan 250061, China;
2. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Jin’an 250061, China;
3. School of Energy and Power Engineering, Shandong University, Ji’nan 250061, China)
2. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials of Ministry of Education, Shandong University, Jin’an 250061, China;
3. School of Energy and Power Engineering, Shandong University, Ji’nan 250061, China)
Abstract: Al2O3 thermal barrier coatings with different TiO2 contents were deposited on 6061 aluminum alloy by plasma spraying. The corrosion resistance, thermal insulation property and phase composition of these coatings were investigated. The results indicate that all the feedstock powders exhibit phase transformation during the spray process. With the increase of the TiO2 content in the powder, the corrosion resistance of the coating is enhanced but the thermal insulation property is decreased. This can be attributed to the higher thermal conductivity but lower melting point and brittleness of TiO2 than those of Al2O3, so it is easy for TiO2 to disperse in the brittle Al2O3 substrate during spraying, in which these dispersively distributed TiO2 play the role of hole sealing, releasing stress and reducing cracks.
Key words: plasma spray; corrosion resistance; thermal insulation property; phase transformation; TiO2