Mechanical and electrical properties of Al2O3-TiO2 coating as electrical insulator

In a fusion reactor (i.e. ITER), the use of a ceramic coating on structural material (SS316LN-IG) has been considered as electrical insulator[1]. Al2O3 including TiO2 (Al2O3-TiO2) is one of most promising materials as coating from a point of high electrical resistivity and so on. However, crack and peeling occur by difference of thermal expansion between substrate material and coating material. Therefore, 80Ni-20Cr was selected as the undercoating between SS316LN-IG substrate and Al2O3-TiO2 coating. In this characterization, Al2O3-3%TiO2 and Al2O3-13%TiO2 were used as ceramic coating material. 80Ni-20Cr undercoating was fabricated by atmospheric plasma spray method. The thickness of 80Ni-20Cr was 50mum. Al2O3-3%TiO2 and Al2O3-13%TiO2 were fabricated by atmospheric plasma spray method. Thickness of these ceramic coatings are 200 and 500mum. From the results of out-of-pile test, it was clear that Al2O3-3%TiO2 and Al2O3-13%TiO2 coating had a good mechanical and electrical properties.