The dense refractory is applied for the high-temperature glass melting equipment. Furthermore, platinum or its alloy-clad refractory bricks are utilized to melt high quality glass in fields of optical and display glasses. From the viewpoint of the resource saving of rare metal, the decreasing of Pt-consumption is very serious problem for glass manufacturing. The platinum thermal spray coating is effective alternative technology to solve this problem for platinum cladding. A Pt-spray coated ceramics is difficult to get reliability due to the large difference of thermal expansion between the ceramic and the metal. In this study, we have investigated the bond strength of the platinum coat on the dense refractories which was textured by the mechanical process. As a result, the bond strength between the ceramic and the metal is 3-5 MPa. It is almost the same as the thermal spray ceramics coating on the metal. Furthermore, in case of the ceramics substrate that contains the glass phase, the bond strength between the ceramic and the metal increased to 14-17 MPa after 1773 K heat treatment.

In the production line of glass sheets, the 8%Y 2 O 3 -ZrO 2 thermal spray coatings have put into practical uses. These coatings have under layers of metal Cr 3 C 2 -Ni/Cr cermets, to improve their bonding strength. In forming process of glass, non-oxygenated atmosphere containing sulfur dioxide is selected continually to improve the surface condition of glass sheets. Degradation and pealing of these coating have been observed frequently due to increasing of SO 2 concentration. In this study, effects of SO 2 on decay durability of the 8YZ coating having meta cermet under coat are examined. Interactions between the atmosphere and the top-layer or the under layer are clarified individually by some basic examinations and analysis. It is clarified that peeling of the bi-layer coating was occurred at the boundary region between top coat and under coat. By exposure test of the coated sample and some powders for N 2 -SO 2 at 113K, following results obtained, 1) Some cracks and fine streaks are observed also, in the bottom region of the ZrO 2 top layer after the exposure test of coated sample.. 2) Main components of these streaks are Cr and S. 3) Sulfur contents of Cr 3 C 2 cermet and Cr 3 C 2 are increased remarkably by the exposure test. 4) By the exposure, Cr 3 C 2 can be converted into a Cr 2 O 3 or a CrSx. due to reaction with SO 2 . As peeling of the coating on carrying roll is induced by oxidation and sulfurization of Cr 3 C 2 , the under layer of Cr 3 C 2 cermet is not suitable especially as its under coat.