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 glass manufacturing, stainless-steel parts are used in characteristic corrosive reduction atmosphere at high temperature. The reactive products, that are induced by volatilization from the stainless steel surface, cause defects of the glass in this usage. Some thermal spraying coating of thermal-resistant alloys is tested in this study for the protection to the volatilization. It is clarified that, the Ni-Cr-Al-Y film, containing plate-like metal oxide dispersions, shows an outstanding effect as followings; 1) The diffusion rate of Fe from a stainless substrate in this coating film is decreased by the dispersions, and Fe is not detected at surface layer of the coating after a long-term exposure test at high temperature. 2) The reaction between Sn and this coating is not active relatively can, and the further inactivation can be possible by pre-existing heat-treatment in oxidant atmosphere. 3) Both effect (decreasing of Fe diffusion rate and inactivation with Sn) are induced by plate-like Al 2 O 3 particles. These particles are generated by oxidation of Al-content in the coating material.

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.

The boride cermets composed of M3B2 (M: metal)-system complex borides and metals, have attained superiority over carbide cermets in various mechanical properties. However, their sintered materials have been put into only limited use due to the cost. Therefore, thermal spray coating of the boride cermets was investigated. The powders for thermal spray were prepared by low temperature sintering, and the spraying was performed by HVOF. Microstructure of the sprayed layer was finer, and its hardness was superior to that of a body sintered in vacuum having the same composition. It is clarified that these boride cermet coated layers have outstanding sliding properties. Instantly frictional stress between this boride cermet layer and glass at high temperature is extremely low compared to other materials.