| 摘要 |
PURPOSE:To make it possible to form easily a strong coated layer substantially without air void and release with the inner face of a tube-like body, by filling and sealing small particles whose thermal expansion coefficient is sufficiently larger than that of the tube-like body in the tube-like body when a ceramic-coated layer is calcinated by heating. CONSTITUTION:The inner face of a metal tube-like body having an oxidized film, for example, an exhaust manifold, is coated with an inorganic binder solution such as sodium silicate and so on by means of spraying and so on. A ceramic powder is adhered on the solution layer obtained of a uniform thickness. Then, if necessary, conditioning with humidity is carried out and a ceramic layer is completely immersed and solidified with the inorganic binder solution. It is generally preferable that the ceramic-coated layer is constituted of a fireproof insulating layer and a fireproof layer. Then, small particles such as steel and copper particles are sealed and packed as dense as possible in the tube-like body. Then, baking is carried out at a temp. lower than 780 deg.C where transformation of a casting generally occurs. As the thermal expansion coefficient of the small particles is sufficiently larger than that of the tube-like body, the ceramic layer is strongly pressed on the inner face of the tube-like body. Then, after baking by heating, the tube-like body is cooled in the oven and the small particles are therefrom taken out.
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