| 摘要 |
PURPOSE:To improve the heat radiation rate of a refractory metal by successively forming a metal bond coating layer, composed of the same material as a refractory metal constituting a substrate, and a ceramic top coat layer on the surface of the substrate composed of the refractory metal and closing the pores in the ceramic top coat layer with the refractory metal by means of vacuum high temp. treatment. CONSTITUTION:The surface of a metallic substrate 1 composed of Ta is blasted and then plasma-arc-sprayed with Ta powder, by which a metal bond coating layer 3 of about 0.05-0.1mm thickness is formed. Subsequently, the surface of the metal bond coating layer 3 is plasma-arc-sprayed with zirconia yttria powder, by which a ceramic top coat layer 5 of 0.15-0.25mm thickness is formed. This metallic substrate 1 is put into a vacuum heating furnace and heated at about 1700 deg.C for about 2hr at about 1X10<-4> Torr degree of vacuum, followed by natural cooling. By this method, the Ta forming the metal bond coating layer 3 is allowed to diffuse into the pores formed in the inner part of the ceramic top coat layer 5 to close the pores with metallic lumps 7, by which the heat radiation rate of the metallic substrate 1 can be improved. |
