| 摘要 |
PURPOSE:To provide a cermet powder containing ZrO2 and Co for preventing oxide scale of steel material from adhering onto the roll surface when the cermet powder is flame spraged onto the roller. CONSTITUTION:A ZrO2 powder and a Co powder are mixed so that the content of Co may become 10-40wt%, the mixture is pressurized, and then heated at 1,400 deg.C for approx. 1hr in non-oxidizing atmosphere or vacuum to produce a sintered lump. Or, cobalt oxide powder is mixed with ZrO2 powder so that the content of Co may become 10-40wt%, the mixture is compressed, and heated at 1,400 deg.C in reducing atmosphere such as hydrogen to reduce the cobalt oxide to Co so as to produce sintered ZrO2-Co lump. The sintered lump is pulverized to produce a ZrO2-Co cermet powder of 200-400 mesh. This cermet powder is flame sprayed to the surface of a hearth roller in a heat-treatment furnace to form a metallized film which is strong against heat shock and difficult to adhere iron oxide scale thereto. |
