Nickel aluminide coated low alloy stainless steel
    2.
    发明授权
    Nickel aluminide coated low alloy stainless steel 失效
    镍合金涂层低合金不锈钢

    公开(公告)号:US3762884A

    公开(公告)日:1973-10-02

    申请号:US3762884D

    申请日:1971-10-18

    申请人: NASA

    发明人: GRISAFFE S KLECHKE E

    摘要: Low alloy austenitic stainless steel is protected from oxidative corrosion and erosion at high temperatures in the presence of exhaust gases from internal combustion engines by flame-spraying a layer between about 0.003 inches and about 0.007 inches thick of an alloy of 80 percent nickel and 20 percent chromium on the steel base, and thereafter converting the layer to an intermetallic chromium containing nickel aluminide coating by a low temperature aluminum cementation process. A cementation pack comprising 96 percent aluminum oxide, 2 percent aluminum, 1 percent sodium chloride, and 1 percent ammonium bifluoride is placed on the nickel-chromium layer in an inert atmosphere for a period between four hours and 24 hours at 1400*F to 1600*F to form an intermetallic chromium containing nickel aluminide coating containing 40 to 60 atomic percent aluminum. The coated steel is highly resistant to oxidation corrosion and erosion by high temperature exhaust gases from internal combustion engines. It is particularly useful in the construction of thermal reactors for exhaust systems in automobiles for the control of pollution from exhausts.