| 摘要 |
<p>The adhesion of a sprayed coating of heat and/or corrosion-resistant alloy based on iron and/or nickel and/or cobalt to a metal base is improved by first spraying a thin interlayer (preferably 0.001 - 0.002 inches thick) containing about 2-8 per cent of boron in combined form or in solid solution, and heating after the main coating has been applied to free the boron and make it diffuse into the base and main coating. Commercial ferro - boron, or nickel - boron, may be used for the interlayer, and the heating may be carried out in dry hydrogen at 800 - 1500 DEG C., or in vacuo, so that the interlayer as such disappears; the thickness of the main layer should for this reason be not less than five times that of the interlayer. The main coating may itself contain boron, e.g. about 0.04 per cent. The securing together of sintered metal bodies described in Specification 691,983 [Group XXII] may be effected. The coating of a high temperature steel containing: carbon 0.25 per cent, manganese 0.9 per cent, silicon 0.3 per cent, chromium 20.0 per cent, nickel 16.0 per cent, cobalt 25.0 per cent, boron 0.03 per cent, tungsten 2.75 per cent, molybdenum 2.4 per cent, niobium 0.5 per cent, titanium 0.6 per cent, iron and impurities the remainder, with a boron-containing alloy and then with a main layer of the same steel (such a steel being within the scope of the claims of Specification 746,472) is referred to.</p> |
