| 摘要 |
1348201 Forming magnesium silicide CHROMALLOY AMERICAN CORP 14 April 1972 [17 May 1971] 17327/72 Heading C1A [Also in Division C7] A substrate is provided with a Si-containing coating and then subjected to pack diffusion coating in a Mg-containing pack containing a small amount of halide energizer whereby a coating containing Mg silicide is formed thereon. The substrate may be steel, Al, Al alloy, Ti, Ti alloy, or a ceramic such as Al 2 O 3 , and may be cleaned, e.g. by honing with powdered Al 2 O 3 prior to applying the Si-containing coating, which is typically applied from a solution of Na, K, Li or ethyl silicate by dipping or spraying followed by drying and curing, e.g. at 400‹ F; more than one coat may be applied. The pack may contain 5-100 wt. per cent Mg, up to 95% inert diluent (ZrO 2 , TiO 2 , HfO 2 , ThO 2 , rare earth oxide, SiC, TiC, WC, or preferably Al 2 O 3 ), and “-5% halide energizer, e.g. an ammonium halide or metal halide, e.g. AlCl 3 , or halogen such as I 2 ; heating in the pack is for “-60 hours at 700-1000‹ F.; a coating 0À2-1 mil. thick may be formed containing typically 20-60 wt. per cent Mg, Si, oxygen, and possibly substrate material. A Si-containing coating may be deposited on this coating and cured, as described above. The coatings so formed provide sacrificial protection for metals in marine environments. |
