| 摘要 |
1318609 Coating with metals DEUTSCHE EDELSTAHLWERKE AG 16 Oct 1970 [3 Nov 1969] 49270/70 Headings C7B and C7F A metal part of e.g. steel, Ni, Co or Ni-Co is coated with Cr and/or Si and a Pt group metal The coatings are completely diffused e.g. by heating in a protective atmosphere or vacuum at 900 to 1250‹ C. The coating may also contain Al. Either the Cr or Si or the Pt group metal may be applied first or both may be applied simultaneously. In an example the surface is wet blasted and degreased in a cyanide bath cathodically for 5 seconds and anodically for 15 seconds, pickled in H 2 SO 4 at a current density of 2 amps/dm<SP>2</SP> for 3 seconds, anodically and then for 2 seconds cathodically, and then immersed in caustic soda for 5 seconds cathodically and 15 seconds anodically. Pt is then electrolytically deposited from a bath consisting of (g/l):- 13 of hexachloroplatinic acid, 45 of triammonium phosphate, 240 of disodium hydrogen phosphate. The coating is then heated for 2 hours at 260‹ C and 3 hours at 450‹ C. The surface is then chromised in a pack at 1100‹ C comprising 12À5% Cr, 12À5% ferrochrome, 75% alumina and 0À2% chromium chloride. In another example Pd is electro-plated from a bath comprising (g/1.) 5 of Pd Cl 2 , 55 of (NH 4 ) 2 HPO 4 , 240 of Na 2 HPO 4 and 3À5 of benzoic acid. The coated surface is then heated at 260‹C for 2 hours and 450‹ C for 3 hours. The Pd-surface is then chromized as in the previous example. The substrates may also be plated with RU 4 or Rh. |
