| 摘要 |
1531056 Electro-deposited chromite coatings BNF METALS TECHNOLOGY CENTRE 1 June 1977 [1 June 1976] 22686/76 Heading C7B Metallic substrates are protected by cathodic electro-deposition of a chromite coating (i.e. containing Cr 2 O 3 ) from a bath containing Cr<SP>III</SP>, A "weak" CrIII complexant sufficient to keep the CrIII in solution and a poison for the cathodic conversion of CrIII to metallic Cr. Poisons specified are of three kinds; (a) oxidants (e.g. H 2 O 2 , peroxyacid salts, H 2 Cro 4 , CrVI and No 3 ); (b) H 2 overvoltage reducers (e.g. polyamines and phosphates) and (c) formaldehyde. The bath may include H 3 BO 3 and conductivity salts. The coating, believed to be Cr VI-free, may be aged to harden it. |
