Abstract: A nitrohydrofluoric development bath for use in an electro-chemical etching rocess, known as the "blue etch process", for the non-destructive inspection of titanium or titanium alloy components such as turbo-machine blades and discs, the bath comprising, per liter, 320 g of nitric acid, from 13 to 22 g of hydrofluoric acid, from 4 to 7 g of dissolved titanium, and water as the balance.

Abstract: A process for depositing an anti-wear coating on a titanium-based substrate comprises:a) roughening the substrate by sanding;b) deposition of a keying nickel sub-layer on the substrate by cathodic spraying (cathode sputtering);c) intermediate cleaning;d) activation of the cleaned part by immersion of the part in a cyanide bath;e) electrolytic deposition of nickel; andf) deposition of a final, anti-wear layer of a material selected from the group consisting of Ag, Cr, Ni, Co, and mixtures thereof, with or without ceramic particles such as SiC, Cr.sub.2 C.sub.3, Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3.

Abstract: Engine components of steel or superalloy subject to wear from alternating friction at medium temperatures in the region of 700.degree. C. are provided with a protective wear-resistant coating bya) electrophoretic deposition of a metal-ceramic structure comprising a mixture of from 85% to 50% of metallic powder and from 15% to 59% of ceramic powder, the metallic powder being a cobalt-based superalloy of type KC 25 NW or of M Cr Al Y wherein M represents at least one metal chosen from the group consisting of Ni, Co and Fe with the possible addition of Ta, and the ceramic powder being an oxide such as Al.sub.2 O.sub.3 or Cr.sub.2 O.sub.3, a carbide such as SiC or Cr.sub.3 C.sub.2, a nitride such as BN or TiN, or a boride such as TiB.sub.2 ;b) electrolytic pre-nickeling said deposit in an electrolysis bath at a pH between 6 and 8, andc) electrolytic nickeling said pre-nickeled deposit in an acid bath of sulphamate type.

Abstract: Engine components of steel or superalloy subject to wear from alternating friction at medium temperatures in the region of 700.degree. C. are provided with a protective wear-resistant coating bya) electrophoretic deposition of a metal-ceramic structure comprising a mixture of from 85% to 50% of metallic powder and from 15% to 50% of ceramic powder, the metallic powder being a cobalt-based superalloy of type KC 25 NW or of M Cr Al Y wherein M represents at least one metal chosen from the group consisting of Ni, Co and Fe with the possible addition of Ta, and the ceramic powder being an oxide such as Al.sub.2 O.sub.3 or Cr.sub.2 O.sub.3, a carbide such as SiC or Cr.sub.3 C.sub.2, a nitride such as BN or TiN, or a boride such as TiB.sub.2 ;b) electrolytic pre-nickeling said deposit in an electrolysis bath at a pH between 6 and 8, andc) electrolytic nickeling said pre-nickeled deposit in an acid bath of sulphamate type.

Abstract: Alloy steel or nickel based superalloy parts may be given protection against oxidation and frictional wear at temperatures below 600.degree. C. by means of a protective coating applied by electrolyte codeposition of a nickel-cobalt matrix comprising a uniform dispersion of ceramic particles selected from a group of carbides and oxides including SiC, Al.sub.2 O.sub.3, and Cr.sub.2 O.sub.3, the mass content of the ceramic particles being between 3.5% and 10%. The deposition is carried out in a sulfamate bath comprising a metallic salts content (Ni+Co) of from 70 g/l to 100 g/l, a Ni/Co mass ratio of from 5 to 33, and a mass content of the ceramic particles in suspension of from 50 g/l to 300 g/l.

Abstract: In an electrolytic process of silvering stainless steel parts having a hardness of at least 58 HRc, the parts are subjected to degreasing with a solvent and by electrolysis in an alkaline atmosphere before undergoing electrolytic attack in an acid atmosphere, Wood prenickeling, electrolytic neutralization and then electroytic silvering in two successive distinct operations, these being a presilvering operation in a cyanide bath such that the free KCN/metal Ag ratio is at least 15, and a silvering operation in a similar bath which also contains potash and in which the free KCN/metal Ag ratio is about 10 times lower than in the presilvering bath. The process enables thin, adherent silver coatings to be deposited in a consistent manner on stainless steel parts, such as ball or roller races, before applying a self-lubricating coating to the parts.