GB1338515A - Chromium electro-plating of titanium - Google Patents

Abstract

1338515 Chromium electro-plating of titanium; cleaning Ti alloys SUPERIOR PLATING CO 19 April 1971 [20 April 1970 5 March 1971] 26234/71 Headings C7B and C7E A method for depositing a hard chromium electro-plate on a Ti or Ti alloy substrate comprises (a) electro-plating a layer of Cr on the substrate, (b) subjecting the electro-plated substrate to a heat treatment at a temperature in the range of 1600‹F. to 1900‹F. for a time sufficient to allow for diffusion bonding of the Cr to the substrate but brief enough so as not to have any significant effect on the physical properties of the substrate, (c) cooling the substrate to approximately room temperature, and (d) electro-plating on the first Cr layer a layer of hard Cr. The substrate may be of Ti alloys containing (a) 6 per cent Al and 4 per cent V or (b) 7 per cent Al and 4 per cent Mo. It can be initially honed, chemically or mechanically polished, and be activated. Activation can be either by anodic treatment in a solution of glacial CH 3 COOH and HF using a Pb or stainless steel cathode and an anode cathode distance of # inch (see Example I) or by soaking in an acidic etching solution, e.g. of H 3 PO 4 , H 2 SO 4 and HF (see Example III). The Cr may be deposited from a conventional bath e.g. of H 2 CrO 4 , H 2 SO 4 and H 2 O. The heat treatment may be in an induction furnace, e.g. in an inert atmosphere of He or Ar. The cooling may be in H 2 O, air or an inert atmosphere. The Cr plated substrate may then be subjected to shot peening to increase its fatigue strength it may be activated by anodic treatment in a Cr plating solution and the second Cr layer then be deposited by switching the leads. Where worn Ti parts are to be electro-plated, additional Cr may be electro-plated with the initial Cr which, after the heat treatment and cooling, can be machined to size thus replacing worn Ti with Cr.