Process for continuous recovery of nitric acid/hydrofluoric acid titanium etchant
AssigneeMcDonnell Douglas Corporation
InventorsDolphus L. Coggins, Walter E. Lindner
Life of this patent
Estimating the term…
Abstract
A process of continuously chemically milling refractory metals, e.g., titanium using a supersaturated milling solution which form a water soluble precipitate, milling at temperatures of 140.degree.-160.degree. F., and using two chemical milling tanks so that the milling solution is pumped from one to the other when the precipitate builds up in the first tank to a predetermined level. The water soluble precipitate is easily and inexpensively disposed of and the process makes more efficient use of chemicals.
Claims8
A process for chemically milling titanium and its alloys comprising:
- (a) forming a chemically milling solution saturated in titanium in a first etch tank;
- (b) immersing titanium containing parts in the solution while maintaining the solution saturated in titanium;
- and
- (c) forming a water soluble precipitate in the tank;
A process for continuously chemically milling titanium and its alloys comprising the steps of:
- (a) forming an etch solution containing a carbonic acid derivative in a first tank;
- (b) etching titanium parts in said first tank until the etchant is substantially saturated;
- (c) transferring the etchant to a second etch tank;
- (d) treating titanium parts in said second etch tank with the etchant substantially supersaturated;
- (e) terminating the chemical milling in the second tank when the sludge has built up to a predetermined point;
- (f) transferring the etchant to the first tank;
- (g) treating the sludge in the second tank with water to solubilize the part of the sludge which is (NH.sub.4).sub.2 TiF.sub.6 ;
- (h) separating the soluble part of the sludge from the insoluble parts;
- (i) neutralizing the soluble part;
- and
- (j) recovering titanium nitride as a precipitate.
Dependencies are inferred from the claim text.