Strippable mask patterning of stop-off for diffusion bond processing

The method of forming a diffusion bond between two titanium base metal sheets in a well-defined pattern comprising the steps of:

• providing at least a first and a second metal article formed of titanium base alloy;
• applying a flexible masking material coating of a strippable mask material to a surface of at least one metal article;
• cutting a pattern in the flexible masking material coating of the at least one metal article to define portions thereof to be removed such that the surface of the at least one metal article is not altered;
• removing a portion of the pattern of masking material coating from the metal surface to expose a pattern of uncoated metal;
• applying a coating of stop-off material over the exposed uncoated metal;
• removing the remainder of the masking material coating from the surface of the at least one metal article, the uncoated metal having an oily residue from the removed flexible masking material coating;
• cleaning the oily residue of the flexible masking material coating from the regions of the at least one article not coated by the stop-off coating sufficiently to eliminate partial interface fractures when diffusion bonded;
• superposing the patterned surface of one article onto a surface of at least one other article;
• and
• applying heat and pressure to induce diffusion bonding between the exposed surface of the opposed surfaces of the at least two (2) articles.

The method of forming a diffusion bond between two titanium base metal sheets in a well-defined pattern comprising the steps of:

• providing first and second metal articles formed of titanium base alloy;
• applying a masking material coating of a strippable mask material to a surface of at least one article;
• cutting a pattern in the masking material coating of the at least one article to define portions thereof to be removed, such that the surface of the at least one article is not altered;
• removing a portion of the pattern of masking material coating from the metal surface to expose a pattern of uncoated metal;
• applying a coating of stop-off material over the exposed uncoated metal;
• removing the remainder of the masking material coating from the surface of the at least one metal article, the surface of the metal article where the masking material coating was removed having an oily residue;
• cleaning the oily residue of the flexible coating from the regions of the article not coated by the stop-off coating by washing in an aqueous solution of Alconox for about five (5) minutes but less than about ten (10) minutes;
• vacuum bakeout of the patterned surface to remove excess organic material and prevent contamination of the titanium alloy components;
• superposing the patterned surface of one article onto a surface of the other article, and
• applying heat and pressure to induce diffusion bonding between the exposed surface of the opposed surfaces of the two articles.