Method of and composition for treating a non-metallic refractory material for brazing
View Patent ↗A coating composition and its use in a metallization process that facilitates bonding of brazing filler metals to treated refractory surfaces, such as ceramics. The coating can be applied in preselected areas of the refractory surface to define a target area for brazing. In one embodiment, the coating composition is applied to a refractory material prior to brazing, the composition including (i) a group IVB transition metal component selected from the group consisting of a group IVB transition metal, a hydride thereof, and mixtures of group IVB metals and/or hydrides thereof, (ii) a binder material, and (iii) a fluid carrier, disclosed embodiments, the group IVB transition metal component is titanium, and the binder material is a combination of a styrene block copolymer and a hydrocarbon resin.
1. A method of treating a non-metallic refractory material for brazing, comprising the steps of:
coating a surface of the material with a coating composition comprising (i) a Group IVB transition metal component selected from the group consisting of a Group IVB transition metal, a Group IVB transition metal hydride, and mixtures thereof, (ii) a binder including a hydrocarbon resin and styrene block copolymer, and (iii) a fluid carrier;
drying the coated surface;
applying a brazing filler material in a selected form on the dried coated surface; and
heating the brazing filler material to a temperature above a liquidus of said material in a substantially oxygen free environment.
2. The method of claim 1 , wherein the drying step is carried out at ambient conditions.
3. The method of claim 1 , wherein the drying step is carried out at elevated temperatures of about 120 to about 150 degrees C. for between 10 and 20 minutes.
4. The method of claim 1 , including selecting the brazing filler material in the form of a wire, a foil, a strip, a shim, a ring, a preform or a powdered metal.
5. The method of claim 1 , wherein the heating step is carried out in a vacuum, or in argon or dry hydrogen.
6. The method of claim 1 , including providing titanium, zirconium, hafnium, or mixtures thereof as the group IVB transition metal component of the coating composition.
7. The method of claim 1 , including formulating the coating composition from between about 10 and about 90 weight percent of the transition metal component and between about 90 and about 10 weight percent of the binder and the fluid carrier combined.
8. The method of claim 1 , including providing one or more of aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohols, ketones, esters, glycol, glycol ether, glycerin, water, paraffinic hydrocarbon solvents, and hydro treated light petroleum distillate hydrocarbon solvents, as the fluid carrier of the coating composition.
9. The method of claim 1 , wherein the coating step is carried out by brushing, spraying or rolling though a masking stencil.
10. The method of claim 1 , including providing the group IVB transition metal component of the coating composition in an amount that is between about 2 weight percent to about 8 weight percent of a combined weight of the group IVB transition metal component and the braze filler material applied to the surface of the refractory material.
11. The method of claim 1 , including providing the transition metal component of the coating composition in an amount that is between about 4 weight percent to about 6 weight percent of a combined weight of the transition metal component and the braze filler material applied to the surface of the refractory material.
12. The method of claim 1 , including formulating the coating composition from about 35 weight percent of the transition metal component and about 65 weight percent of the binder and the fluid carrier combined.
13. The method of claim 1 , including formulating the coating composition from about 65 weight percent of the transition metal component and about 35 weight percent of the binder and the fluid carrier combined.
14. The method of claim 1 , wherein the coating step is carried out by brushing, rolling or spraying the surface of the refractory material.
15. The method of claim 1 , wherein the coating step is carried out by screening or stenciling the surface of the refractory material.
16. The method of claim 1 , including formulating the fluid carrier from both a paraffinic hydrocarbon and a hydro treated light petroleum distillate.
17. The method of claim 1 , including adjusting the viscosity of the coating composition by varying a weight percentage of the fluid carrier in the composition.