# US 11,298,768 B2 · Method of preparing a surface for diffusion bonding and method of diffusion bonding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,768 B2 - Document ID: US11298768B2 - Status: Granted - Kind: B2 - Application number: 16/684,974 - Filed: 2019-11-15 - Published: 2021-05-20 - Granted: 2022-04-12 - Earliest claimed: 2019-11-15 - Assignees: ROLLS-ROYCE plc - Applicants: Rolls-Royce Corporation - Inventors: Timothy Fuesting; Joseph P. Henderkott - Web page: https://patentgrep.com/patent/US11298768B2 ## CPC - B23K 1/20: Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating - B23K 20/026: {with diffusion of soldering material} - B22F 7/08: with one or more parts not made from powder {(B22F7/062 takes precedence)} - B23K 1/0018: {Brazing of turbine parts} - B23K 20/24: Preliminary treatment - B23K 35/0244: {Powders, particles or spheres; Preforms made therefrom} - B23K 35/3033: {Ni as the principal constituent} - B23K 35/325: {Ti as the principal constituent} - B23K 35/3613: {Polymers, e.g. resins} - B23K 2101/001: {Turbines} - B23K 2103/14: Titanium or alloys thereof - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER ## Abstract A method of preparing a surface for diffusion bonding comprises contacting a binder material with a discontinuous surface comprising surface regions separated by gaps. The binder material is selectively deposited onto the surface regions and has a sufficient viscosity to form a self-supporting layer without flowing into the gaps. The self-supporting layer of binder material comprises a mass density in a range from about 0.001 g/in2 to about 0.050 g/in2. A braze powder is distributed over the self-supporting layer of binder material, and a predetermined amount of the braze powder is attached to the binder material. The discontinuous surface is then heated to remove the binder material and adhere the braze powder to the discontinuous surface. Thus, a prewet surface with a braze deposit thereon is formed. ## Claims ### Claim 1 A method of preparing a surface for diffusion bonding, the method comprising: contacting a binder material with a discontinuous surface comprising surface regions separated by gaps, the binder material being selectively deposited onto the surface regions and forming a self-supporting layer without flowing into the gaps, the self-supporting layer of binder material being uniformly deposited on the surface regions with a mass density in a range from about 0.001 g/in2 to about 0.050 g/in2, wherein the contacting comprises rolling a belt or roller coated with the binder material over the discontinuous surface, an axis of rotation of the belt or roller being parallel to the surface regions; distributing a braze powder over the binder material, a predetermined amount of the braze powder being attached to the binder material; and heating the discontinuous surface to remove the binder material and adhere the braze powder to the discontinuous surface, thereby forming a prewet surface with a braze deposit thereon. ### Claim 2 (depends on 1) The method of claim 1, wherein the predetermined amount of braze powder lies in a range from about 0.04 g/in2 to about 0.250 g/in2, and wherein the braze deposit comprises the predetermined amount of braze powder. ### Claim 3 (depends on 1) The method of claim 1, wherein the belt or roller comprises a surface roughness in a range from about 16 rms to about 63 rms. ### Claim 4 (depends on 1) The method of claim 1, wherein the binder material comprises a polymer selected from the group consisting of cyanoacrylate polymers and acrylic polymers. ### Claim 5 (depends on 1) The method of claim 1, wherein binder material comprises a cyanoacrylate polymer or an acrylic polymer. ### Claim 6 (depends on 1) The method of claim 1, wherein the discontinuous surface is heated to a temperature at or above a sintering temperature of the braze powder and below a melting temperature of the braze powder. ### Claim 7 (depends on 6) The method of claim 6, wherein the temperature is in a range from about 100° F. below a solidus to about 30° F. above a liquidus of the braze powder. ### Claim 8 (depends on 1) The method of claim 1, wherein removing the binder material comprises pyrolyzing or vaporizing the binder material. ### Claim 9 (depends on 1) The method of claim 1, wherein the heating is carried out in a vacuum or an inert gas atmosphere. ### Claim 10 (depends on 1) The method of claim 1, wherein the discontinuous surface is part of a first component comprising a metal alloy. ### Claim 11 (depends on 10) The method of claim 10, wherein first component comprises a nickel-base alloy and the braze powder comprises nickel alloyed with boron and/or chromium. ### Claim 12 (depends on 10) The method of claim 10, wherein the first component comprises a titanium-base alloy and the braze powder comprises titanium alloyed with copper, nickel, and/or zirconium. ### Claim 13 (depends on 1) The method of claim 1, wherein the braze powder comprises particles having a particle size in a range from about 44 microns to 63 microns. ### Claim 14 (depends on 1) The method of claim 1, wherein the braze powder comprises particles having a spheroidal, spherical, polygonal, elongated, or irregular morphology. ### Claim 15 (depends on 1) A method of diffusion bonding comprising: assembling a first component comprising the prewet surface of claim 1 with a second component comprising a mating surface to form an assembly, the braze deposit on the prewet surface contacting the mating surface; and exposing the assembly to a bonding temperature and a compressive force, thereby diffusion bonding the first component to the second component to form a monolithic third component comprising a bonded interface. ### Claim 16 (depends on 15) The method of claim 15, wherein the monolithic third component comprises an airfoil, a combustion liner, a heat shield, or another gas turbine engine component. ### Claim 17 (depends on 15) The method of claim 15, wherein the first component comprises a spar and the second component comprises a coversheet. ### Claim 18 (depends on 15) The method of claim 15, wherein the first and second components have a single-crystalline structure, and wherein a directionally solidified microstructure is obtained across the bonded interface. ### Claim 19 (depends on 15) The method of claim 15, wherein the bonding temperature lies in a range from about 900° C. to about 1275° C.