Method for sintering porous titanium to assist in brazing sapphire to metal materials

Abstract

The application discloses a method for connecting sintered porous titanium auxiliary brazing of sapphire and metal material, which comprises the following steps: adding TiZrCuNi filler metal powder into a binder, stirring uniformly, and then preparing TiZrCuNi solder paste, wherein the TiZrCuNi metal powder is 86-91wt.% and the binder is 9-14wt.% according to the mass percentage of raw materials; preparing a sintered porous titanium intermediate layer skeleton material; setting the metal matrix on the lower side, laying a layer of TiZrCuNi solder paste with a thickness of 0.2mm-0.4mm on the upper side; pressing the sintered porous titanium intermediate layer skeleton material into the solder paste layer, and filling the TiZrCuNi metal powder into the sintered porous titanium intermediate layer skeleton material; laying TiZrCuNi solder paste with a thickness of 0.4mm-0.6mm on the upper surface of the sintered porous titanium intermediate layer skeleton material, and pressing the sapphire; and then performing brazing treatment, so as to realize the connection of the sapphire and the metal material. The application relieves the residual stress caused by the difference in characteristics of the two side matrices, and improves the brazing connection reliability of the sapphire and the metal.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal material connection, and particularly relates to a method for sintering porous titanium assisted brazing of sapphire and metal material connection. BACKGROUND

[0002] Sapphire has good light transmission and is an ideal material for making infrared optical windows and radomes, and is widely used in photoelectric equipment inside airplanes, satellites, cruisers and submarines. In actual engineering applications, sapphire is often limited in size and shape due to its high brittleness and poor toughness, and connection with metal materials is the first choice for realizing complex structures and large-size sapphire components.

[0003] Most domestic sapphire precision components use adhesive bonding process and mechanical connection. The service temperature of the adhesive bonding joint should not exceed 300 DEG C, and there is a long-term aging problem. The mechanical connection has low bearing capacity due to stress concentration at the edge of the machined hole of the sapphire brittle material.

[0004] At present, sapphire brazing connection mostly uses low-melting-point Ag-based and Sn-based filler metals (patent CN201810393896.2 and paper: Sn-based filler metal low-temperature brazing of sapphire process and mechanism research), and the reliability of sapphire and metal brazing connection needs to be improved. At the same time, sapphire and metal brazing connection mainly faces two big problems: poor wettability of filler metal on sapphire surface and difficulty in relieving joint residual stress.

[0005] Therefore, it is necessary to improve the reliability of sapphire and metal brazing connection to expand the engineering application of the connected components. SUMMARY

[0006] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0007] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0008] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for sintering porous titanium assisted brazing of sapphire and metal material connection.

[0009] To solve the above technical problems, the present application provides the following technical scheme: a method for sintering porous titanium assisted brazing of sapphire and metal material connection, comprising,

[0010] TiZrCuNi solder powder was added to the binder and stirred evenly to obtain TiZrCuNi solder paste. The TiZrCuNi metal powder was 86-91 wt.% and the binder was 9-14 wt.% by mass percentage of raw materials.

[0011] Preparation of sintered porous titanium interlayer framework material;

[0012] The metal substrate is positioned at the bottom, and a TiZrCuNi solder paste layer with a thickness of 0.2mm to 0.4mm is laid on its upper surface;

[0013] The lower surface of the sintered porous titanium interlayer skeleton material is pressed into the solder paste layer on the upper surface of the metal substrate, and the surrounding area is sealed with TiZrCuNi solder paste. TiZrCuNi metal powder is then filled into the sintered porous titanium interlayer skeleton material.

[0014] TiZrCuNi solder paste with a thickness of 0.4mm to 0.6mm is laid on the surface of the sintered porous titanium intermediate layer skeleton material and then pressed with sapphire.

[0015] Vacuum brazing is then performed to connect the sapphire to the metal material.

[0016] In a preferred embodiment of the method described in this invention, the TiZrCuNi metal powder has a particle size of +300 to -100 mesh.

[0017] In a preferred embodiment of the method described in this invention, the adhesive is composed of a solvent, polyethylene glycol, stearic acid, polyamide wax, oxalic acid, and paraffin oil.

[0018] Of which, by mass percentage, the solvent is 58-60 wt.%, the polyethylene glycol is 12-14 wt.%, the stearic acid is 4-6 wt.%, the polyamide wax is 5-8 wt.%, the oxalic acid is 10-13 wt.%, and the paraffin oil is 3-7 wt.

[0019] In a preferred embodiment of the method described in this invention, the solvent is composed of terpineol and diethylene glycol butyl ether in a volume ratio of 4:3.

[0020] In a preferred embodiment of the method described in this invention, the method for preparing the adhesive includes,

[0021] Heat the solvent, polyethylene glycol, stearic acid, and polyamide wax in a water bath and stir until completely dissolved;

[0022] Add oxalic acid and paraffin oil, heat and stir until dissolved to obtain the binder.

[0023] As a preferred embodiment of the method described in this invention, the preparation method for the sintered porous titanium interlayer framework material includes:

[0024] Φ1.0mm titanium wire was used as the drawing material. After preheating at 150-180℃, titanium fibers with a diameter of Φ100-150um were prepared by multiple drawing passes.

[0025] The titanium fibers are woven and folded into a multi-layer titanium fiber mesh to obtain titanium fiber sheet blocks. The weight of the titanium fibers is calculated by weighing volume method based on the porosity of the porous titanium, which is 50% to 80%.

[0026] Titanium fiber sheet blocks are pre-pressed using a mold, with a pre-pressing stress of 80–100 MPa and a holding time of 30–60 s.

[0027] Stress-relief annealing heat treatment of material blocks;

[0028] Porous titanium blocks are produced by pressing the pre-pressed block with a mold, wherein the pressing stress is 150-180 MPa and the holding time is 60-80 s.

[0029] A porous titanium block is sintered, and sintered porous titanium sheets with a specific porosity are obtained by controlling the sintering process parameters. The sintering temperature is 1050-1300℃ and the holding time is 120-180s.

[0030] The sintered porous titanium sheet is cut into sheets with dimensions of 10mm x 10mm x (0.4 to 1.0mm) in length x width x thickness to obtain the sintered porous titanium intermediate layer skeleton material.

[0031] In a preferred embodiment of the method described in this invention, the TiZrCuNi metal powder is filled into the sintered porous titanium interlayer skeleton material, wherein the percentage of TiZrCuNi metal powder in the total mass of the sintered porous titanium interlayer skeleton material and the sealing TiZrCuNi solder paste is 8% to 15%.

[0032] In a preferred embodiment of the method described in this invention, the surface of the metal substrate to be joined is subjected to a polishing process, the process comprising:

[0033] Use 400# to 1000# metallographic sandpaper to polish the metal substrate surfaces to be joined in sequence, and then clean and dry the polished surfaces before use.

[0034] As a preferred embodiment of the method described in this invention, the upper surface of the sapphire to be brazed is polished to a smooth and flat mirror surface with a surface roughness of 6-10 nm.

[0035] As a preferred embodiment of the method described in this invention, the brazing process includes,

[0036] Start by raising the temperature to 300-350℃ at a rate of 12-18℃ / min, hold for 20-30 minutes to ensure the adhesive fully evaporates, then raise the temperature to 750-800℃ at a rate of 8-11℃ / min, and then raise it to the brazing temperature at a rate of 4-7℃ / min, hold for 15-35 minutes to complete the brazing.

[0037] The temperature is reduced to below 300℃ at a rate of 5-8℃ / min, and then cooled with the furnace.

[0038] Beneficial effects of this invention:

[0039] This invention discloses a method for sintered porous titanium-assisted brazing of sapphire to metal materials. It uses modified TiZrCuNi active brazing filler metal to ensure that the molten filler metal fully wets the sapphire surface. The method introduces sintered porous titanium as an intermediate layer to encourage the porous titanium to retain more pore structure, alleviate residual stress caused by the difference in properties between the two substrates, and improve the reliability of the brazing connection between sapphire and metal. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0041] Figure 1 This is a schematic diagram of module assembly in an embodiment of the present invention.

[0042] Figure 2 This is a diagram illustrating the brazing effect in an embodiment of the present invention.

[0043] Figure 3 This is a diagram showing the relationship between the addition of an intermediate layer and the shear strength of the brazed joint in an embodiment of the present invention.

[0044] Figure 4 This is a microstructure diagram of the interface between the sapphire and TC4 alloy brazed joint when the adhesive formulation is improperly selected in an embodiment of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0046] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0048] (1) Surface pretreatment of substrate: The sapphire surface to be brazed is polished to a smooth and flat mirror surface with a surface roughness of about 6 to 10 nm.

[0049] Use 400# to 1000# metallographic sandpaper to polish the metal substrate surfaces to be joined in sequence, and then clean and dry the polished surfaces before use.

[0050] (2) Brazing system: Sapphire / TiZrCuNi solder tape + sintered porous titanium intermediate layer (intermediate layer thickness is about 0.4mm~1.0mm, and the porous skeleton structure is filled with solder powder) + TiZrCuNi active solder paste / metal matrix.

[0051] A. Preparation of TiZrCuNi active solder paste:

[0052] TiZrCuNi solder paste consists of two parts: approximately 86–91 wt.% TiZrCuNi metal powder and approximately 9–14 wt.% binder.

[0053] TiZrCuNi spherical powder of +300 to -100 mesh was selected (prepared by vacuum atomization method);

[0054] The specific preparation process of TiZrCuNi spherical powder is as follows:

[0055] Ingot smelting: Powdered ingots (composition ratio Ti-37.5Zr-15Cu-10Ni) were obtained by smelting using vacuum arc melting equipment. The furnace was evacuated to 10⁻² Pa by a three-pole vacuum pump, and the furnace was cleaned with argon gas 3-4 times. After evacuation to 10⁻² Pa, the furnace was purged with argon gas again to 0.06 MPa. Before the formal smelting, a piece of industrial pure titanium was repeatedly smelted to further remove residual oxygen in the atmosphere. In order to make the composition of the solidified alloy uniform, the sample in the water-cooled copper crucible was repeatedly smelted 5-6 times under electromagnetic stirring.

[0056] EIGA process for powder preparation: Under vacuum conditions of 10-3 Pa, pre-made alloy rods are refined in a zone. Liquid metal flows continuously and vertically through the nozzle and is atomized and broken into a large number of fine droplets by a high-pressure gas flow through a tightly coupled nozzle. The fine droplets solidify into particles during flight.

[0057] The process parameters adopted are annular slit nozzle, atomization pressure of 5-7 MPa and melting power of 20-30 kW.

[0058] The binder formulation ranges as follows: 58–60 wt.% solvent (terpineol: diethylene glycol butyl ether = 4:3), 12–14 wt.% polyethylene glycol, 4–6 wt.% stearic acid, 5–8 wt.% polyamide wax, 10–13 wt.% oxalic acid, and 3–7 wt.% paraffin oil;

[0059] The powder ball milling in the vacuum mixer lasts for 1 to 2 hours at a speed of 200 to 400 r / min to ensure uniform distribution of the brazing filler powder. The entire process of solder paste preparation is completed in a glove box with an oxygen content of <20 ppm.

[0060] Adhesive preparation process: Water bath heating (temperature about 80-90℃), mechanical stirring to completely dissolve the thickener, then other additives are added in proportion (terpineol and diethylene glycol butyl ether as solvents, polyethylene glycol, stearic acid and polyamide wax as thickeners, oxalic acid and paraffin oil as other additives), heated and stirred until all chemical reagents are dissolved, and the adhesive preparation is completed;

[0061] Add TiZrCuNi solder powder to the binder according to the principle of "small amount, multiple times" (the first addition of TiZrCuNi solder powder is ≤80g, and the amount of powder added each time is <5g. Complete 4 to 5 additions and stir thoroughly. The total amount of powder added is ≥100g and at least 5 additions are required). After stirring evenly, put the solder paste into a special solder bottle, seal it and store it for later use.

[0062] B. Preparation of sintered porous titanium interlayer framework structure:

[0063] The sintered porous titanium interlayer skeleton structure was prepared by using commercially available annealed Φ1.0mm titanium wire as the drawing material. After preheating at 150-180℃, it was drawn in multiple passes to prepare titanium fibers with Φ100-150um.

[0064] Specific preparation process of titanium fiber:

[0065] Before each drawing, the titanium wire is cleaned with a mixture of sulfuric acid, nitric acid and water (volume ratio 1:2:4) for 5-7 minutes. Paraffin oil is used as the drawing lubricant. The wire is annealed in sodium hydroxide melt. The process of drawing from Φ1.0mm to Φ0.4mm is controlled to have a reduction rate of 25%-30% per pass. The process of drawing from Φ0.4mm to Φ0.1-0.15mm is controlled to have a reduction rate of 8%-10% per pass.

[0066] Preparation process of intermediate titanium fiber skeleton structure:

[0067] Titanium fibers are woven and folded to form a multi-layer titanium fiber mesh. The required weight of the titanium fiber mesh is calculated using the direct weighing volume method based on the designed porous titanium porosity (50%–80%). Titanium fiber sheets are pre-pressed using a thin-sheet mold (pre-pressing stress is 80–100 MPa, holding time is 30–60 s). The sheets undergo stress-relief annealing heat treatment (annealing temperature selection principle: 120–150℃ below the α / β phase transformation point of titanium alloys, air cooling; the phase transformation point temperature of pure titanium or titanium fibers is 882.5℃, annealing heat treatment process: annealing temperature 732.5–762℃). 5℃, air cooling) → Pre-pressed block mold re-pressing (re-pressing stress is 150~180MPa, holding time is 60~80s) → Preparation of sintered porous titanium under different sintering processes (holding time 120~180s and sintering temperature 1050~1300℃) → Measurement and verification of porosity and thermal expansion coefficient → Optimization of sintering process parameters → Preparation of sintered porous titanium sheets with specific porosity as intermediate layer → Cutting sintered porous titanium sheets to obtain intermediate layer titanium fiber skeleton structure with size of 10mm×10mm×(0.3~0.5mm).

[0068] C. Assembly of each module of the intermediate layer system: The metal substrate test block is positioned at the bottom, and a layer of TiZrCuNi solder paste with a thickness of 0.1mm to 0.5mm is laid on top of it. The sintered porous titanium intermediate layer skeleton structure is pressed into the solder paste layer (thin bottom sealing). An appropriate amount of +300 to -100 mesh TiZrCuNi spherical powder is filled into the sintered porous titanium intermediate layer skeleton structure (the porous skeleton structure is filled with solder powder). A TiZrCuNi solder tape with a thickness of 0.4mm to 0.6mm is laid on the upper surface of the sintered porous titanium intermediate layer skeleton structure, and the sapphire is pressed firmly.

[0069] (4) Brazing process: Start by raising the temperature to 300-350℃ at 12-18℃ / min and holding for 20-30min to ensure that the binder is fully volatilized. Then raise the temperature to 750-800℃ at 8-11℃ / min and then raise it to the brazing temperature at 4-7℃ / min. Hold for 15-35min to complete the brazing. Then lower the temperature to below 300℃ at 5-8℃ / min and then cool it with the furnace.

[0070] Example 1

[0071] See the module assembly diagram in this embodiment. Figure 1 The specific explanation is as follows:

[0072] (1) Surface pretreatment of substrate: The sapphire surface to be brazed is polished to a smooth and flat mirror surface with a surface roughness of about 6 to 10 nm.

[0073] Use 400# to 1000# metallographic sandpaper to polish the metal substrate surfaces to be joined in sequence, and then clean and dry the polished surfaces before use.

[0074] (2) Preparation of TiZrCuNi active solder paste:

[0075] TiZrCuNi solder paste consists of approximately 86 wt.% TiZrCuNi metal powder and approximately 14 wt.% binder.

[0076] TiZrCuNi metal powder is selected from +300 to -100 mesh powder;

[0077] Adhesive formulation: 58 wt.% solvent (terpineol: diethylene glycol butyl ether = 4:3, V / V), 13 wt.% polyethylene glycol, 6 wt.% stearic acid, 7 wt.% polyamide wax, 12 wt.% oxalic acid, 4 wt.% paraffin oil;

[0078] Adhesive preparation process: Water bath heating (temperature about 80-90℃), mechanical stirring to completely dissolve the thickener, then other additives are added in proportion, heated and stirred until all chemical reagents are dissolved, and the adhesive preparation is completed;

[0079] Add TiZrCuNi solder powder to the binder in small amounts multiple times. After stirring evenly, put the solder paste into a special solder bottle, seal it, and store it for later use.

[0080] (3) Preparation of sintered porous titanium interlayer framework structure:

[0081] Titanium fibers are woven and folded to form a multi-layer titanium fiber mesh → The required weight of the titanium fiber mesh is calculated using the direct weighing volume method based on the designed porous titanium porosity (50%–80%) → Titanium fiber sheet blocks are pre-pressed using a sheet mold (pre-pressing stress is 80–100 MPa, holding time is 30–60 s) → Stress-relief annealing heat treatment of the blocks → The pre-pressed blocks are re-pressed using the mold (re-pressing stress is 150–180 MPa, holding time is 60–80 s) → Sintered porous titanium is prepared under different sintering processes (holding time 130 s and sintering temperature 1100℃) → Porosity and thermal expansion coefficient are measured and verified → Sintering process parameters are optimized → Sintered porous titanium sheets with specific porosity are prepared as an intermediate layer → The sintered porous titanium sheets are cut to obtain an intermediate layer titanium fiber skeleton structure with dimensions of 10 mm × 10 mm × (0.4 mm) (the porosity of the intermediate layer skeleton structure is 58.5%).

[0082] (4) Assembly of each module

[0083] The metal substrate specimen is positioned at the bottom, and a 0.2mm thick layer of TiZrCuNi solder paste is laid on top of it. The sintered porous titanium intermediate layer (0.4mm thick) skeleton structure is pressed into the solder paste layer (thin bottom sealing layer). An appropriate amount (accounting for 8% of the mass of the intermediate layer system: solder paste around the perimeter and bottom + porous titanium intermediate layer skeleton) + 300~-100 mesh TiZrCuNi spherical powder is filled into the sintered porous titanium intermediate layer skeleton structure. A 0.4mm thick TiZrCuNi solder tape is laid on the upper surface of the sintered porous titanium intermediate layer skeleton structure, and the sapphire is pressed firmly.

[0084] (5) Brazing process:

[0085] The temperature was initially increased to 330℃ at a rate of 16℃ / min and held for 25 minutes to ensure sufficient evaporation of the binder. Then, the temperature was increased to 780℃ at a rate of 10℃ / min, followed by a further increase to the brazing temperature at a rate of 6℃ / min and held for 20 minutes. Brazing was then complete. The temperature was then reduced to below 300℃ at a rate of 8℃ / min, and subsequently cooled in the furnace. See the brazing result diagram. Figure 2 .

[0086] (6) Performance testing:

[0087] The relationship between the addition of an intermediate layer and the shear strength of the brazed joint is shown in [reference needed]. Figure 3 .

[0088] The brazed joint shear test was performed in accordance with the relevant requirements of GB / T 11363-2008. The indenter moving speed was 0.5 mm / s, and the shear strength of the joint was taken as the average of three valid test values.

[0089] in, Figure 3The process for direct brazing with medium brazing filler metal is as follows: first, heat up to 330℃ at 16℃ / min, hold for 25min to ensure the binder fully volatilizes, then heat up to 780℃ at 10℃ / min, then heat up to 930℃ at 6℃ / min, hold for 20min to complete brazing, then cool down to below 300℃ at 8℃ / min, and then cool with the furnace.

[0090] It can be seen that, under the same brazing process (930℃ / 20min), the shear strength of the joints is 26.85MPa and 15.62MPa respectively when a 0.4mm thick sintered porous titanium interlayer is introduced and the sapphire and TC4 alloy are directly brazed with brazing filler metal. The former is 11.23MPa higher than the latter.

[0091] Example 2

[0092] (1) Surface pretreatment of substrate: The sapphire surface to be brazed is polished to a smooth and flat mirror surface with a surface roughness of about 6 to 10 nm.

[0093] Use 400# to 1000# metallographic sandpaper to polish the metal substrate surfaces to be joined in sequence, and then clean and dry the polished surfaces before use.

[0094] (2) Preparation of TiZrCuNi active solder paste:

[0095] TiZrCuNi solder paste consists of approximately 86 wt.% TiZrCuNi metal powder and approximately 14 wt.% binder.

[0096] TiZrCuNi metal powder is selected from +300 to -100 mesh powder;

[0097] Adhesive formulation: 58 wt.% solvent (terpineol: diethylene glycol butyl ether = 4:3), 13 wt.% polyethylene glycol, 6 wt.% stearic acid, 7 wt.% polyamide wax, 12 wt.% oxalic acid, 4 wt.% paraffin oil;

[0098] Adhesive preparation process: Water bath heating (temperature about 80-90℃), mechanical stirring to completely dissolve the thickener, then other additives are added in proportion, heated and stirred until all chemical reagents are dissolved, and the adhesive preparation is completed;

[0099] Add TiZrCuNi solder powder to the binder in small amounts multiple times. After stirring evenly, put the solder paste into a special solder bottle, seal it, and store it for later use.

[0100] (3) Preparation of sintered porous titanium interlayer framework structure:

[0101] Titanium fibers are woven and folded to form a multi-layer titanium fiber mesh → The required weight of the titanium fiber mesh is calculated using the direct weighing volume method based on the designed porous titanium porosity (50%–80%) → Titanium fiber sheet blocks are pre-pressed using a sheet mold (pre-pressing stress is 80–100 MPa, holding time is 30–60 s) → Stress-relief annealing heat treatment of the blocks → The pre-pressed blocks are re-pressed using the mold (re-pressing stress is 150–180 MPa, holding time is 60–80 s) → Sintered porous titanium is prepared under different sintering processes (holding time 150 s and sintering temperature 1200℃) → Porosity and thermal expansion coefficient are measured and verified → Sintering process parameters are optimized → Sintered porous titanium sheets with specific porosity are prepared as an intermediate layer → The sintered porous titanium sheets are cut to obtain an intermediate layer titanium fiber skeleton structure with dimensions of 10 mm × 10 mm × (0.8 mm) (porosity is 79.3%).

[0102] (4) Assembly of each module

[0103] The metal substrate specimen is positioned at the bottom, and a 0.2mm thick layer of TiZrCuNi solder paste is laid on top of it. The sintered porous titanium intermediate layer (0.4mm thick) skeleton structure is pressed into the solder paste layer (thin bottom sealing layer). An appropriate amount (accounting for 8% of the mass of the intermediate layer system: solder paste around the perimeter and bottom + porous titanium intermediate layer skeleton) + 300~-100 mesh TiZrCuNi spherical powder is filled into the sintered porous titanium intermediate layer skeleton structure. A 0.8mm thick TiZrCuNi solder tape is laid on the upper surface of the sintered porous titanium intermediate layer skeleton structure, and then the sapphire is pressed firmly.

[0104] (5) Brazing process:

[0105] Start by raising the temperature to 330℃ at 16℃ / min and holding for 25 minutes to ensure the adhesive fully evaporates. Then raise the temperature to 780℃ at 10℃ / min and raise it to the brazing temperature at 6℃ / min. Hold for 20 minutes to complete the brazing. Then lower the temperature to below 300℃ at 8℃ / min and then cool it with the furnace.

[0106] (6) Performance testing:

[0107] The relationship between adding an intermediate layer and the shear strength of the brazed joint is shown in the figure. Figure 3 Shear tests were conducted on brazed joints according to the relevant requirements of GB / T 11363-2008. The indenter moving speed was 0.5 mm / s, and the shear strength of the joint was taken as the average of three valid test values. Under the same brazing process (930℃ / 20min), the shear strengths of sapphire and TC4 alloy directly brazed with a 0.8 mm thick sintered porous titanium interlayer and brazing filler metal were 31.81 MPa and 15.62 MPa, respectively. The former showed a 16.19 MPa increase in shear strength compared to the latter.

[0108] Example 3

[0109] (1) Surface pretreatment of the substrate: The surfaces of the sapphire substrate to be brazed and connected to the metal substrate are polished sequentially with 400# to 1000# metallographic sandpaper. The polished surfaces are then cleaned and dried for later use.

[0110] (2) Preparation of TiZrCuNi active solder paste:

[0111] TiZrCuNi solder paste consists of approximately 86 wt.% TiZrCuNi metal powder and approximately 14 wt.% binder.

[0112] TiZrCuNi metal powder is selected from +300 to -100 mesh powder;

[0113] Adhesive formulation: 58 wt.% solvent (terpineol: diethylene glycol butyl ether = 4:3), 13 wt.% polyethylene glycol, 6 wt.% stearic acid, 7 wt.% polyamide wax, 12 wt.% oxalic acid, 4 wt.% paraffin oil;

[0114] Adhesive preparation process: Water bath heating (temperature about 80-90℃), mechanical stirring to completely dissolve the thickener, then other additives are added in proportion, heated and stirred until all chemical reagents are dissolved, and the adhesive preparation is completed;

[0115] Add TiZrCuNi solder powder to the binder in small amounts multiple times. After stirring evenly, put the solder paste into a special solder bottle, seal it, and store it for later use.

[0116] (3) Preparation of sintered porous titanium interlayer framework structure:

[0117] Titanium fibers are woven and folded to form a multi-layer titanium fiber mesh → The required weight of the titanium fiber mesh is calculated using the direct weighing volume method based on the designed porous titanium porosity (50%–80%) → Titanium fiber sheet blocks are pre-pressed using a sheet mold (pre-pressing stress is 80–100 MPa, holding time is 30–60 s) → Stress-relief annealing heat treatment of the blocks → The pre-pressed blocks are re-pressed using the mold (re-pressing stress is 150–180 MPa, holding time is 60–80 s) → Sintered porous titanium is prepared under different sintering processes (holding time 180 s and sintering temperature 1250℃) → Porosity and thermal expansion coefficient are measured and verified → Sintering process parameters are optimized → Sintered porous titanium sheets with specific porosity are prepared as an intermediate layer → The sintered porous titanium sheets are cut to obtain an intermediate layer titanium fiber skeleton structure with dimensions of 10 mm × 10 mm × (1.0 mm) (porosity is 67.6%).

[0118] (4) Assembly of each module

[0119] The metal substrate specimen is positioned at the bottom, and a 0.2mm thick layer of TiZrCuNi solder paste is laid on top of it. The sintered porous titanium intermediate layer (0.4mm thick) skeleton structure is pressed into the solder paste layer (thin bottom sealing layer). An appropriate amount (accounting for 8% of the mass of the intermediate layer system: solder paste around the perimeter and bottom + porous titanium intermediate layer skeleton) + 300~-100 mesh TiZrCuNi spherical powder is filled into the sintered porous titanium intermediate layer skeleton structure. A 1.0mm thick TiZrCuNi solder tape is laid on the upper surface of the sintered porous titanium intermediate layer skeleton structure, and then the sapphire is pressed firmly.

[0120] (5) Brazing process:

[0121] Start by raising the temperature to 330℃ at 16℃ / min and holding for 25 minutes to ensure the adhesive fully evaporates. Then raise the temperature to 780℃ at 10℃ / min and raise it to the brazing temperature at 6℃ / min. Hold for 20 minutes to complete the brazing. Then lower the temperature to below 300℃ at 8℃ / min and then cool it with the furnace.

[0122] (6) Performance testing:

[0123] The relationship between adding an intermediate layer and the shear strength of the brazed joint is shown in the figure. Figure 3 The brazed joint shear test was performed in accordance with the relevant requirements of GB / T 11363-2008. The indenter moving speed was 0.5 mm / s, and the shear strength of the joint was taken as the average of three valid test values.

[0124] Under the same brazing process (930℃ / 20min), the shear strengths of sapphire and TC4 alloy directly brazed by introducing a 1.0mm thick sintered porous titanium interlayer and brazing filler metal were 27.66MPa and 15.62MPa, respectively. The former was 12.04MPa higher than the latter.

[0125] Comparative Example 1

[0126] Under the conditions of Example 1, the adhesive formulation is different, but all other conditions are the same as in Example 1 for brazing.

[0127] The binder formulation is as follows: 56 wt.% solvent (terpineol: diethylene glycol butyl ether = 4:3, V / V), 13 wt.% polyethylene glycol, 6 wt.% stearic acid, 9 wt.% polyamide wax, 12 wt.% oxalic acid, and 4 wt.% paraffin oil.

[0128] See the microstructure diagram of the interface between the sapphire and TC4 alloy brazed joint. Figure 4 It can be seen that there are obvious high-carbon residual phases in the brazing seam, which significantly reduces the brazing quality between sapphire and metal.

[0129] Meanwhile, if the percentage content of polyethylene glycol or stearic acid exceeds the range required by this invention or if the binder preparation method is improper, it will result in the presence of obvious high-carbon residual phase in the brazed seam.

[0130] This invention directly uses TiZrCuNi-based active brazing filler metal with higher activity and better high-temperature service performance of brazed joints for brazing; it uses sintered porous titanium as the intermediate layer skeleton structure, retaining more pores to alleviate residual stress caused by the difference in matrix properties on both sides of the sapphire / metal matrix; under the same brazing filler metal and the same brazing process conditions, compared with the shear strength of directly brazed joints, the shear strength of brazed sapphire and TC4 alloy joints with 0.4, 0.8 and 1.0 mm sintered porous titanium intermediate layers is increased by 11.23, 16.19 and 12.04 MPa, respectively.

[0131] In this invention, a layer of TiZrCuNi solder paste with a thickness of 0.2 mm to 0.4 mm is laid on the metal substrate specimen. A sintered porous titanium interlayer skeleton structure is pressed into the solder paste layer (thin bottom sealing). A TiZrCuNi solder adhesive tape with a thickness of 0.4 mm to 0.6 mm is laid on the upper surface of the sintered porous titanium interlayer skeleton structure and pressed with sapphire. The thickness of the solder on the metal substrate side is significantly thinner than that on the sapphire side, which promotes the formation of the interface with the sapphire side and inhibits the melting of the metal side interface.

[0132] This invention uses sintered porous titanium as an intermediate layer. The pores provide a channel for the molten solder to flow to the sapphire, and the fiber skeleton provides a Ti source for the solder. The multi-site interface reaction promotes the solder's wetting of the sapphire and accelerates the formation of a continuous interface reaction layer.

[0133] In this invention, an appropriate amount of powdered solder is also filled into the fiber skeleton to provide a sufficient Ti source for the interface reaction between the solder and sapphire.

[0134] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for connecting sapphire to a metal material using sintered porous titanium-assisted brazing, characterized in that: include, TiZrCuNi solder powder was added to the binder and stirred evenly to obtain TiZrCuNi solder paste. The TiZrCuNi metal powder was 86-91 wt.% and the binder was 9-14 wt.% by mass percentage of raw materials. Preparation of sintered porous titanium interlayer framework material; The metal substrate is positioned at the bottom, and a TiZrCuNi solder paste layer with a thickness of 0.2mm to 0.4mm is laid on its upper surface; The lower surface of the sintered porous titanium interlayer skeleton material is pressed into the solder paste layer on the upper surface of the metal substrate, and the surrounding area is sealed with TiZrCuNi solder paste. TiZrCuNi metal powder is then filled into the sintered porous titanium interlayer skeleton material. TiZrCuNi solder paste with a thickness of 0.4mm to 0.6mm is laid on the surface of the sintered porous titanium intermediate layer skeleton material and then pressed with sapphire. Vacuum brazing is then performed to connect the sapphire to the metal material.

2. The method as described in claim 1, characterized in that: The TiZrCuNi metal powder has a particle size of +300 to -100 mesh.

3. The method as described in claim 1 or 2, characterized in that: The adhesive is composed of solvent, polyethylene glycol, stearic acid, polyamide wax, oxalic acid and paraffin oil; Of which, by mass percentage, the solvent is 58-60 wt.%, the polyethylene glycol is 12-14 wt.%, the stearic acid is 4-6 wt.%, the polyamide wax is 5-8 wt.%, the oxalic acid is 10-13 wt.%, and the paraffin oil is 3-7 wt.

4. The method as described in claim 3, characterized in that: The solvent is composed of terpineol and diethylene glycol butyl ether in a volume ratio of 4:

3.

5. The method as described in claim 3, characterized in that: The method for preparing the adhesive includes, Heat the solvent, polyethylene glycol, stearic acid, and polyamide wax in a water bath and stir until completely dissolved; Add oxalic acid and paraffin oil, heat and stir until dissolved to obtain the binder.

6. The method as described in claim 1, characterized in that: The method for preparing the sintered porous titanium interlayer framework material includes, Φ1.0mm titanium wire was used as the drawing material. After preheating at 150-180℃, titanium fibers with a diameter of Φ100-150um were prepared by multiple drawing passes. The titanium fibers are woven and folded into a multi-layer titanium fiber mesh to obtain titanium fiber sheet blocks. The weight of the titanium fibers is calculated by weighing volume method based on the porosity of the porous titanium, which is 50% to 80%. Titanium fiber sheet blocks are pre-pressed using a mold, with a pre-pressing stress of 80–100 MPa and a holding time of 30–60 s. Stress-relief annealing heat treatment of material blocks; Porous titanium blocks are produced by pressing the pre-pressed block with a mold, wherein the pressing stress is 150-180 MPa and the holding time is 60-80 s. A porous titanium block is sintered, and sintered porous titanium sheets with a specific porosity are obtained by controlling the sintering process parameters. The sintering temperature is 1050-1300℃ and the holding time is 120-180s. The sintered porous titanium sheet is cut into sheets with dimensions of 10mm x 10mm x (0.4 to 1.0mm) in length x width x thickness to obtain the sintered porous titanium intermediate layer skeleton material.

7. The method as described in claim 1, characterized in that: The TiZrCuNi metal powder is filled into the sintered porous titanium intermediate layer skeleton material, wherein the percentage of TiZrCuNi metal powder in the total mass of the sintered porous titanium intermediate layer skeleton material and the sealing TiZrCuNi solder paste is 8% to 15%.

8. The method as described in claim 1, characterized in that: The surfaces of the metal substrate to be joined are polished, and the polishing method includes... Use 400# to 1000# metallographic sandpaper to polish the metal substrate surfaces to be joined in sequence, and then clean and dry the polished surfaces before use.

9. The method as described in claim 1 or 8, characterized in that: The sapphire surface to be brazed is polished to a smooth, flat mirror finish with a surface roughness of 6–10 nm.

10. The method according to any one of claims 1, 2, 4 to 8, characterized in that: The brazing process includes, Start by raising the temperature to 300-350℃ at a rate of 12-18℃ / min, hold for 20-30 minutes to ensure the adhesive fully evaporates, then raise the temperature to 750-800℃ at a rate of 8-11℃ / min, and then raise it to the brazing temperature at a rate of 4-7℃ / min, hold for 15-35 minutes to complete the brazing. The temperature is reduced to below 300℃ at a rate of 5-8℃ / min, and then cooled with the furnace.

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