A method for connecting sapphire and porous Si3N4 ceramic by using gradient ZBS glass-ceramic solder
By using a sandwich structure of gradient ZBS microcrystalline glass solder to connect sapphire and porous Si3N4 ceramic, the thermal stress problem caused by the difference in thermal expansion coefficients is solved, achieving excellent connection effect and mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-03-11
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies cannot effectively connect sapphire and porous Si3N4 ceramics, leading to thermal stress problems caused by the large difference in their coefficients of thermal expansion.
Gradient ZBS microcrystalline glass solder is used to prepare two glass solders with different coefficients of thermal expansion, C0 and C5, to form a sandwich structure and perform pressureless connection under a protective atmosphere, thereby mitigating the difference in coefficients of thermal expansion.
An effective connection between sapphire and porous Si3N4 ceramic was achieved. The joint is dense and well bonded, which alleviates thermal stress and yields excellent mechanical properties.
Smart Images
Figure CN122102727A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for joining sapphire and porous Si3N4 ceramics using microcrystalline glass solder. Background Technology
[0002] Sapphire, as a single-crystal Al2O3 ceramic material, not only possesses excellent mechanical properties and high chemical stability but also exhibits outstanding optical performance, thus being widely regarded as an ideal optical window material. Porous Si3N4 ceramic material, with its high-temperature resistance, oxidation resistance, good dielectric properties, and structural characteristics such as high specific surface area, highly interconnected open pores, and controllable pore size distribution, is also widely considered an ideal cover material. Effectively combining these two materials can not only meet the stringent optical performance requirements of the fairing but also further optimize its overall quality and manufacturing process.
[0003] Research and reports have revealed that there is currently no suitable method to connect the two materials. Due to the high dielectric properties required for the fairing material, the commonly used metal brazing method for connecting dissimilar materials cannot meet this requirement. Therefore, microcrystalline glass brazing filler metal is the preferred option for connecting the base materials. However, considering the significant difference in thermal expansion coefficients between the two base materials (temperature range: 30℃~450℃, sapphire CTE: 6.94×10⁻⁶), this method is not feasible. -6 / ℃, the CTE of porous Si3N4 ceramic is 2.74×10 -6 (℃) If a single-layer glass brazing filler metal is used, it cannot effectively alleviate the thermal stress problem caused by the large difference in the coefficients of thermal expansion between the base materials. Therefore, it is desirable to use a gradient thermal expansion microcrystalline glass brazing filler metal to effectively connect the two. Summary of the Invention
[0004] The present invention aims to solve the thermal stress problem caused by the large difference in the coefficients of thermal expansion between sapphire and porous Si3N4 ceramic substrate, and provides a method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder.
[0005] The method of connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder of the present invention is carried out according to the following steps:
[0006] I. Preparation of C0 and C5 glass solders respectively:
[0007] ① Weigh out the raw material powder of the two glass solders according to the following mass percentages:
[0008] C0 glass: ZnO content is 65% by mass, B2O3 content is 20% by mass, and SiO2 content is 15% by mass;
[0009] C5 glass: ZnO content is 60% by mass, B2O3 content is 20% by mass, SiO2 content is 15% by mass, and CaO content is 5% by mass.
[0010] ② The preparation methods for the two glass solders are exactly the same, and they are prepared separately as follows:
[0011] The raw material powder weighed in ① is ball-milled and mixed, then placed in an Al2O3 crucible and melted at high temperature to obtain a glass melt with uniform composition.
[0012] ③ Pour the molten glass into deionized water for water quenching, remove it from the water to obtain broken glass shards, then process it through ball milling to obtain fine glass powder, sieve the glass powder to remove unbroken glass pieces, and finally dry it in an oven to obtain glass solder.
[0013] 2. Use diamond polishing paste to grind and polish the surfaces of the sapphire substrate to be joined, then place it in alcohol for ultrasonic cleaning, and blow it dry for later use.
[0014] 3. Place the two glass solders prepared in step 1 into a pressing mold and press them into sheets. Then place them between two base materials to form a sandwich structure, from top to bottom: base material sapphire, C5 glass layer, C0 glass layer and base material porous Si3N4 ceramic.
[0015] Fourth, place the assembled sandwich structure in an atmosphere tube furnace, achieve pressureless connection under protective atmosphere conditions, and complete the heating connection process according to the set program.
[0016] The present invention has the following beneficial effects:
[0017] This invention prepares microcrystalline glass solders with different coefficients of thermal expansion by replacing part of the ZnO component in a ZnO-B2O3-SiO2 microcrystalline glass solder with CaO. The gradient thermal expansion microcrystalline glass solder successfully achieves effective bonding between sapphire and porous Si3N4 ceramic under argon conditions, forming a composite gradient thermal expansion intermediate layer. The joint is dense overall, with good adhesion between the solder and the base materials on both sides. A reaction layer forms at the sapphire interface, achieving excellent bonding, and a penetration layer forms on the porous Si3N4 ceramic side, also achieving excellent bonding. The overall joint exhibits superior mechanical properties. The glass layer near the sapphire side is C5, with a coefficient of thermal expansion of 5.14 × 10⁻⁶. -6 / ℃ (30℃~450℃), the glass layer near the porous Si3N4 ceramic side is C0, and its coefficient of thermal expansion is 4.58×10. -6 / ℃ (30℃~450℃), sapphire CTE is 6.94×10 -6 / ℃, the CTE of porous Si3N4 ceramic is 2.74×10-6 / ℃, thus achieving a gradient intermediate layer with a coefficient of thermal expansion, effectively alleviating residual stress in the joint; energy dispersive spectroscopy and X-ray diffraction analysis revealed that the main crystalline phases in the weld were Zn3B2O6 and Zn2SiO4. Transmission electron microscopy analysis confirmed that the blocky and short rod-shaped phases in the weld were Zn2SiO4, while the long whiskers were Zn3B2O6. After heating to 760℃ and holding for 30 min in an argon atmosphere, the room temperature mechanical properties of the joint reached 20.5 MPa. Attached Figure Description
[0018] Figure 1 The image shows a backscattered electron scanning image and a magnified view of the connector obtained after Experiment 1 was completed.
[0019] Figure 2 The graphs show the thermal expansion curves of the two base materials and the two types of glass from Experiment 1, measured by a thermal expansion tester.
[0020] Figure 3 X-ray diffraction pattern of double-layer microcrystalline glass under test process;
[0021] Figure 4 This is a transmission image of the joint at the sapphire side interface reaction layer obtained after Experiment 1 was completed. Detailed Implementation
[0022] Specific Implementation Method 1: This implementation method is a method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder, specifically carried out according to the following steps:
[0023] I. Preparation of C0 and C5 glass solders respectively:
[0024] ① Weigh out the raw material powder of the two glass solders according to the following mass percentages:
[0025] C0 glass: ZnO content is 65% by mass, B2O3 content is 20% by mass, and SiO2 content is 15% by mass;
[0026] C5 glass: ZnO content is 60% by mass, B2O3 content is 20% by mass, SiO2 content is 15% by mass, and CaO content is 5% by mass.
[0027] ② The preparation methods for the two glass solders are exactly the same, and they are prepared separately as follows:
[0028] The raw material powder weighed in ① is ball-milled and mixed, then placed in an Al2O3 crucible and melted at high temperature to obtain a glass melt with uniform composition.
[0029] ③ Pour the molten glass into deionized water for water quenching, remove it from the water to obtain broken glass shards, then process it through ball milling to obtain fine glass powder, sieve the glass powder to remove unbroken glass pieces, and finally dry it in an oven to obtain glass solder.
[0030] 2. Use diamond polishing paste to grind and polish the surfaces of the sapphire substrate to be joined, then place it in alcohol for ultrasonic cleaning, and blow it dry for later use.
[0031] 3. Place the two glass solders prepared in step 1 into a pressing mold and press them into sheets. Then place them between two base materials to form a sandwich structure, from top to bottom: base material sapphire, C5 glass layer, C0 glass layer and base material porous Si3N4 ceramic.
[0032] Fourth, place the assembled sandwich structure in an atmosphere tube furnace, achieve pressureless connection under protective atmosphere conditions, and complete the heating connection process according to the set program.
[0033] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the high-temperature melting temperature mentioned in step one ② is 1300℃. Everything else is the same as in Specific Implementation Method One.
[0034] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that the high-temperature melting time in step 1, ② is 1 hour to 1.5 hours. Everything else is the same as in Specific Implementation Method 2.
[0035] Specific Implementation Method Four: This implementation method differs from one of Specific Implementation Methods One to Three in that the drying temperature in step 1③ is 70℃. Everything else is the same as in one of Specific Implementation Methods One to Three.
[0036] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that: in step two, 1μm diamond polishing paste is used to grind and polish the surfaces of the sapphire substrate to be joined. Everything else is the same as in Specific Implementation Method Four.
[0037] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the ultrasonic cleaning time in step two is 15-20 minutes. Everything else is the same as in Specific Implementation Method Five.
[0038] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that, in step three, the two types of glass solder prepared in step one are placed into a pressing mold and pressed into sheets of 0.1mm to 0.3mm in diameter. Everything else is the same as in Specific Implementation Method Six.
[0039] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the protective atmosphere described in step four is argon. Everything else is the same as in Specific Implementation Method Seven.
[0040] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the temperature during the heating and connection process described in step four is 740℃~770℃. Everything else is the same as in Specific Implementation Method Eight.
[0041] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the temperature during the heating and connection process described in step four is 740℃~770℃, and the holding time is 20min~50min. Everything else is the same as in Specific Implementation Method Nine.
[0042] The invention was verified using the following experiments:
[0043] Experiment 1: This experiment demonstrates a method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder. The specific steps are as follows:
[0044] I. Preparation of C0 and C5 glass solders respectively:
[0045] ① Weigh out the raw material powder of the two glass solders according to the following mass percentages:
[0046] C0 glass: ZnO content is 65% by mass, B2O3 content is 20% by mass, and SiO2 content is 15% by mass;
[0047] C5 glass: ZnO content is 60% by mass, B2O3 content is 20% by mass, SiO2 content is 15% by mass, and CaO content is 5% by mass.
[0048] ② The preparation methods for the two glass solders are exactly the same, and they are prepared separately as follows:
[0049] The raw material powder weighed in ① is ball-milled and mixed, then placed in an Al2O3 crucible and melted at a high temperature of 1300℃ for 1 hour to obtain a glass melt with uniform composition.
[0050] ③ Pour the molten glass into deionized water for water quenching, remove it from the water to obtain broken glass shards, then process it through ball milling to obtain fine glass powder, sieve the glass powder to remove unbroken glass pieces, and finally dry it in an oven to obtain glass solder at a drying temperature of 70℃.
[0051] 2. Polish the surfaces of the sapphire substrate to be joined using 1μm diamond polishing paste, then ultrasonically clean them in alcohol for 15 minutes, and blow them dry for later use.
[0052] 3. Place the two glass solders prepared in step 1 into a pressing mold and press them into round sheets with a thickness of 0.1 mm. Then place them between two base materials to form a sandwich structure, which consists of a base material sapphire, a C5 glass layer, a C0 glass layer and a base material porous Si3N4 ceramic from top to bottom.
[0053] Fourth, place the assembled sandwich structure in an atmosphere tube furnace and achieve pressureless connection under argon conditions. Complete the heating connection process according to the set program. The temperature of the heating connection process is 760℃ and the holding time is 30min.
[0054] Experiment 2: This experiment differs from Experiment 1 in that the connection temperature in step four is 740℃. Everything else is the same as Experiment 1.
[0055] Experiment 3: This experiment differs from Experiment 1 in that the connection temperature in step four is 750℃. Everything else is the same as Experiment 1.
[0056] Experiment 4: This experiment differs from Experiment 1 in that the connection temperature in step four is 770℃. Everything else is the same as Experiment 1.
[0057] Experiment 5: This experiment differs from Experiment 1 in that the heat preservation time in step four is 20 minutes. Everything else is the same as Experiment 1.
[0058] Experiment Six: This experiment differs from Experiment One in that the heat preservation time in step four is 40 minutes. Everything else is the same as Experiment One.
[0059] Experiment 7: This experiment differs from Experiment 1 in that the heat preservation time in step four is 50 minutes. Everything else is the same as Experiment 1.
[0060] The mechanical properties of the joints obtained in Experiments 1 to 7 were evaluated by shear strength. The room temperature shear strength of the joints obtained under different connection processes in Experiments 1 to 7 is shown in Table 1. The results show that the gradient thermal expansion glass brazing filler metal of the present invention can be used to obtain joints with excellent mechanical properties. Among them, the room temperature shear strength of the joint obtained in Experiment 1 reached 20.5 MPa.
[0061] Table 1
[0062]
[0063] Figure 1The images show backscattered electron scanning electron microscopy (SEM) images and magnified views of the joint obtained after Experiment 1. Figures (b) and (c) correspond to the positions in Figure (a). The images show good bonding between the solder and the base materials on both sides, resulting in a dense joint with a weld width of 384±12 μm. Magnified observation of the sapphire interface revealed the formation of a reaction layer, achieving a tight bond between the sapphire and the glass-ceramic solder. Magnified observation of the porous Si3N4 ceramic side interface showed that the connection was achieved by the glass-ceramic solder penetrating into the ceramic to form a penetration layer. Observation of the weld microstructure revealed that the precipitated crystal phases in the C5 and C0 glass-ceramic layers were consistent, consisting of blocky crystal phases and surrounding whiskers. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis identified the blocky crystal phase in the weld as Zn2SiO4. However, the nano-whiskers were too small to be analyzed using a scanning electron microscope and required further analysis. Figure 4 Further analysis was conducted using transmission electron microscopy. Table 2 shows... Figure 1 The chemical composition of the blocky phase at point A was preliminarily determined to be the Zn2SiO4 phase.
[0064] Table 2
[0065]
[0066] Take a portion of the molten glass obtained in step 1② of Experiment 1 and quickly pour it into a graphite mold to obtain a block glass. Place the block glass into a muffle furnace that has been preheated to 460°C and keep it at that temperature for 2 hours. Then, cool it to room temperature with the furnace to eliminate the thermal internal stress formed during the glass preparation process. Cut the glass block into 4mm×4mm×12mm cuboids to measure its thermal expansion. Figure 2 The graph shows the thermal expansion curves of two base materials and two types of glass (C5 and C0) measured by a thermal expansion tester. The green line represents the C5 glass layer, the yellow line represents the C0 glass layer, the blue line represents sapphire, and the pink line represents porous Si3N4 ceramic. The graph shows that within the temperature range of 30℃ to 450℃, the coefficients of thermal expansion of sapphire, C5 glass layer, C0 glass layer, and porous Si3N4 ceramic decrease in that order, with values of 6.94 × 10⁻⁶. -6 / ℃, 5.14×10 -6 / ℃, 4.58×10 -6 / ℃ and 2.74×10 -6 / ℃, achieving a gradient intermediate layer for thermal expansion, which can effectively alleviate residual stress in the joint.
[0067] Figure 3 To test the X-ray diffraction pattern of the double-layer microcrystalline glass under the first process (after step four), analysis revealed that the precipitated phases of the double-layer microcrystalline glass were consistent, consisting of Zn3B2O6 and Zn2SiO4 phases.
[0068] Figure 4 The image shows the transmission image of the joint at the sapphire side interface reaction layer after Experiment 1. (a) is the overall interface view, and (bd) are magnified views of the corresponding locations in (a). Elemental analysis of each point in the image yielded the results shown in Table 3. The interface reaction layer is ZnAl2O4 crystal, the blocky crystalline phase in the weld is Zn2SiO4 phase, and the nanofibers are of two types: shorter Zn2SiO4 phase and longer Zn3B2O6 phase. Figure 3 The X-ray diffraction results show that the crystalline phases of the double-layer microcrystalline glass are consistent, so the typical structure of the joint is sapphire / ZnAl2O4 reaction layer / Zn2SiO4+Zn3B2O6+glass phase / infiltrated layer / porous Si3N4 ceramic.
[0069] Table 3
[0070]
Claims
1. A method for joining sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder, characterized in that... The method is performed according to the following steps: I. Preparation of C0 and C5 glass solders respectively: ① Weigh out the raw material powder of the two glass solders according to the following mass percentages: C0 glass: ZnO content is 65% by mass, B2O3 content is 20% by mass, and SiO2 content is 15% by mass; C5 glass: ZnO content is 60% by mass, B2O3 content is 20% by mass, SiO2 content is 15% by mass, and CaO content is 5% by mass. ② The preparation methods for the two glass solders are exactly the same, and they are prepared separately as follows: The raw material powder weighed in ① is ball-milled and mixed, then placed in an Al2O3 crucible and melted at high temperature to obtain a glass melt with uniform composition. ③ Pour the molten glass into deionized water for water quenching, remove it from the water to obtain broken glass shards, then process it through ball milling to obtain fine glass powder, sieve the glass powder to remove unbroken glass pieces, and finally dry it in an oven to obtain glass solder.
2. Use diamond polishing paste to grind and polish the surfaces of the sapphire substrate to be joined, then place it in alcohol for ultrasonic cleaning, and blow it dry for later use.
3. Place the two glass solders prepared in step 1 into a pressing mold and press them into sheets. Then place them between two base materials to form a sandwich structure, from top to bottom: base material sapphire, C5 glass layer, C0 glass layer and base material porous Si3N4 ceramic. Fourth, place the assembled sandwich structure in an atmosphere tube furnace, achieve pressureless connection under protective atmosphere conditions, and complete the heating connection process according to the set program.
2. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... The high-temperature melting temperature mentioned in step 1② is 1300℃.
3. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 2, characterized in that... The high-temperature melting time mentioned in step 1② is 1h~1.5h.
4. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... The drying temperature described in step 1③ is 70℃.
5. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... In step two, 1μm diamond polishing paste is used to polish the surfaces of the sapphire substrate to be joined.
6. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... The ultrasonic cleaning time in step two is 15 min to 20 min.
7. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... In step three, the two types of glass solder prepared in step one are placed into a pressing mold and pressed into sheets of 0.1mm to 0.3mm.
8. The method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... The protective atmosphere described in step four is argon.
9. A method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 1, characterized in that... The temperature for the heating connection process described in step four is 740℃~770℃.
10. A method for connecting sapphire and porous Si3N4 ceramic using gradient ZBS microcrystalline glass solder according to claim 9, characterized in that... The temperature for the heating connection process described in step four is 740℃~770℃, and the holding time is 20min~50min.