CN113121116B - Microcrystalline glass solder, preparation method thereof and method for connecting alumina ceramics - Google Patents

Abstract

The invention discloses a glass-ceramic solder, the chemical composition of which is CaO 15-20wt%, _Al2O3 10-25wt%, _{SiO2 50-55wt} %, ZnO _5-10wt %, B2O3 _5-10wt % %; the glass thermal expansion coefficient of the glass-ceramic solder between 25-700°C is 5.9-6.5× ^10-6 /°C. In addition, the preparation method of the above glass-ceramic solder and the method of connecting alumina ceramics are also disclosed. The glass-ceramic solder of the present invention matches the thermal expansion coefficient of the alumina ceramic base material and has a suitable connection temperature, thereby realizing low-temperature connection of alumina ceramics, reducing the technical difficulty of alumina ceramic connection, and improving the strength of the joint at room temperature, without Defects such as pores and cracks effectively improve the connection quality of alumina ceramics.

Description

A kind of glass-ceramics solder and its preparation method and method for connecting alumina ceramics

technical field

The invention relates to the technical field of alumina ceramic connection, in particular to a glass-ceramic solder, a preparation method thereof and a method for connecting alumina ceramics.

Background technique

Alumina ceramics have the advantages of high mechanical strength, small dielectric loss, high insulation resistance, high hardness, wear resistance, corrosion resistance, high temperature resistance, etc., and are widely used in various fields such as aviation, military, machinery, petroleum, chemical industry and electronics. However, due to the inherent brittleness of ceramic materials and the difficulty in machining, it is difficult to prepare alumina ceramics into components with large sizes and complex shapes, so its application range is greatly limited. In order to construct alumina ceramic components with complex shapes and large sizes, connection technology is required. Combining simple structural components into components with complex shapes is of great significance for reducing its production cost and expanding its application range.

Among various techniques for joining ceramic materials, using glass-ceramics as a joining material is a simple, easy and inexpensive joining method. Glass-ceramic connecting materials have excellent chemical compatibility with ceramics, and can improve their strength through certain crystallization. However, at present, the glass-ceramic solders in the prior art generally have the problems of high melting point and poor matching of thermal expansion coefficient with alumina ceramics, which increases the difficulty of the ceramic connection process and brings defects such as pores and cracks, which greatly affects the joints. The mechanical properties and connection quality of alumina ceramics. Therefore, it is necessary to prepare a glass-ceramic solder suitable for connecting alumina ceramics at low temperature and matching the thermal expansion coefficient of alumina ceramics.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a glass-ceramic solder, which matches the thermal expansion coefficient of the alumina ceramic base material and has a suitable connection temperature through formula design, so as to realize the connection of alumina at low temperature ceramics. Another object of the present invention is to provide a method for preparing the above glass-ceramic solder and a method for connecting alumina ceramics.

The purpose of the present invention is achieved through the following technical solutions:

A glass-ceramic solder provided by the present invention has a chemical composition of 15-20wt% CaO, 10-25wt% Al ₂ O ₃ , 50-55wt% SiO _{2 ,} 5-10wt% ZnO, and 5-10wt% B ₂ O ₃ %; the coefficient of thermal expansion of the glass at 25-700°C of the glass-ceramic solder is 5.9-6.5×10 ^-6 /°C.

Another object of the present invention is achieved through the following technical solutions:

The preparation method of above-mentioned glass-ceramic solder provided by the present invention comprises the following steps:

(1) Ball milling mixture

According to the chemical composition ratio, CaCO ₃ , Al ₂ O ₃ , SiO ₂ , ZnO, H ₃ BO ₃ are weighed as raw materials, and mixed by wet ball milling to obtain a mixed material;

(2) Melting and quenching

The mixed material is melted after drying, grinding and sieving, and then the melted material is quenched to obtain a glass frit;

(3) Ball milled into powder

The glass frit is pulverized by a dry ball mill and sieved to obtain CaO-Al ₂ O ₃ -SiO ₂ -ZnO-B ₂ O ₃ glass-ceramic solder.

Further, in the step (2) of the preparation method of the present invention, the drying temperature is 80-110° C., and the drying time is 6-12 hours; the melting temperature is 1400-1550° C., and the melting time is 1-3 hours. In the step (3), the rotating speed of the dry ball mill is 1000-1400 r/min, and the ball milling time is 5-60 min.

The method provided by the present invention for connecting alumina ceramics using the above-mentioned glass-ceramic solder comprises the following steps:

(1) Grinding and polishing the surfaces to be connected of alumina ceramics to be welded;

(2) After mixing the glass-ceramic solder with a polyvinyl alcohol aqueous solution with a concentration of 9 wt%, granulating and pressing to obtain a sheet-shaped solder body;

(3) Stick the solder body between the surfaces of the alumina ceramic parts to be welded, apply pressure to the parts to be welded, place them in a brazing furnace for welding, and cool with the furnace to complete the alumina Ceramic connections.

Further, the amount of polyvinyl alcohol aqueous solution in the step (2) of the connection method of the present invention is 5-7 wt% of the glass-ceramic solder, the pressure of compression molding is 10-30 MPa, and the thickness of the sheet-shaped solder body is 100-200 wt%. 300 μm. The applied pressure in the step (3) is 0-15KPa; the temperature regime of the welding treatment in the brazing furnace is: heating from room temperature to 350-400°C at a rate of 5-10°C/min, keeping the temperature for 30-60min, and then Continue heating at a rate of 5-15°C/min to 1150-1300°C, keep warm for 20-40min, then cool to 700-900°C at a rate of 10-20°C/min, and keep warm for 1-2h.

The present invention has the following beneficial effects:

(1) The CaO-Al ₂ O ₃ -SiO ₂ -ZnO-B ₂ O ₃ glass-ceramic solder of the present invention belongs to medium-temperature glass solder, and the coefficient of thermal expansion of glass between 25 and 700°C is 5.9 to 6.5×10 ^-6 / ℃, which matches the thermal expansion coefficient of the alumina ceramic base material being connected. CaO-Al ₂ O ₃ -SiO ₂ is the matrix composition of glass-ceramics, in which SiO ₂ is the glass network structure former; the addition of Al ₂ O ₃ forms a unified network with silicon-oxygen tetrahedron; CaO belongs to the outer body of the network, and The form of CaCO ₃ is introduced, and its addition is to precipitate calcium-containing microcrystalline phases, thereby improving the performance of glass-ceramics.

(2) The glass-ceramic solder of the present invention contains a small amount of ZnO and B ₂ O ₃ (B ₂ O ₃ is introduced in the form of H ₃ BO ₃ ), and its purpose is: ZnO reduces the melting temperature of the glass solder on the one hand, and on the other hand Crystal phases such as zinc silicate can be precipitated, which is beneficial to control the thermal expansion coefficient of the solder; B ₂ O ₃ is used to reduce the melting temperature and soldering temperature.

(3) The glass-ceramic solder of the present invention can realize the connection between alumina ceramics at 1150°C to 1300°C, which reduces the difficulty of the connection process of alumina ceramics, and the strength of the joint at room temperature can reach 255 to 280MPa, which is higher than that of ordinary glass joints. 19 to 30%, and because the thermal expansion coefficient of the joint and the alumina base material matches well, and there are no defects such as pores and cracks, the connection quality of alumina ceramics is effectively improved.

Description of drawings

The present invention will be described in further detail below in conjunction with embodiment and accompanying drawing:

Fig. 1 is the welding schematic diagram that adopts the glass-ceramics solder of the embodiment of the present invention to be used for connecting alumina ceramics;

Fig. 2 is a curve of the welding temperature profile for connecting alumina ceramics using a glass-ceramic solder according to an embodiment of the present invention.

In the figure: Alumina ceramics to be welded piece 1, solder body 2, applying pressure P to the piece to be welded

Detailed ways

Embodiment one:

1. A glass-ceramic solder in this embodiment, its chemical composition is CaO 15wt%, _{Al2O3 15wt} %, _SiO2 55wt%, ZnO 5wt%, _{B2O3 10wt} %; said glass-ceramics The glass thermal expansion coefficient of the solder between 25°C and 700°C is 6.2×10 ^-6 /°C.

2. The preparation method of the glass-ceramic solder of the present embodiment, the following steps are as follows:

(1) Ball milling mixture

According to the above chemical composition ratio, after weighing CaCO ₃ , Al ₂ O ₃ , SiO ₂ , ZnO, H ₃ BO ₃ as raw materials, put them in a polytetrafluoroethylene ball mill tank, according to the mass ratio of raw materials: grinding balls: deionized Water=1:2:1, wet ball milling and mixing at 300r/min for 5h to obtain the mixed material;

(2) Melting and quenching

The above mixed material was dried at 100°C for 10 hours, ground and passed through a 200-mesh sieve, then melted at 1450°C for 1 hour, and then poured the melted material into distilled water for quenching to obtain a glass frit;

(3) Ball milled into powder

The above-mentioned glass frit was pulverized by a dry ball mill at a speed of 1200r/min for 30 minutes, and passed through a 250-mesh sieve to obtain CaO-Al ₂ O ₃ -SiO ₂ -ZnO-B ₂ O ₃ glass-ceramic solder.

3. The method for connecting alumina ceramics with the glass-ceramic solder of the present embodiment, the steps are as follows:

(1) Use No. 500, No. 800, No. 1200, and No. 1600 water abrasive paper to grind and polish the surface to be connected of the alumina ceramic part 1 to be welded step by step;

(2) After mixing the above-mentioned glass-ceramic solder with a polyvinyl alcohol aqueous solution (the amount of which is 6 wt% of the glass-ceramic solder) with a concentration of 9wt%, it is granulated and pressed under a pressure of 15MPa to obtain a thickness of 150 μm. Sheet-shaped solder body 2;

(3) As shown in Figure 1, use 502 glue to bond the above-mentioned solder body 2 between the surfaces to be connected of the alumina ceramic piece to be welded 1, apply a pressure P of 10KPa to the piece to be welded, and place it in a brazing furnace Carry out the following soldering treatment (see Figure 2): heat from room temperature to 400°C at a rate of 5°C/min, hold for 30 minutes, then continue heating to 1250°C at a rate of 10°C/min, and after holding for 30 minutes, heat at a rate of 10°C/min Cool to 750°C and keep warm for 1 hour; then cool with the furnace to complete the connection of alumina ceramics.

The room temperature strength of the alumina joints connected by glass-ceramics prepared in this example reaches 263 MPa, which is 22.3% higher than that of ordinary glass joints.

Embodiment two:

This embodiment differs from Embodiment 1 in that:

The chemical composition of the glass-ceramic solder is CaO 10wt%, Al ₂ O ₃ 20 wt%, SiO ₂ 55 wt%, ZnO 10wt%, B ₂ O ₃ 5 wt%; The coefficient of thermal expansion of the glass is 6.5×10 ^-6 /°C.

The room temperature strength of the alumina joints connected by glass-ceramics prepared in this example reaches 280 MPa, which is 30% higher than that of common glass joints.

Embodiment three:

This embodiment differs from Embodiment 1 in that:

In the method for connecting alumina ceramics with the glass-ceramic solder of this embodiment, the welding treatment system of step (3) in the brazing furnace is as follows: heating from room temperature to 350° C. at a rate of 10° C./min, keeping the temperature for 60 minutes, and then heating for 5° C. Continue to heat to 1200°C at a rate of ℃/min, and after holding for 40 minutes, cool to 860°C at a rate of 20°C/min, and hold for 1 hour.

The room temperature strength of the alumina joints connected by glass-ceramics prepared in this example reaches 274 MPa, which is 27.5% higher than that of ordinary glass joints.

Claims (5)

1. A preparation method of glass-ceramic solder, characterized in that: the chemical composition of glass-ceramic solder is CaO 15-20 wt%, Al ₂ O ₃ 10-25 wt%, SiO ₂ 50-55 wt%, ZnO 5～10 wt%, B ₂ O ₃ 5～10 wt%; the preparation method includes the following steps: (1) Ball milling mixture According to the chemical composition ratio, CaCO ₃ , Al ₂ O ₃ , SiO ₂ , ZnO, H ₃ BO ₃ are weighed as raw materials, and mixed by wet ball milling to obtain a mixed material; (2) Melting and quenching The mixed material is dried at 80-110°C for 6-12 hours, ground, passed through a 200-mesh sieve, and then melted at a temperature of 1400-1550°C for 1-3 hours, and then the melted melt material is subjected to quenching treatment to obtain glass Frit; (3) Ball milling into powder The glass frit is crushed with a dry ball mill at a speed of 1000-1400 r/min, and the ball milling time is 5-60 minutes. After sieving, CaO-Al ₂ O ₃ -SiO ₂ -ZnO-B ₂ O ₃ is obtained Glass-ceramic solder, CaO-Al ₂ O ₃ -SiO ₂ is the matrix composition of glass-ceramic, in which SiO ₂ is the glass network structure forming body, the addition of Al ₂ O ₃ forms a unified network with silicon-oxygen tetrahedron, and CaO belongs to The outer body of the network is introduced in the form of CaCO ₃ to precipitate calcium-containing microcrystalline phases; the glass thermal expansion coefficient of the glass-ceramics solder is 5.9-6.5×10 ^-6 /°C at 25-700°C, and at 1150-1300°C The connection between alumina ceramics is realized, and the strength of the joint at room temperature reaches 255-280 MPa. 2. adopt claim 1 preparation method gained glass-ceramics solder to connect the method for alumina ceramics, it is characterized in that comprising the following steps: (1) Grinding and polishing the surfaces to be connected of alumina ceramics to be welded; (2) After mixing the glass-ceramic solder with a polyvinyl alcohol aqueous solution with a concentration of 9 wt%, granulation and compression molding are performed to obtain a sheet-shaped solder body; (3) Stick the solder body between the surfaces of the alumina ceramic parts to be welded, apply pressure to the parts to be welded, place them in a brazing furnace for welding, and cool with the furnace to complete the alumina Ceramic connection. 3. The method for connecting alumina ceramics according to claim 2, characterized in that: the consumption of polyvinyl alcohol aqueous solution in the step (2) is 5-7 wt% of the glass-ceramic solder, and the pressure of compression molding is 10-30MPa, and the thickness of the sheet-shaped solder body is 100-300 μm. 4. The method for connecting alumina ceramics according to claim 2, characterized in that the pressure applied in the step (3) is 0-15 kPa. 5. The method for connecting alumina ceramics according to claim 2, characterized in that: the temperature regime of the brazing furnace in the step (3) is: heating from room temperature to 350-400°C, keep warm for 30-60min, then continue to heat at 5-15°C/min to 1150-1300°C, keep warm for 20-40min, then cool to 700-900°C at 10-20°C/min, hold for 1 ~2h.

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