CN113666766B - A method for glass solder to infiltrate and connect zirconia ceramics - Google Patents

Abstract

The invention discloses a method for connecting zirconia ceramics by glass solder in a penetrating way, belonging to the technical field of welding. The method comprises the steps of grinding and polishing the surfaces of two pieces of zirconia ceramics to be weldedLeveling; preparing glass solder powder according to the route of ball milling, drying, melting, water quenching, ball milling, drying and sieving, pressing the glass solder powder into sheets, and presintering for densification; placing a glass solder sheet between two ceramics to be welded for assembly; and (4) putting the assembled sample into a muffle furnace, heating to a welding temperature, preserving heat for a certain time, and cooling along with the furnace. The glass solder comprises the following components: caO:30 to 38 percent of TiO ₂ ：20％～26％，REO：5％～10％，B ₂ O ₃ ：1‑5％，SiO ₂ :34 to 44 percent. The invention can eliminate brazing seams existing in the traditional glass connection method, realize the uniform mixing of glass solder and ceramic grains, and further improve the strength, the thermal shock resistance and the high temperature resistance of the joint.

Description

A method for glass solder to infiltrate and connect zirconia ceramics

technical field

The invention relates to the field of welding technology, in particular to a method for infiltrating and connecting zirconia ceramics with glass solder.

Background technique

Zirconia ceramics have many advantages such as high hardness, high strength, high toughness, good corrosion resistance, etc., and are widely used in machinery, chemical industry, aerospace and other fields. However, due to the inherent brittleness and difficulty in machining of ceramic materials, in order to construct ceramic parts with complex shapes and large sizes, it is often necessary to use joining techniques.

Among the connection methods of various ceramic materials, glass connection is more suitable for the connection of ceramic itself due to the good chemical compatibility between glass solder and ceramics. However, the principle of the traditional glass joining method is similar to that of brazing, and the structure and physical and chemical properties of the weld are quite different from those of the base metal. For example, the thermal expansion coefficient, elastic modulus, and softening temperature of the weld are different from those of the ceramic base There is a large difference, which leads to insufficient thermal shock resistance and high temperature resistance of the joint. According to the principle of liquid infiltration into polycrystalline solids, the invention proposes a method for infiltration and connection of zirconia ceramics based on glass solder.

Contents of the invention

The purpose of the present invention is to obtain a joint connection layer similar to the structure of the ceramic base material, thereby improving the joint strength, thermal shock resistance and service temperature.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A method for infiltrating and connecting zirconia ceramics with glass solder, the method uses glass solder to infiltrate and connect zirconia ceramic base materials, and the composition of the glass solder is as follows by weight percentage:

CaO: 30%～38%, TiO ₂ : 20%～26%, REO: 5%～10%, B ₂ O ₃ : 1-5%, Li ₂ O: 1-5%; SiO ₂ : 34%～ 44%.

Preferably, the REO is one or more of La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , Dy ₂ O ₃ and Ho ₂ O ₃ .

The method for infiltrating and connecting zirconia ceramics with glass solder specifically comprises the following steps:

(1) Material preparation: Grind and polish the surface of the zirconia ceramics to be welded, perform ultrasonic cleaning with acetone as the medium for 5-20 minutes, and dry it for later use.

(2) Preparation of glass solder: Weigh each oxide raw material according to the composition of glass solder, and prepare glass solder powder by melting-water quenching method after uniform mixing;

(3) Solder pre-sintering: add polyvinyl alcohol to the glass powder and stir evenly, then put it into a tablet mold and press it into a sheet structure with a certain thickness, and then put it in a muffle furnace for pre-sintering to obtain a glass solder sheet ;

(4) Joint assembly: Cut the pre-sintered glass solder sheet into the same shape as the surface size of the ceramic to be welded, and then place it between two polished zirconia ceramics to form a "sandwich" assembly structure. During the connection process Do not use any pressure;

(5) Joint connection: put the joint assembled in step (4) into the muffle furnace in the air atmosphere and heat it quickly to the welding temperature. The purpose of rapid heating is to prevent the glass solder from excessive penetration before heat preservation. Heating to the welding temperature and keeping it warm for a long enough time to ensure that the glass solder and ceramic grains are evenly mixed; after the heat preservation is over, the joint is cooled to room temperature with the furnace.

In the step (1), the grinding and polishing method is to use 400#, 800#, and 1200# sandpaper to grind in sequence, and then use diamond polishing paste with a particle size of 2.5 μm, 1.5 μm, and 0.5 μm for polishing.

In the step (2), the preparation process of the glass solder is as follows: put the weighed oxide raw material powder into a polytetrafluoroethylene ball milling jar, use alcohol as the ball milling medium, _ZrO2 as the balls for ball milling, ball milling The rotation speed is 400-500 rpm, and the ball milling time is 2-5 hours; after the ball milling, the composite powder is dried, and the dried material is poured into a platinum crucible, and heated in an air atmosphere muffle furnace to 1500-1600°C, keep warm for 1-3 hours, pour the obtained glass melt into deionized water, and then obtain glass pieces; put the glass pieces into an agate ball mill jar, use agate as a ball for ball milling, and the ball milling speed is 400 -500 revolutions/min, the ball milling time is 2-5h, after the ball milling is completed, dry and pass through a 200-mesh sieve to obtain the glass powder.

In the step (3), the weight of polyvinyl alcohol added is 1-5% of the weight of the glass powder. The pressing process is as follows: the pressure is 20-40MPa, and the holding time is 1-5min. The sintering process is as follows: the heating rate is 5-10°C/min, the holding temperature is 750-850°C, and the holding time is 30-60min. The purpose of pre-sintering is to sinter and densify the glass solder sheet and reduce the gas content contained in the solder powder.

In the step (3), the obtained glass solder sheet has a thickness of 0.1-0.3 mm, a thermal expansion coefficient of 7-10×10 ^-6 /°C, and a wetting angle of the solder on the surface of the zirconia ceramic is less than 10°.

In the step (5), the heating rate of the assembled structure in the muffle furnace is 30-60min/min, the joint connection temperature is 1350-1500°C, and the holding time is 40-90min.

In the step (5), after the joint is cooled to room temperature, the joint can be heated again to the crystallization temperature of 900-1100°C and kept for 1-4 hours to promote the crystallization of the glass phase between the base material ceramic grains in the joint connection area.

Design mechanism of the present invention and beneficial effect are as follows:

1. The present invention designs a glass solder having a thermal expansion coefficient close to that of zirconia ceramics and having good wettability and permeability on the surface of zirconia ceramics. The glass solder with this composition has low interfacial tension, good wettability and fast penetration speed with zirconia ceramics after melting. As shown in Figure 1, when σ _SS /σ _SL >2, liquid glass can penetrate into polycrystalline zirconia ceramics. The glass solder of the present invention has relatively small solid-liquid interfacial tension between the zirconia ceramics and thus has good permeability.

2. In the pre-sintering process of the glass solder sheet, the present invention heats up to 750-850°C at a heating rate of 5-10°C/min and keeps the temperature for 30-60min. The purpose of pre-sintering is to sinter and densify the glass solder sheet and reduce the gas content contained in the solder powder.

3. In the joint connection process of the present invention, the assembled joint is put into a muffle furnace for heating and rapidly heated to the welding temperature. The purpose of rapid heating is to prevent the transitional penetration of the glass solder before heat preservation. Heat to soldering temperature and hold for a sufficient time. During the heat preservation process, on the one hand, the glass solder penetrates into the ceramic base material, and at the same time, the grains of the ceramic base material will also move due to the buoyancy and gravity. Only the joint action of the two can ensure the uniform mixing of the glass solder and the ceramic grains. In order to achieve permeable connection.

4. The infiltration connection method proposed by the present invention can eliminate the brazing seam existing in the traditional glass connection method, and can obtain a joint connection layer composed of "base metal grains + glass solder", and the tissue structure, thermal expansion coefficient, and elastic modulus of the joint connection layer can be obtained. Quantity and other physical and chemical properties are very close to the ceramic base material. Therefore, the present invention can obtain a zirconia ceramic joint with high strength, low stress, high thermal shock resistance and high heat resistance.

Description of drawings

Figure 1 is a schematic diagram of the interfacial tension in the infiltration process.

Fig. 2 is a photograph of the microstructure of the zirconia ceramic joint obtained in Example 1; wherein (a) and (b) are different magnifications.

FIG. 3 is a photograph of the microstructure of the zirconia ceramic joint obtained in Comparative Example 1.

Fig. 4 is a photograph of the microstructure of the zirconia ceramic joint obtained in Comparative Example 2; wherein (a) and (b) are different magnifications.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Example 1

This embodiment is a method for infiltrating and connecting zirconia ceramics with glass solder, comprising the following steps:

(1) Material preparation: use 400#, 800#, and 1200# sandpaper to polish the surface of the zirconia ceramics to be welded in sequence, and then use diamond polishing paste with a particle size of 2.5 μm, 1.5 μm, and 0.5 μm to polish the surface of the ceramics to be welded. The polished zirconia ceramics were ultrasonically cleaned with acetone for 20 min, and then dried for later use.

(2) Glass solder preparation: The components and mass fractions of the glass solder used are: CaO: 32%, TiO ₂ : 23%, Dy ₂ O ₃ : 5%, B ₂ O ₃ : 3%, SiO ₂ : 37% . Weigh the oxide raw material according to the above ratio, put it into a polytetrafluoroethylene ball mill jar, use alcohol as the milling medium, _ZrO2 as the ball for ball milling, the milling speed is 450 rpm, and the ball milling time is 4h. After ball milling, dry in a vacuum oven at 70°C for 2 hours. The dried raw materials were poured into a platinum crucible and heated to 1550°C in a muffle furnace. After 2 hours of heat preservation, the glass melt was poured into deionized water to obtain glass shards. The glass fragments were put into an agate ball mill jar for ball milling, the ball milling speed was 500 rpm, and the ball milling time was 4 hours. After ball milling, dry and pass through a 200-mesh sieve for later use.

(3) Solder pre-sintering: Add polyvinyl alcohol with a weight percentage of 2% to the glass powder and stir evenly, then put it into a tablet mold and press it into a sheet with a thickness of 0.2mm, and then put it in a muffle furnace to Heating at a heating rate of 10°C/min to 800°C, holding for 30 minutes to sinter and densify the solder, and finally cooling to room temperature with the furnace for use.

(4) Joint assembly: Cut the pre-sintered glass solder sheet into the same shape as the surface size of the ceramic to be welded, and then place it between two polished zirconia ceramics to form a "sandwich" structure. Use any pressure.

(5) Joint connection: put the assembled joint into an air atmosphere muffle furnace for heating, and do not use any pressure during the connection process. Rapidly heat to 1400°C at a heating rate of 30°C/min and keep for 50 minutes. After the heat preservation is over, the joint is cooled to room temperature with the furnace.

Figure 2 is a photo of the microstructure of the zirconia ceramic joint obtained in Example 1. It can be seen from the figure that the glass solder has completely penetrated into the base material and formed a good connection. There are no defects such as holes and cracks in the joint. From the central area of the joint to the side of the base metal, the content of the glass phase gradually decreases, and the grain content of the base metal gradually increases, showing a gradient transition structure.

Example 2

This embodiment is a method for infiltrating and connecting zirconia ceramics with glass solder, comprising the following steps:

(1) Material preparation: use 400#, 800#, and 1200# sandpaper to polish the surface of the zirconia ceramics to be welded in sequence, and then use diamond polishing paste with a particle size of 2.5 μm, 1.5 μm, and 0.5 μm to polish the surface of the ceramics to be welded. The polished zirconia ceramics were ultrasonically cleaned with acetone for 20 min, and then dried for later use.

(2) Preparation of glass solder powder: The composition and mass fraction of the glass solder used are: CaO: 32%, TiO ₂ : 23%, Nd ₂ O ₃ : 5%, B ₂ O ₃ : 3%, SiO ₂ : 37%. Weigh the oxide raw material according to the above ratio, put it into a polytetrafluoroethylene ball mill jar, use alcohol as the ball mill medium, _ZrO2 as the ball for ball milling, the ball milling speed is 450 rpm, and the ball milling time is 4h. After ball milling, dry in a vacuum oven at 70°C for 2 hours. The dried raw materials were poured into a platinum crucible and heated to 1550°C in a muffle furnace. After 2 hours of heat preservation, the glass melt was poured into deionized water to obtain glass shards. The glass fragments were put into an agate ball mill jar for ball milling, the ball milling speed was 500 rpm, and the ball milling time was 4 hours. After ball milling, dry and pass through a 200-mesh sieve to obtain glass solder powder.

(3) Solder pre-sintering: Add polyvinyl alcohol to the glass powder and stir evenly, then put it into a tablet mold and press it into a sheet with a thickness of 0.2mm, and then put it in a muffle furnace to heat up at a rate of 10°C/min Heating at a speed of 800°C, holding the temperature for 30 minutes to sinter and densify the solder, and finally cooling down to room temperature with the furnace to obtain a glass solder sheet.

(4) Joint assembly: Cut the pre-sintered glass solder sheet into the same shape as the surface size of the ceramic to be welded, and then place it between two polished zirconia ceramics to form a "sandwich" structure. Use any pressure.

(5) Joint connection: put the assembled joint into an air atmosphere muffle furnace for heating, and do not use any pressure during the connection process. Rapidly heat to 1400°C at a heating rate of 30°C/min and keep for 40min. After the heat preservation is over, the joint is cooled to room temperature with the furnace, and the zirconia ceramics are infiltrated and joined by glass solder.

Example 3

This embodiment is a method for infiltrating and connecting zirconia ceramics with glass solder, comprising the following steps:

(1) Material preparation: use 400#, 800#, and 1200# sandpaper to polish the surface of the zirconia ceramics to be welded in sequence, and then use diamond polishing paste with a particle size of 2.5 μm, 1.5 μm, and 0.5 μm to polish the surface of the ceramics to be welded. The polished zirconia ceramics were ultrasonically cleaned with acetone for 20 min, and then dried for later use.

(2) Preparation of glass solder powder: The composition and mass fraction of the glass solder used are: CaO: 38%, TiO ₂ : 20%, Nd ₂ O ₃ : 5%, B ₂ O ₃ : 1%, SiO ₂ : 36%. Weigh the oxide raw material according to the above ratio, put it into a polytetrafluoroethylene ball mill jar, use alcohol as the ball mill medium, _ZrO2 as the ball for ball milling, the ball milling speed is 450 rpm, and the ball milling time is 4h. After ball milling, dry in a vacuum oven at 70°C for 2 hours. The dried raw materials were poured into a platinum crucible and heated to 1550°C in a muffle furnace. After 2 hours of heat preservation, the glass melt was poured into deionized water to obtain glass shards. The glass fragments were put into an agate ball mill jar for ball milling, the ball milling speed was 500 rpm, and the ball milling time was 4 hours. After ball milling, dry and pass through a 200-mesh sieve to obtain glass solder powder.

(3) Solder pre-sintering: Add polyvinyl alcohol to the glass powder and stir evenly, then put it into a tablet mold and press it into a sheet with a thickness of 0.2mm, and then put it in a muffle furnace to heat up at a rate of 10°C/min Heating at a speed of 800°C, holding the temperature for 30 minutes to sinter and densify the solder, and finally cooling down to room temperature with the furnace to obtain a glass solder sheet.

(4) Joint assembly: Cut the pre-sintered glass solder sheet into the same shape as the surface size of the ceramic to be welded, and then place it between two polished zirconia ceramics to form a "sandwich" structure. Use any pressure.

(5) Joint connection: put the assembled joint into an air atmosphere muffle furnace for heating, and do not use any pressure during the connection process. Rapidly heat to 1450°C at a heating rate of 30°C/min and keep for 40min. After the heat preservation is over, the joint is cooled to room temperature with the furnace, and the zirconia ceramics are infiltrated and joined by glass solder.

Comparative example 1

In step (5), the heat preservation time is 10min, and other steps are all the same as in Example 1. Due to the short holding time, the solder did not completely penetrate into the zirconia ceramics, thus forming a glassy brazing seam, as shown in Figure 3.

Comparative example 2

In step (5), the heating rate is 5° C./min, and other steps are all the same as in Example 1. Due to the slow heating rate, the glass solder has penetrated into the zirconia ceramic matrix during the heating process, resulting in failure to form an effective connection at the joint. The microstructure of the joint is shown in Figure 4. Therefore, a faster heating rate must be adopted to ensure that there is liquid solder in the weld during the heat preservation process, so that the base metal grains and solder can produce relative motion, and then mix evenly to form a reliable connection.

The mechanical property data of joints obtained in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1. It can be seen from the table that Example 1, Example 2, and Example 3 all obtained excellent room temperature strength, high temperature strength and strength after thermal shock cycle. In Comparative Example 1, the high-temperature strength decreased significantly due to the glassy weld. At the same time, due to the thermal expansion coefficient mismatch between the base metal and the solder, the strength of the joint after thermal shock cycles is low. In Comparative Example 2, due to failure to form an effective connection, the room temperature strength, high temperature strength and strength of the joint after thermal shock cycle are all the lowest.

Table 1 The joint bending strength data of the embodiment and the comparative example

Claims (10)

1. A method for infiltrating and connecting zirconia ceramics with glass solder, characterized in that: the method is to adopt glass solder to infiltrate and connect zirconia ceramic base material, and the raw material of said glass solder has the following components by weight percentage: CaO: 30%-38%, TiO ₂ : 20%-26%, REO: 5%-10%, B ₂ O ₃ : 1-5%, SiO ₂ : 34%-44%. 2. The method for infiltrating and joining zirconia ceramics with glass solder according to claim 1, characterized in that: said REO is La ₂ O ₃ , Y ₂ O ₃ , Nd ₂ O ₃ , Dy ₂ O ₃ and Ho ₂ O One or more of ₃ . 3. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 1, characterized in that: the method specifically comprises the following steps: (1) Material preparation: After grinding and polishing the surface of the zirconia ceramics to be welded, perform ultrasonic cleaning with acetone as the medium for 5-20 minutes, and dry it for later use; (2) Preparation of glass solder: Weigh each oxide raw material according to the composition of glass solder, and prepare glass solder powder by melting-water quenching method after uniform mixing; (3) Solder pre-sintering: Add polyvinyl alcohol to the glass solder powder and stir evenly, then put it into a tablet mold and press it into a sheet-like structure with a certain thickness, and then put it in a muffle furnace for pre-sintering to obtain glass Solder sheet; (4) Joint assembly: Cut the pre-sintered glass solder sheet into the same shape as the surface size of the ceramic to be welded, and then place it between two polished zirconia ceramics to form a "sandwich" assembly structure. During the connection process Do not use any pressure; (5) Joint connection: put the joint assembled in step (4) into the muffle furnace in the air atmosphere and heat it quickly to the welding temperature, and keep it warm for a long enough time to ensure that the glass solder and ceramic grains are evenly mixed and kept warm After the end, the joint is cooled to room temperature with the furnace. 4. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 3, characterized in that: in step (1), the grinding and polishing method is as follows: sequentially use 400#, 800#, 1200# sandpaper to polish, and then sequentially use Diamond polishing paste with a particle size of 2.5 μm, 1.5 μm, and 0.5 μm is used for polishing. 5. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 3, characterized in that: in step (2), the process of preparing glass solder powder by the melting-water quenching method is: the weighed oxidized Put the raw material powder into a polytetrafluoroethylene ball milling tank, use alcohol as the ball milling medium and _ZrO2 as the ball for ball milling, the ball milling speed is 400-500 rpm, and the ball milling time is 2-5h; after the ball milling is completed, bake Dry, pour the dried material into a platinum crucible, put it into an air atmosphere muffle furnace and heat it to 1500-1600°C, keep it warm for 1-3h, pour the obtained glass melt into deionized water, and then obtain glass cullet block; put the glass pieces into the agate ball mill jar, use agate as the ball for ball milling, the ball milling speed is 400-500 rpm, the ball milling time is 2-5h, after the ball milling is completed, dry and pass through a 200-mesh sieve to get The glass solder powder is for future use. 6. the method for glass solder penetration connection zirconia ceramics according to claim 3, is characterized in that: in step (3), adding polyvinyl alcohol weight is 1-5% of glass solder powder weight; The pressing thickness is 0.1-0.3 mm, the pressing pressure is 20-40 MPa, and the holding time is 1-5 min. 7. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 3, characterized in that: in step (3), the pre-sintering process is: heating to 750-850°C at a heating rate of 5-10°C/min , keep warm for 30-60 minutes, and finally cool down to room temperature with the furnace for later use. 8. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 3, characterized in that: in step (3), the thermal expansion coefficient of the prepared glass solder is 8-10×10 ^-6 /°C, and the solder The optimum wetting angle on the surface of zirconia ceramics is less than 10°. 9. The method for infiltrating and connecting zirconia ceramics with glass solder according to claim 3, characterized in that in step (5), the heating rate of the joint is 30-60 min/min, the joint connection temperature is 1350-1500 °C, and the holding time 40-90 minutes. 10. The method for infiltrating and joining zirconia ceramics with glass solder according to claim 3, characterized in that: in step (5), after the joint is cooled to room temperature, the joint is heated again to the crystallization temperature of 900-1100°C, and kept warm for 1 -4h, to promote the crystallization of the glass phase between the base material ceramic grains in the joint connection area.

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