JPS60171273A - Method of bonding ceramic containing si3n4 as chief component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining ceramics containing Si3N4 as a main component, and particularly to a method for joining ceramics that is effective in developing the ceramic into a complex shape.

[Prior art]

Ceramic containing Si3N4 as a main component is a ceramic that has high strength, excellent thermal shock resistance, and excellent chemical corrosion resistance and wear resistance at high temperatures. In other words, it has already been used as engine parts, heat exchanger parts, turbine parts, etc., and is used in steel manufacturing,
Non-ferrous metals, furnaces, glass, cement, nuclear crab industry, automobiles,
It is a ceramic material that is permeating the fields of chemical engineering, electronic engineering, etc.

However, the drawback of ceramics containing Si3N4 as a main component is that it is difficult to obtain complex shapes, and the current situation is that the rate at which ceramics are gaining popularity as a material useful in the above fields is slow.

Conventionally, joining of ceramics whose main component is Si3N4 is
There are a method in which an oxide is interposed in the joint portion, a method in which a metal is interposed in the joint portion, a method in which St powder is interposed in the joint portion and reaction sintering is performed in a nitriding atmosphere, and the like. Among these methods, the method of interposing oxide or metal in the joint part is Si3
This breaks the continuity between ceramics whose main component is N4. In other words, the continuous chemical bonds of the ceramic mainly composed of Si3N4 are broken by the oxides and metals in the bonded parts, resulting in a decrease in heat resistance and strength and creep in the parts. As long as it is bonded with oxide or metal, Si3N4
The scope of application of ceramics whose main components are as hot members is very narrowly limited.

In addition, in the case of a method in which Si powder is interposed in the joint part and reaction sintering is performed in a nitriding atmosphere, S
Since the structure of i3N4 is porous and the bond at the interface between the object to be joined and the joining layer is weak, it has the disadvantage of lowering strength and other properties.

[Purpose of the invention]

The present invention has a highly reliable bonded part by using the same Si3N4-based ceramic material for bonding Si3N4-based ceramics.
The object of the present invention is to provide a joining method for obtaining a ceramic joined body containing N4 as a main component.

[Structure of the invention]

In the present invention, when bonding ceramics mainly composed of Si3N4, a mixture of Si powder of 44μ or less and resin is interposed in the bonded part, and
This is a method for joining ceramics mainly composed of Si3N4, which is characterized by nitriding the Si powder of 44 μm or less in the joint part in a temperature range of 10°C and joining by continuous Si3N4 bonding.

The joining method of the present invention will be described in detail below.

When bonding ceramics whose main component is Si3N4 with Si3N4 produced by reaction sintering, the various properties of the bonded part, such as strength, corrosion resistance, and wear resistance, depend on the interface between the objects to be bonded and the bonding layer. It is clear that the bonding and the bonding within the bonding layer dominate.

In other words, Si
By increasing the frequency of contact between the ceramic mainly composed of 3N4 and the Si particles of the bonding layer, and by nitriding synthesis in a nitriding atmosphere, forming a continuous chemical bond of Si3N4 at the interface between the object to be bonded and the bonding layer, bonding. In intralayer bonding, the frequency of contact between Si particles in the bonding layer is increased, and continuous S
Forming a large amount of i3N4 chemical bonds leads to obtaining highly reliable bonding strength.

However, numerous experiments conducted by the present inventors have revealed that it is not necessarily possible to obtain highly reliable bonding strength simply by increasing the contact frequency.

The present inventors further investigated and found that the factor that lowers the reliability of the joint is the presence of an oxide film on the surface of the Si powder or the surface of the ceramic whose main component is Si3N4.

Normally, it is said that the oxide film on the ceramic surface containing Si powder or Si3N4 as a main component decomposes at around 1200°C in a non-oxidizing atmosphere, but the nitridation starting temperature of Si powder (approximately 1100°C) Below, since there is still an oxide film on the surface, the Si powder particles are separated by Si particles - Si.
No sintering of the particles takes place, only sintering between the oxide coatings. Moreover, the sintering between the oxide films does not cause the volume diffusion that causes interparticle shrinkage, and thus does not cause bulk shrinkage.

In other words, nitriding begins with the Si powder grains in contact with each other through the oxide film, and the oxide film eventually scatters, leaving the Si powder particles without a direct bond between the Si particles and the St particles.
3 N4 forms. The same applies to Si powder grains and ceramics whose main component is Si3N4. Therefore, even if Si powder is simply interposed between ceramics mainly composed of Si3N4 and nitrided, the bonding strength is low and only a porous bonding layer can be obtained.

Therefore, the present inventors removed these oxide films at a relatively low temperature, and brought Si and St, whose surfaces were deoxidized, and St and Si3N4 into direct contact without using the oxide film.
By introducing increased neck formation at the contact area through mechanisms such as evaporation-condensation into the joining reaction, a reliable joined body could be obtained.

Specifically, in order to increase the contact frequency of the Si powder used as a bonding agent, the particle size structure should be designed to improve the backing of the Si powder, and the resin should be
A resin that generates a component containing 3N4 as a main component that removes the oxide film on the ceramic surface is used. The most effective components for removing the oxide film are reactive hydrogen and hydrocarbons generated during resin decomposition, and the generation temperature range is 50°C.
A range of 0 to 1200°C is desirable. At temperatures below 500°C, no matter how much reactive hydrogen and hydrocarbons are generated, the oxide film is thermally stable, so only a small amount is removed, and above 200°C, nitriding reactions occur preferentially. It is from. Reactive hydrogen and hydrocarbons generated by decomposition of the resin in the temperature range of 500 to 1200°C remove the oxide film, so that before the start of nitriding, St powder particles or St powder particles and Si3N4 are the main components. Since the ceramics come into direct contact with each other, a neck is formed due to evaporation and condensation of St, and shrinkage occurs due to grain boundary diffusion or volume diffusion. Therefore, in nitriding, these Si particles -S
A continuum in which direct bonds between i-particles and direct bonds between Si particles and ceramics mainly composed of Si3N4 are formed is nitrided, and continuous Si3N4 bonds are reliably formed even after nitriding, ensuring reliability. A highly conjugated product can be obtained.

Specifically, the resin referred to in the present invention is an organosilicon polymer compound whose main skeleton components are silicon and carbon.

Examples include phenol resin, furan resin, xylene resin, diunsaturated polyester, and epoxy resin. Organosilicon compounds (hereinafter referred to as organosilicon polymers) whose main skeleton components are silicon and carbon were developed by the present inventors in JP-A-56-
This is the series disclosed in No. 120574.

The amount of reactive hydrogen and hydrocarbons generated in a non-oxidizing atmosphere at a temperature range of 500-1200°C is, for example, about 30-40% by weight for organosilicon polymers and 3% by weight for phenolic resins.
It is 0 to 60% by weight.

The Si powder has a particle size of 44 μm or less, and it is desirable to have a particle size configuration depending on the purpose or method of joining. If the Si powder rice grain is 44μ or more, it is difficult to be nitrided and unreacted Si remains, resulting in a mixed phase of Si3N4 and Si in the bonding layer, reducing the reliability of the bonded portion.

[Examples and effects of the invention]

Example 1 Four types of ceramics mainly composed of Si3N4 shown in Table 1 were cut into 5 vsm x 15x20+i.
The surfaces of 5 dragons x 15 fins were used as the joint surfaces. 44 μ~ for bonding agent
Has a wide range of particle sizes down to submicrons, with an average particle size of 15
μ Si powder (purity 99.1%) and organosilicon polymer are used, and the ratio is sim powder/organosilicon polymer = 8
It was 5/15. Using xylene as a solvent, frequency 6
011z, on a vibration table with an amplitude of 0.2, 2 ml/
The viscosity was adjusted to spread at a speed of sec.

Apply the adjusted bonding agent to a thickness of approximately 1.2 fins on a 5 m x 15 m surface to be bonded, apply the other surface to be bonded over it, and vibrate on a vibration table under the above vibration conditions. The adhesive was squeezed out.

The final bonding layer had a thickness of 0.5 mm and was dried at 150° C. for one day.

After drying, no defects such as cranks were found within the bonding layer or at the bonding interface.

This bonded body was heated at a heating rate of 100℃/in a nitrogen gas atmosphere.
The temperature was raised in hr. During the reaction, the temperature was maintained at 1000°C for 2 hours within the reaction-active hydrogen and hydrocarbon release temperature range, and further at 1300°C and 1350°C in the nitriding reaction region above 1200°C.
and 1420''c for 5 hours to promote nitriding.

All of the bonded bodies obtained in this way showed shrinkage in the direction perpendicular to the tangent 2ζ plane, and as a result of measurement with a micrometer, the bonding layer was 2
．． It shrunk by 5-3.5%. The strength of the joints of these joined bodies was evaluated by a bending test.

The sample was cut out to a size of 3 mm x 3 m * x 4 Q + n, supported with a span of 30, and carefully set so that the maximum stress was at the center of the bonding layer for measurement. The results are shown in Table 2.

Table 1 Table 2 Example 2 In the same manner as in Example 1, for the four types of ceramics mainly composed of Si3N4 shown in Table 1, a bonding agent (Si powder 87% by weight, phenolic resin 13% by weight). The shrinkage at this time was 1.8 to 2.8%. (bending strength at room temperature)
The measurement results are shown in Table 3.

Table 3 Furthermore, almost the same bonding strength was obtained even when furan resin, xylene resin, unsaturated polyester, and epoxy resin were used.

Comparative Example 1 Regarding the four types of ceramics mainly composed of Si3N4 shown in Table 1, the temperature was 500 to 1200 in a non-oxidizing gas atmosphere.
A bonded body was prepared in the same manner as in Example 1 using a bonding agent made of polyvinyl butyral which does not release reactive hydrogen and hydrocarbons in the temperature range of .degree. At this time, almost no contraction was observed. Table 4 shows the bending strength (at room temperature).

Table 4 Examples 1 and 2 are examples in which ceramics containing Si3N4 as a main component were bonded by adjusting the bonding agent using organosilicon polymers and phenolic resins listed in the text. A bonding strength of 13 kg/w2 or more was obtained except for those exhibiting a value lower than the strength of . Comparative Example 1 is an example of experiments conducted by the present inventors using various resins.
In the case of resins that do not release reactive hydrogen and hydrocarbons upon decomposition in the temperature range of 00°C, almost no shrinkage was observed, and the minimum bond strength was extremely low, resulting in unreliable results. .

Example 3 Organosilicon polymer and phenolic resin are used as resin.

A bonding agent was prepared using the above four types of polyvinyl butyral and sodium alginate. Hydrogen gas generation in a nitrogen atmosphere starts from around 250°C for organosilicon polymers and almost ends at 1100°C, and is 1.5% by weight in the range from 250 to 500°C and 3.2% by weight in the range from 500 to 1200°C. The amount generated was % by weight. The generation of phenol resin started around 450°C and almost finished at 1200°C, and the amount generated in this range was 3.8% by weight.

Polyvinyl butyral almost completely decomposes at 500°C.
The decomposition of sodium alginate was almost completed at 380°C.

The same Si powder as in Example 1 was used, and 15% by weight of an organosilicon polymer, 13% by weight of a phenol resin, 18% by weight of polyvinyl butyral, and 16% by weight of sodium alginate were each blended. The solvent used is xylene for organosilicon polymers, ethyl alcohol for phenolic resins and butyl alcohol, and water for sodium alginate.
The viscosity was adjusted to be the same as in Example 1 by adjusting the amount of solvent. Reactive sintered Si3N4 shown in Table 1 was selected as the object to be joined, and the same as in Example 1 was used for joining using a vibrating table to scatter the solvent. The thickness of the bonding layer was adjusted to about 0.5 mm, and changes in dimensions after solvent scattering and after bonding synthesis, and bonding strength were measured.

The bonding synthesis conditions were to hold the temperature at 1000°C in the reactive hydrogen and hydrocarbon generation temperature range for 2 hours at a rising speed of 100°C/hr, and then to hold the temperature at 130°C over 1200°C in the nitriding reaction range.
The temperature was maintained at 0°C, 1350°C and 1420°C for 5 hours each.

The results are shown in Table 5.

Table 5 In this example, organosilicon polymers and phenolic resins that generate reactive hydrogen and hydrocarbons within the temperature range of 500 to 1200°C are compared to polyvinyl butyral and sodium alginate, which almost completely decompose at 500°C or below. This results in a significant difference in shrinkage effect and bonding strength, demonstrating that the present invention is extremely superior.

Example 4 Among the bonded bodies obtained in Example 3, the inside of the bonding layer and the bonding interface of the bonded body using a phenolic resin were observed using a transmission electron microscope. As a result, continuous chemical bonds were found to be α-type or It was found that it is made of β-type Si3N4, and each crystal interface contains a distorted lattice image. The maximum strain angle is about 6°, which is presumed to have high energy, and is thought to be a factor in developing high bonding strength. A similar observation was made for a sample using polyvinyl butyral and sodium alginate, but there were very few strained crystal interfaces.

Example 5 Of the objects to be joined shown in Table 1, the reaction sintered body B was used to produce an end-sealed tube having the shape shown in the drawings. This object to be joined 1.2
The outer and inner diameters are 60 fin φ and 50 crane φ, and the length of l is 5
The thickness of 00 Tsuru and 2 was 5 Tsuru.

Both were tapered at an angle of 45° and the tapered surface was used as the bonding surface. Xylene resin was used as the bonding agent, and the bonding thickness was adjusted to 0.3+u by vibration as in Example 1.

After drying at 150°C for a day and night, the heating rate was 100°C/hr under a nitrogen gas atmosphere, and the temperature was maintained at 1100°C for 2 hours within the reaction active hydrogen and hydrocarbon release temperature range, and further at 1300°C above 1200°C in the nitriding reaction zone. ℃, 1350℃ and 14
Each was held at 50°C for 5 hours.

Approximately 250 fins were removed from the joint of the end-sealed joint obtained in this manner.
The sample was placed in an electric furnace maintained at 00°C and heated for 20 minutes, then taken out and cooled in the air. Since there was no abnormality at all after one cycle, a total of 30 cycles were repeated, but no abnormality was observed.

Example 6 An end-sealed tube with a length of 2000 m was manufactured in the same manner as in Example 5. The bonding agent used was 12% by weight of furan resin and 88% by weight of Si powder. There was no abnormality after 1000 hours of immersion of approximately 1000 mm of the end sealing side in molten aluminum at 800 to 900°C.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of an end-sealed tube used in an embodiment of the present invention. Agent: Masu Kobori (and 2 others) Procedural amendments: 1. Indication of the case: 1982 Patent Application No. 27756 2, Title of invention: Method for joining ceramics containing SiB N+ as the main component 3,
Relationship with the case of the person making the amendment Patent Applicant 4, Agent 6, Specification subject to amendment and drawings 7, Contents of amendment (1) Specification page 19, page 1, and bottom line of page 20, “
"Drawings" should be corrected to "Figure 1." (2) Off to the drawing! As per the author, the figure number of ``Figure 1'' is added. Figure 1

Claims (1)

[Claims] 1. When joining ceramics mainly composed of 5i3 N4, a mixture of St powder of 44μ or less and resin is interposed in the joint part, and the temperature is 1200 to 1500 in a nitriding gas atmosphere.
A method for joining ceramics containing Si3N4 as a main component, characterized by nitriding St powder of 44 μm or less in the joint part in a temperature range of 0.degree. C. and joining by continuous Si3N4 bonding. 2. A method for joining ceramics mainly composed of Si3N4 according to claim 1, wherein the resin is a resin that releases hydrogen and hydrocarbons when decomposed in a non-oxidizing gas atmosphere in a temperature range of 500 to 1200°C. .