JPS6026075B2 - Production method of β-SiC-Si↓3N↓4-based composite ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composite structure of a bonded structure of SIC and a bonded structure of Si3N4, in which fibrous 8-SIC or thin film ribbon-shaped 8-SIC is distributed between Si3N4 grains and mutually bonded. The present invention relates to a method for manufacturing ceramics of pongee weave, which exists intermittently intertwined with each other, and its purpose is to provide ceramics that are high-strength, high-temperature materials with excellent thermal shock resistance and thermal fatigue fracture resistance.

Ceramics have attracted particular attention and have been developed as high-strength, high-temperature materials because they can be used as materials for high-temperature gas turbines, ceramic automobile engines, and as special high-temperature structural materials under harsh conditions where traditional metal materials cannot be used. This is because there is a strong demand for products that can be used in

Ceramics can generally withstand use at high temperatures and have excellent wear resistance, but their brittleness is a major drawback when compared to metal materials, making them unsuitable as thermal fatigue resistant materials. However, as a result of recent rapid research and development, products that can withstand considerable stress have appeared.

As high-strength, high-temperature materials, carbides such as SIC, WC, and TIC, nitrides such as Si3N4, AIN, and BN, and Si-N-○-N have been particularly researched and developed. There has been a lot of research on silicon compounds such as Si3N4, which have excellent high-temperature strength, thermal shock resistance, abrasion resistance, corrosion resistance, etc., and so far, prototypes have been made and used regularly in various fields. It is something. These SIC and Si3N4 are manufactured by heat treatment of green compacts, and attempts have been made to improve high-temperature strength, thermal shock resistance, abrasion resistance, corrosion resistance, etc. by increasing the density.

However, SIC and Si3N4 have almost no self-refining properties, and various additives (viscous agents) are required to achieve high density.
must be added.

However, when additives are used, although high density can be achieved, the disadvantage is that they soften at high temperatures due to the formation of a glassy phase, resulting in a decrease in strength at high temperatures. For example, in the case of producing a SIC molded body, A', Fe, B, Y203, etc. are added and a high-density molded body is obtained by normal pressure pressing or hot pressing. In addition, in the case of a Si3N4 molded body, Mg
0, AI203, Yama203-Y203, etc. are added and densified mainly by hot pressing at 1700 to 1900°C, but in both cases a glassy phase is formed at high temperatures,
It has the disadvantage that the strength at high temperatures decreases due to the softening of this glassy phase.

Among these, AI203-Y3, Y203 is a glassy phase that forms at high temperature, Si02-Y203-N203, Si0
Because the glass transition temperature of 2-Y203 is high, Mg○,N
Compared to the case where 203 is added, there is a slight decrease in strength at high temperatures.
However, it is not possible to overcome the drawback that the strength decreases at around 1000 oo. The methods described above are the so-called normal pressure compaction and hot press methods, and in addition to these methods, the reaction compaction method is first considered, and in the case of SIC molded bodies, Si02
In the high temperature firing process of mixed powder of and C, Si vapor is reacted,
There is a product that produces a solid vapor reaction product 3-SIC with residual C and is highly densified, but it is unavoidable that Si remains in an unreacted state, making it difficult to use at high temperatures in an oxidizing atmosphere. This easily becomes Si02, which causes abnormal expansion and tends to cause a significant decrease in strength.

Next, in the case of a reaction structure i3N4 compact, it is obtained by firing a compact of Si powder in a nitrogen atmosphere, but the porosity is much larger and the strength is weaker than when a binder is used. have a property. Despite its high porosity, it has a uniform structure of Sj3N4, so it does not have the ability to relax stress, and when used at high temperatures for long periods of time, it may cause fatigue failure due to the accumulation of thermal stress. An elephant arises. As mentioned above, the conventional SIC and Si3N4 high-density molded bodies have very high strength in combat, but their strength decreases sharply during long-term use at high temperatures, and fatigue phenomena due to thermal stress cannot be avoided. It has the disadvantage that it is not.

In order to overcome the drawbacks of conventional SIC molded bodies and Si3N4 molded bodies, the present invention first aims to reduce thermal stress without leaving reactive Si and without using unnecessary binders. The main purpose is to create an organization with a mechanism.

Therefore, the present inventors focused on the fact that SIC and Si3N4 do not have a chemical bond, and found that SIC fibers and/or thin film IJ-bonds are interposed between the total Si3N particles, and physically between SIC and Si3N4. We predicted that a bonded structure would be formed by entanglement, and furthermore, due to the physical properties of SIC fibers and thin film ribbons, the strain caused by thermal stress could be reduced by SI.
We have come to believe that a flexible tissue with excellent thermal shock resistance can be created by absorption by the fiber portions and thin film ribbon-like portions of C. In addition, it was thought that the strength and thermal shock resistance would be further improved if a structure in which moderately continuous bonded portions of SIC and moderately continuous bonded portions of Si3N4 were intertwined was added. The organosilicon polymer compound referred to here (hereinafter simply referred to as organosilicon polymer) was invented by Professor Seibin Yajima and his colleagues at Tohoku University Institute for Materials Research, and is an organosilicon polymer compound whose skeleton components are mainly silicon and carbon.

As is well known, SIC fibers using these organosilicon polymers are world-famous inventions by Professor Seibin Yajima and others, and have been reported in many papers and patents. Other inventions include composite materials of SIC fibers and metal or non-metallic materials, inventions of using organosilicon polymers as binders for metal or non-metal material powders, or inventions of using organic silicon polymers as raw materials for SIC fired bodies, etc. This is a new field that has brought about an epoch in the fields of inorganic fibers, high-strength materials, and heat-resistant materials. The main object of the present invention is to provide a special heat-resistant ceramic material having excellent thermal shock resistance, thermal fatigue fracture resistance, and oxidation resistance, manufactured using the above-mentioned organic silicon polymer and silicon powder. The organosilicon polymer used in the present invention basically has the following basic structures (i) and (V). However, during the ceremony,
Regarding R,, R2, R3 and R4, R is a -C ratio and R2, R3 and R4 are hydrogen, an alkyl group, an aryl group,
(C&)2CH-, (C64)2SiH- and (CH3
) 3Si-, or a combination of two or more thereof.

In addition, k, 1, m, n indicate the average number of repetitions of the structure ( ) and [ ], k = 1 to 80, 1:15 to 350
, m=1-80 and n=15-350. Note that the average molecular weight is 800 to 20,000. Furthermore, M in (iii) is an element contained in the starting material when synthesizing rigidity with a metal or nonmetal element such as Si, B, Ti, Fe, Zr, etc., or an element mixed when using a catalyst. indicates the elements contained in the main skeleton, R5, R6, R7 and R8 are hydrogen, alkyl group, aryl group, (C ratio) 2CH-, (C6 day 5
)2SiH- and (C)3Si-, one or a combination of two or more thereof may be used, but depending on the valence and structure of M, any of R5, R6, R7 and R8 may be deleted. be. , Q above (i) to ``A compound containing the skeleton component of W as a partial structure of any one of a chain structure and a three-dimensional structure, or a mixture thereof.

According to the research by Professor Yajima et al., when these organosilicon polymers are heat-treated in a non-oxidizing atmosphere, they become an amorphous material consisting of Si and C, and furthermore, form 8-SIC containing a portion of free carbon. It's clear.

The present inventors have made full use of the characteristics of the above organosilicon polymer, and fabricated paper threads from the organosilicon polymer using conventional methods, such as ozone treatment, in-air heat treatment, y-ray irradiation, organic peroxide treatment, etc. Infusible synthetic fibers are made by forming infusible fibers and organosilicon polymers into thin film ribbons, which are made infusible by the above method so that these fibers retain their original shape without liquefying during the heating process. Using a thin film ribbon-like material or a mixture thereof made infusible in the same manner as above,
It was confirmed that these were heat-treated for 140,000 degrees Celsius in a non-oxidizing atmosphere to form 6-SIC while maintaining the shape of thin film ribbons of fiber and SIC.

In order to achieve the object of the present invention, the present inventors have developed an infusible organosilicon polymer fiber (hereinafter referred to as an infusible fiber) and an infusible organosilicon polymer thin film ribbon (hereinafter referred to as an infusible thin film). Taking advantage of the fact that a ribbon-like material (referred to as a ribbon-like material) is converted into 8-SIC while maintaining its shape, a molded body of a mixture of silicon powder, infusible fibers, and/or non-selective ribbon-like material is heated to a temperature of 450 oo. By heat treatment under nitrogen gas or a mixed gas atmosphere of nitrogen gas and ammonia gas, the infusible organosilicon polymer is converted into t8-SIC, and the reaction between free carbon and silicon powder converts the infusible organosilicon polymer into t8-SIC. They form SIC, and they also take the form of fibers and thin film ribbons and are interposed between Si3N4 particles produced by the reaction of Si with N2, forming a state in which both are entangled with each other. are doing.

The generated SIC and Si3N4 are in microcrystal units ranging from submicrons to several tens of microns, and these 8-SIC and Si3N4
Since i3N4 and Si3N4 do not have a chemical bond with each other or do not dissolve into each other, a gap is created between the generated SIC and Si3N4. 81 At the stage of converting into SIC, their mutual bonding depends on whether or not they are in direct contact during the molding stage; SIC fibers are shown in a connected state.

By increasing the number and complexity of the intertwined structure between the Si3N4 bonding structure and the B-SIC fibrous portion (or thin film ribbon-like portion), we can improve the strength of the entire tissue and improve its thermal shock resistance. It is also possible to improve gender.

There are two main methods for increasing the number of entangled structures between the Si3N4 part and the B-SIC part and making them more complicated. The first method is to form a potted clay composition in which silicon powder is mixed with infusible fibers and an infusible thin film ribbon, and then fired in a nitriding atmosphere. Adding a non-containing organosilicon polymer as a binder.

The organosilicon polymer that has not been made infusible softens during the heating process and remains in a liquefied state for a certain period of time. During this liquefied state, it infiltrates between Sj particles and between infusible fibers and infusible thin film ribbons. During the SIC process at a temperature of 120 pi or more, bonds are formed between the SIC fibers and thin film ribbon-like SIC, and excessive carbon diffuses from the Si particle surface during the SIC process. 8-1 SIC is formed by 4 Si particles and ``SIC fiber and/or
or forming entanglements between thin film ribbon-like SICs. However, since the addition of the non-infusible organosilicon polymer may fill the gaps between the SIC fibers and/or the thin film ribbon-like SIC and cause them to be integrated, the amount added must be appropriate.

This will be described in Examples. The second method uses a mixture of organosilicon polymer and silicon powder as ~, He, Ne, N2
500qo to 1400qo in a non-oxidizing atmosphere such as
A pulverized product obtained by processing the organosilicon polymer in a temperature range of (excluding N2 if it is over 000 000 mm), decomposing the organosilicon polymer in advance, and optionally converting it into 8-SIC so that it does not liquefy, and then pulverizing it to a size of 105 μm or less. In other words, K powder (Showa 5
9) (named by the applicant in the machine specification issued on January 25), a molded body containing infusible fibers, infusible thin film ribbons, and silicon powder was heated with nitrogen gas or nitrogen gas. It is obtained by firing in a mixed gas of gas and ammonia gas at a temperature range of 1200 to 18000C.

In this method, the pretreated organosilicon polymer has a sufficiently high activity that when it comes into contact with the infusible organosilicon polymer fiber and/or the infusible thin film ribbon-like organosilicon polymer, the bond between the two can be increased. It is possible to form a strong bond between the Si3N4 connective tissue and the 3-SIC fibers and the thin film ribbon-like 6-SIC to make the intertwining structure more complex. Furthermore, a similar effect can be observed by adding a non-infusible organosilicon polymer as a binder to the compounding ratio of the second method, but even in this case, the non-infusible organic The amount of silicon polymer added must be moderate for the same reasons as in the first method. This will be explained using examples. Infusible 8-SIC fiber of the present invention and infusible B
- The SIC thin film ribbon can be made into the special heat-resistant ceramic of the present invention by using silicon powder and/or K powder as a binder, and optionally an organic silicon polymer compound as a binder. can be made into the special heat-resistant ceramic of the present invention.

8-SIC-Si3 of the present invention produced in this way
As described in the Examples below, the N4-based composite special heat-resistant ceramic has a weight composition ratio of 8-SIC:Si3N4 in the range of 3 to 40:97 to 60, and the 8-SIC in the structure is in the range of 97 to 60. SIC is distributed between the particles of i3N4 having a fibrous and/or thin film ribbon-like shape, and the 8
The SIC and the Si3N4 have a unique structure in which they intersect with each other, thereby forming a structure with "excellent impact resistance and fatigue fracture resistance," as shown in the following examples.

However, there is an upper limit to the proportion of these fibrous and thin film ribbon stress relaxation structures in the entire tissue. The reason for this is that these stress relaxation structures have sufficient deformability against external forces, and therefore become a negative factor for the strength and density of the entire tissue. This is because if an excessive number of stress relaxation structures are provided, the function as a structure will be lost. Regarding these, specific examples of implementation of the product of the present invention and the excellence of its effects will be described in the following examples. Example 1 Fibers obtained from organosilicon polymers by a conventional method were made infusible by heat treatment in air up to 200 oo, and the infusible fibers had diameters of 10 to 100 (in the initial state, the ratio was about 500 to 100). Cut the aggregate into appropriate lengths of 5 to 10 mm, and add silicon powder of 44 mm or less and polyvinyl butyral (PVB) in the proportions shown in Table 1. ) of ethyl alcohol solution (P.V
．． The amount of B is 2 in terms of the total amount of silicon powder and infusible fiber.
~3% by weight) and the ethyl alcohol was vaporized.

This mixture was molded into 20 x 20 x 80 pieces at a molding pressure of 800 k9/me.
The molded body was molded to the size of the ribs, and the molded body was brought to 1500 qo at a rising rate of 100 °C/min in a nitrogen atmosphere.
It was held for 1 feeding period. After cooling in the furnace, the sample was taken out and its physical properties were measured. In addition, after disintegrating the pre-fired molded body by dipping it in the ethyl alcohol solution again, the length of the infusible fibers was examined by microscopic observation. , the diameter ranged from 1 to 3M. This is because long fibers (
5 to 10) are cut off. Physical property measurements are
Thermal shock resistance, bending strength at room temperature and hot temperature, fatigue fracture resistance, and structure observation using a scanning electron microscope were conducted.

Thermal shock resistance was measured by holding a sample size of 5 x 10 x 3 pieces in a nitrogen gas stream at 1200 qo for 20 minutes, and then quenching the furnace in flowing water.

Each sample was placed in running water and then taken out. After drying, the test sample was repeatedly tested using various dyes until cracks were found in the sample. Thermal shock resistance was determined by the number of repetitions. The bending strength was measured using a sample size of 5 x 5 x 5 pieces with a span of 3 peaks at room temperature and at a temperature of 1400 qo.

Fatigue fracture resistance was measured by boiling a sample size 5 x 5 x 5 Qianqi with a span ratio of 3, contacting the center with a vertical head with a radius of 1, and applying a load of 1% of the bending strength as an initial load. Ta. Then, the sample was oscillated with a total deflection of 10 μm, and the head was maintained to follow the displacement. This condition was reproduced in a furnace maintained at 1300 oo, and oscillations were repeated at a rate of 3M groups per second. Evaluation was made based on the number of times it took for the mystery sample to break and the time it took for the sample to deform until the head could no longer follow it. Microstructure observation using a scanning electron microscope reveals the state of aggregation of 3-SIC fibers interposed between Si3N4 particles, the degree of independence of each fiber, or the degree of entanglement between Si3N aggregates and 61-SIC fibers. We mainly observed.

As a method for evaluating physical properties, similar methods were used to evaluate the reaction sintered Si3N4, reaction sintered SIC, and reaction competitive Si3N4.
Bonded SIC, Mg0-added hot pressed Si3N4,
and B03-added hot-pressed SIC wood. Table 2 shows the physical property values of various samples for comparison. The weight composition ratio of the generated phase of B-SIC and Sj3N4 is
It was determined by linear diffraction using cristopalite as a standard substance and creating a calibration curve. Table 1 Table 2 As can be seen by comparing the results in Tables 1 and 2, the products of the present invention have excellent impact resistance and fatigue fracture resistance.

These properties are the most suitable for radiant tubes and recuberator tubes. A sufficient effect of non-synthesizing fibers is recognized when the amount added is 6% or more, but when the amount is 50% or more, the quality deteriorates. Example
2. A thin film of the organosilicon polymer is obtained by spreading a thin layer of a solution of an organosilicon polymer dissolved in n-hexane on a vat and evaporating the n-hexane.

This was heat-treated in air at a temperature of up to 200 qC to make it into a mold, and a rectangular thin film of about 5 sides to 1 side was prepared. When the thickness of this thin film was observed under a microscope, it was found that the thickness was distributed within a range of about 10 to 100 peaks. Using this thin film, a fired body was obtained in the same manner as in Example 1, and physical properties were measured in the same manner as in Example 1. The results are shown in Table 3. In addition, in Example 2, after immersing the pre-fired molded body in an ethyl alcohol solution and allowing it to dissolve, the length and inside of the film were examined using a microscope. , all the infusible thin films were less than 3 skins, ranging from 5 times the thickness to about 3 tones.

This is a long infusible suppuration during mixing (initial dimensions are 5 skin to 10
skin) has been shredded. Table 3 Similar to Example 1, the thin film ribbon-like 8-SIC was
It is recognized that the thermal shock resistance and fatigue fracture resistance are improved by forming a stress relaxation structure between the N4 grains, but it is found that the thermal shock resistance and fatigue fracture resistance are improved by the N4 grains. The effect is not very obvious below 3%, and from 3%
It is observed in the range of 40%, and the effect decreases to medium when it exceeds 50%.

As can be seen from Examples 1 and 2, the effects of the added amounts of infusible fibers and infusible thin film ribbons are almost the same, so the effects of the combination of the two are also similar. . Example 3 First, K powder used in the present invention is manufactured as follows.

1 part n-hexane per 10 parts by weight of organosilicon polymer
After adding the solution dissolved using 0 parts by weight to silicon powder with a diameter of 44 mm or less and wet mixing, the mixture in which n-hexane was evaporated was heated to 300 qo~1 in a non-oxidizing atmosphere.
40,000°C, and the heat-treated product was heated to 105°C.
It was crushed to a fine size.

The pulverized product is hereinafter referred to as K powder (Details issued on January 25, 1972). Table 4 lists the properties of K powder. Table 4 The significance of using K powder is that a silicon powder compact containing 35% by weight or more of non-infusible organosilicon polymer
This is because when nitriding is performed in the range of oC to 1800 qo, the molded body is deformed due to softening of the organosilicon polymer and a perfect molded body cannot be obtained, which limits the amount of organosilicon polymer used. In order to use a silicon polymer, it is necessary to heat-treat the organosilicon polymer in advance to modify it so that it does not become soft.

However, in this case, if the organosilicon polymer alone is heat-treated without containing silicon powder, it will become integrated during softening, making it difficult to crush after heat treatment and causing contact between the heat-treated organosilicon polymer and the silicon powder during molding. Because the degree decreases, 31S
The amount of entanglement between the IC and Si3N4 is reduced. Therefore, the heat treatment temperature range of ~K powder is 50 and 0 to 14 from Table 4.
A range of 00oo is preferred.

It is obvious that at 1,500 qo or more, the crystallization of 8-SIC becomes more complete, making it difficult to combine with 8-SIC produced from the total infusible synthetic fiber or the infusible thin film ribbon.

Next, the K powder (A to F) silicon powder listed in Table 4 was added to the required amount within the range of 6 to 4 weight percent of the infusible fiber or infusible thin film ribbon known from Examples 1 and 2. The amount of K powder at this time is determined by first calculating the chemical theoretical amount of SIC produced from the content of C and Si in the K powder, and then calculating the amount added as SIC. ``Determine the amount of K powder to be added from the content and determine the amount of K powder to be added between 3 and 25%. ``Determine the remaining amount of the above infusible fiber and/or infusible thin film sheet and the above K powder amount as the amount of silicon powder, and make a rest composition. Construct and shape things.

Table 5 shows typical blending ratios and physical properties of the molded bodies obtained by the same method as described in Example 1. However, the formulation number in the table is Example 1.
and the number of the blending ratio of 2 are shown. Table 5 - Organizational situation shame. 8-SIC and 8-SIC produced from 13K powder
Bonds were observed between the fibers, stronger entanglement bonds were observed between the S and N4 grains produced by nitriding the K powder, and 81 SIC fibers were distributed between the Si3N4 grains.

No. Bonding was observed between the 81 SIC produced from the 14 K powder and the thin film ribbon-like 81 SIC, and the stronger entanglement with the Si3N4 grains produced by nitriding the K powder was complicated.

Thin film ribbon-like 8-SIC is 8-SI produced from K powder.
Some particles interposed between C grains and Si3N4 grains are also observed.

8-SIC and fibrous B-S produced from M15 K powder
A bond was observed between the K powder and the nitrided S;3N4 grains, and the fibrous 81 SIC was three-dimensionally and intricately distributed between the Si3N4 grains. The organization has become extremely complex.

M. Bonding is observed between the B-SIC grains produced from the 16K powder and the thin film ribbon-like 8-SIC.

S N4 grains produced by nitriding K powder and 81 SIC
The entanglement and bonding with grains is large. Thin film ribbon-shaped Mu SI
C has a complex three-dimensional distribution. No. The 8-SIC grains produced from the 17 K powder were distributed in an aggregated state, and bonding with the fibrous 8-SIC was observed in many parts, resulting in a decrease in the flexibility of the fibrous B-SIC. It seems that there are.

Fibrous 8-SI in the gap between 4 Si3N grains and 3-SIC grains
Intervention of C is observed. No. 3-SIC grains produced from 18K powder occupy about 1/3 of the structure, and bonding with fibrous B-SIC occurs in many parts.

The entanglement between the 8-SIC grains and Si3N4 is simple.

The effect of K powder contributes to tissue densification and improved strength.

No. As seen in 18, the fibrous 8-SIC amount is 35
%, thermal shock resistance and fatigue fracture resistance are significantly reduced. Example 4 Example 1 was prepared by adding non-infusible organosilicon polymer to the preferable blending ratio ranges 2 to 5 and 8 to 11 shown in Examples 1 and 2. A molded body was produced in the same manner as shown in .

Table 6 shows typical blending ratios and physical property values of the molded product. However, the organosilicon polymer that has not been made infusible is dissolved in n-hexane, mixed with silicon powder first, and then the n-hexane is evaporated to form a mixture that contains infusible fibers and an infusible thin film ribbon. A method of adding similar substances is used. The blending numbers in Table 6 indicate the blending ratios of Examples 1 and 2.

Table 6 No chemical bond was observed between Si3N4 grains and 81 SIC produced from non-infusible organosilicon polymer, but
Excess carbon produced when the organosilicon polymer is converted into 8-SIC penetrates into the surface of the silicon powder grains, and entanglement occurs between the 8-SIC produced and the Si3N4 grains produced by the chambering reaction.

This intertwining forms a physical bond. Since P-SIC, fibrous 8-SIC, and thin film ribbon-like 8-SIC formed from non-infusible organosilicon polymers are easily bonded to each other, non-infusible organic matter is formed between these fibers and thin films. Upon entry from the silicon polymer, the resulting 3-SIC forms connections that compromise the stress-relaxing structure to integrate the fibers and membranes.

No. 24 means that. No. listed in Table 6. 19~No. As shown in No. 23, these physical property values are extremely superior to those of the conventional products listed in Table 2. Example 5 K powder and silicon powder are blended into the required amount of infusible fibers or infusible thin film ribbons in the range of 6 to 4% by weight as known from Examples 1 and 2 to form a cup composition. At this time, the amount of K powder to be blended is determined by first calculating the amount of SIC produced in Ib stoichiometry from the content of C and Si in the K powder, and then calculating the amount added as SIC by 3.
-25%, determine the amount of K powder to be added from the content, define the remaining amount of the above infusible fiber and/or infusible thin film ribbon and the above K powder amount as the silicon powder amount, and further An organic silicone polymer was added in an amount of 3 to 40% by weight to form a clay composition, and a molded article was produced in the same manner as in Example 1 using this composition.

Table 7 shows typical blending ratios and physical property values of the molded product. However, the organosilicon polymer that has not been infusible is dissolved in n-hexane, mixed with silicon powder first, and then the n-hexane is evaporated.・The method of adding similar items is used. The blending numbers in Table 7 refer to the blending ratios of Examples 1 and 2. 7. Organizational situation. B-SIC and 8-SI produced by 25K powder
A bond was observed between the C fiber and the 6-SIC produced from the non-infusible organosilicon polymer.
It can be seen that thin connections are partially formed between the IC fibers and the four Si3N grains.

A stronger entanglement bond exists between the Si3N4 grains and the 81 SIC grains produced by nitriding the K powder.

The gunwale. 26 Bonds were observed between the 8-SIC produced from the K powder and the thin film ribbon-like 8-SIC, and the strong entanglement with the Si3N4 grains produced by nitriding the K powder was complicated. is a part of 8-SIC between thin film ribbon-like SICs. Connecting parts are more visible.

Many thin SIC connections are observed between the Si3N4 grains and the thin film ribbon-like 81 SIC. Earth. 27 A bond was observed between 8-SIC produced from K powder and fibrous 8-SIC, and both 4 Si particles produced by nitriding K powder and 4 Si3N particles produced by nitriding silicon powder were observed. Tomo 8
- There are bonds between the SIC grains due to complicated entanglement, and there are also many bonds between the 8-SIC grains and the fibrous 8-SIC.

Fibrous SIC is three-dimensionally and complexly distributed. ship. 28
B-SIC produced from K powder and thin film ribbon-shaped 81S
Bonding is observed between the IC and the IC.

8-S produced from non-infusible organosilicon polymers
The IC constitutes a thin connection between the Si3N4 grains and the thin film ribbon-like SIC, and the thin film ribbon-like 81 SIC is three-dimensionally distributed in a complicated manner.

No. The 81 SIC grains produced from the 29 K powder are distributed in an aggregated state, and bonds with fibrous SIC are observed in many parts, and there are also many bonding parts between the fibrous SICs, indicating that they are ``integrated''. In some parts, fibrous 8
-It seems that the flexibility of SIC is decreasing.

Fibrous 8-SIC is observed between the Si3N4 grains and the B-SIC grains.

No. 3-SIC and fibrous 3-SIC produced from 30K powder
Bonding with SIC is observed, and 81 SIC produced from the non-infusible organosilicon polymer is fibrous 81 S.
It is thought that the fibrous 8-SIC often found between ICs is integrated, and the flexibility of the fibrous 3-SIC is greatly reduced.

As mentioned above, if the amount of 8-SIC exceeds 35%, fibrous 8-SIC and/or thin film ribbon-like 3-SIC
``Thermal shock resistance and fatigue fracture resistance are significantly reduced because the stress relaxation absorption structure of the material is damaged.

This is the same even when the amount of the organic silicon polymer that has not been made invulnerable is increased to 20% or more. Since the product of the present invention is manufactured by the reaction molding method, it is possible to use many molding methods such as extrusion molding, injection molding, coin molding, isostatic press molding, and mold molding.
Since it is possible to obtain irregular shapes, it has a wide range of applications in the fields of special heat-resistant materials and high-temperature structural materials.

Further, even if the material is nitrided to the extent that it can be easily machined, machined such as thread cutting, and then nitrided again, a fired body can be obtained, so that even complex shapes can be obtained. Therefore,
The strength of the product of the present invention can be applied to automobile engine parts, heat exchange pipes, turbine parts, radiant tubes, jigs used in hot conditions, as a substitute for metal parts such as support stands, and as a ceramic field. ,
It is expected that the product of the present invention will be effectively used in fields that require thermal shock resistance and thermal fatigue fracture resistance, such as the nuclear power field, the chemical and chemical engineering field, and the steel manufacturing field.

Claims (1)

[Scope of Claims] 1 (1) 6 to 40% by weight of infusible fiber obtained by spinning an organic silicon polymer compound whose main skeleton components are carbon and silicon and subjecting it to infusibility treatment, and (2) the balance being A mixture with silicon powder with a diameter of 44 μm or less was molded and heated at 1200 μm in a nitriding gas atmosphere.
β-Si characterized by being nitrided and fired at ~1800°C
A method for manufacturing C-Si_3N_4-based composite ceramics. 2 (1) 6 to 40% by weight of infusible fibers obtained by spinning an organic silicon polymer compound whose main skeleton components are carbon and silicon and subjecting it to infusibility treatment, and (2) the remainder being silicon with a diameter of 44 μm or less. powder, a powder obtained by heat treating a mixture of an organic silicon polymer compound whose main skeleton components are carbon and silicon, and silicon powder in a non-oxidizing atmosphere, and a mixed powder of carbon and silicon. 1. A method for producing a β-SiC-Si_3N_4 composite ceramic, comprising forming a mixture with at least one of the ceramics and nitriding it at 1200 to 1800°C in a nitriding gas atmosphere.