JPH01179709A - Combined material of silicon carbide with silicon nitride and its production - Google Patents

Abstract

PURPOSE:To obtain the title material capable of giving a product having improved strength as a base material by forming silicon nitride and carbon by decomposing partly silicon carbide in a specified silicon carbide material and removing the formed carbon thereafter. CONSTITUTION:Silicon nitride and carbon are formed by decomposing partly silicon carbide in silicon carbide powder, silicon carbide whisker, or silicon carbide fiber having >=50wt.% purity. Then, the carbon formed in the decomposition stage is removed. By this method, (i) silicon carbide powder, silicon carbide whisker, or silicon carbide fiber can be combined directly with silicon nitride, (ii) a large amt. of silicon carbide powder, silicon carbide whisker, or silicon carbide fiber can be compounded inexpensively with silicon nitride, and (iii) the size of the combined material of silicon carbide with silicon nitride can be adjusted appropriately by selecting the size of silicon carbide powder, silicon carbide whisker, or silicon carbide fiber previously.

Description

[Detailed Description of the Invention] (]) Object of the Invention [Industrial Application Field] The present invention relates to a composite of silicon carbide and silicon nitride and a method for producing the same, and in particular to a composite of silicon carbide, silicon carbide whiskers, or silicon carbide fiber. The present invention relates to a composite of silicon carbide and silicon nitride, which is obtained by partially decomposing silicon carbide therein to produce silicon nitride and carbon, and then removing the carbon by oxidation or the like, and a method for manufacturing the same.

[Prior Art] Until now, no composite of this type of silicon carbide and silicon nitride and a method for producing the same have been proposed.

[Problems to be Solved] Therefore, in the past, no composites of silicon carbide and silicon nitride have been manufactured at all, and it has been difficult to strengthen the material by compounding silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with silicon nitride. It has the disadvantage that properties such as performance cannot be improved, and the scope of use of silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers cannot be sufficiently expanded.

Therefore, in order to solve these drawbacks, the present invention composites silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with silicon nitride produced by partially decomposing the silicon carbide present therein. The present invention aims to provide a composite of silicon carbide and silicon nitride, and a method for producing the same.

(2) Structure of the Invention [Means for Solving the Problems] The means for solving the problems provided by the present invention is that [silicon carbide powder, silicon carbide whiskers or silicon carbide fibers are Silicon carbide and nitride, characterized in that silicon nitride produced by partially decomposing silicon carbide in silicon fiber is contained inside the same silicon carbide powder, silicon carbide whisker, or silicon carbide fiber. It is a silicon composite.

Another solution to the problem provided by the wood discovery method is ``(a) partially decomposing silicon carbide in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers having a purity of 50% by weight or more. (b) a carbon removal step to remove the carbon produced in the decomposition step; manufacturing a composite of silicon carbide and silicon nitride; method”.

[Function] The composite of silicon carbide and silicon nitride according to the present invention is a composite of silicon carbide and silicon nitride that is produced by partially decomposing silicon carbide in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers. Since it is contained inside silicon powder, silicon carbide whiskers, or silicon carbide fibers, it acts to finely compose the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with silicon nitride, and as a result, the silicon carbide powder and the silicon carbide It acts to improve the properties of silicon whiskers or silicon carbide fibers, such as their ability to strengthen the material.

Furthermore, the method for producing a composite of silicon carbide and silicon nitride according to the present invention includes partially decomposing silicon carbide in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers having a purity of 50% by weight or more in a decomposition step. After producing silicon nitride and carbon, the carbon is removed by a carbon removal process such as oxidation, so there is no effect of directly compositing silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with silicon nitride. In addition, by selecting the size of silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers in advance, silicon carbide and silicon nitride composites can be produced in large quantities at low cost. It functions to appropriately adjust the size of the silicon nitride composite.

[Example] Next, the present invention will be specifically described with reference to Examples.

First, the details of the composite of silicon carbide and silicon nitride according to the present invention will be explained.

The composite of silicon carbide and silicon nitride according to the present invention is silicon carbide powder, silicon carbide whisker, or silicon carbide! ! !
Silicon nitride 513N4, produced by partially decomposing SiC, is contained inside the same silicon carbide powder, silicon carbide whisker, or silicon carbide fiber. In other words, the composite of the present invention is produced by decomposing silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers, and a portion of silicon carbide (SiC) in the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers. and silicon nitride SjJ< which is contained inside the same silicon carbide powder, silicon carbide whisker, or silicon carbide fiber and reinforces the same silicon carbide powder, silicon carbide whisker, or silicon carbide fiber. Silicon carbide SiC and silicon nitride Si, N, in the composite of the present invention
The abundance ratio can be selected as desired.

Further, an embodiment of the method for producing a composite of silicon carbide and silicon nitride according to the present invention will be described in detail.

Silicon carbide powder, silicon carbide whisker, or silicon carbide fiber having a purity of 50% by weight or more is prepared as a starting material. The size of the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers may be appropriately selected depending on the size of the resulting composite of the present invention.

Silicon carbide SiC in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers as a starting material is partially decomposed in a decomposition step to generate silicon nitride 5iJ4 and carbon C. That is, by performing hot isostatic pressing treatment by heating to a temperature of 1200° C. or higher in an atmosphere having a nitrogen partial pressure of 100 atmospheres or more, 3S]C+ 282 → Si:+N4+ 3G silicon carbide is produced as shown in the following formula. Silicon carbide SjC in powder, silicon carbide whiskers or silicon carbide fibers is partially decomposed inside the same silicon carbide powder, silicon carbide whiskers or silicon carbide fibers to generate silicon nitride Si3N and carbon C, and carbonization Create a composite of silicon, silicon nitride and carbon.

In other words, by continuing the above-described decomposition step for a predetermined period of time, silicon carbide (SiC) in the starting material, i.e., silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers is
can be decomposed into silicon nitride Si3N4 and carbon C in an appropriate ratio. Furthermore, silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers are composited with silicon nitride 5iJ4 and carbon C in a desired ratio to produce a composite of silicon carbide, silicon nitride, and carbon.

After that, carbon C contained in the composite of silicon carbide, silicon nitride, and carbon is removed by a carbon removal process such as an oxidation process.

Through the above steps, a composite of silicon carbide and silicon nitride of the present invention is produced.

Furthermore, details of other embodiments of the method for producing a composite of silicon carbide and silicon nitride according to the present invention will be described.

The silicon carbide powder, silicon carbide whisker or silicon carbide fiber as the starting material described above was heated at 40°C in a stream of ammonia gas.
By heating to a temperature above 0'C, as follows: lSiC+ 48H3→ SiJ, + + 3CH4
Silicon carbide (SiC) in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers is decomposed to form silicon nitride S! 3tL to create a composite of silicon carbide and silicon nitride.

In this case, methane CH is produced during the decomposition of silicon carbide SiC in the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers, but it can be removed by exhausting in parallel with the decomposition process, so the heat Compared to the case where an isostatic press treatment is performed, the subsequent carbon removal step can be carried out in parallel with the decomposition step, and as a result, the manufacturing process of the silicon carbide and silicon nitride composite of the present invention can be streamlined.

Through the above steps, the composite of silicon carbide and silicon nitride of the present invention can be produced.

Next, in order to better understand the silicon carbide and silicon nitride composite and its manufacturing method according to the present invention described above, specific numerical values will be given and explained in detail.

(Examples 1 and 2) Silicon carbide (SiC) in silicon carbide powder with a purity of 95% by weight or more and an average particle size of 0.9 was heated to 1250% by weight, respectively, in an atmosphere having a nitrogen partial pressure of 100 atmospheres or more. Hot isostatic pressing was carried out at temperatures of 1450° C. and 1450° C. for 4 hours and 2 hours.

As a result, silicon carbide SiC in the silicon carbide powder is partially decomposed into silicon nitride Si, N, and carbon C, as shown in Table 1, and powdered composites of silicon carbide, silicon nitride, and carbon are respectively formed. generated.

Thereafter, carbon C present in the powdered composite of silicon carbide, silicon nitride, and carbon removes the powdered composite from the atmosphere.
．． It was oxidized and removed by heating to a temperature of 800° C. for 5 hours.

As a result, silicon carbide SiC in the silicon carbide powder is partially converted to silicon nitride Si:+)L as shown in Table 1, thereby converting the silicon carbide powder into the silicon carbide and silicon nitride of the present invention. A powdered composite was produced.

(Examples 3 and 4) The nitrogen partial pressure in the atmosphere in which the hot isostatic pressing treatment was performed was both 1000 atm, and the temperature at that time was 120 atm.
Examples 1 and 2 were repeated except that the temperatures were 0°C and 1350°C, respectively.

The results at this time are shown in Table 1, and as in Examples 1 and 2, silicon carbide SiC in the silicon carbide powder was partially decomposed into silicon nitride Si3N and carbon C. A powdered composite of silicon, silicon nitride and carbon was produced.

Thereafter, carbon C present in the powdered composite of silicon carbide, silicon nitride, and carbon was removed in the same manner as in Examples 1 and 2.

As a result, silicon carbide SiC in the silicon carbide powder is partially converted to silicon nitride 5IJ4, as shown in Table 1, similar to Examples 1 and 2, thereby converting the silicon carbide powder into silicon carbide 5IJ4 of the present invention. A powdered composite of silicon carbide and silicon nitride was produced.

(Comparative Example 1) Example except that the nitrogen partial pressure in the atmosphere in which the hot isostatic pressing treatment was performed was 9 atm, the temperature at that time was 17700C, and the time was 10 hours. 1 was repeated.

The results at this time are shown in Table 1, and unlike in Example 1, silicon carbide SiC in the silicon carbide powder was not decomposed into silicon nitride Si3N4 and carbon C at all.

Comparative Example 2 Example 2 was repeated, except that the temperature in the atmosphere in which the hot isostatic pressing was performed was 1700°C.

The results at this time are shown in Table 1, but unlike in Example 2, silicon carbide SiC in the silicon carbide powder was completely decomposed into silicon nitride Si, 3N, and carbon C, and silicon carbide and A powdered composite of carbon was produced.

Comparative Example 3 Example 4 was repeated, except that the temperature in the atmosphere in which the hot isostatic pressing was performed was 1450°C.

The results at this time are shown in Table 1, but unlike in Example 4, silicon carbide SiC in the silicon carbide powder was completely decomposed into silicon nitride 5iJ4 and carbon C, and the silicon carbide SiC in the silicon carbide powder was decomposed into silicon nitride and carbon powder. A similar composite was produced.

The surface of the powdered composite of silicon nitride and carbon was black, but when it was oxidized by heating at 9800°C for 0.5 hours in the air, it became white or had a white edge color. Became.

Afterwards, when we analyzed the composition of the powdered composite of silicon nitride and carbon, we found that most of the carbon C was oxidized and carbon dioxide CO
2, and carbon C was reduced to 0.5% by weight. At this time, it is known that oxygen 02 in the atmosphere does not penetrate into the interior of the powdered composite of silicon nitride and carbon, so from the change in color of the surface, the oxidation of carbon C mainly occurs on the surface. and carbon C
It was determined that this existed near the surface.

From this, it can be determined that in Examples 4 and 3, carbon C is similarly present near the surface of the powdered composite of silicon carbide and silicon nitride of the present invention.

(Examples 5 and 6) Silicon carbide SiC in a silicon carbide powder having a purity of 95% by weight or more and an average radius of 0.9 months was prepared in an ammonia gas flow supplied at a rate of 10 grams/minute. Decomposition was effected by heating to temperatures of 1150° C. and 1200° C. for 10 hours, respectively.

As a result, silicon carbide SiC in the silicon carbide powder is partially converted into silicon nitride S! as shown in Table 2. :++L
8 and methane CH. At this time, methane C
Since H, was removed by exhaust in parallel with the decomposition of silicon carbide (SiC), the powdered composite of silicon carbide and silicon nitride of the present invention was directly produced from the silicon carbide powder.

Comparative Example 4 Example 5 was repeated, except that the temperature of the ammonia gas stream and the treatment time were 1400° C. and 15 hours, respectively.

The results at this time are shown in Table 2, but unlike in Example 5, silicon carbide SiC in the silicon carbide powder was entirely silicon nitride Sl:+! L and methane CH4 are decomposed, and the methane CH4 is decomposed into silicon carbide SiC as in Example 5.
was removed by exhaust gas in parallel with the decomposition.

As a result, silicon nitride powder was produced directly from silicon carbide powder.

(Examples 7 and 8) Silicon carbide SiC in silicon carbide whiskers with a purity of 95% by weight or more and an average outer diameter and an average length of 0.5 JL and 20 JL, respectively, was subjected to a nitrogen partial pressure of 100 atmospheres or more. 1250” cJ and 14
Hot isostatic pressing was carried out at a temperature of 50° C. for 4 and 2 hours.

As a result, silicon carbide SiC in the silicon carbide whiskers was partially decomposed into silicon nitride SiJ and carbon C, as shown in Table 3, and a whisker composite of silicon carbide, silicon nitride, and carbon was produced.

The carbon C present in the silicon carbide, silicon nitride, and carbon whisker composite was then oxidized and removed by heating the whisker composite to 800° C. for 0.5 hours in air.

As a result, the silicon carbide SiC in the silicon carbide whiskers was partially converted to silicon nitride Si:+N+, thereby producing the silicon carbide and silicon nitride whisker composite of the present invention from the silicon carbide whiskers.

Working Examples 9 and 10) Example 7, respectively, except that the nitrogen partial pressure in the atmosphere in which the hot isostatic pressing was performed was 1000 atm, and the temperatures at that time were 1200°C and 1350°C.
and 8 were repeated.

The results at this time are shown in Table 3, and as in Examples 7 and 8, silicon carbide SiC in the silicon carbide whisker was partially decomposed into silicon nitride Si3N and carbon C. The carbon C was removed by oxidation, thus producing the silicon carbide and silicon nitride whisker composite of the present invention from the silicon carbide whiskers.

(Comparative Example 5) Example except that the nitrogen partial pressure in the atmosphere in which hot isostatic pressing was performed was 9 atm, the temperature at that time was 17700C, and the time was 10 hours. It was repeated 7 times.

The results at this time are shown in Table 3, and unlike in Example 7, silicon carbide SiC in the silicon carbide whiskers was not decomposed into silicon nitride Si3N4 and carbon C at all.

Comparative Example 6 Example 8 was repeated in each case, except that the temperature in the atmosphere in which the hot isostatic pressing was carried out was 1700°C.

The results of this poem are shown in Table 3, and unlike in Example 8, silicon carbide SiG in the silicon carbide whisker is completely decomposed into silicon nitride SjJ< and carbon C, and silicon carbide and carbon A whisker composite was generated.

(Comparative Example 7) Example 0 was repeated, except that the temperature in the atmosphere in which the hot isostatic pressing treatment was performed was 1450°C.

The results at this time are shown in Table 3, but unlike in Example 10, silicon carbide SiC in the silicon carbide whisker was
All were decomposed into silicon nitride 5iJ4 and carbon C, producing a whisker composite of silicon nitride and carbon.

(Examples 11 and 12) Silicon carbide SiC in silicon carbide whiskers with a purity of 95% by weight or more and an average outer diameter and an average length of 0.5 mm and 20 mm, respectively, was supplied at a rate of 10 g/min. 1150 for 10 hours each in a stream of ammonia gas
decomposition by heating to a temperature of 1200°C and 1200°C.

As a result, silicon carbide SiC in the silicon carbide whiskers is partially converted into silicon nitride Si:+ as shown in Table 4.
84 and methane CH4, and this methane C
H, was evacuated in parallel with the decomposition of the silicon carbide SiC, resulting in the silicon carbide and silicon nitride whisker composite of the present invention being produced directly from the silicon carbide whiskers.

Comparative Example 8 Example 11 was repeated, except that the temperature of the ammonia gas stream and the treatment time were 1400° C. and 15 hours, respectively.

The results at this time are shown in Table 4, but unlike in Example 11, silicon carbide SiC in the silicon carbide whisker was
All were decomposed into silicon nitride Si:+N4 and carbon C, and a whisker composite of silicon nitride and carbon was produced from the silicon carbide whiskers.

(Examples 13 and 14) Silicon carbide fibers with a purity of 50% by weight or more, an average outer diameter of 15 cm, and an average length of 10 cm by cutting
Silicon carbide (SiC) in the silicon carbide fiber "Nicalon" manufactured by Nippon Carbon ■ was heated to 1250 °C and 1450 °C, respectively, in an atmosphere with a nitrogen partial pressure of 100 atmospheres or more.
Hot isostatic pressing was carried out for 4 hours and 2 hours.

As a result, silicon carbide SiC in the silicon carbide fiber was partially decomposed into silicon nitride SL+N4 and carbon C, as shown in Table 5, and fibrous composites of silicon carbide, silicon nitride, and carbon were respectively produced. .

After that, the carbon C present in the fibrous composite of silicon carbide, silicon nitride, and carbon causes the fibrous composite to become zero in the atmosphere.
．． It was oxidized and removed by heating to a temperature of 800° C. for 5 hours.

As a result, silicon carbide SiC in the silicon carbide fiber is partially converted to silicon nitride 5iJ4 as shown in Table 5,
As a result, the fibrous composite of silicon carbide and silicon nitride of the present invention was produced from the silicon carbide fibers.

(Examples 15 and 16) The nitrogen partial pressure in the atmosphere in which the hot isostatic pressing treatment was performed was both 1000 atm, and the temperature at that time was 120 atm.
Examples 13 and 14 were repeated except that the temperatures were 0°C and 1350°C, respectively.

The results at this time are shown in Table 5, and as in Examples 13 and 14, silicon carbide SiC in the silicon carbide fiber was partially decomposed into silicon nitride 5IJ4 and carbon C.
Fibrous composites of silicon carbide, silicon nitride, and carbon were produced, respectively.

After that, carbon C present in the fibrous composite of silicon carbide, silicon nitride, and carbon removes the fibrous composite from the atmosphere.
．． It was oxidized and removed by heating to a temperature of 800° C. for 5 hours.

As a result, silicon carbide SiC in the silicon carbide fiber is partially converted to silicon nitride Si3N4 as shown in Table 5, thereby converting the silicon carbide fiber into the fibrous composite of silicon carbide and silicon nitride of the present invention. something was created.

(Comparative Example 9) Example except that the partial pressure of nitrogen in the atmosphere in which the hot isostatic pressing treatment was performed was 9 atm, the temperature at that time was 177,000, and the time was 10 hours. 13
or repeated.

The results at this time are shown in Table 5, and unlike in Example 13, silicon carbide SiC in the silicon carbide fiber was not decomposed into silicon nitride Si3N4 and carbon C at all.

Comparative Example 10 Example 14 was repeated, except that the temperature in the atmosphere in which the hot isostatic pressing was performed was 1700°C.

The results at this time are shown in Table 5, but unlike in Example 14, silicon carbide SiC in the silicon carbide fiber was completely decomposed into silicon nitride Si:+Nn and carbon C, and silicon carbide and carbon A fibrous composite was produced.

Comparative Example 11 Example 16 was repeated, except that the temperature in the atmosphere in which the hot isostatic pressing was performed was 1450°C.

The results at this time are shown in Table 5, but unlike in Example 16, silicon carbide SiC in the silicon carbide fiber was completely decomposed into silicon nitride Si, N, and carbon C, and silicon carbide and A fibrous composite of carbon was produced.

(Example 17'!6 and 18) Silicon carbide fibers with a purity of 50% by weight or more, an average outer diameter of 15 cm, and an average length of 10 cm by cutting (silicon carbide manufactured by Nippon Carbon Co., Ltd.) Silicon carbide (SiC) in the fiber "Nicalon") was heated at 1150°C for 10 hours in a stream of ammonia gas supplied at a rate of 10 sentences/min.
and decomposed by heating to a temperature of 1200°C.

As a result, silicon carbide SiC in the silicon carbide fiber is partially decomposed into silicon nitride Si:lN4 and methane C114, as shown in Table 6, and this methane CH4 is exhausted in parallel with the decomposition of silicon carbide SiC. As a result, the m-pyramidal composite of silicon carbide 3 and silicon nitride of the present invention was produced directly from the silicon carbide fibers.

Comparative Example 12 Example 17 was repeated, except that the temperature of the ammonia gas stream and the treatment time were 1400° C. and 15 hours, respectively.

The results at this time are shown in Table 6, but unlike in Example 17, silicon carbide SiC in the silicon carbide fiber was completely decomposed into silicon nitride Si3N and carbon C, and the silicon carbide fiber was nitrided from the silicon carbide fiber. A fibrous composite of silicon and carbon was produced.

(3) Effects of the invention As is clear from the above, the silicon carbide and silicon nitride composite according to the present invention is such that the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers are the silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers. Silicon carbide powder, silicon carbide whisker, or silicon carbide fiber contains silicon nitride produced by partially decomposing silicon carbide in the fiber, so (i) silicon carbide powder, carbonized It has the effect of finely compounding silicon whiskers or silicon carbide fibers with silicon nitride, and (ii) the ability to strengthen the material of silicon carbide powder, silicon carbide whiskers, or silicon carbide LA fibers (for example, the ability to improve fracture toughness). ) has the effect of further improving the characteristics of

Further, the method for producing a composite of silicon carbide and silicon nitride according to the present invention includes: (a) partially decomposing silicon carbide in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers having a purity of 50% by weight or more; (b) a carbon removal step to remove the carbon produced in the decomposition step; (i) silicon carbide powder, silicon carbide whiskers or carbonization; It has the effect of directly compositing silicon fibers with silicon nitride, and (11) simultaneously has the effect of inexpensively compositing a large amount of silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with silicon nitride, In addition, (iii) by pre-selecting the size of silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers, there is an effect that the size of the composite of silicon carbide and silicon nitride can be adjusted as appropriate.

Claims (4)

[Claims] (1) The silicon carbide powder, silicon carbide whiskers or silicon carbide fibers contain silicon nitride produced by partially decomposing silicon carbide in the silicon carbide powder, silicon carbide whiskers or silicon carbide fibers. A composite of silicon carbide and silicon nitride, characterized in that it is contained inside a powder, a silicon carbide whisker, or a silicon carbide fiber. (2) (a) Carbon that partially decomposes silicon carbide in silicon carbide powder, silicon carbide whiskers, or silicon carbide fibers with a purity of 50% by weight or more and (b) removes carbon generated in the decomposition process. 1. A method for producing a composite of silicon carbide and silicon nitride, comprising the step of removing. (3) The decomposition step is achieved by heating to a temperature of 1200° C. or higher and hot isostatic pressing in an atmosphere having a nitrogen partial pressure of 100 atmospheres or higher. A method for producing a composite of silicon carbide and silicon nitride according to scope (2). (4) The composite of silicon carbide and silicon nitride according to claim (2), wherein the decomposition step is achieved by heating to a temperature of 1150° C. or higher in an ammonia gas flow. manufacturing method.