JP2011088804A - Method for producing titanium silicon carbide ceramics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dissolve the problem that porous titanium silicon carbide ceramics is synthesized and the synthesized matter is destroyed and to provide a mass production technique of a low cost in synthesis of a titanium silicon carbide ceramic member by normal pressure sintering of mixed powder consisting of titanium, silicon carbide and carbon. <P>SOLUTION: The mixed powder consisting of titanium, silicon carbide, carbon and titanium carbide with a composition corresponding to a stoichiometric composition of titanium silicon carbide (Ti<SB>3</SB>SiC<SB>2</SB>) is subjected to compression molding and then to normal pressure sintering. Otherwise powder, which is obtained by adding to the mixed powder an element that forms a liquid phase by eutectic reaction with raw material titanium and/or an element that has a low melting point and can substitute a silicon site in titanium silicon carbide as a component segregation inhibitor and in which amount of carbon included in the titanium carbide is in a range of 60 to 100% of total carbon amount except carbon included in the silicon carbide and amount of titanium included in the titanium carbide is in a range of 20 to 33.3% of total titanium amount, is subjected to compression molding and then to normal pressure sintering. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing titanium silicon carbide ceramics, and more particularly, to provide a production method suitable for mass production of titanium silicon carbide ceramic members.

The composition of titanium silicon carbide ceramics is mainly composed of titanium silicon carbide (Ti ₃ SiC ₂ ), and titanium carbide (TiC), pentasilicon trisilicate (Ti ₅ Si ₃ ), titanium disilicide (TiSi ₂ ) as impurities. ), Ceramics containing a small amount of silicon carbide (SiC) and the like. It is a conductive machinable ceramic that exhibits metal conductivity (conductivity by free electrons) and can be cut like graphite, and is expected as a functional material and a structural material. Titanium silicon carbide ceramics are titanium, silicon, carbon, or titanium, silicon, titanium carbide, or titanium, silicon carbide, carbon, or mixed powder of titanium, silicon carbide, titanium carbide at atmospheric pressure or pressure sintering (For example, Documents 1, 2, and 3).

  In the synthesis by pressure sintering, the raw material mixed powder is put into a heat-resistant mold such as a graphite mold, heated while being pressurized, and simultaneously sintered and densified. Alternatively, the raw material mixed powder is compression-molded by a mold press, or put in a rubber mold and compression-molded by a hydrostatic pressure press (Cold Isostatic Press, abbreviated as CIP). It is heated while being pressed by a hot isostatic press (abbreviated as HIP), and sintered and densified simultaneously with synthesis. Therefore, it is possible to synthesize dense titanium silicon carbide ceramics having a relative density (the ratio of the actual density to the theoretical density in percentage) of 99% or more. However, the pressure sintering method has low productivity and high cost, and cannot be said to be a method suitable for mass production.

  On the other hand, in the synthesis by atmospheric pressure sintering, the raw material mixed powder is compression-molded by a mold press, or put in a rubber mold and compressed by an isostatic press (CIP), and this is vacuum or atmospheric pressure in a heating furnace. It is heated in an inert gas and sintered and densified simultaneously with synthesis. Although the relative density of titanium silicon carbide ceramics synthesized because it is not pressurized is low, the atmospheric pressure sintering method is high in productivity, low in cost, and suitable for mass production.

  However, synthesis of titanium, silicon carbide, and carbon mixed powder corresponding to the stoichiometric composition of titanium silicon carbide by pressureless sintering (Reference 3) enables the synthesis of titanium silicon carbide ceramics with a relative density of 97% or more. Although it is a result obtained based on the synthesis of a small disk-shaped member having a weight of about 2 g, a diameter of 14 mm, and a thickness of about 4 mm in a laboratory, a large-sized member having a high industrial utility value, for example, FIG. When applied to the synthesis of a cylindrical member having a weight of about 100 g, a diameter of about 25 mm, and a length of about 60 mm as shown in FIG. 1, there is a problem that porous titanium silicon carbide ceramics are synthesized and the composite is destroyed. I understood.

JP 2003-2745 A Japanese Patent No. 3995143 JP 2005-89252 A

  The present invention overcomes the above-mentioned problems of the prior art, and can be produced in large quantities at a low cost by a normal pressure sintering method without causing destruction or breakage of a large-sized titanium silicon carbide member having high industrial utility value. The challenge is to provide a method.

The present invention for solving the above problems is characterized by comprising the following technical means.
(1) Manufacture of a titanium silicon carbide ceramic member that is sintered under pressure after compression molding of a mixed powder of titanium, silicon carbide, carbon, and titanium carbide corresponding to the stoichiometric composition of titanium silicon carbide (Ti ₃ SiC ₂ ) Method.
(2) The amount of carbon contained in titanium carbide in the raw material mixed powder is in the range of 60% to 100% of the total amount of carbon excluding carbon contained in silicon carbide, and the amount of titanium contained in titanium carbide is all The manufacturing method of the titanium silicon carbide ceramic member as described in said (1) which is the range of 20%-33.3% of titanium amount.
(3) As a component segregation inhibitor to a mixed powder of titanium, silicon carbide, carbon and titanium carbide corresponding to the stoichiometric composition of titanium silicon carbide (Ti ₃ SiC ₂ ) (a) A liquid phase is formed by eutectic reaction with titanium. The method for producing a titanium silicon carbide ceramic member according to (1) or (2), wherein an element to be generated and / or (b) an element having a low melting point and capable of substituting a silicon site of titanium silicon carbide is added.
(4) The titanium silicon carbide ceramic member according to any one of (1) to (3), wherein the atmospheric pressure sintering temperature is in the range of 1200 to 1500 ° C. and the sintering temperature holding time is in the range of 30 minutes to 6 hours. Manufacturing method.

  The present invention having the features as described above is based on the new knowledge obtained by the experimental investigation by the inventors as follows.

The inventor firstly synthesized titanium silicon carbide ceramics by heating a compression molded body of a mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide. In order to investigate the above, a small cylindrical compression-molded body having a weight of about 5 g, a diameter of 14 mm, and a length of about 11.5 mm was subjected to a predetermined temperature (100 ° C. within a range of 750 ° C. to 1550 ° C. at a heating rate of 20 ° C. C.) and rapidly cooled (temperature decrease rate> 100 ° C. per minute). When the X-ray diffraction pattern of this sample was measured to identify the formation phase at each temperature, titanium silicide (mainly trititanium pentasilicate Ti ₅ Si ₃ ) and titanium carbide TiC began to form from around 850 ° C., It was found that titanium silicide and titanium carbide began to be synthesized from around 1350 ° C. by reaction of titanium silicide and titanium carbide (literature Hitoshi Hashimoto, Zheng Ming Sun, Shuji Tada, “Morphological Evolution Circading Sintering Reaction Reaction Singing "Journal of Alloys and Compounds, Vol.441, pp.174-180, (2007)). That is, the reaction is roughly divided into two stages. The first stage is a reaction in which titanium silicide and titanium carbide are formed from titanium and silicon carbide starting from around 850 ° C., and a reaction in which titanium carbide is formed from titanium and carbon. Is a reaction in which titanium silicon carbide is formed from titanium silicide and titanium carbide starting from around 1350 ° C. When the heating rate is small, the first stage reaction is considered to proceed mainly by the diffusion of silicon and carbon from silicon carbide particles to titanium particles and the diffusion of carbon from carbon particles to titanium particles. Therefore, when the temperature rising rate is high, it is considered that the reaction proceeds mainly by a solid phase reaction called a combustion synthesis reaction or a self-propagating high-temperature synthesis reaction (SHS).

  When applied to the synthesis of a large-sized member, the cause of the problem that the porous titanium silicon carbide ceramics are synthesized and the composite is destroyed is considered as follows.

The synthetic reaction of titanium silicon carbide is an exothermic reaction, and the calorific value per unit time [Js ^-1 ] is the mass [kg] of the raw material mixed powder compression molding, the calorific value [J / kg] and the mass per unit mass. It increases in proportion to the product of the standard reaction rate [kg / s]. On the other hand, the heat release amount [J / s] per unit time from the compressed compact that has generated heat is proportional to the product of the surface area [m ² ] and the heat transfer rate [J / m ² s] of the compact. If the compression-molded body has a similar shape, its mass increases in proportion to the cube of the representative dimension, while its surface area is proportional to the square. Since the calorific value per unit mass and the mass-based reaction rate do not vary depending on the size of the molded body, the calorific value is proportional to the cube of the representative dimension. The heat transfer rate is affected by the temperature gradient inside the molded body and the temperature difference between the molded body surface and the atmosphere gas, but assuming that the heat transfer rate does not change depending on the size (in fact, if the molded body size increases, Since the temperature gradient inside the compact is small, the heat transfer rate is small), and the amount of heat released is proportional to the surface area, and therefore proportional to the square of the representative dimension. Therefore, while the heat generation amount increases in proportion to the cube of the size of the molded body, the heat dissipation amount increases in proportion to the square of the size, so that the heat generation amount per unit time as the size increases. The increase will greatly exceed the increase in heat dissipation.

  As described above, the synthesis reaction is a two-stage reaction starting from around 850 ° C. and around 1350 ° C. As the size increases, the first stage reaction starting from around 850 ° C., in particular, the heat generated by the reaction of titanium and carbon, which generate a large amount of heat, to form titanium carbide exceeds the heat dissipation, and the temperature of the molded body When the temperature rapidly rises and reaches around 1350 ° C., the second-stage reaction is immediately induced. The temperature further rapidly rises due to the heat of reaction, and finally the gas melts beyond the melting point of the composite, and the gas adsorbed or dissolved in the raw material is explosively released. Therefore, it is considered that the composite becomes porous and is broken and cannot maintain its shape. That is, when the raw material mixed powder compression-molded body becomes large, the first-stage reaction and the second-stage reaction are likely to occur almost simultaneously. The dissolved gas is explosively released, and the composite becomes porous and is considered to be destroyed.

In order to verify this, a substance for improving component segregation in a mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide (component segregation inhibitor) ) 3% by weight of the mixed powder compression molded body (weight: about 7 g, diameter: about 14 mm, length: about 15 mm) while heating the molded body surface temperature to 1500 ° C. at a heating rate of 75 ° C./min. It measured with the infrared radiation thermometer. Even in a small compression-molded body, there is no convection in a vacuum, heat transfer is only heat conduction and radiation, and the heat transfer rate is reduced. Therefore, the amount of heat release is reduced, and the heating rate is 75 ° C per minute. By increasing the temperature, the temperature rise increases together with the temperature rise due to heat generation. Therefore, the same effect as increasing the size of the molded body can be expected. In fact, twice of the three experiments, as shown in FIG. 2, the temperature of the molded body began to rise rapidly in the vicinity of the molded body surface temperature exceeding 950 ° C., and instantaneously generated heat exceeding 1800 ° C. A peak was observed. In this case, as shown in FIG. 3, the composite was porous and was broken and did not maintain its original shape. In the X-ray diffraction pattern of the powder obtained by pulverizing this composite, only the peak of titanium silicon carbide Ti ₃ SiC ₂ is seen as shown in FIG. 4, and high-purity Ti ₃ SiC ₂ can be synthesized. Recognize.

On the other hand, one out of three experiments under the same conditions, as shown in FIG. 5, has an exothermic peak that rises from around 950 ° C. and rises to 1070 ° C. and two exothermic peaks that rise from around 1060 ° C. It was. As shown in FIG. 6, the composite in this case is deformed but not broken. Also in this case, as shown in FIG. 7, only the peak of titanium silicon carbide Ti ₃ SiC ₂ was seen in the X-ray diffraction pattern of this composite, indicating that high-purity Ti ₃ SiC ₂ could be synthesized. . That is, it was found that when the first-stage reaction and the second-stage reaction occur separately, the composite is deformed but not destroyed.

  From the above, if the temperature rise due to the exothermic heat of the first stage reaction can be suppressed below the temperature at which the second stage reaction occurs, the first stage reaction and the second stage reaction occur separately, It turns out that it does not occur.

In this way, if the temperature rise due to the exothermic heat of the first stage reaction can be suppressed below the temperature at which the second stage reaction occurs, the first stage reaction and the second stage reaction occur separately, and the composite is destroyed. In order to suppress the amount of heat generated by the solid-phase reaction in which titanium carbide is synthesized from titanium and carbon, which is considered to be the main exothermic reaction in the first stage, the stoichiometric composition of titanium silicon carbide It is envisioned that titanium and carbon in a mixed powder having a molar ratio of titanium: silicon carbide: carbon = 3: 1: 1 are replaced with titanium carbide (TiC). First, 10% of titanium and 30 of carbon % Was replaced with titanium carbide, that is, a mixed powder having a molar ratio of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 was used. Specifically, 2 mass% of silicon, which is an element that forms a liquid phase by eutectic reaction with titanium as a component segregation inhibitor, can be substituted into the mixed powder, and the silicon site of titanium silicon carbide can be substituted. The compression molded body (weight: about 7 g, diameter: about 14 mm, length: about 15 mm) after addition of 3% by mass of the element aluminum is heated to 1500 ° C. at a heating rate of 75 ° C. per minute. The molded body surface temperature was measured with an infrared radiation thermometer. As shown in FIG. 8, two exothermic peaks were observed once in three experiments, and the composite was deformed as shown in FIG. 9, but no destruction occurred. As shown in FIG. 10, only the peak of titanium silicon carbide Ti ₃ SiC ₂ is seen in the X-ray diffraction pattern of this composite, indicating that high-purity Ti ₃ SiC ₂ can be synthesized. The stoichiometric composition of titanium silicon carbide is titanium: silicon: carbon = 3: 1: 2 (molar ratio). When titanium, silicon carbide, or carbon is used as a raw material, titanium: silicon carbide: Carbon = 3: 1: 1 (molar ratio) corresponds to titanium: silicon: carbon = 3: 1: 2 (molar ratio). When titanium, silicon carbide, carbon, or titanium carbide is used as a raw material, the number of moles of titanium, silicon carbide, or carbon is calculated from the following formula, where x is the number of moles of titanium carbide.

Titanium = 3-x
Silicon carbide = 1
Carbon = 1-x
In this case, x ÷ 3 × 100% of titanium and x × 100% of carbon in the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 were replaced with titanium carbide.

On the other hand, as shown in FIG. 11, many small exothermic peaks were observed twice in the three experiments. In this case, as shown in FIG. 12, it was found that the composite body maintained its original shape without deformation. Further, as shown in FIG. 13, only the peak of titanium silicon carbide Ti ₃ SiC ₂ is seen in the X-ray diffraction pattern of the composite, and it can be seen that high-purity Ti ₃ SiC ₂ can be synthesized.

  From the above, it has been found that substituting a part of titanium and carbon in the raw material mixed powder with titanium carbide is an effective means for preventing destruction of the composite and further preventing deformation of the composite. In particular, three or more exothermic peaks as shown in FIG. 11 were observed, and it was found that a substitution amount to titanium carbide that does not cause deformation of the composite as shown in FIG. 12 was desirable.

  Therefore, while increasing the amount of substitution to titanium carbide to 40%, 50% and 70% of carbon (the amounts of substitution of titanium to titanium carbide are 13.3%, 16.7% and 23.3%, respectively) A synthetic experiment was conducted. As a result, when the amount of substitution to titanium carbide is 70% of carbon (the amount of substitution of titanium to titanium carbide is 23.3%), many exothermic peaks are clearly seen in all four experiments, The result was obtained without deformation of the composite. This is a case where the amount of substitution to titanium carbide is 70% of carbon, that is, the composition is titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 (molar ratio).

  Next, a large size compression molded body was examined. CIP compression of mixed powder with 50%, 60% and 70% substitution of titanium carbide (16.7%, 20% and 23.3% substitution of titanium to titanium carbide, respectively) The formed body (weight: about 100 g, diameter: about 25 mm, length: about 60 mm) was heated to 1500 ° C. at a heating rate of 6.25 ° C./min in a 150 Pa vacuum argon atmosphere. As a result, it was found that all the samples maintained the original shape and had little deformation. Further, the composite had no segregation of components, and as a result of phase identification by X-ray diffraction, no components other than titanium silicon carbide were detected. However, in the case of 50%, the composite is not necessarily sufficiently dense, and in order to synthesize a dense titanium silicon carbide member, 60% or more of carbon (20% or more of titanium) is replaced with titanium carbide. It was confirmed that it was more preferable.

According to the present invention as described above,
A titanium silicon carbide ceramic member having a size having high industrial utility value can be produced at low cost and in large quantities.

A cylindrical molded body obtained by compression molding a mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide by hydrostatic pressing is heated in a heat treatment furnace and synthesized. Appearance photograph of the sample The temperature of the compression molded body of the mixed powder obtained by adding 3 mass% of the component segregation inhibitor to the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide is raised. Change with time of the molded body surface temperature measured with an infrared radiation thermometer while heating to 1500 ° C at a rate of 75 ° C per minute Heating up to 1500 ° C. at a heating rate of 75 ° C. per minute with a powder mixture of 3% by mass of component segregation inhibitor added to a titanium: silicon carbide: carbon mixed powder corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the synthesized sample The temperature of the compression molded body of the mixed powder obtained by adding 3 mass% of the component segregation inhibitor to the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide is raised. X-ray diffraction pattern of a sample synthesized by heating to 1500 ° C at a rate of 75 ° C per minute The temperature of the compression molded body of the mixed powder obtained by adding 3 mass% of the component segregation inhibitor to the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide is raised. Change with time of the molded body surface temperature measured with an infrared radiation thermometer while heating to 1500 ° C at a rate of 75 ° C per minute The temperature of the compression molded body of the mixed powder obtained by adding 3 mass% of the component segregation inhibitor to the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide is raised. Appearance photo of a sample synthesized by heating to 1500 ° C at a rate of 75 ° C per minute The temperature of the compression molded body of the mixed powder obtained by adding 3 mass% of the component segregation inhibitor to the mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide is raised. X-ray diffraction pattern of a sample synthesized by heating to 1500 ° C at a rate of 75 ° C per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Changes in the surface temperature of the molded body measured with an infrared radiation thermometer while heating the compression molded body of the added mixed powder to 1500 ° C at a heating rate of 75 ° C per minute. 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the sample synthesized by heating the compression mixture of the added mixed powder to 1500 ° C at a heating rate of 75 ° C per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide X-ray diffraction pattern of a sample synthesized by heating the added powder compact to 1500 ° C at a heating rate of 75 ° C per minute) 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Changes in the surface temperature of the molded body measured with an infrared radiation thermometer while heating the compression molded body of the added mixed powder to 1500 ° C at a heating rate of 75 ° C per minute. 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the sample synthesized by heating the compression mixture of the added mixed powder to 1500 ° C at a heating rate of 75 ° C per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.7: 1: 0.7: 0.3 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide X-ray diffraction pattern of a sample synthesized by heating the compression mixture of the added mixed powder to 1500 ° C. at a heating rate of 75 ° C. per minute Mixed powder obtained by adding 3% by mass of component segregation inhibitor to mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 corresponding to the stoichiometric composition of titanium silicon carbide Change in the surface temperature of the molded body measured with an infrared radiation thermometer while heating the compression molded body of 1,500 ° C at a heating rate of 75 ° C per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the sample synthesized by heating the compression mixture of the added mixed powder to 1500 ° C at a heating rate of 75 ° C per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide X-ray diffraction pattern of a sample synthesized by heating the compression mixture of the added mixed powder to 1500 ° C. at a heating rate of 75 ° C. per minute 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the sample synthesized by heating the compacted body by CIP of the added mixed powder 3% by mass of component segregation inhibitor in a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide X-ray diffraction patterns measured at three locations on a sample synthesized by heating a compact formed by CIP of the mixed powder added. 3% by mass of component segregation inhibitor in mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Appearance photograph of the sample synthesized by heating the compacted body by CIP of the added mixed powder 3% by mass of component segregation inhibitor in mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide X-ray diffraction patterns measured at three locations on a sample synthesized by heating a compact formed by CIP of the mixed powder added. X-ray of a sample (ground powder) synthesized by heating a compression molded body by CIP of a mixed powder of titanium: silicon carbide: carbon = 3: 1: 1 (molar ratio) corresponding to the stoichiometric composition of titanium silicon carbide Diffraction pattern A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. Temporal change of molded body surface temperature measured with infrared radiation thermometer while heating to 1500 ° C A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. Appearance photo of the sample synthesized by heating up to 1500 ° C A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. X-ray diffraction patterns of the top and bottom surfaces of a cylindrical sample synthesized by heating to 1500 ° C A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. Temporal change of molded body surface temperature measured with infrared radiation thermometer while heating to 1500 ° C A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. Appearance photo of the sample synthesized by heating up to 1500 ° C A compression molded body of a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7 corresponding to the stoichiometric composition of titanium silicon carbide is heated at a rate of 75 ° C. per minute. X-ray diffraction patterns of the top and bottom surfaces of a cylindrical sample synthesized by heating to 1500 ° C

In the method of the present invention, in the production of titanium silicon carbide (Ti ₃ SiC ₂ ) by atmospheric pressure sintering, the blending composition (molar ratio) of the raw material mixed powder corresponding to the stoichiometric composition,
Titanium (Ti): 3-x
Silicon carbide (SiC): 1
Carbon (C): 1-x
Titanium carbide (TiC): x
Assuming that 0 <x ≦ 1. In the present invention, the mixed powder having such a blending composition (molar ratio) is compression molded and then subjected to atmospheric pressure sintering.

  In the above-described molar ratio display, in the present invention, x is preferably changed each time depending on the size of the compression molded body, the heating rate, and the sintering atmosphere. That is, it is necessary to increase x as the size increases, the temperature increase rate increases, and the pressure of the sintering atmosphere gas decreases. For example, specifically, when a compression molded body having a diameter of 14 mm, a height of 15 mm, and a weight of 7 g is heated in an argon gas having a pressure rising rate of 30 ° C./min and a pressure of 0.1 MPa, x = 0.1 is sufficient. It is. On the other hand, when a compression molded body having a diameter of 14 mm, a height of 15 mm, and a weight of 7 g is heated in a vacuum at a heating rate of 75 ° C./min, x = 0.7 or more is desirable. In the case of heating a large-size molded body having a diameter of 25 mm, a height of 60 mm, and a weight of 100 g, which is a target in the present invention, in an argon gas having a temperature rising rate of 6.25 ° C./min and a pressure of 150 Pa, x = 0 .6 or more is desirable.

  The upper limit of x is preferably less than 0.9. The reason is that when x = 0.9 or more, the compression moldability of the mixed powder and the shape retention of the molded body are significantly deteriorated.

  In addition, the raw material mixed powder of the present invention includes (a) an element such as silicon (Si), iron (Fe), cobalt (Co), and the like that generate a liquid phase by eutectic reaction with titanium as a component segregation preventing agent, and ( b) It is effective to add at least one of elements such as aluminum (Al) which has a low melting point and can replace silicon sites of titanium silicon carbide. Of course, although not essential, the addition of these suppresses the segregation of impurities such as titanium carbide, thereby realizing the synthesis of a titanium silicon carbide ceramic member having a uniform component.

  When adding such a component segregation inhibitor, the range of the optimum addition amount varies depending on the type of additive in the raw material mixed powder, but when adding Si, Fe, Co alone, On the other hand, it is usually added in the range of 0.9 mass% or more and less than 3 mass%. If it is less than 0.9%, the component segregation preventing effect tends to be insufficient, and if it is 3% or more, a substance other than titanium carbide is synthesized and the purity of titanium silicon carbide is lowered, or a rapid exothermic reaction occurs and the material is not densified. This is likely to cause harmful effects.

  When adding Al alone, it is usually added within a range of 1% by mass or more and less than 2% by mass. If it is less than 1%, the effect of preventing component segregation is insufficient, and if it is 2% or more, there is a problem that densification becomes uneven.

  On the other hand, when both Si and Al are added, they are usually added in the range of 2% by mass or more and less than 5% by mass, more preferably 3 to 4% by mass in total of the additive elements. If it is less than 1%, the effect of preventing segregation of components is insufficient, and if it is 5% or more, substances other than titanium carbide are also synthesized, and adverse effects such as a decrease in the purity of titanium silicon carbide tend to occur.

  The component of the mixed powder in the present invention is composed of titanium, titanium carbide, carbon, titanium carbide, and, if necessary, the above-described component segregation preventing agent. These are either commercial products or synthetic products. In general, however, the average particle diameter is desirably in the range of 100 μm or less. When it exceeds 100 μm, uniform reaction tends to be difficult.

  The mixing operation and the compression molding means may be the same as in the prior art. The means for atmospheric pressure sintering is the same.

  For example, the mixing operation can be performed using a general powder mixer such as a V mixer or a TURBULA mixer, and the compression molding can be performed using a mold powder press, a rubber press, or a CIP.

  Further, the normal pressure sintering can be carried out in an inert gas such as argon or in a vacuum using a heating furnace.

  About normal pressure sintering, it is preferable to set it as the holding time of the range of 30 minutes-6 hours in the range of the temperature of 1200-1500 degreeC in this invention. By setting it within these ranges, the effects of the present invention are more reliably and stably realized.

  Next, the present invention will be described specifically by way of examples. Of course, this invention is not limited at all by these examples, and includes all aspects or modifications other than the following Examples, as long as it is within the scope of the technical idea.

The molar ratio corresponding to the stoichiometric composition of titanium silicon carbide is a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7, that is, titanium carbide in the raw material mixed powder. To improve component segregation in the raw material mixed powder in which the amount of carbon contained is 70% of the total carbon amount excluding the carbon contained in silicon carbide, and the amount of titanium contained in titanium carbide is 23.3% of the total titanium amount. 2% by mass of silicon, which is an element that forms a liquid phase by eutectic reaction with titanium as a raw material, and 1% by mass of aluminum, which is an element that has a low melting point and can replace silicon sites of titanium silicon carbide, 3% in total The mixed powder added with mass% was compression-molded at a pressure of 500 MPa using a mold to obtain a cylindrical sample having a weight of about 7 g, a diameter of about 14 mm, and a length of about 15 mm. The surface temperature of the molded body was measured with an infrared radiation thermometer while heating to 1500 ° C. at a rate of temperature increase of 75 ° C. per minute in a vacuum. The experiment was performed four times, and in all, three small exothermic peaks were observed as shown in FIG. 14, and the composite did not break or deform as shown in FIG. Moreover, as shown in FIG. 16, only the peak of titanium silicon carbide Ti ₃ SiC ₂ is seen in the X-ray diffraction pattern of this composite, indicating that high-purity titanium silicon carbide can be synthesized.

  The molar ratio corresponding to the stoichiometric composition of titanium silicon carbide is titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6, that is, titanium carbide in the raw material mixed powder. Substance for improving component segregation in raw material mixed powder in which the amount of carbon contained is 60% of the total carbon amount excluding the carbon contained in silicon carbide, and the amount of titanium contained in titanium carbide is 20% of the total titanium amount. 2% by mass of silicon, which is an element that forms a liquid phase by eutectic reaction with titanium as a raw material, and 3% by mass of aluminum, which is an element that has a low melting point and can replace silicon sites of titanium silicon carbide, 1% by mass The added mixed powder was put into a rubber mold and compression-molded by CIP at a pressure of 400 MPa to obtain a cylindrical formed body having a weight of about 100 g, a diameter of about 25 mm, and a length of about 60 mm. This was placed on an alumina plate so that the axial direction of the cylinder was vertical, and heated at 1500 ° C. for 2 hours under reduced pressure (argon gas 150 Pa) using a heat treatment furnace. As a result, as shown in FIG. 17, it was found that the composite body maintained the original shape and there was little deformation. Further, when the composite was divided into two on the plane passing through the central axis of the cylinder, and the X-ray diffraction pattern was measured at three positions of 10 mm from the bottom surface, the center in the axial direction, and 10 mm from the top surface, as shown in FIG. X-ray diffraction peaks other than titanium silicon carbide were not detected.

  When a test piece (4 mm × 3 mm × 36 mm) was cut out from this composite and subjected to a 4-point bending test at room temperature, an average strength of 125 MPa was shown.

  The molar ratio corresponding to the stoichiometric composition of titanium silicon carbide is a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7, that is, titanium carbide in the raw material mixed powder. To improve component segregation in the raw material mixed powder in which the amount of carbon contained is 70% of the total carbon amount excluding the carbon contained in silicon carbide, and the amount of titanium contained in titanium carbide is 23.3% of the total titanium amount. 2% by mass of silicon, which is an element that forms a liquid phase by eutectic reaction with titanium as a raw material, and 1% by mass of aluminum, which is an element that has a low melting point and can replace silicon sites of titanium silicon carbide, 3% in total The mixed powder added by mass% was put into a rubber mold and compression molded by CIP at a pressure of 400 MPa to obtain a cylindrical formed body having a weight of about 100 g, a diameter of about 25 mm, and a length of about 60 mm. This was placed on an alumina plate so that the axial direction of the cylinder was vertical, and heated at 1500 ° C. for 2 hours under reduced pressure (argon gas 150 Pa) using a heat treatment furnace. As a result, as shown in FIG. 19, it was found that the composite body maintained the original shape and there was little deformation. Further, when the composite was divided into two on the plane passing through the central axis of the cylinder, and X-ray diffraction patterns were measured at three positions of 10 mm from the bottom surface, the center in the axial direction, and 10 mm from the top surface, as shown in FIG. X-ray diffraction peaks other than titanium silicon carbide were not detected.

The molar ratio corresponding to the stoichiometric composition of titanium silicon carbide is titanium: silicon carbide: carbon: titanium carbide = 2.4: 1: 0.4: 0.6, that is, titanium carbide in the raw material mixed powder. The raw material mixed powder in which the amount of carbon contained is 60% of the total carbon amount excluding the carbon contained in silicon carbide and the amount of titanium contained in titanium carbide is 20% of the total titanium amount is compressed by a mold at a pressure of 400 MPa. A cylindrical sample having a weight of about 7 g, a diameter of about 14 mm, and a length of about 15 mm was obtained. While the axial direction of the cylindrical sample was set to the vertical direction, the surface temperature of the molded body was measured with an infrared radiation thermometer while heating in a vacuum to 1500 ° C. at a heating rate of 75 ° C. per minute. The experiment was performed four times. In all cases, as shown in FIG. 22, a plurality of exothermic peaks were observed during the temperature rise, and the composite was not destroyed as shown in FIG. Further, as shown in FIG. 24, the top and bottom X-ray diffraction patterns of this cylindrical composite have a strong peak of titanium silicon carbide Ti ₃ SiC ₂ and a weak peak of TiC, which are relatively high purity. It can be seen that titanium silicon carbide has been synthesized.
[Comparative Example 1]

A mixed powder having a molar ratio of titanium: silicon carbide: carbon = 3: 1: 1 corresponding to the stoichiometric composition of titanium silicon carbide is placed in a rubber mold and compression-molded with a CIP at a pressure of 200 MPa. A cylindrical sample having a diameter of about 25 mm and a length of about 60 mm was obtained. This was placed on an alumina plate so that the axial direction of the cylinder was vertical, and heated at 1500 ° C. for 2 hours under reduced pressure (argon gas 150 Pa) using a heat treatment furnace. As a result, as already shown in FIG. 1, the composite was destroyed and a porous titanium silicon carbide ceramic was synthesized. When some pieces were crushed and the X-ray diffraction pattern was measured, as shown in FIG. 21, the X-ray diffraction peaks of titanium silicon carbide and titanium carbide were seen, and high-purity titanium silicon carbide could not be synthesized. I understood.
[Comparative Example 2]

  The molar ratio corresponding to the stoichiometric composition of titanium silicon carbide is a mixed powder of titanium: silicon carbide: carbon: titanium carbide = 2.3: 1: 0.3: 0.7, that is, titanium carbide in the raw material mixed powder. The raw material mixed powder in which the amount of carbon contained is 70% of the total amount of carbon excluding the carbon contained in silicon carbide and the amount of titanium contained in titanium carbide is 23.3% of the total amount of titanium is pressed by a mold at a pressure of 400 MPa. And a cylindrical sample having a weight of about 7 g, a diameter of about 14 mm, and a length of about 15 mm was obtained. While the axial direction of the cylindrical sample was set to the vertical direction, the surface temperature of the molded body was measured with an infrared radiation thermometer while heating in a vacuum to 1500 ° C. at a heating rate of 75 ° C. per minute. The experiment was performed four times. In all cases, a plurality of exothermic peaks were observed as shown in FIG. 25, and the composite was not destroyed as shown in FIG. However, since no component segregation inhibitor is added, when the amount of substitution by TiC increases, as shown in FIG. 27, the X-ray diffraction pattern on the top surface of this cylindrical composite has an X-ray diffraction pattern on the bottom surface. In comparison, a strong TiC peak is seen, indicating that segregation of components occurs.

  According to the present invention, it is possible to produce a titanium silicon carbide ceramic member having a size having high industrial utility value at low cost and in large quantities. This makes it possible to develop structural materials and functional materials that take advantage of the unique properties of titanium silicon carbide ceramics. For example, heat treatment jigs that can be used in semiconductor manufacturing processes that take advantage of good thermal conductivity, high-temperature oxidation resistance as ceramics, chemical resistance and high-temperature stability, and easy cutting processability comparable to graphite, comparable to alumina ceramics High rigidity and vibration damping ability comparable to nylon, heavy duty vibration damping mounting material utilizing high temperature compressive strength comparable to titanium carbide, heater with complex shape utilizing electrical conductivity, high temperature oxidation resistance, easy cutting workability Application development that is impossible with conventional materials such as elements can be expected.

Claims (4)

A titanium silicon carbide ceramic member characterized by compression-molding a mixed powder of titanium, silicon carbide, carbon, and titanium carbide corresponding to the stoichiometric composition of titanium silicon carbide (Ti ₃ SiC ₂ ) and then sintering at normal pressure Manufacturing method.   The amount of carbon contained in titanium carbide in the raw material mixed powder is in the range of 60% to 100% of the total carbon amount excluding the carbon contained in silicon carbide, and the amount of titanium contained in titanium carbide is 20% to the total titanium amount. The method for producing a titanium silicon carbide ceramic member according to claim 1, wherein the content is in the range of 33.3%. (A) an element that forms a liquid phase by eutectic reaction with titanium as a component segregation inhibitor in a mixed powder of titanium, silicon carbide, carbon, and titanium carbide corresponding to the stoichiometric composition of titanium silicon carbide (Ti ₃ SiC ₂ ) And / or (b) an element capable of substituting a silicon site of titanium silicon carbide having a low melting point, and adding a titanium silicon carbide ceramic member according to claim 1.   4. The titanium silicon carbide ceramic member according to claim 1, wherein the atmospheric pressure sintering temperature is in the range of 1200 to 1500 ° C. and the sintering temperature holding time is in the range of 30 minutes to 6 hours. 5. Production method.