Al4SiC4 powder and its manufacturing method

Abstract

To provide Al4SiC4 powder substantially free of Al4C3.SOLUTION: Al4SiC4 powder is provided in which the ratio IAl4C3 / IAl4SiC4 of the peak integrated intensity IAl4C3(cps / deg), which originates from Al4C3 around 2θ=55.1°, to the peak integrated intensity IAl4SiC4(cps / deg), which originates from Al4SiC4 around 2θ=56.0°, is 0.1% or less, and the color space (L*,a*,b*) is within the range of any of (22 to 29, 11 to 14, 12 to 20), (16 to 26, 12 to 13, 20 to 23), (0 to 5, 0 to 2, -4 to 0), and (2 to 15,0 to 2, -4 to 0).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to Al4SiC4 powder and a method for producing the same. [Background technology]

[0002] Aluminum silicon carbide (Al4SiC4) is a carbide composed of aluminum and silicon. In recent years, Al4SiC4 powder has attracted attention as a new functional additive for carbon-containing refractories. One of the effects of adding Al4SiC4 powder is the densification of the refractory structure. It is believed that the densification of the refractory structure occurs when the Al4SiC4 present in the refractory structure reacts with CO gas in the atmosphere. That is, as shown in equation (1), at high temperatures, a gas containing Al is generated from Al4SiC4, which diffuses into the voids in the refractory structure, reacts with CO gas, and condenses again as Al2O3 and carbon, filling the voids. Al4SiC4+6CO→2Al2O3+SiC+9C (1)

[0003] Non-Patent Document 1 discloses a method for synthesizing Al4SiC4 powder, in which raw materials containing aluminum powder, silicon powder, and carbon powder are blended in a theoretical molar ratio of Al:Si:C = 4:1:4, mixed, and heated in an inert gas atmosphere to synthesize Al4SiC4 powder. It is believed that Al4SiC4 is synthesized in the following two stages: As the temperature rises due to heating, Al4C3 and SiC are first produced as shown in equations (2) and (3), and then, at temperatures above 1300°C, Al4C3 and SiC react to produce Al4SiC4 as shown in equation (4). 4Al+3C→Al4C3(2) Si+C→SiC (3) Al4C3+SiC→Al4SiC4(4) [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Journal of the Ceramic Society of Japan 103 [1] 20-24 (1995) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional methods for synthesizing Al4SiC4 powder, if the raw material ratio is inappropriate or the heating temperature is insufficient, reaction (4) does not proceed, resulting in the formation of unreacted Al4C3. Al4C3 hydrates easily, and adding Al4SiC4 powder containing Al4C3 to refractories can hydrate the Al4C3, causing it to expand in volume and potentially impairing the refractory's dimensional stability. Therefore, it is necessary to synthesize Al4SiC4 powder in a way that prevents the formation of Al4C3. Al4C3 is a Class 3 hazardous material under the Fire Service Act, and is designated as a pyrophoric and water-reactive substance. Care must be taken when storing and handling Al4SiC4 powder containing unreacted Al4C3.

[0006] The present invention has been made in view of the above problems, and aims to provide an Al4SiC4 powder that is substantially free of Al4C3 and a method for producing the same. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the present invention is to provide a powder X-ray diffraction method for determining an integrated intensity I of a peak attributable to Al4C3 at around 2θ=55.1°. Al4C3 (cps / deg) and the integrated intensity of the peak due to Al4SiC4 around 2θ=56.0° I Al4SiC4 (cps / deg) Al4C3 / I Al4SiC4 The Al4SiC4 powder is characterized in that the content of SiO2 is 0.1% or less, and the color space (L*, a*, b*) is within any of the following ranges: (22-29, 11-14, 12-20), (16-26, 12-13, 20-23), (0-5, 0-2, -4-0), or (2-15, 0-2, -4-0).

[0008] Another aspect of the present invention is Al 4 C 3 Contains Al 4 SiC 4 The particle size of the powder is adjusted to 500 μm or less, and after particle size adjustment This is a method for producing Al4SiC4 powder by heating Al4SiC4 powder containing Al4C3 at 400℃ to 1000℃ in an air atmosphere. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide an Al4SiC4 powder that is substantially free of Al4C3. The Al4SiC4 powder of the present invention has a color space (L*, a*, b*) within the above range, and is therefore clearly distinguishable from the color space (L*, a*, b*) of conventional Al4SiC4 powder synthesized so as not to produce Al4C3.

[0010] According to another aspect of the present invention, Al4C3-containing Al4SiC4 powder is heated at 400°C to 1000°C in an air atmosphere, so that Al4C3 can be decomposed and eliminated. Meanwhile, the composition of Al4SiC4 can be left unchanged. Therefore, Al4SiC4 powder that is substantially free of Al4C3 can be produced from Al4SiC4 powder that contains Al4C3. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows the mineral composition of Al4SiC4 powder before heating. [Figure 2] FIG. 1 shows the mineral composition of Al4SiC4 powder after heating. [Figure 3] 1 is a graph showing the relationship between the heating temperature and the ratio IAl4C3 / IAl4SiC4·IAl2O3 / IAl4SiC4. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the Al4SiC4 powder and its manufacturing method of the present invention will be described in detail with reference to the accompanying drawings. However, the Al4SiC4 powder and its manufacturing method of the present invention can be embodied in various forms and are not limited to the embodiments described herein. The present embodiments are provided with the intention of enabling those skilled in the art to fully understand the invention by fully disclosing the specification. (Al4SiC4 powder)

[0013] The Al4SiC4 powder of this embodiment is substantially free of Al4C3. This can be seen from the integrated intensity I of the peak attributable to Al4C3 at around 2θ = 55.1° measured by powder X-ray diffraction. Al4C3 (cps / deg) and the integrated intensity of the peak due to Al4SiC4 around 2θ=56.0° I Al4SiC4 (cps / deg) Al4C3 / I Al4SiC4 It is determined by calculating the ratio I Al4C3 / I Al4SiC4 is 0.1% or less, preferably 0.05% or less, more preferably 0.01%, and even more preferably, a diffraction peak due to Al4C3 near 2θ=55.1° is not observed.

[0014] When Al4C3-containing Al4SiC4 powder is added to a refractory, the Al4C3 is hydrated and expands in volume, impairing the shape stability of the refractory. Al4C3 / I Al4SiC4 to 0.1% or less.

[0015] Of the information obtained from powder X-ray diffraction, the area occupied by the waveform of the diffraction peak is the integrated intensity. The integrated intensity is the product of the diffraction angle of the sample in the powder and the geometric probability of the existence of a certain crystal grain (peak height). By calculating the ratio of the integrated intensities, it is possible to quantitatively evaluate the probability of the existence of a certain crystal grain. Here, the ratio of Al4C3 in Al4SiC4 powder can be quantitatively analyzed.

[0016] Powder X-ray diffraction was carried out under the following conditions. TIFF0007776961000001.tif121138

[0017] The powder X-ray diffraction using CuKα radiation was performed using a RINT2000 manufactured by Rigaku Corporation. The measured diffraction intensity was plotted on a graph with the X-ray incident angle 2θ (°) on the horizontal axis and the diffraction intensity (cps) on the vertical axis. The integrated intensity (cps·deg) was calculated using the "PDXL" integrated powder X-ray analysis software version 2.7.3.0 manufactured by Rigaku Corporation.

[0018] Furthermore, the color space (L*, a*, b*) of the Al4SiC4 powder of this embodiment is within any of the following ranges: (22-29, 11-14, 12-20), (16-26, 12-13, 20-23), (0-5, 0-2, -4-0), or (2-15, 0-2, -4-0). The reason why the color space is within the above ranges will be described later in [Examples]. The color space (L*, a*, b*) of the Al4SiC4 powder of this embodiment is clearly distinguishable from the color space (L*, a*, b*) of conventional Al4SiC4 powder synthesized so as not to produce Al4C3.

[0019] The color space (L*, a*, b*) is a type of color system used to represent the color of an object, and was standardized by the International Commission on Illumination (CIE) in 1976. It is also standardized in Japan as JIS Z 8781-4:2013.

[0020] To measure the color space (L*, a*, b*), a sample was prepared by leveling the Al4SiC4 powder in a 10 cc container and smoothing the surface. The color space (L*, a*, b*) was then measured at any point on the powder surface of the sample. The color space (L*, a*, b*) at any point within the above-mentioned range is within the scope of the present invention. The measurement method conformed to JIS Z 8722:2009. The color space (L*, a*, b*) was measured under a D65 light source at a viewing angle of 10° using a color difference meter (color analyzer, TC-8600A, manufactured by Tokyo Denshoku Co., Ltd.).

[0021] The Al4SiC4 powder of this embodiment is preferably substantially free of Al2O3. This can be seen from the peak integrated intensity I Al2O3 (cps / deg) and the integrated intensity of the peak due to Al4SiC4 around 2θ=31.7° I Al4SiC4 (cps / deg) Al2O3 / I Al4SiC4 It is determined by calculating the ratio I Al2O3 / I Al4SiC4 is 0.1% or less, preferably 0.05% or less, and more preferably, a diffraction peak caused by Al2O3 near 35.1° is not observed.

[0022] When Al2O3-containing Al4SiC4 powder is added to a refractory, there is a problem that the fine particles of Al2O3 affect the structure of the refractory, such as the bulk density and porosity of the refractory. Al2O3 / I Al4SiC4 It is desirable to keep it below 0.1%.

[0023] Furthermore, the Al4SiC4 powder of this embodiment desirably has a large crystallite size. The crystallite size is 1000 to 1500 Å, more preferably 1100 to 1500 Å, and even more preferably 1100 to 1450 Å. A large crystallite size indicates that the crystal morphology has grown. Al4SiC4 particles with a large crystallite size have enhanced hydration resistance. Therefore, the functionality in the refractory structure is less likely to be reduced. On the other hand, if the crystallite size is too large, the functionality (reactivity with CO gas) will be reduced, so a crystallite size of 1000 to 1500 Å is optimal.

[0024] The crystallite size was determined by measuring the half-width of the (101) diffraction peak at around 2θ = 31.74° in powder X-ray diffraction and calculating it using the Scherrer formula. The crystallite size was calculated using the "PDXL" integrated powder X-ray analysis software version 2.7.3.0 manufactured by Rigaku Corporation. (Method for synthesizing Al4SiC4 powder)

[0025] An example of a method for synthesizing Al4SiC4 powder will be described.

[0026] The starting materials are an aluminum source, a silicon source, and a carbon source. The aluminum source can be metallic Al, aluminum oxide, or aluminum hydroxide. From the standpoints of purity and production efficiency, it is desirable to use metallic Al powder.

[0027] As the silicon source, metal silicon or silicon dioxide, etc., is used. Metal silicon powder is preferably used in terms of purity and production efficiency. Note that Al-Si alloy powder can also be used as the aluminum source and silicon source.

[0028] As the carbon source, flake graphite, artificial graphite, carbon black, etc. are used.

[0029] The aluminum source, silicon source, and carbon source are weighed in amounts such that the molar ratio of aluminum, silicon, and carbon contained therein is 4:1:4.

[0030] Next, the starting materials are mixed using a mixer such as a dry Henschel mixer, a dry ball mill, etc. The mixing time is not particularly limited, but it is desirable to mix for 5 minutes or more to thoroughly mix the materials.

[0031] Next, the resulting mixed raw material is loaded into a crucible, which is then placed in a furnace such as a tubular furnace or resistance heating furnace. The mixed raw material is heated in an argon gas stream at, for example, 1650°C to 1900°C for 1 to 10 hours. This results in the synthesis of Al4SiC4 powder. Al4SiC4 is synthesized in the following two stages. As the temperature rises with heating, Al4C3 and SiC are first produced as shown in equations (2) and (3). Then, at temperatures above 1300°C, Al4C3 and SiC react to produce Al4SiC4 as shown in equation (4). Because Al4C3 tends to remain after the reaction at temperatures below 1650°C and the rate of Al4SiC4 production increases significantly at temperatures above 1650°C, it is desirable to set the heating temperature to 1650°C or higher. 4Al+3C→Al4C3(2) Si+C→SiC (3) Al4C3+SiC→Al4SiC4(4)

[0032] After synthesis, the crucible is removed from the furnace, and the synthesized Al4SiC4 powder is taken out from the crucible and crushed in a crusher such as a roll crusher or a ball mill. (Method for producing Al4SiC4 powder according to this embodiment)

[0033] A method for producing Al4SiC4 powder of this embodiment will be described.

[0034] In the synthesis of Al4SiC4 powder, if the theoretical molar composition ratio of the starting materials is inappropriate or the heating temperature is insufficient, Al4C3 may be generated as an unreacted product. Al4C3 is highly susceptible to hydration, and adding Al4C3-containing Al4SiC4 powder to a refractory may cause the Al4C3 to hydrate and expand in volume, potentially impairing the dimensional stability of the refractory. For this reason, the method for producing Al4SiC4 powder of this embodiment converts Al4C3-containing Al4SiC4 powder into Al4SiC4 powder that is substantially free of Al4C3.

[0035] In the method for producing Al4SiC4 powder of this embodiment, first, Al4SiC4 powder containing Al4C3 is heated to 400°C to 1000°C in an air atmosphere. Specifically, the Al4SiC4 powder containing Al4C3 is filled into a crucible, and the crucible is placed in a furnace such as a tubular furnace or a resistance heating furnace, and heated to 400°C to 1000°C in an air atmosphere (RH (humidity) 20 to 90%). After reaching 400°C to 1000°C, the temperature is maintained for, for example, 1 to 10 hours, and then the temperature is lowered. Note that after reaching 400°C to 1000°C, the temperature may be lowered without maintaining the temperature. The rate of temperature increase and decrease is, for example, 5°C to 15°C / min.

[0036] When heated in an air atmosphere, Al4C3 reacts with water vapor in the air as shown in formula (5) or with oxygen in the air as shown in formula (6). As a result, Al4C3 decomposes and disappears. On the other hand, the composition of Al4SiC4 remains almost unchanged. Therefore, it is possible to produce Al4SiC4 powder that is substantially free of Al4C3. Al4C3+12H2O→4Al(OH)3+3CH4(5) Al4C3+6O2→2Al2O3+3CO2(6)

[0037] Here, Al2O3 in formula (6) is amorphous Al2O3. Al(OH)3 in formula (5) also changes to amorphous Al2O3. For this reason, even if the mineral composition of Al4SiC4 powder is analyzed by powder X-ray diffraction, Al2O3 will not be identified. Amorphous Al2O3 does not change to crystalline when heated again from 400°C to 1000°C after the above heating, and remains amorphous, so no problems arise.

[0038] The optimum heating temperature range is 400°C to 1000°C. At heating temperatures below 400°C, Al4C3 cannot be fully decomposed, whereas at temperatures above 400°C, Al4C3 can be completely eliminated. At heating temperatures above 1000°C, amorphous Al2O3 changes to crystalline Al2O3, which affects the mineral composition of the Al4SiC4 powder.

[0039] After the Al4C3-containing Al4SiC4 powder is heated as described above, the crucible is removed from the furnace, and Al4SiC4 powder substantially free of Al4C3 is taken out from the crucible.

[0040] In the method for producing Al4SiC4 powder according to this embodiment, the particle size of the Al4C3-containing Al4SiC4 powder is adjusted to 500 μm or less, preferably 250 μm or less, and more preferably 150 μm or less, before heating. The particle size adjustment is performed by pulverizing the Al4C3-containing Al4SiC4 powder using a pulverizer such as a roll crusher or ball mill, and then adjusting the particle size to 500 μm or less by dry sieving based on the sieving test method defined in JIS Z 8815:1994. If the particle size of the Al4C3-containing Al4SiC4 powder is larger than 500 μm, uneven heating occurs, preventing the Al4C3 from being completely removed. Note that if the particle size of the Al4C3-containing Al4SiC4 powder is 500 μm or less, particle size adjustment is not necessary.

[0041] In the method for producing Al4SiC4 powder according to this embodiment, it is desirable to analyze the mineral composition of the Al4SiC4 powder before and after heating using powder X-ray diffraction. Specifically, it is desirable to measure the Al4C3 content of the Al4SiC4 powder before and after heating. By measuring the Al4C3 content before heating, it is possible to know whether heating is necessary. Furthermore, by measuring the Al4C3 content after heating, it is possible to know whether Al4C3 has disappeared. To measure the Al4C3 content, the above-mentioned ratio I Al4C3 / I Al4SiC4 The Al4C3 content before heating is greater than 0.1% (for example, 4%), and the Al4C3 content after heating is 0.1% or less.

[0042] It is also desirable to measure the Al2O3 content of the Al4SiC4 powder after heating. By measuring the Al2O3 content, it is possible to know whether the amorphous Al2O3 has changed to crystalline Al2O3. To measure the Al2O3 content, the above-mentioned ratio I Al2O3 / I Al4SiC4 After heating, the Al2O3 content is 0.1% or less.

[0043] In the method for producing Al4SiC4 powder according to this embodiment, it is desirable to calculate the crystallite size of Al4SiC4 in the Al4SiC4 powder before and after heating using powder X-ray diffraction. The crystallite size can be calculated as described above. By calculating the crystallite size of Al4SiC4 before and after heating, it is possible to know whether the Al4SiC4 crystals have been affected by heating. [Example]

[0044] Metallic Al powder (-45μm), metallic Si powder (-45μm), and graphite (-75μm) were mixed in a theoretical molar ratio of Al:Si:C = 4:1:4 and mixed in a ball mill for 5 hours. The mixed raw materials were loaded into a carbon crucible and heated at 1700°C (heating rate 10°C / min) in an argon gas atmosphere for 5 hours to synthesize Al4SiC4 powder.

[0045] The synthesized Al4SiC4 powder was crushed using a roll crusher, and the mineral composition of the crushed Al4SiC4 powder was analyzed by powder X-ray diffraction.

[0046] Figure 1 shows the mineral composition of the Al4SiC4 powder before heating. Not only the Al4SiC4 peak but also the Al4C3 peak was confirmed, indicating that the Al4SiC4 powder also contained Al4C3, with an Al4C3 content of 4%. The crystallite size of the Al4SiC4 was 1143 Å.

[0047] Next, the Al4SiC4 powder containing Al4C3 was heated to 400°C in an air atmosphere at a heating rate of 10°C / min. After the furnace temperature reached 400°C, it was held at 400°C for 5 hours and then cooled at a rate of 10°C / min.

[0048] Figure 2 shows the mineral composition of the Al4SiC4 powder after heating. No peaks for Al4C3 were observed, and the ratio I Al4C3 / I Al4SiC4 The peak of Al2O3 was not observed. Al2O3 / I Al4SiC4The crystallite size was 1111 Å, and there was almost no change in the crystallite size before and after heating. There was also no aggregation of the Al4SiC4 powder.

[0049] The color space (L*, a*, b*) of the four points on the surface of the Al4SiC4 powder was (22,12,13), (22,11,20), (29,11,14), and (24,14,12), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the ranges of (22~29, 11~14, 12~20). [Example]

[0050] The heating temperature of the Al4C3-containing Al4SiC4 powder was set to 600° C. Except for this, the same method as in Example 1 was used to obtain Al4SiC4 powder that was substantially free of Al4C3.

[0051] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0, the ratio I Al2O3 / I Al4SiC4 The crystallite size was 1122 Å and the Al4SiC4 was single phase, and there was no agglomeration of the Al4SiC4 powder.

[0052] The color space (L*, a*, b*) of the four points on the surface of the Al4SiC4 powder was (26, 13, 23), (20, 12, 20), (16, 13, 20), and (21, 13, 22), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the ranges of (16~26, 12~13, 20~23). [Example]

[0053] The heating temperature of the Al4C3-containing Al4SiC4 powder was set to 800° C. Except for this, the same method as in Example 1 was used to obtain Al4SiC4 powder that was substantially free of Al4C3.

[0054] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0, the ratio I Al2O3 / I Al4SiC4The crystallite size was 1122 Å and the Al4SiC4 was single phase, and there was no agglomeration of the Al4SiC4 powder.

[0055] The color space (L*, a*, b*) of the four points on the surface of the Al4SiC4 powder was (5, 2, -4), (0, 0, 0), (1, 1, -2), and (0, 1, -2), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the ranges of (0~5, 0~2, -4~0). [Example]

[0056] The heating temperature of the Al4C3-containing Al4SiC4 powder was set to 1000° C. Except for this, the same method as in Example 1 was used to obtain Al4SiC4 powder that was substantially free of Al4C3.

[0057] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0, the ratio I Al2O3 / I Al4SiC4 The crystallite size was 1110 Å and the Al4SiC4 was single phase, with some agglomeration of the Al4SiC4 powder.

[0058] The color space (L*, a*, b*) of four points on the surface of the Al4SiC4 powder was (2,0,-1), (10,2,-4), (2,1,-3), and (15,0,0), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the range of (2~15,0~2,-4~0). (Comparative Example 1)

[0059] The heating temperature of the Al4SiC4 powder containing Al4C3 was set to 200° C. Except for this, the same method as in Example 1 was used to obtain the Al4SiC4 powder.

[0060] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0.04 (4%), ratio I Al2O3 / I Al4SiC4 The crystallite size was 1129 Å and the mineral phases were Al4SiC4 and Al4C3, and no aggregation of Al4SiC4 powder was observed.

[0061] The color space (L*, a*, b*) of four points on the surface of the Al4SiC4 powder was (18,16,19), (16,12,15), (11,14,15), and (21,14,16), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the ranges of (11~21, 12~16, 15~19). (Comparative Example 2)

[0062] The heating temperature of the Al4SiC4 powder containing Al4C3 was set to 300°C, and the holding time was set to 20 hours. Except for this, the same method as in Example 1 was used to obtain the Al4SiC4 powder.

[0063] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0.03 (3%), ratio I Al2O3 / I Al4SiC4 The crystallite size was 1118 Å and the mineral phases were Al4SiC4 and Al4C3, and there was no aggregation of Al4SiC4 powder.

[0064] The color space (L*, a*, b*) of the four points on the surface of the Al4SiC4 powder was (18, 16, 17), (20, 17, 15), (9, 14, 17), and (14, 14, 17), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the ranges of (9~20, 14~17, 15~17). (Comparative Example 3)

[0065] The heating temperature of the Al4SiC4 powder containing Al4C3 was set to 1100° C. Except for this, the same method as in Example 1 was used to obtain the Al4SiC4 powder.

[0066] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0, the ratio I Al2O3 / I Al4SiC4 The crystallite size was 1120 Å and the mineral phases were Al4SiC4 and Al2O3, with the presence of agglomerates of Al4SiC4 powder.

[0067] The color space (L*, a*, b*) of four points on the surface of the Al4SiC4 powder was (18,-3,-2), (5,0,-3), (0,-1,0), and (32,-1,0), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the range of (0~32,-3~0,-3~0). Comparative Example 4

[0068] The heating temperature of the Al4SiC4 powder containing Al4C3 was set to 1200° C. Except for this, the same method as in Example 1 was used to obtain the Al4SiC4 powder.

[0069] The ratio of the obtained Al4SiC4 powder I Al4C3 / I Al4SiC4 is 0, the ratio I Al2O3 / I Al4SiC4 The SiO2 content was 0.65 (65%) and the crystallite size was 1123 Å. The mineral phases were Al4SiC4, Al2O3, and mullite, with some aggregation of Al4SiC4 powder.

[0070] The color space (L*, a*, b*) of four points on the surface of the Al4SiC4 powder was (25,-1,-2), (5,0,-3), (20,0,-2), and (52,-3,0), and the ranges of the minimum and maximum values ​​of L*, a*, and b* were within the range of (0~52,-3~0,-3~0).

[0071] The above results are summarized in Tables 1 and 2. [Table 1] [Table 2] In addition, Fig. 3 shows the relationship between the heating temperature and the ratio I Al4C3 / I Al4SiC4 ·Comparison Al2O3 / I Al4SiC4 The relationship between is graphed. (Comparative Example 5)

[0072] Using the same synthesis method as in Example 1, Al4SiC4 powder was synthesized so as not to produce Al4C3, and the Al4SiC4 powder was pulverized and adjusted to a dry sieving particle size (defined in JIS Z 8815:1994) of 45-32 μm.

[0073] The color space (L*, a*, b*) of four points on the surface of the obtained Al4SiC4 powder was (27, 8, 32), (26, 8, 33), (25, 10, 31), and (23, 11, 33), which was within the range of (23-27, 8-11, 31-33). This was different from the range of the color space (L*, a*, b*) of this embodiment.

Claims

1. Al at around 2θ=55.1° measured by powder X-ray diffraction ４ C ３ The peak integrated intensity I due to Ａｌ４Ｃ３ (cps / deg) and Al around 2θ = 56.0° ４ SiC ４ The peak integrated intensity I due to Ａｌ４ＳｉＣ４ (cps / deg) ratio I Ａｌ４Ｃ３ / I Ａｌ４ＳｉＣ４ is 0.1% or less, The color space (L*, a*, b*) is within any of the ranges of (22 to 29, 11 to 14, 12 to 20), (16 to 26, 12 to 13, 20 to 23), (0 to 5, 0 to 2, -4 to 0), and (2 to 15, 0 to 2, -4 to 0). ４ SiC ４ powder.

2. Al at around 2θ=35.1° measured by powder X-ray diffraction ２ O ３ The peak integrated intensity I due to Ａｌ２Ｏ３ (cps / deg) and Al around 2θ = 31.7° ４ SiC ４ The peak integrated intensity I due to Ａｌ４ＳｉＣ４ (cps / deg) ratio I Ａｌ２Ｏ３ / I Ａｌ４ＳｉＣ４ 2. The Al according to claim 1, wherein the content of Al is 0.1% or less. ４ SiC ４ powder.

3. 3. The Al according to claim 1, wherein the crystallite size of the (101) plane at about 2θ=31.7° measured by powder X-ray diffraction is 1000 Å to 1500 Å. ４ SiC ４ powder.

4. The particle size of Al 4 SiC 4 powder containing Al 4 C 3 is adjusted to 500 μm or less, Al after particle size adjustment ４ C ３ Al containing ４ SiC ４ The powder is heated at 400 to 1000°C in an air atmosphere. ４ SiC ４ Powder manufacturing method.

5. Using powder X-ray diffraction, Al before and after heating ４ SiC ４ The Al powder according to claim 4, characterized in that the mineral composition of the powder is analyzed. ４ SiC ４ Powder manufacturing method.

6. Using powder X-ray diffraction, Al before and after heating ４ SiC ４ Powdered Al ４ SiC ４ 6. The Al according to claim 4 or 5, characterized in that the crystallite size of ４ SiC ４ Powder manufacturing method.

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