JPH0323278A - Whisker reinforced ceramic sintered body and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title sintered body having superior strength at high temp. at a low cost by incorporating a prescribed amt. of ceramic whiskers into a matrix composed of a specified compd. and Al2O3. CONSTITUTION:Ceramic whiskers, preferably whiskers of one or more among Al2O3, SiC and Si3N4 are incorporated into a matrix by 10-50vol.% and the matrix is composed of one or more kinds of compds. selected among boron carbide, the carbides and borides of the groups IVa, Va and VIa metals of the periodic table, e.g. TiC and Al2O3.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a high-density, high-strength RZ whisker-reinforced sintered body dispersion-strengthened by ceramic-based ivy whiskers. R4 high density is popular as a structural ceramic material including wear-resistant tool materials.
The present invention relates to a whisker-reinforced ceramic sintered body having high strength and toughness, and a method for manufacturing the same. [Prior Art] In recent years, ceramic materials are expected to be used as new structural materials due to their excellent heat resistance, wear resistance, and chemical stability. Among these, applications as materials for high-temperature structures such as gas turbines and automobile engine components are attracting particular attention, and research and development in this field is active. However, at present, three major problems remain to be solved when ceramic materials are widely applied for these purposes. One of them is that the target material is extremely difficult to sinter, which reflects the excellent mti properties of the target material at high temperatures. Another reason is that processing sintered materials is difficult. This difficulty in processing also reflects the high strength and hardness of the target material, and is an issue that cannot be dealt with beyond the properties of the material. This is due to its properties, but it is brittle, prone to sudden failure, and has low reliability as a material. Research has been actively conducted to overcome the difficulty of sintering of material powders intended for high-temperature structures.
A method has been adopted in which a second phase called a sintering aid, which has the role of assisting sintering, is added to the IliX material powder. However, these sintering aids produce a small amount of liquid phase during sintering, which helps sintering, but has the problem of degrading the high temperature strength of the sintered body, which is not preferable. Currently, improvements to the starting material powder and the search for new sintering methods are continuing. Next, the machinability of the ceramic material is determined by the collapsed f of ε.
It originates from mechanical sex buying. Although ceramic materials are generally brittle, they have high strength and hardness, and are often difficult to process.

Recently, high-purity, high-hardness diamond sintered bodies have been developed, and cutting processes using them have been attempted, but satisfactory results have not yet been obtained in terms of cutting performance and processing costs. Currently, it is mainly processed using expensive diamond grinding wheels, which contributes to high processing costs. As mentioned above, ceramic powders intended for high-temperature structural materials have general &:H sinterability, and even when using additives, sintering under pressure is used. This method is suitable for sintering materials with simple shapes such as flat plates and cylinders, but is it? lDo not pass through sintering of irregularly shaped items. For this reason, when molding actual parts from materials manufactured using this method, the machining allowance is large, which not only causes inefficiency, but also causes abnormally high processing costs. Therefore, in order to reduce the processing cost, which accounts for a large proportion of the product cost, there is a strong desire to develop a technology for manufacturing sintered bodies as close to the final part shape as possible. The brittleness of ceramic materials is essentially related to the chemical bonding of the atoms that make up the material. Many attempts have been made to improve this weakness, and some results have been achieved. However, the properties required of materials are becoming stricter by the minute, and new material design and development are essential to meet these requirements. One way to strengthen ceramic materials is! ! One method is to combine it with a metal material that has I-type deformability, and the other is a fracture strengthening method that uses a mixture of a second ceramic phase that increases the fracture energy or causes fracture. ．． The former method of compounding with metal components certainly improves the brittleness of the material. However, the strength of metals decreases significantly at high temperatures, so materials produced using this method cannot be used as materials for high-temperature structures. On the other hand, with Ceramic Ceramic Oku Tsuta composite, there is no worry of such deterioration, and it is a preferable method for manufacturing forest materials for high-temperature structures. The whisker-strengthening method of dispersing ceramic-based whiskers has a very good compounding effect, and is highly regarded as one of the ways to improve the toughness of ceramics.
It is the main focus. For example, U.S. Patent No. 4,543.34
Specification No. 5 states that silicon carbide (hereinafter S) is contained in the powder.
iC) An alumina sintered body in which whiskers are dispersed and a method for producing the same are described. In this patent, fracture toughness values (It l c) of 4.6 to 9.0 are obtained by partitioning 20 volume % SiC whiskers into alumina.
0 MPaJm, and it is stated that there was a remarkable effect of improving toughness. In this method, fine-grained alumina powder Reni-SiC whiskers are uniformly I.D. : Mix and press the molded product at 28 to 7014 Pa
A method of sintering by heating at 1,600 to 1,950°C while pressurizing is used. In addition to alumina, 3^1x (h-25IO2 and MgO -
There is also a whisker-reinforced sintered body using ^1211 as the matrix material. These 1tonox 4Afi. including alumina. Material is non-oxide ceramic material I1
It is an easier material to sinter than E, and has the advantage of being able to be sintered densely using the Ho-7F-Buinos method at a temperature where there is no fear of reaction with whiskers. However, on the other hand, there is a problem in that bending strength and creep properties decrease at temperatures above 1000°C. One m expected for whisker-reinforced ceramic sintered bodies
The essential tt characteristics are high-temperature characteristics that show little decrease in strength even at high temperatures of 1000°C or higher and are resistant to mechanical and thermal shocks. is strongly desired. The above-mentioned whisker-reinforced ceramic materials are manufactured using powder-song sintering process. In this method, consider shrinkage! From the viewpoint of homogeneous sintering and reduction of the processing cost of the sintered body, the density of the pre-sintered ceramic material before sintering is preferably high. When compacting powder, there is a problem in that the density of the compact cannot be increased using the normal mold shaping method because the high-strength, high-elasticity whiskers that break down impede the filling of ceramic powder particles. This phenomenon is the same in the heating stage during sintering, which inhibits the shrinkage of the matrix ceramic powder and makes densification difficult. At present, it is extremely difficult to densify ceramic powder, and a hot press method using high temperature and pressure is essential to obtain a densified, high-strength material.Using high pressure to densify ceramic powder is effective. However, the strength of the pot press mold at high temperature ε
Due to this, the limit is several tens of MPa. Therefore, a method of increasing the sintering temperature was considered. However,
In this case, the following two constraints also apply to this temperature. One is that in order to exhibit the effect of dispersion strengthening, the temperature must be low enough to prevent a chemical reaction between the whiskers and the ceramic, which is the 71 lix, and the other is that the matrix particles must be The temperature must be at a level that does not cause grain growth. The temperature range in which densification can be achieved while satisfying these temperature conditions is quite narrow for general ceramic materials.
There is a problem that Additionally, there was a drawback in terms of quality control, as it was difficult to obtain a sintered body with consistent properties under optimal conditions. In addition, as mentioned above, in the conventional manufacturing method, pressure of several tens of MPa is essential for C to promote its densification.
For this I had to use hot breath T-extraction. With this method, products with simple shapes can be manufactured relatively easily, but for example, turbine bolts, bolts, etc.
It was extremely difficult to directly sinter objects with irregular shapes such as nuts into a shape close to that shape. In order to make parts with such complex shapes, there was no other way than to process the vertical or cylindrical sintered bodies by time-consuming grinding, mainly using a diamond grindstone. [Problems to be solved by the invention] The conventional techniques described above had the following problems. Processing costs can account for up to 50% of the product cost, leading to further increases in the cost of whisker-reinforced ceramic materials and hindering the wider use of this type of superior material. This invention was made in view of the above circumstances, and aims to improve the drawbacks of the conventional manufacturing method described above while maintaining the excellent properties of whisker-reinforced ceramic materials, and to improve the quality of cutting tools and other products. The purpose of this study is to provide a method for manufacturing whisker-reinforced ceramic sintered bodies that have high density, high strength, and high toughness and are suitable for various structural materials. [Means for Solving Problem A] In order to combine the above objects, the present invention is as follows. As mentioned above, the whisker-reinforced ceramic sintered body using only the conventional oxide ceramic as a matrix has an I0
There was a problem in that the mechanical properties deteriorated significantly at high temperatures of 00°C or higher. In order to solve such problems, the inventors have been developing whisker-reinforced ceramic sintered bodies containing non-oxide ceramics as a matrix, which have better high-temperature properties than oxide ceramics. In the course of this research, the sintering of non-oxide ceramic powders such as carbides and borides without sintering aids was achieved using a hot press method at tens of MPa or an ultra-high pressure sintering method capable of generating high pressures of several GPa. It was found that sintering becomes even more difficult when whiskers are dispersed in this material. Rather than directly sintering the non-oxide ceramic and oxide ceramic that make up the matrix from their compound powders, the inventor uses an exothermic chemical reaction to synthesize and simultaneously sinter the compounds. As a result, we have discovered that dense whisker-containing oxide and non-oxide ceramic sintered bodies can be obtained using simple equipment and methods. In addition, by choosing a reaction involving metal aluminum as the exothermic chemical reaction, it was found that the mixed powder could be formed extremely easily, and defects such as cracks were less likely to occur even when compacted at high density. ．． Based on these two main findings, we have conducted intensive research with the aim of developing a whisker-reinforced ceramic sintered body with excellent high-temperature properties and a simple manufacturing method. As a result, first, oxide powder, aluminum powder, and non-metal powder, which are the raw materials for forming the matrix, are mixed uniformly through an exothermic chemical reaction. By uniformly splitting the mixed powder, adjusting the mixed powder, and then impact-compressing this mixed powder, it has a strength that can be cut.
After obtaining a molded body with a density of 90% or more, this molded body is cut into the required material shape taking into account sintering shrinkage, and this processed material, that is, a high-density molded body, is sintered under normal pressure. The inventors have discovered that a whisker-reinforced ceramic sintered body having a high density that closely approximates the final shape and excellent high-temperature properties can be obtained by sintering or, if necessary, by hot isostatic pressing MtA. It came to pass, that is,
This invention provides a method for producing a whisker-reinforced ceramic sintered body containing 10 to 50% by volume of ceramic whiskers, in which ceramic whiskers are added to ceramic whiskers 4a and 55 of the periodic table.
At least one of the oxides of Group A, 6A metals and the oxides of boron oxide, at least one of the nonmetals of carbon, boron, and carbide, and aluminum are uniformly mixed; After filling the mixed powder into a mold and impact-compressing the mixed powder to form a powder mold with a relative density of 90% or more (empty ratio of 10% or less), a part of the powder mold or By heating the whole, the powder body is sintered while igniting and advancing an exothermic reaction between at least one of the oxides, at least one of the nonmetals, and aluminum. The remaining matrix contains at least I fi of carbides, borides, carbides and boron carbides of metals of groups 4a, 5a and 6a of the periodic table.
The present invention provides a whisker-reinforced ceramic sintered body characterized by being made of alumina and alumina. In the amalgamation of certain ceramics, especially high-melting ceramics, the heat of formation of the compound from its constituent elements can be on the order of 10' Joule fJ/kg. This large heat of formation propagates through the raw material powder one after another, exciting and starting reactions one after another, and the reactions continue. For example, when synthesizing a mixed ceramic of titanium carbide (Tic) and alumina, titanium oxide (TIOz). Aluminum and carbon powders are uniformly mixed, and a heating wire such as tungsten is used to ignite and start the reaction from one end of the molded body.This reaction spreads throughout the molded body without external heating. A mixture of TIC and alumina can be synthesized. In some cases, sintering also occurs at the same time as this synthesis. This ceramic synthesis method does not require a special furnace for gathering purposes and is economical. This reaction is called a self-heating reaction or a self-combustion reaction due to its nature, and the former term will be used hereinafter. There are many known examples of high-melting point ceramics that can be synthesized by self-heating reactions, but in this invention, we specifically selected ceramics from groups 4g, 5g, and 6a of the periodic table from the viewpoint of easy deformability and easy sintering. A self-heating reaction takes place between at least one of metal oxides and boron oxide, at least one of carbon, boron, boron carbide, and aluminum. An example of this is the following source. I1 system components and their reactions can be listed. (1) 3TiO, + 4^1 + 3C → 3T
iC+ 2AI, 0, (2) 3CrJs + 8^1
+ 4G −” 2(:r3[:2+ 3^120,
(3) MoO3+ 2^1+8-4MoB+^1,0,
(4) 3TaO, + 4^1 + BaC = 2Ta
B. + TaC +2^l20, The temperature increase due to the self-heating reaction can be calculated by assuming that all of the heat of formation is used to raise the temperature of the product. For example, in the case of example (1) above, the heat of formation is approximately 3.5
ho5a, +/'Kg, and it can be seen that the salinity of the reaction system increases up to about 3250°C. In this case, this temperature is higher than the melting point of TiC, which is a raw material, and this indicates that a liquid phase appears during the reaction. Helps sintering this kind of ceramic which is sinterable! It plays an important role. Furthermore, the reaction rate of this self-heating reaction depends on the sample temperature at the time of ignition, but it is a fairly fast reaction reaching several centimeters per second to several tens of centimeters per second. In the conventional manufacturing method of whisker-containing ceramic sintered bodies, it is desirable to sinter the matrix at a high enough temperature to generate a liquid phase in that part, but the reaction between the whiskers and the matrix material at that point is desirable. This caused the problem that the mechanical properties of the resulting sintered body deteriorated. In this invention, sintering is carried out at a temperature higher than that which has been attempted in the past, but because the reaction rate here is fast, the high-temperature retention is difficult. , y time is extremely short, and the chemical reaction between the whisker and matrix material that would cause deterioration can be suppressed to a negligible level. On the other hand, the liquid phase generated in the area where the reaction is progressing surrounds the dispersed whiskers more uniformly than in the case of solid phase sintering, and as a result, the whiskers are mechanically held more firmly in the sintered body. It plays an essential role in creating a tissue that is capable of The present invention is characterized in that the matrix of the whisker-reinforced ceramic sintered body is composed of at least one of carbides, borides, carborides, and boron carbides of metals in groups 45a, 55a, and 6a of the periodic table, and alumina. However, this makes it possible to further improve the heat resistance of the matrix material. For example, the melting point of alumina is 2050°C, but Tic
．． The melting points of TaC are 3250°C and 3800°C, respectively.
There is also little decrease in strength at high temperatures. In addition, in the sintered body 71-Rix obtained by the method of the present invention, a structure is formed in which carbides and borides, which are reaction products, are separated into a high density of C in alumina, and these carbides, Borides have higher hardness and elastic modulus than alumina, and can act as dispersion-strengthening grains T. The above-mentioned I1 thermal properties improvement and decomposition strengthening effect due to the borides and carbides constituting the matrix together with alumina are effective only at temperatures below 1000°C, and even at higher temperatures. , which significantly contributes to the improvement of high-temperature strength and the improvement of kelev properties at high temperatures. In the case of normal powder compaction methods using molds, it is much more difficult to make ceramic powder with uniformly mixed and dispersed ceramic whiskers more dense than that of single ceramic powder for the reasons mentioned above. Se'j '4 containing 20 volume% SiC whiskers
When the powder is molded with a mold at about 2 ton/cm', the density of the compact that can be reached is at most 55% (4
5% pores). Therefore, in this case, l! In order to obtain a dense sintered body, it is necessary to densify the remaining 45% during sintering. However, in reality, as mentioned above, this densification during sintering is also inhibited by the dispersed ceramic whiskers, so densification is performed slowly under pressure at a higher temperature than in the case of ceramic powder alone. A method is adopted to do so. However, under normal pressures of several tens of MPa, sufficient densification does not occur, and in this case, a method of adding a small amount of auxiliary agent to aid sintering is also used. The sintering aid used here is also undesirable because it causes a decrease in the high temperature strength of the obtained sintered body. One way to solve the above-mentioned difficulties, including processing problems, is to use static and dynamic ultra-high pressure sintering technology that can utilize high pressures of several GPa to promote densification. The other method is to first create a high-density molded body using those same ultra-high pressure techniques, and then sinter the molded body without applying pressure. Among the former methods, the method using static ultra-high pressure technology requires large-scale and expensive equipment, and
The drawback is that it is difficult to operate. On the other hand, although the dynamic method is effective for densification and sintering of powder, it is not practical due to the problem of small and large cracks in the resulting sintered body.
Furthermore, what these two methods have in common is that they are easy to refine, but... 3LIt is extremely difficult to manufacture sintered bodies with irregular shapes, which increases the amount of processing required to make the final part, resulting in higher costs. On the other hand, in the latter method, the starting material is made into a high-density shaped body with enough strength to be cut before main sintering, and after being processed into the required shape, main sintering is carried out. The amount of processing when finishing parts can be kept to a minimum. Static high-pressure technology can also be used in this latter method, but this method has the aforementioned problems and is not practical. This invention first molds whisker-containing ceramic-based powder to a high density using dynamic ultra-high pressure, that is, street compression, and then cuts and sinters the shaped body to produce an inexpensive, high-density, high-density powder. The aim is to obtain a whisker-reinforced ceramic sintered body with high strength and toughness. Dense compacts can be made by using the ffilE pressure that is instantaneously generated due to the explosion of explosives or the collision of objects flying at high speed. With this method, it is difficult to achieve a density of M by ordinary mold molding.
High-strength ceramic powders such as IC and 51 mountains can be densified relatively easily. One of the characteristics of Zukegun compression is 10-6
It is capable of generating high pressures of several GPa to several + GPa in a short time of seconds, and this makes it possible to instantaneously densify high-strength ceramic powder to a relative density of over 90%. In particular, in this invention, by always using metal aluminum as the starting mixed powder C, it is easier to densify the powder, reach a high compact density at a low pressure level, and the resulting compact has no residue. This is extremely advantageous as it can suppress the occurrence of distortion and cracks. [Effect] Explain along with the effects. [Embodiment of the Invention] An embodiment of the invention will be described below with reference to the drawings. There are two ways to obtain a high-density compact by impact compression: using explosives and colliding high-speed projectiles fired with high-pressure gas. Regardless of which of these methods is used, it is important to collect the sample as a single lump without breaking it into pieces. Fortunately, this sample collection technology is progressing. Reference numeral 1 in FIG. 1 is a planar compressor that can be used in the method of this invention, and is composed of a lower part 2 and an upper part 3. 2A is a sample container having a sample chamber 2B filled with mixed powder 4 containing whiskers. An iron momentum trap 2C is placed outside of the sample container 2A to facilitate collection of the sample container 2A after impact treatment, and an iron momentum trap 2D is placed below it. The sample container 2A has a downward U-shaped cross section ii2A that is removably fitted into the bottom plate 2AI from above.
It consists of 2. The momentum trap 2C mainly absorbs the momentum in the side direction of the sample container, and the momentum trap 2D mainly absorbs the momentum in the downward direction of the sample container, and as a result, it facilitates the collection of the sample after impact treatment. be. Although it is not easy to homogeneously mix whiskers into the starting material powder for matrix composition with as little damage as possible, the $P precipitates are first made into a slurry state using a wet ball mill or stirrer C, and then blended. By mixing again using a ball mill or a stirrer, it is possible to reduce whisker breakage and achieve relatively uniform mixing. The state of dispersion of ceramic whiskers in the matrix is important because it greatly influences the properties of the obtained sintered body. It is desirable to fill the mixed powder into the sample container 2A as densely as possible, preferably at a relative density of 40% or more. In addition, a wide range of materials can be selected for the sample container 2A depending on the impact treatment conditions required to shape the target material, but iron, copper, brass, and stainless steel are suitable from a cost standpoint. The upper part 3 in Fig. 1 is the exploding part of this device, and the conical explosive lens 3A is ignited at its apex by the detonator 3B, and the combustion in the explosive lens 3A propagates downward in a plane. It is now possible to do so. Furthermore, the planar combustion is propagated to the candlestick 3C below, causing the explosive (planar combustion) and propagating downward. This collision generates a plane shock wave in the sample container, which is further propagated to the mixed powder 4, and the mixed powder is impact compressed and shaped. Due to the passage of the shock wave The pressure and temperature generated in the mixed powder area can be controlled mainly by the amount of explosive used and the filling rate of the mixed powder, and the duration can be controlled by the thickness of the flying plate shown in Figure 1. It can be changed by 3■
When an iron plate of about 2k18 collides with a sample container, the pressure duration is about 1.5 x 10-' seconds, which is extremely short. Further, in the method shown in FIG. 1, it is possible to relatively easily generate a temperature of up to 1500° C. and a pressure of up to 50 GPa at the same time in the sample portion.

Figure 2 is a vertical cross-sectional view showing one embodiment of a cylindrical compaction device 5 that can be used in the method of the present invention. 6 is an expulsion container, which has an outer cylinder 6A and an outer cylinder arranged above and below the outer cylinder. It is composed of an upper plate 6B and a lower plate 6C. 7 is a cylindrical sample container coaxially located at the center of the explosive container 6, and upper and lower plugs 7A, 7B are placed above and below it.
is provided. 4 is a mixed powder filled in a cylindrical sample container 7. This figure shows a state in which the explosive 3C is placed in contact with the cylindrical sample container 7 and the explosive 3C is detonated by the detonator 3B.
The in-situ roar wave propagates downward, and the accompanying detonation shock wave first shock-compresses the cylindrical sample container 7 inside the sample container 7 in the axial direction, and then the mixed powder 4 inside the container 7 is impact-compressed in the same way. It will be done. The pressure generated in the mixed powder 4 part can be adjusted by the type and amount of explosive used. Here, the outer cylinder 6A of the cylindrical sample container 7 and the explosive container 6
Materials that can be used include metal, paper, wood, and plastic. Further, the conical plug 7A located above the cylindrical sample container 7 can be made of metal or wood, and this part is detonated by the detonator 3B and causes a detonation wave that spreads in a spherical shape inside the explosive 3C. It plays the role of shaping this spherical spreading candle wave into a flat detonation wave before reaching the cylindrical sample container 7, and is essential for uniform impact compression of the sample. ．． The method of this invention aims to obtain a sintered body close to true density by heating a part or the whole of the whisker-containing molded body to ignite and start an exothermic reaction. For body cutting, the relative density of the compact before reaction ignition must be 90% or more. Although it depends on the proportion of metallic aluminum in the starting material for forming the matrix, a molded body with a relative density of less than 90% will not be sufficiently densified by sintering, and the desired sintered body will not be obtained. Furthermore, the strength of such sintered bodies is not high enough and cutting is difficult. The rj impact pressure required to convert a mixed powder containing 10 to 50% by volume of ceramic whiskers to a relative density of 90% or more -E is the f of the whiskers used. In addition to type and quantity,
It is determined by the amount of aluminum, and it is necessary to determine the optimal conditions for each combination of materials. Sintering of the high-density compact obtained by impact compression can be achieved by heating part or all of the compact under normal pressure to ignite and start an exothermic reaction, but more preferably under gas pressure. The exothermic reactions used in the method of this invention, which is sintering by reaction ignition under hydrostatic pressure using This is particularly useful in cases where shrinkage occurs and cannot be followed by pressureless sintering. When the degree of impact pressure is in a suitable range, the relative density is 9
A uniform molded product without cracks can be obtained at 0% or more. However, if the processing pressure exceeds the limit pressure determined by the combination of materials, seizure between powder particles, or intergranular bonding due to sintering, will occur, and as a result, large and small cracks will occur in the recovered rod. , undesirable. The range of impact pressure used in the method of the present invention is limited to a moderate pressure at which sintering does not occur during the impact treatment, or even if sintering does not occur, grain growth does not occur. On the other hand, if the pressure is too low, the mixed powder will not be able to become M1 dense to a relative density of 90% or more, and as mentioned above, the strength of the obtained compact will be low, and not only will it not be possible to cut it, but it will also become dense even after main sintering. As a result, a whisker-reinforced ceramic sintered body with high strength and toughness cannot be obtained. This invention will be explained in more detail with reference to Examples below. (Example 1) Titanium oxide powder with an average particle size of less than 1 μm, aluminum powder with an average particle size of 10 μm, and carbon black powder with an average particle size of less than 1 μm were mixed in a ratio of 3:43, and water was added. A slurry material for the matrix structure was made by mixing in a pole mill. Next, a volume ratio of 2
．． Silicon carbide whiskers (hereinafter referred to as SiC whiskers) with an average whisker diameter of 1 μm and an average length of 30 μm were weighed so that the whisker size was 1 μm, and water was also added thereto, stirred, and separated.
After making it into a muddy state, apply it to the above matrix 4ll.
The mixture was added to the raw material slurry and mixed in a ball mill for 1 hour. After drying this ball mill mixed powder, it was vacuum degassed and buried at 600°C to obtain the mixed powder of this example. This mixed powder was processed using a flat impact compression device as shown in the figure. Here, the mixed powder is added to sample N2B in Figure 1 with a relative density of approximately 6.
Iron is used as the material for the sample chamber 2B, which is filled to a concentration of 0%.
It was amm. Explosive speed 7.2 k days/S Joubon's data sheet was used as explosive 3C, and the thickness was 3.
．． A 2-weight iron plate was used. Here, the flying board speed shown in Table 1 is 0.2 to 2.0.
Molding and sintering tests were conducted at km/s. After impact treatment,
The sample container was collected, the iron part on the outside of the sample was removed by cutting, the sample was taken out, and the top and bottom surfaces were lightly polished with abrasive paper, and the appearance was observed. Next, the bulk densities of the recovered compacts were measured using the Archimedes method using water, and the relative density of the compacts was calculated. A cutting test was conducted on each molded body using a diamond sintered body as a cutting tool at a circumferential speed of approximately 35@/sin, and it was determined whether cutting was possible or not based on the degree of cracking and chipping. i Oh, tt. obtained at a flying speed of 2.0 km. As a result of X-ray diffraction, I1 has already undergone an exothermic reaction of about H at this point and is in a semi-sintered state.
Many laminar cracks had occurred. For this reason, cutting was also impossible. Next, each molded body was placed on a flat zirconia sintered body.
One end of the wire was heated and ignited by energizing an ignition jig (tungsten wire) to start the reaction. The reaction is 3
After 0 to 40 seconds, the relative density of the sintered body was measured after cooling, and one end of the sintered body was polished with a diamond rotary grindstone, mirror-finished, and then processed using the Vickers indentation method.
Fracture toughness values (hereinafter referred to as Kic values) were measured using a load of 20 kg. Next, using the same mirror-finished sample, the Vickers microhardness was measured under vacuum at a high temperature of 1200° C. using a load of 100 g. Table 1 summarizes the results obtained for the samples at each flying plate speed. At a flying plate speed of 0.2 ka/s, the appearance of the recovered sintered body was good with no cracks, but the density of the compact was low and the strength was not high enough to allow cutting. In this compact, the reaction could be initiated by heating with a tungsten wire, but the relative density of the obtained sintered compact was as low as 89%. As shown in Table 1, the compacts obtained at a plate speed of 0.5 to 1.5 km/s had no defects such as cracks in appearance, and the relative density of the compacts was 90%. % or more, and cutting processing was also possible. The sintered bodies of these samples reached a relative density of 97% or more, and K
The ic value was also approximately sMpaJ■, indicating that it had sufficiently high toughness. In addition, 12 of these sintered bodies
High 4 hardness at 00℃ is 1540~1820kg/■1
Met. Further, as a result of X-ray diffraction, the constituent phases other than whiskers in the sintered body obtained after the exothermic reaction were mainly alumina and titanium carbide (Tic). For comparison, a powder obtained by mixing 40% by volume of alumina of 1μ or less, 40% by volume of titanium carbide (TiC) of 1μ or less, and 20% by volume of SiC whiskers similar to those used in this example was prepared at 3011Pa. The same evaluation as above was carried out on a sample obtained by holding and sintering at 1900°C for 1 hour. As a result, the relative density of the sintered body was 92%, and the Kic value was 4. 1P a J @, and the high temperature hardness at 1200℃ is 12
101 kg/am2, both of which were inferior to the values of the sintered body produced by the method of this invention. Table 1 (37I02+ 3G+ 4^1) + lO volume deprivation S
IC whisker * O △ × No chipping or cracking Small chipping or pores on the outer periphery (Example 2) Tantalum oxide powder with an average particle size of 10μ or less, boron carbide powder with a particle size of 325 mesh or less, and an average particle size of 1Oμ1 The following aluminum powders were used in a molar ratio of 3:I:4 and tj
The slurry used as a raw material for matrix composition was obtained in the same manner as in Example 1. Next, the ceramic whisker component was weighed to give a volume ratio of 4.1 to the raw material for forming the matrix. Here, the average whisker diameter is 0,
A mixed whisker consisting of 50% by volume of 5μ-5 aspect ratio 200 nitrided ui whiskers and 50% by volume of alumina whiskers with an average whisker diameter of 3 (rva) and an average whisker length of 40μ was used. This whisker component was also used in Examples. After making it into a slurry state by the same method as in 1, it was added to the slurry of the raw material for matrix bridge precepts, mixed in a ball mill for another 1 hour, dried, vacuum degassed, buried in lA, and the mixed powder of this example was obtained. I got it.

This mixed @powder was blown using the same equipment and method as Example 1ε.
A molding test was conducted at a plate speed of 0.2 to 2.4 ks/s, and a sintering test was conducted.

Table 2 shows the results obtained under each condition. City! ! After treatment,
Samples were collected and evaluated in the same manner as in Example 1. The molded product obtained at a low flying plate speed of 0.2 ka+/s had a relative density of less than 90%, and cutting was impossible. On the other hand, the sample obtained at a plate speed of 2.4 kIl/s had many lamellar cracks, and X-ray diffraction analysis revealed that the reaction had already progressed to about 3/4 of the time during the impact treatment and sintering had occurred. I found out what happened. The samples obtained at flying plate speeds of 06 to 1.8 km/s were all densified to a relative density of 90% or more, and had the strength to be cut. These compacts were heated to I 000° C. for about 1 hour under normal pressure to ignite and start an exothermic reaction, and a sintered compact was obtained. As a result of X-ray diffraction, the constituent phases other than the whisker component of the obtained sintered body were alumina, tantalum carbide (Ta(:)), and tantalum boride [TaB,), all of which were over 96%!
l! density and Xic{a is also 7.8 ~ 8.9 MPaJs
reached. In addition, the high temperature microhardness at 1200℃ is...
The hardness was 0 to 1720 kg/m2, and high hardness was maintained.

Table 2 (3Ta02+ B, C + 4All+
(10 volumes of XSI384 whiskers + 10 volume of alumina whiskers) Small cracks and pores on the outer periphery (Example 3) Niobium oxide powder with an average particle size of 20 μ■ and an average particle size of 15 μ
Molybdenum oxide powder and average particle size of 1μ or less)
' Carbon black with a particle size of 1 μm or less and boron powder with a grain size of 1 μm or less were mixed in a molar ratio of 3 + 1 + 6 + 3: I, and
In the same manner as in Example 1, slurry as a raw material for constructing Malinks was obtained. Next (, 1 volume ratio for this matrix constituent raw material
1, whisker diameter 3μ, aspect ratio 2
0 alumina whiskers were weighed. This alumina whisker was made into a slurry state by the same method as in Example 1, and then added to the slurry of the raw material for forming the matrix, mixed in a ball mill, dried, and vacuum degassed. A mixed powder was obtained. This mixed powder was prepared in the same manner as in Example 1 using the planar impact compression apparatus shown in FIG. 1 at a flying plate speed of 0.1 to 1. 8k
■A molding test was conducted in the range of /S, and then a sintering test was conducted. The impact-treated ridge sample was evaluated in the same manner as in Example 1. Table 3 shows the results obtained under each condition. The sample obtained at a flying plate speed of 0.1 km/s was in good condition with no cracks, but was insufficiently densified and did not have the strength to be cut. On the other hand, many cracks occurred in the compact obtained at a flying speed of 1.8 km/s, and observation of the fracture surface revealed that an exothermic reaction had already occurred and sintering had occurred. Flying m@speed 0.4~I. The molded bodies obtained at Okm/s reached relative densities of 95% and 97%, respectively, and were good molded bodies. With respect to these compacts, an exothermic reaction was ignited and started in the same manner as in Example 1, and sintered compacts were obtained. The constituent phases of the obtained sintered body other than whiskers were niobium carbide, niobium boride, and alumina. In addition, the relative density reached 98% in both cases, and Kic{! are 7.2 MPa each
J m , 6.8 MPaJm, and the microhardness at 1200°C were l4δ[lkg/am2, 1420k, respectively.
g/1st in junior high school. No. 3 (3Nb02+ Mo03+ 6Al t alumina whiskers) Table + 3C+ 81 + (50 volume * O △ No chipping or cracking Small chipping or pores on the outer periphery (Example 4) Zirconium oxide powder and grains with a particle size of 2 Gμ or less Diameter 10
Aluminum powder with a particle diameter of less than 5 μm and boron carbide powder with an average particle size of 5 μm were mixed in a molar ratio of 3, 4, and 1, respectively. I got it. Next, a volume ratio of 8
．． 1, silicon nitride whiskers with an average whisker of 410.5μ and an average whisker length of 30μ were weighed, made into a slurry state in the same manner as in Example 1, and then mixed with the raw material for forming matrix 1a. The mixture was added to slurry, mixed in a ball mill, dried, and vacuum degassed to obtain the mixed powder of this example. This mixed powder was subjected to impact treatment using the cylindrical impact compression device shown in Figure 2. Here, a brass vibrator with an inner diameter of 20 ms and an outer diameter of 25 mm is used as the cylindrical sample container 7.
The length of the sample part was 100 D. In addition, a molding test was conducted using ampho explosive as the OI agent and with a thickness of 5 to 75 mm. After the impact treatment, the sample was collected, and after observing its appearance, a disk-shaped sample with a thickness of 5I1- was cut out from its axial center and its density was measured. In addition, in the cutting test, one end of the molded body was cut using a diamond tool as in Example 1, and the machinability was determined by cutting.
It was decided that it was not possible. The results are shown in Table 4, and at the explosive thickness of 5 cm, the densification was not sufficient and the strength was low. On the other hand, when the explosive thickness was 75 mm, cracks occurred in the sample and the relative density was as low as 89%. Explosive thickness 1
The relative density of the rods obtained from 0 to 75 im reached 90%;
Cutting was possible. A disk-shaped sample of these molded bodies was
It was heated to 1000°C for 1 hour in argon gas at MPa to ignite and start the reaction, and a sintered body was obtained. As a result of X-ray diffraction, the constituent phases of the obtained sintered body other than whiskers were found to be composed of zirconium carbide, zirconium boride, and alumina, and the relative density of the sintered body was approximately 100%.
It had reached . Also, the Kic value is 7.8 ~ 8.6M
PaJ@, and the high temperature hardness at 1200℃ is 1580 ~
It showed a high value of 1660. Table 4 f3ZrO, + 4AI + B. C)+
(10 volume tshNa u [car) × Cracks and pores generated [Effects of the invention] As described above, according to the method of the present invention, whisker-reinforced ceramic containing 10 to 50 volume % of ceramic whiskers can be formed by impact pressure. The starting raw material powder for the sintered body can be relatively easily densified to a relative density of 90% or more, and a rod-shaped body strong enough to be cut can be obtained. In the method of this invention, the remaining raw material powder for the matrix structure excluding the whiskers is a powder capable of causing a self-heating reaction, and a special There is no need for a high-temperature furnace, and by ignition at one end, the matrix becomes a carbide with excellent high-temperature strength.
A whisker-reinforced ceramic sintered body with improved high-temperature strength than borides and alumina can be obtained. In addition, in the method for manufacturing whisker-reinforced ceramic sintered bodies according to the present invention, shrinkage of the high-density compacts during the sintering process is extremely small, so processing costs after sintering can be significantly reduced, and the industrial It is of great significance.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing an embodiment of a planar impact compression device that can be used in the method for producing a whisker-reinforced ceramic sintered body of the present invention, and Fig. 2 is a longitudinal cross-sectional view showing an embodiment of a planar impact compression device that can be used in the method for producing a whisker-reinforced ceramic sintered body according to the present invention. This is a vertical cross-sectional view showing an example of a cylindrical street car compression device. Plane 'a' compression device, lower part, sample container, sample chamber, momentum trap, momentum trap, upper part, . Explosive lens. if tube, . Explosives, ． Flying board, . Mixed powder, cylinder ifi! [Compression device, 1. 2. 2A. 2B. 2 C 2 D 3 . 3A. 3 B 3C. 3D. 4. 5 6. 6A. 6 8 6C. 7. 7 A 7B. Explosive container, outer cylinder, upper plate 5 lower plate, cylindrical sample container, plug plug. Figure 2

Claims (4)

[Claims] 1. Contains 10-50% by volume of ceramic whiskers,
A whisker-reinforced ceramic sintered body characterized in that the remaining matrix is comprised of at least one of carbides, borides, and boron carbide of metals from groups 4a, 5a, and 6a of the periodic table, and aluminum oxide (hereinafter referred to as alumina). 2. The ceramic whiskers include at least one of alumina whiskers, silicon carbide whiskers, and silicon nitride whiskers.
The whisker-reinforced ceramic sintered body of claim 1 comprising seeds. 3. In a method for manufacturing a whisker-reinforced ceramic sintered body containing 10 to 50% by volume of ceramic whiskers, the ceramic whiskers include elements 4a, 5a, and 6a of the periodic table.
At least one member of the oxide group of group metals and boron oxide, at least one member of the non-metal group of carbon, boron, and boron carbide, and aluminum are uniformly mixed, and this mixed powder is By filling a mold and impact-compressing the mixed powder to form a powder compact with a relative density of 90% or more (porosity of 10% or less), by heating a part or the whole of the powder compact. , a whisker-reinforced ceramic characterized in that the powder compact is sintered while an exothermic reaction between at least one member of the oxide group, at least one member of the non-metal group, and aluminum is ignited and progresses. A method for producing a sintered body. 4. The ceramic whiskers include at least one of alumina whiskers, silicon carbide whiskers, and silicon nitride whiskers.
The method for producing a whisker-reinforced ceramic sintered body according to claim 3, wherein the whisker-reinforced ceramic sintered body comprises seeds.