JPH0611670B2 - Ceramic sintered body with composite structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a composite structure that can be applied from tool materials such as cutting tool materials and wear resistant tool materials to corrosion resistant materials or various mechanical parts and electrical parts. And a ceramics sintered body having

(Prior Art) It has been performed to increase the strength of materials by incorporating whiskers and fibers into conventional materials. Of these, whiskers are contained in the ceramic matrix. Many studies have been conducted on so-called fiber reinforced ceramics (FRC). Typical examples of this FRC are JP-A-61-174165 and JP-A-61-274803.

(Problems to be Solved by the Invention) Japanese Patent Laid-Open No. 174165/1986 discloses that 1 μm is contained in an alumina substrate.
Disclosed is an alumina-silicon carbide heat resistant composite sintered body in which 2 to 30% by volume of silicon carbide whiskers having the following diameter and a length of 20 μm or less are dispersed. In addition, JP-A-61-274803
The publication discloses a reinforced ceramic cutting tool in which 2 to 40% by volume of ceramic whiskers are dispersed in a ceramic matrix.

Of these two publications, the former is suggested to be significantly improved in bending strength and hardness at high temperature, and is expected to be expected to be significantly improved as a cutting tool tip, and the latter is actually used for a cutting tool, particularly metal. Although it is said that it has a remarkable effect as a cutting tool material for cutting the work material of
Since both of them are simply dispersed whiskers in the matrix, there is a problem that the cutting tool does not have a satisfactory life.

The present invention solves the above-mentioned problems, and specifically, a whisker dispersed phase obtained by dispersing whiskers in a ceramic matrix is a ceramic matrix phase containing no whiskers or a small amount of whiskers. It is an object of the present invention to provide a ceramics sintered body having a structure configuration surrounded by a ceramics matrix phase containing the above and achieving an improvement in cutting tool life.

(Means for Solving Problems) From the viewpoint of the strength of FRC, the present inventors prefer a larger content of whiskers, but, for example, SiC whiskers easily react with an iron group metal and reduce wear resistance. It is preferable to reduce the content as much as possible in the contradictory direction, and the whisker-containing ceramics having the strength and wear resistance capable of breaking through the contradictory directions, and particularly capable of being practically used as a cutting tool material. In order to improve the strength of FRC, the dispersion state of whiskers in the sintered body has a great effect.The dispersion of the whiskers in the matrix is more uniform than that in the sintered body. A densely mixed whisker phase was surrounded by a matrix phase or a roughly mixed whisker phase in the matrix. The present inventors have obtained the knowledge that the strength and wear resistance are remarkably improved and the life of the cutting tool is remarkably improved when the structure of the structure is changed. The present invention has been completed based on this finding.

That is, a ceramics sintered body having a composite structure of the present invention is a ceramics sintered body consisting of 10 to 60% by weight of whiskers, hard particles containing the remaining metal oxide as a main component, and unavoidable impurities. The ceramics sintered body contains a first phase in which first hard particles containing a metal oxide as a main component and whiskers are mixed, and a second hard particle or a second hard particle containing a metal oxide as a main component in the first phase. It is characterized in that it comprises a second phase containing whiskers that are poorer than the first phase, and that the first phase is surrounded by the second phase. is there.

The first phase in the ceramics sintered body having the composite structure of the present invention is a mixture of the first hard particles and the whiskers, and the details of the size and shape of this phase will be described in detail, but generally 10 to several. The metal oxide as the main component of the first hard particles includes, for example, aluminum oxide, zirconium oxide, chromium oxide, magnesium oxide, mullite (3Al). ₂ O ₃
・ 2SiO ₂ ), spinel (MgO ・ Al ₂ O ₃ ), zircon (ZrO ・ SiO
₄ ) and cordierite (2MgO ・ 2Al ₂ O ₃・ 5SiO ₂ ) as typical examples, silicon carbide whiskers, silicon nitride whiskers, titanium carbide whiskers, titanium nitride whiskers, boron carbide whiskers, boron nitride whiskers, and boron nitride whiskers are typical examples. Can be mentioned as. Of these, the first phase is 30
It is preferable that the content of silicon carbide whiskers is up to 60% by weight and the remaining first hard particles containing aluminum oxide as a main component because the strength is remarkably improved. When the first hard particles in the first phase consist only of aluminum oxide, the strength is remarkably improved.
When the content of at least one of hafnium oxide or rare earth metal oxide and at least one of these mutual solid solutions is 15% by weight or less and the balance is aluminum oxide, the promotion of sintering and the improvement of strength are remarkable, and Ti, V , Ta, Cr, Mo, W, Si carbides, nitrides, oxides, Zr, Hf carbides, nitrides, carbooxides, nitric oxides and at least one of these mutual solid solutions, up to 30% by weight And the balance of aluminum oxide, the wear resistance and the strength are remarkably improved, which is particularly preferable.

The second phase in the ceramic sintered body having the composite structure of the present invention becomes poorer than the second hard particles containing metal oxide as a main component, or the whisker content in the second hard particles and the first phase. Whiskers, specifically, for example, the first
It is a phase in which 50% or less, preferably 20% or less of the whisker content in the layer is mixed in the second hard particles.

The second hard particles in the second phase are, for example, specifically,
In the case of only aluminum oxide, in the case of at least one oxide of zirconium oxide, hafnium oxide or rare earth metal and 15% by weight or less and the rest aluminum oxide, or in the case of Ti, V, Nd, Ta, Cr, Mo. , W, Si carbides, nitrides, oxides, Zr, Hf carbides, nitrides, carbooxides, nitric oxides, and at least one of these mutual solid solutions from 30% by weight or less and the balance of aluminum oxide. Can be mentioned. The second hard particles are
The first hard particles may have the same composition component or may have different composition components.

The first phase and the second phase described above can be combined in various ways. For example, the first phase is a silicon carbide whisker 30.
-60% by weight and the remaining first hard particles of aluminum oxide, the second phase being a combination of second hard particles of aluminum oxide (containing a trace amount of silicon carbide whiskers), or the first phase being silicon carbide whiskers. 30-60% by weight, 15% by weight or less of at least one of zirconium oxide, hafnium oxide or oxides of rare earth metals and mutual solid solutions thereof, and 40-70% of the first aluminum oxide hard particles.
The second phase is a combination with second hard particles of aluminum oxide (containing a trace amount of silicon carbide whiskers), or the first phase is 30 to 60% by weight of silicon carbide whiskers, zirconium oxide, hafnium oxide. Or at least one of rare earth metal oxides and their mutual solid solutions.
The second phase consists of Ti, V, Nb, and T, and is composed of 15% by weight or less of the seed and 40 to 70% by weight of the first hard particles of aluminum oxide.
At least one of a, Cr, Mo, W, Si carbides, nitrides, oxides, Zr, Hf carbides, nitrides, carbonates, oxynitrides and mutual solid solutions thereof is set to 30% by weight or less. , In the case of the combination with the second hard particles of the remaining aluminum oxide (containing a trace amount of silicon carbide whiskers), especially promotion of sintering, suppression of grain growth, improvement of wear resistance, improvement of heat resistance and strength. It is preferable because the improvement becomes remarkable.

The first phase in the ceramics sintered body having the composite structure of the present invention is preferably oriented, for example, in a cross section in one direction, an elliptical battle and / or a circular shape of about 10 to several 100 μm. On the other hand, the cross section perpendicular to this cross section has a needle-like shape, a rod-like shape, or an elliptical shape. It is composed of a tissue in which the periphery of the first phase is surrounded by a continuous second phase having a width of about 5 to 20 μm.

When the content of whiskers in the ceramics sintered body having the composite structure of the present invention is less than 10% by weight, the effect of improving the strength by the whiskers is weak, and conversely, when the content of whiskers exceeds 60% by weight and increases, It is difficult to sinter, and it becomes difficult to obtain a dense sintered body, resulting in a decrease in strength. For this reason, the whiskers contained in the sintered body of the present invention are defined as 10 to 60% by weight.

The ceramic sintered body having the composite structure of the present invention can be obtained by applying the conventional method of manufacturing powder metallurgy, but it is particularly important to granulate the compound having the first phase as a compound. Then, it is preferable to mix the granulated powder with the powder of the composition component to be the second phase, and then form and sinter. Of these, the size, shape, and hardness of the granulated powder for forming the first phase influences the size and shape of the first phase when it actually becomes a crystal, and therefore becomes important. It is a thing.

(Operation) The ceramic sintered body having the composite structure of the present invention is the first
The phase contributes to the improvement of strength as a seed, and particularly when the first phase contains at least one kind of oxides of zirconium oxide, hafnium oxide or a rare earth metal, it has an effect of enhancing the promotion of sintering. Therefore, the second phase mainly contributes to the improvement of wear resistance, and especially Ti, V, Nb, Ta, Cr and M are contained in the second phase.
o, W, Si carbide, nitride, oxide, Zr, Hf carbide,
If it contains at least one of nitrides, carbonates, oxynitrides and their mutual solid solutions, atomization,
It contributes to higher hardness and wear resistance, and it is possible to make the second phase continuous by surrounding the first phase with the second phase in combination with the first phase and the second phase. In addition to enhancing the heat resistance, the heat resistance and the oxidation resistance, it further enhances the strength.

(Example) Example 1 Starting with Al ₂ O ₃ powder having an average particle size of 0.5 μm and SiC whiskers [described as SiC (W)] having an average diameter of 0.5 μm and an average length of 20 μm, first of all, The composition components shown in Table 1 as the granules for forming the first phase were wet mixed by a ball mill using alumina balls (the ratio of the compounding components and the balls was 1: 1). After this mixture was dried, 3% paraffin wax was added, granulated by a rolling method, and then sieved to obtain a granulated powder for forming a first phase of -60 to +325 mesh. The composition components shown as the granules for forming the second phase in Table 1 were additionally added to the granulated powder for forming the first phase and mixed by a V blender to obtain a mixture. This mixture is filled in a carbon mold, and 50 × by hot pressing by Ar atmosphere, 500 kg / cm ² pressure, 1850 ° C.-1 hour holding.
A sintered body having a size of 50 × 6 mm ² was obtained. Each of the sintered products of the invention products 1 to 11 and comparative products 1 to 6 thus obtained was cut into a predetermined shape, and the structure of each material was observed with a metallographic microscope. The invention products 1 to 11 and the invention product. The comparative products 5 and 6 that are out of the range have a cross-sectional structure perpendicular to the press pressure direction of the hot press (first
(Fig.) Is a composite structure consisting of a circular battle-elliptical first phase of about 50 to 150 μm consisting of high content whiskers, and a continuous second phase surrounding this first phase. Is a composite structure consisting of a needle-like or rod-like first phase made of high-content whiskers and a continuous second phase surrounding the first phase. It was On the other hand, Comparative Products 1 to 4 corresponding to the conventional products had a uniform single-phase structure throughout the cross sections parallel and perpendicular to the pressing direction.

The composition components of the first phase and the second phase of the invention products 1 to 11 and the comparative products 5 and 6 thus obtained were observed by a metallographic microscope, SEM observation, E
When examined by PMA analysis, it was found that the blended compositional components shown in Table 1 were contained, and particularly that the second phase contained about 5% by weight of silicon carbide whiskers. The products 1 to 11 of the present invention and the comparative products 1 to 6 are SNG 120408 (pre-honing 0.1
5mm x -25 °) tip, work material: Waspaloy, cutting speed: 150m / min, depth of cut: 1.0mm, feed: 0.1
Cutting was performed under the conditions of mm / rev and wet cutting until the chip was chipped or chipped, and the cutting time at that time was obtained and is also shown in Table 1.

Example 2 Al ₂ O ₃ powder used in Example 1, SiC (W) and an average particle size of 0.5
Using a ZrO ₂ (containing ₃ mol% Y ₂ O ₃ solid solution) powder of μm as a starting material, the first phase-forming granules shown in Table 2 were ball-mill wet-mixed and granulated in the same manner as in Example 1. Separately, the second layer forming powder shown in Table 2 was ball-mill wet mixed, and then the first phase forming granulated powder and the second layer forming powder were mixed in the V blender as in Example 1 to obtain a mixture. . This mixture was hot-pressed in an Ar atmosphere at a pressure of 200 to 500 kgf / cm ² at a temperature of 1700 to 1850 ° C. for 1 hour to obtain a sintered body. The structures of the sintered bodies of the inventive products 12 to 21 and the comparative products 7 to 9 thus obtained were confirmed in the same manner as in Example 1, and a cutting test was conducted under the same conditions as in Example 1, and the results are shown in Table 2. Also described in.

Example 3 Al ₂ O ₃ powder used in Example 1, SiC (W) and average particle size 0.5 μ
Using the TiC powder of m as a starting material, each sample composed of the composition components shown in Table 3 was processed in the same manner as in Example 1 to obtain sintered bodies of the inventions 22 to 31 and comparative products 10 to 12. . The structures of these sintered bodies were confirmed in the same manner as in Example 1, and the hardness was measured with a Vickers hardness tester. As for the products 22 to 31, the first phase was about 2400 to 2600 Hv and the second phase was 1900. The average hardness was about 2250 to 2350 Hv at 2,000 Hv, whereas the hardness of the comparative product 12 was about 2300 Hv and almost uniform.

Next, the present invention products 21 to 29 and the comparative products 10 to 12 were subjected to a cutting test under the same conditions as in Example 1, and the results are also shown in Table 3.

Example 4 Using the starting materials used in Examples 2 and 3, 38 wt% A
l ₂ O ₃ -60wt% SiC (W) -8wt% ZrO ₂ granulated powder and 70wt% Al ₂
A granulated powder of O ₃ -30 wt% TiC was prepared in the same manner as in Example 1, and then each granulated powder was mixed at 1: 1 with a V blender to obtain a mixture. This mixture is put under pressure of 200 kgf / cm ² , 1700
Hot pressing was performed at a temperature of ℃ for 1 hour. When the product 32 of the present invention thus obtained was examined in the same manner as in Example 1, the relative density 1
00%, average hardness 2300Hv, microstructure of sintered body is approximately 38wt% Al ₂
O ₃ -60wt% SiC (W) -8wt% ZrO ₂ 1st phase and 70wt% Al ₂ O ₃
-30 wt% TiC [containing approximately 5 wt% SiC (W)].

Next, a cutting test was carried out under the same conditions as in Example 1, and the cutting time (life time) until chipping at that time was obtained.
It was 30 minutes.

(Effect of the invention) The ceramic sintered body having the composite structure of the present invention is a ceramic sintered body having a single-phase structure in which conventional whiskers are uniformly dispersed and a ceramic sintered body outside the scope of the present invention. Compared with this, it is superior in wear resistance and fracture resistance, and as a result, when it is used as a cutting tool, there is a remarkable effect that the life is improved by about 1.6 to 7.8 times. From this, the ceramic sintered body having the composite structure of the present invention,
Applications or shapes that could not be put to practical use due to lack of strength from cutting tool materials, tool materials such as wear-resistant materials, corrosion-resistant materials, mechanical part materials and electrical part materials that used conventional ceramics sintered bodies It is an industrially useful material that can be put to practical use.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the structure outside of the ceramic sintered body of the present invention obtained in Example 1 in a cross section perpendicular to the pressing direction. FIG. 2 is a schematic diagram of the structure of the ceramic sintered body of the present invention obtained in Example 1 in a cross section parallel to the press pressure direction. In the figure, 1 indicates the first phase and 2 indicates the second phase.

Claims (7)

[Claims] 1. A ceramic sintered body comprising 10 to 60% by weight of whiskers, hard particles containing the remaining metal oxide as a main component, and unavoidable impurities. The ceramic sintered body contains a metal oxide as a main component. A first phase in which the first hard particles and whiskers are mixed, and second hard particles containing a metal oxide as a main component or whiskers formed in the second hard particles as compared with the first phase. A ceramic sintered body having a composite structure, characterized in that the second phase is contained, and the first phase is surrounded by the second phase. 2. A silicon carbide whisker from the first phase as described above.
A ceramic sintered body having a composite structure according to claim 1, characterized in that it comprises -60% by weight and the first hard particles containing aluminum oxide as a main component. 3. A silicon carbide whisker from the first phase as described above.
2. 60% by weight and the remaining first hard particles containing aluminum oxide as a main component, and the second phase is second hard particles of aluminum oxide. A ceramic sintered body having a composite structure of 4. A silicon carbide whisker from the first phase as described above.
-60% by weight, 15% by weight or less of at least one of zirconium oxide, hafnium oxide or rare earth metal oxides and mutual solid solutions thereof, and 40-70% by weight of the remaining first hard aluminum oxide particles. A ceramics sintered body having a composite structure according to claim 1, characterized in that 5. The silicon carbide whiskers are used as the first phase in an amount of 30 to 30.
60% by weight, 15% by weight or less of at least one of zirconium oxide, hafnium oxide or rare earth metal oxides and mutual solid solutions thereof, and the first aluminum oxide
The ceramic sintered body having a composite structure according to claim 1, wherein the hard particles are 40 to 70% by weight and the second phase is the second hard particles of aluminum oxide. 6. The second phase comprises Ti, V, Nb, Ta, Cr, Mo,
W and Si carbides, nitrides, oxides, Zr and Hf carbides, nitrides, carbooxides, nitric oxides and at least one of these mutual solid solutions are contained in an amount of 30% by weight or less and the balance of aluminum oxide 2. A ceramic sintered body having a composite structure according to claim 1, which is composed of 2 hard particles. 7. The first phase comprises 30 to 30 silicon carbide whiskers.
60% by weight, 15% by weight or less of at least one kind of oxides of zirconium oxide, hafnium oxide or rare earth metal, and 40 to 70% by weight of the first hard particles of the remaining aluminum oxide, and Two phases are Ti, V, Nb, Ta, Cr,
Mo, W, Si carbides, nitrides, oxides, Zr, Hf carbides, nitrides, carbooxides, nitric oxides, and at least one of these mutual solid solutions, up to 30% by weight, and the balance aluminum oxide 2. The ceramic sintered body having the composite structure according to claim 1, wherein the sintered body has the second hard particle.