JP2012087042A - Titanium diboride-based sintered compact, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce production cost by lowering a sintering temperature furthermore, when producing a high-density and high-hardness titanium diboride-based sintered compact which is necessary for application to a structural member or the like.SOLUTION: A sintering aid containing as a main component, ALTi, or (Al, M)Ti wherein M is one or two or more kinds of combinations of Ni, Cr, Fe, Mo and Cu is used at the weight ratio of the sintering aid of ≥10% and ≤50%, and a sintering material which is mixed powder with a metal boride base component containing TiBas a main component is sintered at 1,000°C, and thereby a high-denseness and high-hardness titanium diboride-based sintered compact having Vickers hardness of ≥500 and bending strength of ≥200 MPa can be produced. By using the sintering aid containing (Al, M)Ti as the main component at the weight ratio of ≥20% and ≤40%, a high-denseness, high-hardness and high-strength titanium diboride-based sintered compact having Vickers hardness of ≥800 and bending strength of ≥300 MPa can be produced at the sintering temperature of 1,000°C.

Description

  The present invention relates to a titanium diboride-based sintered body and a method for producing the same, and particularly useful as various materials and structural members such as a high-temperature heat-resistant member, a wear-resistant member, or a member that requires electrical properties along with their physical properties. The present invention relates to a titanium diboride-based sintered body and a method for producing the same.

Titanium diboride (TiB ₂ ) is a ceramic that has excellent heat resistance, oxidation resistance, and high temperature strength, is conductive, and is abundant in resources. It is expected to be used in various fields of manufacturing technology such as members and mold materials that require electrical conductivity.

  However, titanium diboride is a hardly sintered material, and it is difficult to sinter a dense sintered body at a relatively low temperature. Therefore, as a method for obtaining a sintered body having high density, high hardness, and high wear resistance, at present, pressure sintering such as hot pressing at a high temperature of 1500 ° C. or higher, hot isostatic pressing sintering method, etc. The conclusion method is used. Thus, when sintering titanium diboride at a high temperature of 1500 ° C. or higher, the manufacturing cost of the sintered body increases. In order to suppress this high cost and facilitate manufacture, a method of sintering at a low temperature is used, and a search for a sintering aid therefor has been made.

Examples of sintering aids for titanium diboride include borides of iron group metals such as Co, Ni, and Fe (Patent Document 1), iron group metals such as Ni and Fe, and Ti, Hf, W, and Zr. A mixture of carbide (Patent Document 2), a mixture of Ni-Zr alloy powder and WC powder (Patent Document 3), a mixture of NiO, MnO and WC (Patent Document 4), Ni, WC and Cr ₃ C ₂ What has various component compositions, such as a mixture (patent document 5), is used. However, even if these sintering aids are used, it is necessary to perform sintering at a high temperature of 1500 ° C. or higher in order to obtain a sintered body having high hardness and high density.

Japanese Examined Patent Publication No. 56-41690 Japanese Patent Publication No. 7-822 Japanese Patent Laid-Open No. 9-3586 JP 2000-290744 A JP 2001-146474 A

  In order to sinter titanium diboride, which is a difficult-to-sinter material, into a sintered body with high density, high hardness, and high wear resistance, conventional sintering aids have been added and sintered. ing. As the sintering aid, borides of iron group metals, mixtures containing carbides of iron group metals, various alloy powders, etc. are used. In any case, the sintering temperature should be 1500 ° C. or higher. Inevitably, the manufacturing temperature is high because the sintering temperature is high.

  From this, in producing a titanium diboride-based sintered body, the titanium diboride sintering reactivity is increased, and in addition to the high density and high hardness required for applications such as structural members, high strength There has been a demand for lower production costs by synthesizing a titanium diboride sintered body at a sintering temperature as low as possible. Further, it has been demanded that the titanium diboride sintered body produced at such a relatively low sintering temperature has high hardness and high bending strength.

The present invention has been made to solve the above-mentioned problems, and the titanium diboride-based sintered body according to the present invention includes a metal boride basic component mainly composed of TiB ₂ and sintering as a sintering aid. Titanium diboride-based sintered body composed of auxiliary materials, Al ₃ Ti or (Al, M) ₃ Ti (M is selected from the group of Ni, Cr, Fe, Mo, Cu) The sintering aid is composed of 10% to 50% of the total weight, and the other part is composed of a hexagonal metal boride composed mainly of TiB ₂ It is. It is more preferable that the sintering aid containing (Al, M) ₃ Ti as a main component has a content of 20% to 40% of the total weight.

In addition, the method for producing a titanium diboride-based sintered body according to the present invention is obtained by sintering a mixture of a metal boride basic component mainly composed of TiB ₂ and a sintering aid as a sintering aid. A method for producing a titanium boride-based sintered body, in which Al ₃ Ti or M is combined with one or more of Ni, Cr, Fe, Mo, Cu, and (Al, M) ₃ Ti is used. A sintering aid powder body having a content of 10% or more and 50% or less of the total weight as a main component and a hexagonal metal boride powder body having TiB ₂ as a main component as a main component are prepared. And a mixture of the hexagonal metal boride powder body and the sintering aid powder produced respectively, and sintering the mixture of the hexagonal metal boride powder body and the sintering aid powder. It comprises heating to a temperature of 800 ° C. or higher and 1300 ° C. or lower in a body manufacturing apparatus to manufacture a sintered body. The sintering aid is a sintering aid powder body comprising (Al, M) ₃ Ti as a main component and having a content of 20% to 40% of the total weight, the hexagonal metal boride powder body It is more desirable to produce a sintered body by heating the mixture of the sintering aid powder to a temperature of 900 ° C. or higher and 1100 ° C. or lower in a sintered body producing apparatus.

In the present invention, a sintering aid containing Al ₃ Ti or (Al, M) ₃ Ti as a main component is used, and the weight ratio is 10% or more and 50% or less, so that the firing rate is much lower than that of the prior art. A sintered body can be produced at the sintering temperature. However, M represents an element selected from the group of Ni, Cr, Fe, Mo and Cu, and one or more elements are selected, and the molar ratio of M and Al is between 5/70 and 20/55, and is more desirable. Is between 5/70 and 15/60. Moreover, a sintered body is produced at a sintering temperature of 800 ° C. or higher and 1300 ° C. or lower by setting the polymerization ratio of the sintering aid mainly composed of (Al, M) ₃ Ti to 10% or more and 50% or less. be able to. In this way, the sintering temperature can be significantly reduced compared to the production of a conventional sintered body, and the obtained sintered body is a sintering aid mainly composed of (Al, M) ₃ Ti. Bending strength is 300 MPa or more when the weight ratio is 10% or more and 50% or less, and bending strength is 20% or more and 40% or less when the weight ratio of the sintering aid mainly composed of (Al, M) ₃ Ti is used. Is 500 MPa or more, and a high-density, high-strength sintered body is obtained. Thereby, the manufacturing cost can be significantly reduced, and the application can be expanded.

FIG. 1 is a view schematically showing a configuration of a discharge plasma sintered body manufacturing apparatus for sintering a mixed powder of sintered materials. FIG. 2 shows the Vickers hardness of a sample obtained by sintering a sintered material of TiB ₂ -Al ₃ Ti mixed powder with varying weight ratio of Al ₃ Ti at a temperature of 1000 ° C. by a discharge plasma sintering method. It is a graph. FIG. 3 is obtained by sintering a sintered material of TiB _2- (Al, M) ₃ Ti mixed powder in which the weight ratio of (Al, M) ₃ Ti is changed at a temperature of 1000 ° C. by a discharge plasma sintering method. FIG. 3A is a graph showing the Vickers hardness of the obtained sample, FIG. 3A shows the case where M is Ni, FIG. 3B shows the case where M is Cr, and the number of moles of (Al + M) is 75 moles. It was measured for five types of samples with the number of moles of M being 0, 5, 10, 15, and 20. FIG. 4 shows the sintering temperature and the Vickers temperature of the sample obtained when the sintered material of TiB ₂ -Al ₃ Ti mixed powder is sintered by the discharge plasma sintering method with the Al ₃ Ti weight ratio being 30%. It is a graph which shows the relationship. Figure 5 _{is, (Al, M) 3 TiB} 2 having different weight percentage of Ti - (Al, M) is obtained by sintering at a temperature 1000 ° C. The sintering material ₃ Ti powder mixture Spark Plasma Sintering 5A is a graph showing the bending strength of a sample, FIG. 5A shows the case where M is Ni, FIG. 5B shows the case where M is Cr, and the number of moles of (Al + M) is 75 moles. Measured with respect to five types of samples in which the number of moles of M is 0, 5, 10, 15, and 20. FIG. 6A is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered materials at 1000 ° C. by a discharge plasma sintering method. The sintered material is not added with Al ₃ Ti. In the case of TiB ₂ only. FIG. 6B is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered material at 1000 ° C. by a discharge plasma sintering method. The sintered material is TiB ₂ and Al ₃ Ti. Is 5% by weight. FIG. 6C is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered materials at 1000 ° C. by a discharge plasma sintering method. The sintered material is TiB ₂ and Al ₃ Ti. Is 20% by weight. FIG. 6D is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered materials at 1000 ° C. by a discharge plasma sintering method. The sintered material is TiB ₂ and Al ₃ Ti. Is 30% by weight. FIG. 6 (e) is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered material at 1000 ° C. by a discharge plasma sintering method. The sintered material is TiB ₂ (Al, Ni) ₃ Ti is added 30% (Al: Ni molar ratio is 65:10). FIG. 6F is an SEM image of the surface of a sample prepared by sintering a mixed powder of sintered materials at 1000 ° C. by a discharge plasma sintering method. The sintered material is TiB ₂ (Al, This is the case when 30% of Cr) ₃ Ti is added (the molar ratio of Al to Cr is 65:10). FIG. 7 shows that the sintered material of TiB ₂ -Al ₃ Ti mixed powder is sintered at a sintering temperature of 1000 ° C. by the discharge plasma sintering method, changing the weight ratio of Al ₃ Ti in the range of 5% to 60%. It is the X-ray diffraction spectrum of the surface of the sample obtained by the above. FIG. 8 shows a sintered material of TiB ₂ -Al ₃ Ti mixed powder in which the weight ratio of Al ₃ Ti is changed in the range of 5% to 60%, and sintered at a sintering temperature of 1000 ° C. by the discharge plasma sintering method. 2 is an X-ray diffraction spectrum of a cross section of a sample obtained in this manner. FIG. 9 is an X-ray diffraction spectrum of a sample obtained by sintering 70% TiB ₂ -30% (Al, M) ₃ Ti mixed powder by a spark plasma sintering method at a sintering temperature of 1000 ° C. (A) is the case where M is Ni and (b) is the case where M is Cr.

The titanium diboride-based sintered body according to the present invention is prepared by mixing a TiB ₂ powder with an Al ₃ Ti powder or (Al, M) ₃ Ti as a sintering aid, and preparing a sintered material. It is produced by sintering powder in a sintered material sintered body producing apparatus. M is an element selected from the group consisting of Ni, Cr, Fe, Mo, and Cu, and more preferably Ni or Cr. TiB ₂ powder is a commercially available powder (average particle size 4 to 12 μm), Al ₃ Ti powder is prepared by mixing Al powder and Ti powder and heating and reacting in an electric furnace. M) ₃ Ti powder is made by mixing Al powder, Ti powder and M powder and heating and reacting them in an electric furnace. Since it is difficult to obtain a Ti powder having a particle size of 10 μm or less, Ti powder having a particle size of 10 μm or less is obtained by hydrogenating the Ti powder having a particle size of about 100 μm and then grinding it with a ball mill or the like. This can be mixed with a commercially available Al powder having a particle diameter of around 10 μm or Al powder and M powder and reacted by heating to obtain Al ₃ Ti powder or (Al, M) ₃ Ti.

To sinter mixed powder of TiB ₂ and Al ₃ Ti or (Al, M) ₃ Ti, the sintered material can be easily heated to about 1000 ° C in a short time or by pressure molding at room temperature. A method of heating and sintering in an electric furnace is preferably used, but other sintering methods may be used.

The content of sintering aid Al ₃ Ti or (Al, M) ₃ Ti should be in the range of 10-50%, and if the content of Al ₃ Ti or (Al, M) ₃ Ti is less than 10%, TiB ₂ This is because sintering does not proceed sufficiently and a sintered body with low hardness is obtained. Al ₃ Ti and (Al, M) ₃ Ti originally have a Vickers hardness of about 300 to 600, which is lower than TiB _2, and if the content of Al ₃ Ti or (Al, M) ₃ Ti is too high Since the hardness of the sintered body is lowered, the content of Al ₃ Ti or (Al, M) ₃ Ti should be 50% or less.

In the production of the titanium diboride-based sintered body according to the present invention, TiB ₂ is typical as the main component, but it may contain other hexagonal metal borides while mainly containing TiB _2. . Although as a sintering aid Al ₃ Ti or (Al, M) ₃ Ti is typical, Al ₃ Ti or (Al, M) ₃ while mainly Ti those containing other alloying ingredients It is good. The content of the sintering aid containing them is set to 10 to 50%. Further, as a sintering method, a discharge plasma sintering method, a method of pressure forming at room temperature, and heating and sintering in an electric furnace are typical, but in the present invention, a hot press sintering method, a reaction sintering method are used. Even if other sintering methods such as a sintering method are used, the sintering temperature can be lowered.

Examples will be described. The case where (Al, M) ₃ Ti is used will be described. However, when Al ₃ Ti is used, the same applies except that M is not included. In order to synthesize (Al, M) ₃ Ti, first, titanium powder having a particle size of 100 μm and a purity of 99.9% was hydrogenated, and then pulverized by ball milling after hydrogenation. Hydrogenation was performed by heating the Ti powder to 600 ° C. in an Ar: 20% hydrogen mixed gas. After hydrogenation, 10 g of the powder was put in an alumina container having a capacity of 1 liter, 500 g of an alumina ball having a diameter of 5 mm was added, and milling was performed by milling for 30 hours at a rotation speed of 20 revolutions per minute. By this process, titanium hydride powder having a particle size of several μm was obtained.

Next, the titanium hydride powder is mixed with Al powder having a purity of 99.9% and a particle size of 5 μm and M metal (M is Ni or Cr) having a purity of 99.9% and a particle size of 10 μm. (Al, M) ₃ Ti powder was synthesized by reacting at 1 ° C. for 1 hour. Further, (Al, M) ₃ Ti and TiB ₂ powder having a particle size of 5 μm and a purity of 99.9% were mixed in a predetermined ratio, and ball milling was performed. The (Al, M) ₃ Ti: TiB ₂ mixed powder thus produced was sintered by the discharge plasma sintering method.

FIG. 1 shows a spark plasma type sintered body preparation apparatus (SPS1050: manufactured by Sumitomo Coal Mining Co., Ltd.) for sintering Al ₃ Ti: TiB ₂ mixed powder or (Al, M) ₃ Ti: TiB ₂ mixed powder. ) Is a diagram showing the configuration of the cross section. Reference numeral 1 is a water-cooled vacuum chamber, and 2 is a pump device that is connected to the water-cooled vacuum chamber 1 and that uses a rotary pump and a mechanical booster pump to give an internal vacuum. An upper punch electrode 3 has an upper punch 4 on the tip side (inside the chamber). Reference numeral 5 denotes a lower electrode punch having a lower punch 6 on the tip side (inside the chamber).

  The upper punch 4 and the lower punch 6 are positioned so as to face each other with a space therebetween, and a cylindrical sintered die 7 is disposed so as to surround and cover the space between the punches. 6. The space surrounded by the sintering die 7 is filled with the mixed powder 10 of the sintering material. The inner diameter of the sintering die 7 of the used apparatus is 20 mm and the height is 40 mm. The sintered die 7 is filled with the mixed powder of the sintered material, and the sintered material is sandwiched between the upper punch 4 and the lower punch 6, and then the chamber is closed. The pump 2 exhausts the chamber. A stress load is applied by the lower part of the upper punch electrode 3 and the punch electrode 5 and a pulse voltage / current is applied to the mixed powder 10 of the sintered material through the upper punch 4 and the lower punch 6.

  In the discharge plasma type sintered compact manufacturing apparatus, the mixed powder can be sintered by rapidly raising the temperature to the sintering temperature by applying a large current in a stress load state. The rate of temperature increase is 100 ° C./min. After maintaining at a predetermined sintering temperature for 10 minutes and performing sintering, cooling is performed by furnace cooling. The degree of vacuum during sintering is evacuated to 50 Pa by a rotary pump and a mechanical booster pump, and the load stress during sintering is 20 Pa. In the implemented example, the sintered die 7 is filled with 5 g of a mixed powder of sintered material.

FIG. 2 shows a sample obtained by changing the Al ₃ Ti ratio (weight ratio) from 0% to 70%, and maintaining the sintering temperature at 1000 ° C. for 10 minutes by the spark plasma sintering method. The result of having measured Vickers hardness at room temperature about is shown. When no Al ₃ Ti is added, the sample has a Vickers hardness of 100, which is very low. This indicates that TiB ₂ is a hardly sinterable material and hardly sinters at 1000 ° C. It can be seen that when 5% Al ₃ Ti is added, the Vickers hardness is as high as 1000 or more, and the hardness is dramatically improved.

Furthermore, when the proportion of Al ₃ Ti is between 20% and 40%, a high value of Vickers hardness of 2000 or more is obtained, and when the proportion of Al ₃ Ti exceeds 50%, the Vickers hardness decreases and the proportion of Al ₃ Ti further increases. Then, the Vickers hardness gradually decreases. This is because the hardness decreases as the proportion of Al ₃ Ti having a Vickers hardness of 600 increases. Therefore, from the result of the Vickers hardness shown in FIG. 2, the present invention has a practically appropriate range of 5% to 50% as the weight ratio of Al ₃ Ti that can obtain a Vickers hardness of 1000 or more. It can be said that a range of 20% to 40% in which the hardness is about 2000 is a more desirable range.

In FIG. 3, the ratio (weight ratio) of (Al, M) ₃ Ti is changed from 0% to 50%, and is held by sintering at a sintering temperature of 1000 ° C. for 10 minutes by the spark plasma sintering method. The result of having measured the Vickers hardness at room temperature about the obtained sample is shown. (A) is the case where M is Ni and (b) is the case where M is Cr. When no (Al, M) ₃ Ti is added, the sample has a Vickers hardness of 100, which is very low. This indicates that TiB ₂ is a hardly sinterable material and hardly sinters at 1000 ° C. It can be seen that when 10% or more of (Al, M) ₃ Ti is added, the Vickers hardness shows a high value of 500 or more, and the hardness is drastically improved.

Furthermore, when the ratio of (Al, M) ₃ Ti is between 20% and 40%, a high value of Vickers hardness of 800 or more is obtained, and when (Al, M) ₃ Ti is 40% or more, the Vickers hardness decreases, As the proportion of (Al, M) ₃ Ti further increases, the Vickers hardness gradually decreases. This is because the hardness decreases as the proportion of (Al, M) ₃ Ti having a Vickers hardness of 200 to 300 increases. Therefore, from the results of the Vickers hardness shown in FIG. 2, in the present invention, a Vickers hardness of 500 or more is obtained, and the weight ratio of (Al, M) ₃ Ti is 10% or more and 50% or less in a practically appropriate range. Furthermore, it can be said that a range of 20% to 40% in which the Vickers hardness is about 800 is a more desirable range.

Fig. 4 shows the sintering temperature and the Vickers hardness of the resulting sintered body when a powder mixture containing Al ₃ Ti added to TiB ₂ at 30% by weight is sintered by the spark plasma sintering method. Shows the relationship. A high hardness material having a Vickers hardness of 1000 at a sintering temperature of 800 ° C. and a Vickers hardness of 2000 at a sintering temperature of 900 ° C. is obtained. Even if the sintering temperature is higher than 1000 ° C., no improvement is observed in terms of Vickers hardness. Therefore, in the present invention, as an actual sintering temperature, a sintered body having a Vickers hardness of 1000 is obtained, and an appropriate range is 800 ° C. or higher and 1300 ° C. or lower, which is lower than the conventional sintering temperature. It can be said that a range of 900 ° C. or higher and 1100 ° C. or lower at which a Vickers hardness of a certain degree is obtained is a more desirable range.

In FIG. 5, the ratio (weight ratio) of (Al, M) ₃ Ti is changed from 0% to 50%, and is held at a sintering temperature of 1000 ° C. for 10 minutes by the spark plasma sintering method. The result of having measured bending strength at room temperature about the obtained sample is shown. (A) is the case where M is Ni and (b) is the case where M is Cr. It can be seen that the bending strength of the sample in which Al ₃ Ti not containing M is added is 200 MPa, whereas the bending strength is improved in the sample in which a part of Al is replaced with M.

  Therefore, from the results of bending strength shown in FIG. 5, the addition of M so that the molar ratio of M and Al is from 5/70 to 20/55 improves the bending strength. In particular, the range where the molar ratio of M to Al is from 10/65 to 15/60 is a more desirable range.

FIG. 6 shows an SEM image of the surface of a sample prepared by sintering the mixed powder of the sintered material at 1000 ° C. by the discharge plasma sintering method. (A) is a case of a sample material obtained by sintering only TiB ₂ without adding Al ₃ Ti, and (b) is a case of a sintered material obtained by adding 5% by weight of Al ₃ Ti to TiB ₂ ( c) in the case of a sintered material obtained by adding 20% Al ₃ Ti in a weight ratio to the _{TiB 2, (d) TiB 30} 2 in the Al ₃ Ti in a weight ratio% added sample made in the case of the sintered material (E) is a SEM image of a sample sintered at 1000 ° C. by adding 30% (Al, Ni) ₃ Ti to TiB ₂ and sintered at 1000 ° C. The molar ratio of Al to Ni is 65:10, (f) is an SEM image of a sample sintered at 1000 ° C. by adding 30% of (Al, Cr) ₃ Ti to TiB ₂ , and the molar ratio of Al to Cr is 65:10.

In the sample in which only TiB ₂ is sintered without adding Al ₃ Ti in (a), TiB ₂ particles having a particle diameter of 5 μm before sintering are observed as they are. In contrast, observed region TiB ₂ is fused around (b) 5%, (c ) 20%, with (d) 30% sample plus Al ₃ Ti as is the TiB ₂ particles It can be seen that the sintering is progressing. Further, (e), of (f) (Al, M) in ₃ Ti added sample, observed region TiB ₂ is fused around the particle TiB _2, it can be seen that advanced sintering.

FIG. 7 shows the surface X-rays measured for a sample obtained by changing the Al ₃ Ti ratio (weight ratio) from 5% to 60% and holding and sintering at 1000 ° C. for 10 minutes by the discharge plasma sintering method. A diffraction spectrum is shown. In the figure, the peak with a downward arrow (↓) on the upper side is the TiB ₂ diffraction line. It can be seen that the surface is almost TiB ₂ even in a sample to which 60% Al ₃ Ti is added. The sample was polished with SiC abrasive paper to remove the graphite layer on the surface after sintering.

In FIG. 8, the sample obtained by changing the Al ₃ Ti ratio (weight ratio) from 5% to 60% and holding at 1000 ° C. for 10 minutes by the discharge plasma sintering method is cut with a cutting machine. The result of having measured the X-ray diffraction spectrum of the cross section is shown. In the figure, it can be seen that a sample to which 40% or more of Al ₃ Ti is added contains a large amount of Al ₃ Ti (peak marked with ▲) inside the sample.

In FIG. 9, the ratio (weight ratio) of (Al, M) ₃ Ti is added to TiB ₂ at 30%, the molar ratio of M to Al is 10/65, and the discharge plasma sintering method is performed at 1000 ° C. for 10 minutes. The X-ray diffraction spectrum measured about the sample obtained by hold | maintaining and sintering is shown. In (a), M is Ni, and in (b), M is Cr. The peak with a downward arrow (↓) on the upper side is the TiB ₂ diffraction line. Arrow (Al, M) ₃ peaks indicated as Ti cubic L1 ₂ type (Al, M) is a diffraction line ₃ Ti structure. 7, 8, and 9, the horizontal axis represents the rotation angle (degree) of the sample during diffraction line measurement, and the vertical axis represents the diffraction intensity.

According to the present invention, titanium diboride and Al ₃ Ti or M as one or a combination of two or more of Ni, Cr, Fe, Mo and Cu, and (Al, M) ₃ Ti as a sintering aid As a result, it is possible to obtain a sintered body having high hardness and high density even when sintered at 1000 ° C., which is overwhelmingly lower than the conventional sintering temperature. Further, when the sintering aid is (Al, M) ₃ Ti, the bending strength can be higher than that of Al ₃ Ti.

Al ₃ Ti has a high hardness, but has a brittle defect. In metal material science, the higher the symmetry of the crystal structure and the smaller the unit cell size, the easier the plastic deformation. Al ₃ Ti has a tetragonal crystal structure, but if a part of Al is replaced with a transition metal such as Ni, Cr, Fe, Mo, or Cu, the crystal structure changes to cubic, and the size of the crystal structure is almost 1 / 2 is known to be. The reason why the bending strength of the Al ₃ Ti-added TiB ₂ sintered body is lower than that in the case of (AL, M) ₃ Ti addition is considered to be due to the brittleness of Al ₃ Ti. Assuming that M is one or more combinations of Ni, Cr, Fe, Mo, and Cu, the sintered body of (Al, M) ₃ Ti-added TiB ₂ has a low temperature of 1000 ° C. as in the case of Al ₃ Ti addition. In addition to being sintered, a sintered body with high density and hardness is obtained, which is improved in terms of bending strength.

DESCRIPTION OF SYMBOLS 1 Water-cooled vacuum chamber 2 Pump apparatus 3 Upper punch electrode 4 Upper punch 5 Lower punch electrode 6 Lower punch 7 Sintering die 10 Mixed powder

Claims (4)

A titanium diboride-based sintered body comprising a basic component of a metal boride mainly composed of TiB ₂ and a sintering aid as a sintering aid, wherein Al ₃ Ti or M is Ni, Cr, Fe As a combination of one, two or more of Mo, Cu, the sintering aid mainly composed of (Al, M) ₃ Ti has a content of 10% to 50% of the total weight, and the other parts are A titanium diboride sintered body made of hexagonal metal boride containing TiB ₂ as a main component. 2. The titanium diboride-based sintered body according to claim 1, wherein the sintering aid mainly composed of (Al, M) ₃ Ti has a content of 20% to 40% of the total weight. A method for producing a titanium diboride-based sintered body by sintering a mixture of a metal boride basic component mainly composed of TiB ₂ and a sintering aid as a sintering aid, comprising Al ₃ Ti or , M as a combination of one or more of Ni, Cr, Fe, Mo, Cu, and sintering aids with a content of 10% to 50% of the total weight with (Al, M) ₃ Ti as the main component Respectively, and a hexagonal metal boride powder body mainly composed of TiB ₂ as a main component, and a hexagonal metal boride powder body and a sintering aid respectively produced. Obtaining a mixture obtained by mixing the powder, and heating the mixture of the hexagonal metal boride powder and the sintering aid powder to a temperature of 800 ° C. or higher and 1300 ° C. or lower in a sintered body manufacturing apparatus. A method for producing a titanium diboride-based sintered body comprising: The sintering aid is a sintering aid powder body containing (Al, M) ₃ Ti as a main component and having a content of 20% to 40% of the total weight, comprising a hexagonal metal boride powder body and a sintered body. 4. The titanium diboride-based sintering according to claim 3, wherein the mixture with the binder powder is heated to a temperature of 900 ° C. or higher and 1100 ° C. or lower in a sintered body manufacturing apparatus to prepare a sintered body. A method of manufacturing a body.