JPS58221205A - Production device of hard alloy - Google Patents

Abstract

PURPOSE:To provide a titled device which improves electric power efficiency and yields various hard alloys such as hard crystals having prescribed performances by enclosing a cylindrical body which has heat resistance and thermal conductivity and is to be inserted therein with powder of a raw material mixture with a heat insulating material and a reinforcing material, and providing a pair of electrodes at both ends of the cylindrical body. CONSTITUTION:A green compact mixture 4 for a hard alloy is packed in a cylindrical body 1 having heat resistance and thermal conductivity. A heat insulating material 5A and a reinforcing material 5B having heat resistance are provided coaxially to the body 1. A pair of electrodes 2, 3 and conducting plates 6, 7 are provided at the top and bottom of the cylindrical body (furnace body) 1 so as not to contact with the material 5B. Heating current is flowed concentrically among the plate 6-the electrode 2-the body 1-the electrode 3-the plate 7 so that the mixture 4 is subjected to a heating and synthesizing treatment. When the synthesis of the hard alloy of the composite body advances and a liquid phase state is generated, the condition of conducting electricity is controlled according to the intended alloy. This device is adaptable for synthesizing and producing abrasive grains of an SiC-B4C alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for firing or synthesizing hard alloys such as high-hardness materials and heat-resistant materials that can be used as wear-resistant materials, abrasive grains, etc., or manufacturing apparatus. The synthetic sintered body is a combination of two or more types, for example, a combination of boron carbide and silicon carbide, a composite or composite carbide or eutectic of both, and K is a composite containing nitride, boride, or silicide #+ at the same time. (llI!
This invention relates to an apparatus for producing hard alloys (including i'l solution).

W, T i, 'I' a, B, S i
, Mo, Nl), Hf.

It is well known that various carbides and nitrides of transition metals such as Zr and V, and also borides and silicides such as compounds of rfl i and B, are hard alloys such as high-hardness materials and heat-resistant materials. For example, the particles are widely used in various wear-resistant materials, tool chips, and high-hardness particles such as abrasive grains.

A composite or composite carbide as described above is produced mainly by appropriately selecting a combination of two or more of metal carbides and metal nitrides or metal borides and borides, particularly preferably by combining a high hardness material and a high toughness material. A composite obtained by synthesizing a hard alloy of a nitride, preferably a composite such as a eutectic or solid solution made of a combination of two types of carbides, or a composite polycrystal, is used after being molded, pulverized, crushed, and sieved in the same manner. It is preferable to do so.

Examples of combinations constituting the hard alloy of the composite or composite polycrystalline body are as follows.

In addition, in the following combinations, the former is a high hardness material, and the latter is a high strength or toughness imparting material.
Naturally, it changes depending on the combination.

■Boron carbide (e.g. B 4 C, or B13C2) -
Titanium carbide (e.g. TiC), ■Boron carbide-nitride 5i
C), ■Titanium boride (e.g. '1'' i 82 )-
Silicon carbide, ■Titanium boride-tungsten carbide, ■Titanium boride-titanium carbide, ■Molybdenum carbide (e.g., MO2
C) - titanium carbide, ■ tungsten carbide W2O - tungsten carbide WC, [phase] titanium nitride - titanium carbide, ■ zirconium carbide (e.g. ZrC) - tungsten carbide, The above examples include high hardness metal carbide (boron carbide) and A composite such as a solid solution or eutectic of a metal boride (titanium boronide) and a metal carbide or nitride that has a hardness comparable to or lower than that of the high hardness metal and has high strength (tensile or bending strength, toughness). Alternatively, by producing a hard alloy made of a composite polycrystalline body, it is possible to obtain a useful high-hardness material or heat-resistant material with high hardness and high strength by compensating for each of the drawbacks of the above-mentioned combinations.

Examples of composite polycrystals such as the above-mentioned eutectic include the combination of B4C-8IC described in 5.
4C is written as an example of boron carbide, for example B1
It is allowed to contain boron carbide compounds other than 11C2, and the same applies to other carbides, nitrides, and borides. ), it is generally desirable to have a composition around a eutectic state (approximately 35 wt% 8iC-55 wt% B4C), but it is also useful to have a hypoeutectic state or, conversely, a hypereutectic state. So, the above B4C-8iC
In the case of the combination, B4C
Since SiC is distributed and mixed in the matrix in the form of elongated, short threads, short rods, pieces or strips, whiskers, etc., the intervening f9ic strengthens the high hardness matrix B4C as a kind of fiber reinforcement. Therefore, the mixed content range of both is 10 to 7Qwt%S i
It may have a composition such as C-remainder B4C, but in general, depending on the combination of carbides etc., a eutectic or hypereutectic composition, for example 25 to 60% 8iC-remainder B4C, seems to be a good range. be.

In addition, although it is an intervening or contained impurity, a composite body such as the above-mentioned eutectic body or a composite polycrystalline body is synthesized and sintered by heating it at a high temperature such that a liquid phase exists in a part using an apparatus described later. When producing SiC, it inhibits the formation of a eutectic between B4C and 8iC (9F), and decomposes or combines one or both of B4C and SiC, resulting in substantial changes (for example, a decrease in hardness or density). For example, when using a mixture of B15i1 and C as a starting material for synthetic production, B-
? It is sufficient that it does not particularly inhibit the synthesis of F), B4C and SiC combined with 8t.

For example, various metals (including rare earth metals) are present to a considerable extent (
For example, substances containing about 10W (around 5) form carbides, or form solid solutions, and substances that do not combine with carbides, B, and 81 are manufactured eutectic composites or composite polyesters. In most cases, they are unevenly distributed or segregated in the crystal or at its edges, so as long as the impurities mentioned above are mixed in, there is no problem, and the production amount of eutectic composites can be reduced. When using the hard alloy such as the composite material or composite polycrystalline material synthesized by sintering, it may be advantageous if there is some inclusion of impurities in order to make the crushing process smoother. Also, some impurity metals and alloys may be distributed and contained in hard alloys such as composites or composite polycrystals, increasing the toughness and elasticity of the compact.
Depending on the purpose, use, etc., such as use as a molded body, several wt% to about 10W1% of metal may be contained as an impurity.

However, in the production according to the present invention, the above-mentioned impurity metals and alloys are not used for the purpose of producing a molded body that serves as a binder for a composite polycrystalline body.

Next, we will explain the manufacturing method of hard alloys such as composites or composite polycrystals in the eutectic state such as metal carbides as mentioned above. First, the raw material composition includes the following (1) to (3). It is possible to implement by sending three letters9 or a combination thereof. In addition,
In the case of disembarkation, the eutectic composite or composite polycrystalline
This is an example of a case where the material is composed of a combination of metal carbides of Class 211.

(1) Two types of metal carbides For example, in the case of the above-mentioned B4C-8iC, each powder of boron carbide and silicon carbide (for mixing) (2) Two types of metals and carbon For example, in the case of the above-mentioned 13a C-8iC In the case, (gold
) Each powder of boron (B), metallic silicon (8i), and carbon (
(for mixing), and in this case, carbon and t, -ct may be of any type, such as carbon black, as long as it is commonly called carbon or graphite. Also, for example, the above '17i
In the case of Bg-TiC, metallic titanium (Ti) and boron (
B) and carbon powder.

(3) one or two types of metal oxide or metal hydride, further metal and carbon, and optionally a catalyst, for example, in the case of the above-mentioned B4Q-8iC, boron oxide (B20g); Silicon oxide (Si(h)) and the above (
Carbon similar to 2), and preferably each powder of boron nitride (BN) that promotes decomposition and reaction (for mixing), and, for example, in the case of the above TiBz-TiC, titanium hydride ( TiH), boron (B), and carbon powders.

It is necessary to mix each of the above raw materials well during heat synthesis, especially when the metal carbide mentioned in (1) above is used as a raw material, and to mix well, and to form a composite polycrystalline material to be heat synthesized and sintered. In order to obtain microcrystals with a crystal size of several μm to several tens of μm or less, it is preferable to use fine powder of around several μm or less, but the metals and metal oxides of (2) and (3) above are preferred. In the case of metal hydrides, carbon, etc., it may be a powder of about 10 μm in size, for example, probably because it undergoes a reaction process such as decomposition of the oxide and formation of a carbon compound. However, when using a metal compound, such as a metal oxide, due to powder size, cost, etc., it may be necessary to create a reducing state such as a hydrogen gas atmosphere to remove generated oxygen.

In obtaining the powder mixtures according to the above (1) to (3) and combinations thereof, the metal carbide, metal chain, or metal boride, etc. having higher hardness is a composite material from which impurities have been removed = 10- at least 20%, usually 30%
The metal carbide, metal nitride, or metal boride, which accounts for a maximum of about 90% of the above and therefore contributes to increasing or increasing the toughness of the other, is 30 to 90%, preferably 40 to 75%, in the composite. It is preferable to select the composition so that the amount of formation and inclusion is distributed.

Then, the thoroughly mixed powder is lightly compacted or compacted into a graphite or other heat-resistant container, and heated in a furnace, electrically heated, or by other appropriate heating means.
Temperatures at which hard alloys are synthesized, such as decomposition of oxides, carbonization, nitridation, boronization, solid solution of two or more carbides, composites such as eutectics, or composite polycrystals (some of them are heated to a temperature or heating conditions at which it melts or a liquid phase exists),
By detecting the amount of heat supplied, temperature, heating time, electrical resistance, changes in its reliability, etc., by some means, it is possible to check the progress of synthesis of the hard alloy such as the above-mentioned composite or composite polycrystal, and also the completion state of the synthesis. Upon detection, the heating is stopped, and in order to prevent crystal growth, preferably high-speed or rapid cooling is performed, or crystal growth is controlled by controlling the cooling rate or applying vibration during cooling. That is, a sintered body of a composite or a composite polycrystalline body consisting of a eutectic such as a different type of carbide or the like is obtained, which has high heat resistance, high hardness, and high strength.

For example, in the case of the above-mentioned B4CSiC mixture, the eutectic synthesis temperature for both is around 2070°C, so the temperature of the mixed green compact is 2000°C or above and about 4070 to 100°0, but the entire mixed green compact is molten. Before it becomes a free-flowing state, the eutectic synthesis portion is heated and held for about 10 minutes, depending on the amount, to perform eutectic synthesis treatment on the entire mixed powder compact. However, there are no particular restrictions on the synthesis atmosphere. When the mixed powder in the compacted powder state is heated as it is in a bare exposed state in a furnace or the like,
In particular, if a part or more of the mixed powder is metal oxide, etc., an inert or reducing atmosphere such as a vacuum furnace or Ayagon may be used to remove oxygen. [In the case of Ti, B1 and carbon, TiBg and T
If you want to composite a small amount of TiN outside of the IC,
'jj1 It is sufficient to create a reducing atmosphere with a hydrogen gas intervening atmosphere containing a gas containing N2 (N2), for example, ammonia gas, and supplying the m element for nitriding and eating up the decomposed oxygen, but for example, it is possible to create an unholy TlO2. It is desirable that oxygen (02) is not interposed by direct contact. However, 7. When manufacturing by inserting and removing the mixed powder in a powder state into the energized heating container of the apparatus of the present invention to be heated, which will be explained later, a heat-shielding heat-resistant material or a reinforcing material is provided outside the heating container. Since the mixed powder is wrapped in multiple layers, the atmosphere outside the powder may normally be air.

Figure 1 is a front sectional view showing the basic structure of an apparatus for heating and synthesizing hard alloys such as composites or composite polycrystals using the energized heating furnace method of the present invention. A cylindrical current-carrying heating element (furnace body) 2.3 is a pair of current-carrying electrodes inserted into the furnace body 1 from opposite directions, such as the top and bottom, between which a lightly compacted powder mixture 4 is inserted. When inserted, the mixed powder compact 4 does not necessarily need to be in contact with the inner circumference 13-wall of the furnace body 1 and the tip surfaces of the current-carrying electrodes 2, 3, etc., as will be described later. 5 is a heat-insulating heat-resistant material and reinforcing material provided coaxially around the outer periphery of the furnace body, 6.7 is a pair of upper and lower current-carrying plates, 6
A, 7 people are equipped with cooling means such as water cooling, 9 are the holding and feeding control head of the current-carrying plate 6, and a holding stand for the current-carrying plate 7, 8 is the electrode 2
A feed spindle that applies controlled pressure and feed as necessary, 9 a power supply for energizing heating, and a lower energizing plate 7 and a holding table 7 placed on a bed (not shown). do. Further, 10 is a temperature detector for measuring heating temperature.

It seems that no special power source is required as the power source 9 for energizing heating, and direct current and/or alternating current may be used, but for example, a power source with a frequency of about 200 as described in 4I Publication No. 111841-12.885 and elsewhere. The voltage number 1 is obtained by superimposing an AC component of ~2QOOOOHz on a DC at an appropriate ratio (approximately ~5%)
It is preferable to use a so-called energization or discharge sintering power source with a relatively low voltage of around 0 V or less and a large current.

The current flows between the current-carrying plate 6 - the electrode 2 - the furnace body 1 - the electrode 314 - and the current-carrying plate 7, heating the electrode 2.3 and especially the heating element 1, and heating the mixed compact 4. When heating and increasing the temperature, the rate of heating and increasing the temperature should be appropriately controlled to prevent explosions and fractures, etc., and when the predetermined temperature is reached for various reactions such as carbonization of the mixed green compact, diffusion and eutectic reactions, etc. controls the power supply 9 based on the temperature detected by the temperature detector 10 so as to maintain the predetermined temperature. That is, although it depends on the composition of the mixed powder compact 4, many carbide and boride synthesis reactions are exothermic reactions, and thus require energization control based on temperature detection as described above. Then, the synthesis state of a composite such as a eutectic or a composite polycrystal is detected or determined based on the heat treatment for a predetermined time and the change in temperature detected by the detector IO, and the mixed compact 4 is transferred to the electrode 2. 3 and the furnace body 1, so the heat-resistant and reinforcing material 5 is preferably removed, etc., and inserted into cooling water, ie, usually rapidly cooled.

However, when the temperature of the mixed powder 4 rises during the electrical heating, the electrical conductivity of the mixed powder compact 4 also increases, and the mixed powder compact 4 itself comes to be electrically heated, but magnesia etc. There is a problem that a large amount of current is diverted to the ceramic heat-resistant material and the heat-resistant reinforcing material 5 other than graphite, and the heating power efficiency is poor, and only a small amount of mixed compact 4 can be synthesized considering the large power consumption. be.

FIG. 2 is a front cross-sectional view of a preferred embodiment of the production apparatus for electrical heating synthesis of the present invention, which eliminates such drawbacks, and the same components or the same agents as those in FIG. 1 are designated by the same reference numerals. is attached.

The furnace body 1, which is made of graphite or the like as a heating element, has a thin wall structure to increase heat generation efficiency, and has an upper part IA and a lower part IB so that a part of the upper part can be reused as described later.
The two are coaxially integrated and can be separated freely. The mixed powder compact 4 is preferably filled and held in the axially intermediate portion of the furnace body 1 so as to have spaces a at the top and bottom, respectively, as shown in the figure. To perform this type of filling, align the furnace bodies IA and IB coaxially, fit a filler into the lower cavity a, fill it with the mixed powder, and apply pressure from above. The punches are fitted and pressurized to compress and mold the mixed green compact 4, and then the lower filler and upper punch mentioned above can be pulled out, and if necessary, a mixture is added to the mixed green compact 4 to maintain the compacted shape. Sometimes. 5B is a reinforcing material or a holding material for the heat-resistant material 5A described later, which is usually made of graphite or the like, and a heat-resistant insulating material 11 such as mica is placed on the lower current-carrying plate 7.
It is placed through. Five people use a ceramic heat-resistant material such as magnesia (MgO) for heat and electrical insulation, and a powdered material is coaxially placed in the gap between the outside of the furnace body 1 and the reinforcing material 5B for insulation and heat insulation. It is pressurized and filled as a filling. Also, the difference from the case shown in FIG. Although it is constructed so that it does not come into contact with the surrounding reinforcing material 5B, if it does come into contact with it, it is necessary to interpose an insulating material such as the mica.

In the illustrated device, the heating current is applied to the current-carrying plate 6 - electrode 2 - furnace body 1 -
The flow concentrates between the electrode 3 and the current-carrying plate 7, and even if the electrical resistance of the five heat-resistant materials decreases significantly due to the rise in the energization heating temperature of the furnace body 1, the current flows from the current-carrying plate 6, electrode 2, or 17- to the furnace body 1. Compared to the case where current is allowed to flow to the reinforcing material 5 as shown in FIG. , at least about 50% or more, usually easily several 1
There is an advantage that the power efficiency is improved by a factor of 0 or more, and a large amount of mixed green compact 4 can be heated and synthesized with a small capacity power source.

Of course, in this case as well, the current flowing from the current-carrying plate 6, the electrode 2, and the furnace body 1 to the electrode 3 and the current-carrying plate 7 via the electrically-resistant material 5A cannot be prevented.

In the above-mentioned apparatus, the mixed powder compact 4 is heated to a predetermined temperature at which a part of it melts or has a liquid phase, and as the synthesis and production of hard alloys such as composites such as eutectics progresses, the synthesis process progresses. The mixed powder compact 4 shrinks due to the generation of a liquid phase state due to the progress, or the synthesis of the eutectic in a partially melted or softened state, and the upper part of the mixed powder compact 4 is separated from the inner circumferential wall of the furnace body 1. Peel off and dashed line 4
As shown in A, the shape is like the top of a bottle, and the top swings and repeatedly comes into contact with and separates from the inner wall of the furnace body 1. Therefore, the resistance between the current-carrying plates 6 and 7, and therefore 18- The occurrence of a liquid phase state accompanying the progress of the eutectic synthesis is detected as a variation in the applied voltage. Therefore, the synthesis is completed while maintaining this state to some extent.

The synthetic material t varies depending on the material, but the above-mentioned B4C-8i
In the case of C, when the heating power is further increased and the temperature is raised in the state where the liquid phase state has occurred, the mixed powder compact 4 melts and falls onto the electrode 3, causing intense grain growth. However, such a situation must be avoided since the synthetic product will become brittle.

Then, as described above, since the composite is completely welded to the lower furnace body IB, the lower furnace body IB has to be destroyed in order to take out the composite, but the composite is welded to the upper furnace body IA. can be taken out without welding, and the upper furnace body 1 can be used as a part of the furnace body 1 during the next synthesis production of the mixed powder compact 4.
For example, it can be reused as the lower furnace body IB. However, if excessive heating is performed, the synthetic product will also be welded to the electrode 3, making repeated use difficult.

In addition, the heat-resistant material 5A is used as the reinforcing material 5B when taking out the composite material.
Although it is scraped off from the furnace body 1, it can be reused, and it is usually quickly scraped off from the furnace body 1 during water cooling or the like, or it is directly cooled in water. As described above, the mixed powder compact 4 does not form the cavity a in the furnace body 1, but instead forms only the cavity a in the upper part, as in the case of FIG. However, it is also possible to heat the mixed powder by applying electricity to it, but a drop in power efficiency is unavoidable, and the mixed compact 4 is connected to the electrode 2 or the electrode 2 - the furnace body 1 - the mixed powder compact 4 -
If a considerable amount of heating current flows in the path of the electrode 3, the temperature at the center in the axial direction is likely to rise due to internal heat generation within the mixed powder compact 4, causing crystallization due to overheating. It is important to be careful as this may cause growth. In addition, in FIG. 2 above, the whole part of the heat-resistant material 5A or the cylindrical body part on the side in contact with the outer circumferential wall of the furnace body 1 (that is, a part of the five heat-resistant materials) is removed from the mixed compact 4. A mixed powder of the same or different composition is filled completely or in a part of the axially intermediate part in place of the heat-resistant material 5A, and a composite of the same or different types of eutectic etc. is simultaneously filled on both the inside and outside of the furnace body 1. Equihard alloys can also be synthesized. In any case, the apparatus shown in FIG. 2 is extremely efficient and useful as a manufacturing apparatus for high-temperature heating or high-temperature firing synthesis. However, it is not suitable for applications that require a certain level of pressure retention for heating or firing because the pressure resistance of the furnace body portion is low. As mentioned above, when pressurizing the mixed powder compact 4 is not necessary during heating synthesis, the furnace body 1
Since the reinforcing material 5B does not require much pressure resistance in the direction perpendicular to the axial direction, the furnace body 1 and the reinforcing material 5B do not need to be an integral cylindrical body. , a cylindrical body having a triangular, square, or polygonal cross section can be used.

Further, FIG. 3 is a partial view showing different loading arrangements of the compacted mixed compact 4 into the furnace body 1 in the production apparatus for thermal synthesis shown in FIG. The powder compact 4 is made small in size so that an annular gap 13 is formed between its outer periphery and the inner circumferential wall of the furnace body 1, and an upper space is provided instead of the upper and lower spaces a in the case of FIG. 2. It is compacted and placed on the electrode 3 with an insulating plate 12 in between. Note that this insulating plate 21-12 usually burns out during synthesis because there is virtually no insulator that can withstand the eutectic synthesis temperature of B4C-8iC. It's okay. The surroundings of the furnace body 1 are similar to those shown in FIG. can.

Next, hard alloys such as composite polycrystals produced by the manufacturing apparatus of the present invention,
In particular, examples of synthetic production as abrasive grains and their results will be explained using experimental examples.

(Experimental Example 1) Silicon, boron, and graphite with a particle size of about 5 μml or less were mixed in a molar ratio of about 0.35:2.6:1 (weight percentage of about 19.7%:I56.3%:24%). ratio··
...Approximately 2 g of a well-mixed mixture of approximately 32% 5iC - 68% B4C) was placed in a graphite mold with an inner diameter of 15 mm (first
Figure) After increasing the heating current at a rate of about 250 A/ml to about 2.25 KA and heating to a reaction and eutectic temperature of 2000°C or higher for about 10 minutes, water was poured from the outside of the graphite mold and the mixture was heated for several minutes. Cooled. The product was pulverized and treated with a mixed acid of nitric acid and sulfuric acid to remove free boron, carbon, etc., and particles with a particle size of about #170 to #270 were sieved and subjected to a pink test.

The lapping test was conducted using 8KD-11 material and carbide 5% Co=W.
Do this for 5 minutes each for C.

Compared to the former 5KD-11 material, the surface roughness is 1.5 μmRr.
nax, the machining speed was 9 mg/min, which was about 3 times faster than that using known B4C abrasive grains for same-surface roughness processing, and about 6 times faster than that using diamond abrasive grains. In addition, for the latter carbide 5% Co-WC, the surface roughness is 7 μm and 1 μm in terms of surface roughness.
Rmax was 13 mg/min in terms of processing speed, which was equivalent to the processing performance with diamond abrasive grains.

(Experimental Example 2) The weight percentages of boron carbide powder and silicon carbide powder of about 2 μmy or less are: ■ About 50% boron carbide - 30% silicon carbide, ■ About 50% BaC - 50% silicon carbide, and 2. Mix each type well and add 200g of each type to the above-mentioned second
The mixed green compact 4 of the apparatus shown in the figure is packed, and about 20 KW of power is supplied with the apparatus configuration shown in FIG. temperature cannot be measured directly) for about 10 minutes to cause a eutectic reaction between silicon carbide and boron carbide, and then cooled with water for about 5 minutes and pulverized.

Figures 4 and 5 are backscattered electron composition images taken by a scanning electron microscope of the fractured surface of the eutectic of silicon carbide and boron carbide synthesized as described above. % boron carbide - 30% silicon carbide Figure 5 shows approximately 50% of the above ■
This is the case of boron carbide - 50% silicon carbide, each with a magnification of 2
At 50x magnification, the white flakes, stripes, short rods, or platelets in each backscattered electron composition image are silicon carbide, and the black parts around them are boron carbide. The structure differs depending on the composition as shown in (1) and (2) above, but in both cases silicon carbide, such as flakes, is dispersed and oriented in various directions relative to the matrix boron carbide. For example, It has a structure similar to that of fiber-reinforced composite materials.
It can be seen that the weakness of boron carbide, which has high hardness but is weak against thermal shock, can be compensated for by the presence of silicon carbide in the form of flakes.

The Gwickers hardness of the eutectic shown in Figure 4 above (slightly more boron carbide than the complete eutectic composition) is approximately 4000.
-4500HV, the hardness is approximately 3.800-4,
It was 000HV.

Figure 6 shows the machined surface roughness (μmRmax) and grinding speed (
The relationship between the particle size (mg/min) and the three types of particle sizes (μ
m) is shown in comparison with the case using diamond abrasive grains of the same grain size.

In addition, Fig. 7 shows the G type (6% Co-WC ) and 8 types (10
%TiC-6%Co-WC) and the grinding speed of the machined surface roughness for each grain size.

25- According to the results shown in FIGS. 6 and 7, the abrasive grains made of hard alloys produced by the manufacturing apparatus of the present invention are equivalent to diamond abrasive grains for iron materials and cemented carbide materials. It was found that the grinding performance exceeded the above.

(Experimental Example 3) Approximately -〇3250'l'iH (or 'I'i) powder and approx.
The ratio of boron powder and graphite powder of ttmS is approximately 1:1.
4: Mix thoroughly at a ratio of 0.3.

This mixed powder was compacted and heated to approximately L200°C using the apparatus shown in Figure 2.
When heated to
C) reacts, forming a composite of titanium boride (e.g. TiB2) and titanium carbide (e.g. Tic) (compositionally about 58.7% TiBz-41.3%T by weight percentage).
iC) is obtained. The cutting performance of this abrasive when crushed into abrasive grains was about the same as that of boron carbide. When the heating atmosphere is in a nitrogen-containing gas (for example, NHa), titanium nitride (TiN) is also synthesized and composited.

-26= (Experiment Example 4) Titanium, molybdenum, tungsten, and graphite powders of about 10 μm were mixed in an atomic weight ratio of about 1:1:1:3, and the mixed powder was mixed with an inner diameter of 15 mm, 4 Filled in a carbon mold for electrical heating, the top and bottom were covered with carbon plates, and the current applied to the carbon mold was increased at a rate of approximately 25 OA/m I to approximately 2.25 KA, and this state was maintained for approximately 3 minutes. The calcination synthesis was performed while maintaining the temperature.

The product was a titanium carbide-based solid solution with a lattice constant of approximately 4287. 8KD-11 in the same manner as Experimental Example 1
The machining performance was 0.5 μmRmax in terms of machined surface roughness, which was equivalent to diamond abrasive grains.

(Experimental Example 5) Titanium carbide of about #60 and titanium nitride of about -#325 were mixed at a weight ratio of about 3=1 and fired under the same conditions as in Experimental Example 2. However, when a similar lapping test was conducted, the machined surface roughness was 0.25μmRmax,
A processing speed of about Q and a performance of 4 mg/min were obtained.

(Experimental Example 6) Approximately 10"μm titanium, approximately 2μmyf chromium, and graphite powder were mixed in an atomic weight ratio of approximately 1:0.2:1.2 under the same conditions as in Experimental Example 2 above. It was synthesized and sintered.

The sintered body is a titanium carbide-based solid solution with a bulk density of approximately 99% or more, and its fractured surface is approximately 10 μm d in size, with large diamond-shaped titanium carbide crystals tightly bonded to each other in an aligned manner. Ta.

According to the configuration of the apparatus used for the synthesis and production of hard alloys of the present invention, the power efficiency in heating synthesis using an electric resistance heating furnace method is significantly increased, and it is possible to heat synthesis of a large amount of mixed powder with a small capacity power source. Moreover, the produced hard alloys are extremely useful because they have certain properties such as hardness and crystallinity.

According to the apparatus of the present invention as described above, for example, the MBg type boride and the MgBs type boride (wherein M is a metal element) described in JP-A No. 57-42578 can be used. The basic composition is one or more borides selected from among them, one or more binders selected from borides or nickel-phosphorous alloys, and if necessary, an MB type boride additive, and a metal carbide. , silicide, nitride, and oxide.

The basic composition is one or more metal borides described in JP-A No. 57-42,578, or M2BB type metal borides and one or more binders, and a combination selected from MB type borides. Production of a hard heat-resistant sintered body containing at least one additive component.

Alternatively, a titanium carbide-based hard alloy, for example, a titanium carbide-based solid solution containing one or more transition metals (Ti, V, Cr, ZrIMOIHf, 'ral or W), wherein the solid solution has a bulk density of at least 80 % or more, and the size of the unit crystal constituting the solid solution is several tens of microns.
It can also be applied to the case where a powder having a diameter of less than m1 is produced by sintering from a green compact of raw material mixed powder.

If it is necessary to pressurize the mixed compact, pre-pressure is applied.
− Use powder compacted at a sufficiently high pressure, or insert the mixed compact into a container made of ceramic or the like that can withstand a specified pressure and insert it into the furnace body, or alternatively, A structure or mechanism that can apply pressure in an insulated state may be used.

[Brief explanation of drawings]

Figure 1 is a front sectional view showing the basic configuration of the apparatus of the present invention when producing hard metals using the electric heating furnace method, and Figure 2 shows an example of the configuration of a preferred apparatus using the electric heating furnace method of the present invention. 3 is a sectional view of a portion showing different usage states of the device shown in FIG. A photograph of a backscattered electron composition image taken with a scanning chamber microscope, and FIGS. 6 and 7 are grinding characteristic curve diagrams when the above-mentioned synthetically manufactured hard alloy was crushed and subjected to a lapping test as abrasive grains. 30-

Claims (9)

[Claims] (1) A heat-resistant conductive cylindrical body into which a mixture of raw material powder for hard alloy production is inserted, and a heat-resistant heat insulating and reinforcing material coaxially surrounding the cylindrical body. A hard metal manufacturing apparatus comprising: a pair of electrodes provided in contact with both ends of the cylindrical body so as to energize the cylindrical body in the axial direction; and a heating power source. (2) A lower current-carrying plate placed on a table and connected to the - terminal of the heating current-carrying source, a lower current-carrying electrode placed on the current-carrying plate, and a hard metal alloy on the current-carrying front electrode. A cylindrical body as a heat-resistant conductive thin-walled current-carrying heating body into which a mixture of raw material powder for manufacturing is inserted, an acid part, and the other upper current-carrying electrode is placed on the top of the armpit-shaped body. At the same time, a heat-resistant reinforcing tube is provided coaxially with the cylindrical body and at a predetermined interval, and is mounted insulated on the lower current-carrying plate, and a cylindrical gap between the cylindrical body and the reinforcing tube is provided. A heat-resistant electrical and thermal insulating material is filled and interposed, and an upper current-carrying plate connected to the other terminal of the heating current-carrying power source is provided so as to be able to conduct current to and separate from and press the upper current-carrying electrodes. Hard alloy manufacturing equipment consisting of: (3) The hard alloy manufacturing apparatus according to claim 1 or 2, wherein the heat-resistant conductive cylindrical body is a carbon material. (4) The hard alloy manufacturing apparatus according to any one of claims 1 to 3, wherein the pair of current-carrying electrodes is made of a carbon material. (5) The hard alloy manufacturing apparatus according to any one of claims 1 to 4, wherein the pair of current-carrying plates are made of carbon material. (6) The hard alloy manufacturing apparatus according to any one of claims 1 to 5, wherein the reinforcing material or the reinforcing tube is a carbon material. (7) The hard metal manufacturing equipment according to any one of claims 1 to M6, wherein the heat-resistant heat insulating material or electrical and thermal insulator is magnesia (MgO). (8) The hard alloy according to any one of Items 2 to 1g7, wherein the electrical insulation between the reinforcing material and the lower current-carrying plate is provided by interposing a base material plate. Manufacturing equipment. (9) A patent in which the mixture is inserted into the heat-resistant conductive cylindrical body, the mixture is a mixed green compact, and the mixture is inserted into the axially intermediate portion of the cylindrical body. A hard metal manufacturing apparatus according to any one of claims 1 to 8.