JPH05140689A - High corrosion resistant and high wear resistant boride tungsten base alloy - Google Patents

Abstract

PURPOSE:To obtain a boride W base sintered alloy excellent in corrosion resistance, hardness, wear resistance, coagulating resistance, thermal shock resistance, toughness and machinability by subjecting a mixture of the powder of specified ternary complex boride or moreover binary boride and the powder of W to compacting and sintering. CONSTITUTION:Mixed powder constituted of, by volume, 1 to 30% powder of one or more kinds among ternary complex boride such as Mo2FeB2, Mo2NiB2, Mo2CoB2, W2FeB2, W2NiB2, W2CoB2, MoCoB, WFeB and WCoB and the balance W powder or mixed powder constituted of l to 20% of at least one kind among the powder of the above ternary complex boride and 1 to 20% of at least one kind among the powder of MxBy type binary boride such as TiB2, ZrB2, TaB2 and CrB2 (where M denotes Ti, Zr. Ta, Nb, Cr, V or the like as well as X=1 to 2 and Y=1 to 4) and the balance W powder is subjected to press forming into a desired shape and is sintered at a high temp., e.g. of 1700 deg.C in an Ar atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a sintered alloy of boride and tungsten. More specifically, it shows extremely excellent corrosion resistance to molten metals such as aluminum, magnesium, zinc, lead and sodium. The present invention relates to a boride-based tungsten-based alloy having high hardness at room temperature and high temperature, excellent wear resistance, adhesion resistance, thermal shock resistance and toughness, and good workability.

[0002]

2. Description of the Related Art As industrial machines become more automated, faster, and maintenance-free, performance requirements for wear-resistant materials used therein are becoming more and more demanding.
For example, die-casting related parts and hot or cold extrusion dies have come to be used at higher temperatures and in a stronger corrosive environment, so that in addition to wear resistance, they also have excellent corrosion resistance and adhesion resistance. In other words, it has been required more than ever before that the material has no sticking property with the mating material, has high hardness at normal temperature and high temperature, can withstand deformation, and has high thermal shock resistance.

The die-casting method is suitable for mass production due to its extremely high productivity, and has many advantages such as high product quality and high dimensional accuracy. Therefore, it is suitable for relatively low melting point metals such as zinc alloys, magnesium alloys and aluminum alloys. It is a widely used casting method, and die-casting-related parts refer to dies, sleeves, plunger chips, and the like used in this die-casting method. The properties commonly required for these are that they are not corroded by molten metal, have high hardness and excellent wear resistance, have high temperature hardness and withstand deformation at high temperatures, do not break by thermal shock, and have workability. Good things. In cold or hot extrusion dies, copper or aluminum is a viscous material when performing extrusion, drawing or forming of copper or aluminum. Will be important to increase.

In response to such a demand, a material obtained by subjecting a hot work tool steel such as SKD61 to a heat treatment or a nitriding treatment has been used for a long time. However, even if the nitriding treatment is performed, the nitrided layer is as thin as about 20 to 30 μm and the corrosion resistance to molten metal for a long time cannot be said to be sufficient. For this reason,
When this is used for an aluminum die casting sleeve, the life of the sleeve is short, so that the sleeve must be replaced frequently, resulting in a high running cost and a marked decrease in productivity in continuous operation. Further, iron eroded by aluminum may be melted out and may be caught in the die-cast product, resulting in deterioration of product quality.

Further, carbides and carbonitrides WC and TiCN having excellent corrosion resistance and adhesion resistance to molten metal are used, and WC-which is sintered by adding an iron group metal such as Ni and Co thereto. Co-based cemented carbide and TiCN-Ni-based cermet have been developed and used as tools. However, since the added iron group metal remains as a binder phase after sintering in both cases, this binder phase is eroded by the molten metal or causes adhesion with the mating material, which causes problems in corrosion resistance and adhesion resistance. There is.

Further, there is ceramics as a material having excellent corrosion resistance and high hardness at room temperature and high temperature. Among them, it is said that it is particularly excellent in adhesion resistance to non-ferrous metal such as aluminum and corrosion resistance to molten metal thereof. Boride-based ceramics (for example, JP-A-59-4597).
1, JP-A-57-129876, JP-A-5
7-42578). However, since ceramics is a brittle material, it cannot be applied to die-casting-related parts that require high toughness and thermal shock resistance, and its application is mainly tools such as cutting tools. Among ceramics, application of sialon, which has a relatively high thermal shock resistance, to die-cast sleeves has also been tried, but the manufacturing cost is very high, there is a problem in workability, and the hardness is too high. Therefore, when sliding on a low hardness material such as a plunger tip, there is also a drawback that the mating material is worn away.

Tungsten is mentioned as a material which is excellent in corrosion resistance, adhesion resistance, toughness and thermal shock resistance and which is much easier to process than ceramics. Tungsten is stable to many molten metals such as aluminum, magnesium, zinc, lead, and sodium at high temperatures and has excellent corrosion resistance. Also, since it has low reactivity with them, it has excellent adhesion resistance at normal and high temperatures. It was known early on. Since tungsten has the highest melting point of 3410 ° C. among metals, it is difficult to obtain an ingot by an industrial melting-casting method, and a powder metallurgy method is usually used. However, sintering requires a high temperature of about 2500 ° C. or higher and high-purity hydrogen gas, and further swaging, forging, rolling, etc. are required for 100% densification, resulting in high manufacturing costs. .. In addition, since tungsten has a low hardness of about 400 in Hv (Vickers hardness), there is a problem in wear resistance. Further, it exhibits extensibility from around 300 ° C. and easily deforms at high temperatures. Yes, it is used as a structural material only for a small number of applications such as wires and filaments.

It is a known technique to add an iron group metal such as Fe, Ni or Co in order to accelerate the sintering of tungsten in order to carry out the sintering at a lower temperature. Many alloys have been developed. However, in such a sintered tungsten alloy, the added iron group metal remains as a binder phase after sintering, and the above-mentioned WC-
Similar to Co-based cemented carbide and TiCN-Ni-based cermet, this binder phase is eroded by the molten metal, resulting in poor corrosion resistance and poor adhesion resistance with the mating material. Furthermore, the drawback that tungsten has low hardness and softens at high temperature has not been solved at all. Further, an electric contact material (Japanese Patent Laid-Open No. 56-55548) in which a small amount of TiB ₂ is added to a sintered tungsten alloy to improve the oxidation resistance, hardness and wear resistance is also proposed, but it is also bonded. Since the phase is Ni, which is an iron group metal, this binder phase is eroded by the molten metal, and the corrosion resistance and the adhesion resistance with the mating material are not improved. Also, T
Since the iB ₂ content is small and the hardness is low, it is not suitable for applications such as die casting sleeves that require high wear resistance.

[0009]

The present invention does not impair the excellent corrosion resistance and toughness of tungsten, yet has high room temperature and high temperature hardness, excellent wear resistance, adhesion resistance, thermal shock resistance and workability. It is intended to provide a tungsten-based alloy having the same.

[0010]

Means for Solving the Problems Mo ₂ FeB ₂ , Mo ₂
CoB ₂ , Mo ₂ NiB ₂ , W ₂ FeB ₂ , W ₂ CoB
₂ , W ₂ NiB ₂ , MoCoB, WFeB, WCoB selected from one or more ternary compound boride powders of 1 to 3
By molding and sintering a mixed powder of 0% by volume and the balance consisting of tungsten powder and unavoidable impurities, the excellent corrosion resistance and toughness of tungsten are not impaired, and high room temperature and high temperature hardness and excellent wear resistance are provided. sex,
A boride-based tungsten-based alloy having adhesion resistance, thermal shock resistance, and workability can be obtained. This alloy is called alloy A.
The ternary compound boride does not necessarily have to match the stoichiometric ratio, and may contain inevitable impurities. Incidentally, these ternary compound boride may be used alone, and
A combination of two or more kinds may be used, or a combination of two or more kinds may be used.

The first effect of the ternary compound boride is that it becomes a liquid phase at the time of sintering to promote the sintering and to make the sintered body dense. Since these ternary compound borides themselves have excellent corrosion resistance, they do not deteriorate the corrosion resistance of the sintered body. Tungsten is a difficult-to-sinter material, but it is well known that a dense sintered body can be obtained at a relatively low temperature by performing so-called liquid phase sintering, which promotes densification by the appearance of a liquid phase. It is necessary that the material used as the liquid phase has excellent corrosion resistance, and that the material becomes the liquid phase at a temperature as low as 2000 ° C. or less and promotes sintering. For example, when an iron group metal such as Fe, Ni, Co is used as a liquid phase, the iron group metal remains as a binder phase even after sintering, and this binder phase is corroded by the molten metal, so that the corrosion resistance to the molten metal is Markedly reduced. In addition, intermetallic compounds and ceramics that are generally excellent in corrosion resistance have high melting points,
At 2000 ° C. or less, there are few that become a liquid phase, and even if they become a liquid phase, the wettability with tungsten is poor, and the number that can sufficiently densify tungsten becomes even smaller. Materials that satisfy such conditions include Mo ₂ FeB ₂ and Mo.
₂ CoB ₂ , Mo ₂ NiB ₂ , W ₂ FeB ₂ , W ₂ Co
B ₂ , W ₂ NiB ₂ , MoCoB, WFeB, WCoB
Such as ternary compound boride is suitable.

The second effect of the ternary compound boride is to eliminate the disadvantage of tungsten, which remains in the form of surrounding tungsten after sintering and is easily deformed at a high temperature of 300 ° C. or higher. Further, the third effect is to prevent the deterioration of the high temperature transverse rupture strength and high temperature hardness of tungsten.

Due to the above effects, Alloy A has excellent corrosion resistance,
It has high-temperature deformation resistance, high-temperature transverse rupture strength, and high-temperature hardness, but also has excellent toughness, thermal shock resistance, and workability. The reason for this has not been clarified exactly, but it is considered as follows. When the material added to cause the appearance of the liquid phase reacts with tungsten and most of it forms an intermetallic compound or coarsens the crystal grains, the high toughness and thermal shock resistance of tungsten are impaired. However, when the ternary compound boride of the present invention is used, there is no rapid reaction between the ternary compound compound and tungsten, the crystal grains of the alloy are not coarsened even after sintering, and the crystal structure of metallic tungsten is small. It is presumed that the high toughness, thermal shock resistance, and good workability of tungsten will not be impaired, since the alloy has almost no loss.

The amount of the ternary compound boride added is preferably 1 to 30%, more preferably 3 to 20%. If it is less than 1%, the above-mentioned first, second and third effects are not sufficiently exhibited. Also, 30
If it exceeds 0.1%, the amount of boride formed by the reaction between tungsten and the ternary compound boride increases, and the toughness, thermal shock resistance, and workability are remarkably lowered due to the influence of this boride. Also, when the addition amount is 1% or more and less than 3%, the sintered body is almost densified, but it is difficult to densify it to 100% because the amount of liquid phase is small, and microscopic pores are slightly left and the strength is slightly lowered. .. On the other hand, if it exceeds 20%, the amount of tungsten becomes relatively small and the toughness is slightly lowered. Therefore, in order to obtain high strength and high toughness, the addition amount of 3 to 20% is more preferable.

The alloy A has a very good workability such that it can be processed by a lathe, and has an extremely excellent corrosion resistance against molten metals, acids and alkalis. Therefore, it is a suitable material for crucibles for melting metals that require high corrosion resistance, protective tubes for thermocouples for measuring molten metal temperature, ladles for die casting machines, evaporation plates for acid and alkaline solutions, and the like.

Next, as a result of examining the room temperature and high temperature hardness and wear resistance of alloy A, it is extremely superior to pure tungsten and a sintered tungsten alloy to which an iron group metal is added, and is suitable for the above-mentioned applications. Although it is a material, it was considered to be somewhat low in application to sleeves and plunger chips for molten metal die casting machines that require very high wear resistance in addition to corrosion resistance. Therefore, Mo ₂ FeB ₂ , Mo
₂ CoB ₂ , Mo ₂ NiB ₂ , W ₂ FeB ₂ , W ₂ Co
B ₂ , W ₂ NiB ₂ , MoCoB, WFeB, WCoB
1 to 20 of one or more ternary compound boride selected from among
% And MxBy (where M is Ti, Zr, Ta, N
represents b, Cr, and V, and x = 1 to 2 and y = 1 to 4)
Of at least one selected from the binary boride powders represented by 1 to 20% and the balance consisting of tungsten powder and unavoidable impurities are molded and sintered to obtain a sintered body. By this, the normal temperature and high temperature hardness can be increased and the wear resistance can be improved without impairing the corrosion resistance. It should be noted that these ternary compound boride and binary boride do not necessarily have to match the stoichiometric ratio.
It may also contain unavoidable impurities. The ternary compound boride and the ternary boride may be used alone, two or more kinds may be used in combination, and two or more kinds may be used as a solid solution with each other. This alloy is called alloy B. That is, Alloy B is a material in which the binary boride having extremely high hardness and wear resistance is added to Alloy A to increase the room temperature and high temperature hardness of the alloy and further improve the wear resistance. is there.

The effect of the ternary compound boride of alloy B is the same as that of alloy A. Similar effects can be obtained by adding these ternary compound boride and the binary compound boride together.

The addition amount of the ternary compound boride of alloy B is 1 to 2
0% is good, and preferably 3 to 15%. If it is less than 1%, the effect of adding the ternary compound boride is not sufficiently exhibited. On the other hand, if the addition amount exceeds 20%, the amount of boride formed by the reaction of tungsten and the ternary compound boride increases, and the toughness and thermal shock resistance significantly decrease due to the influence of this boride. Also, when the addition amount is 1% or more and less than 3%, the sintered body is densified, but since the liquid phase amount is small, it is difficult to densify it to 100%, and microscopic pores are slightly left and the strength is slightly lowered. On the other hand, if it exceeds 15%, the toughness is slightly lowered because the amount of tungsten is relatively small. Therefore, in order to obtain high strength and high toughness, the addition amount of 3 to 15% is more preferable.

Next, the first effect of the binary boride is to increase the room temperature and high temperature hardness of the alloy by uniformly dispersing it in the sintered body and further improve the wear resistance. The hardness of binary borides such as TiB ₂ , ZrB ₂ and CrB ₂ is Hv3400, Hv2200 and Hv, respectively.
Since it is extremely high at 1700 and has excellent wear resistance, it is possible to increase the room temperature and high temperature hardness of the alloy and improve the wear resistance even if added in a small amount. The second effect is to improve the strength of the alloy. It is known that tungsten has a large grain growth at high temperature, but in alloy A, ternary compound boride suppresses grain growth, and in alloy B, grain growth of binary borides is further suppressed. Since the effect is great, the crystal grains become finer, and due to this grain refinement effect, alloy B
It is considered that the strength of the is improved.

The addition amount of the binary boride is preferably 1 to 20%, more preferably 5 to 15%. If it is less than 1%, the above-described effect of adding the binary boride will not be exhibited. If it exceeds 20%, the amount of boride formed by the reaction of tungsten and the binary boride increases, so that the toughness and thermal shock resistance are remarkably lowered, and the hardness becomes too high, resulting in the workability. Sex is also reduced. If the amount of addition is 1% or more and less than 5%, the effect of addition is not sufficient, but strength, hardness, and wear resistance are slightly improved compared to alloy A. Further, addition of more than 15% and up to 20% results in a relatively small amount of tungsten, resulting in a slight decrease in toughness. Therefore, the addition amount is more preferably 5 to 15%.

Alloy B is a material having excellent corrosion resistance, high hardness at room temperature and high temperature, and excellent wear resistance. Further, although the workability of the alloy B is inferior to that of the alloy A, it is also possible to perform cutting work, and is a material that is far easier to process than ceramics. Therefore, the sleeve for molten metal die casting machine, plunger tip, mold,
It is suitable for extrusion dies.

The high corrosion resistance and wear resistance boride-based tungsten-based alloy of the present invention can be manufactured as follows.
In alloy A, for example, ternary compound boride Mo ₂ NiB ₂ powder is added to tungsten powder so as to have a predetermined composition, and in alloy B, for example, ternary compound boride Mo ₂ FeB ₂ is added to tungsten powder. The powder and the binary boride ZrB ₂ powder are added so as to have a predetermined composition, sufficiently wet-mixed and pulverized by an attritor or a vibrating ball mill, and then dry granulated in a nitrogen gas. This mixed powder is filled in a graphite mold, and the mixture is vacuumed or in a neutral or reducing atmosphere such as argon gas, nitrogen gas and hydrogen gas at 100 k.
1400 ° C to 1900 under pressure of g / cm ² or more
By hot pressing to heat at a temperature of ℃, or
The mixed powder is pre-compacted by a hydraulic press into a compact, and in vacuum or in a neutral or reducing atmosphere such as argon gas, nitrogen gas and hydrogen gas,
Alternatively, it can be produced by ordinary sintering by heating at a temperature of 1500 ° C. to 2000 ° C. while pressurizing in an atmosphere. The sintered body obtained by hot pressing or ordinary sintering may be further subjected to hot isostatic pressing. Further, the powder compacting may be performed by cold isostatic pressing without using a hydraulic press, or by sintering the mixed powder and directly performing hot isostatic pressing to obtain a sintered body.

[0023]

The present invention will be described in more detail with reference to the following examples. The compositions of the materials used in the examples are shown in Table 1.
In Comparative Example 1, SKD6 produced by melting-casting
1 (87.8Fe-1.1C-5.3Cr-0.9Mo
The steel material obtained by nitriding -1.3V-3.6 (Si, Mn, P, S) is shown, and the sintered tungsten alloy (84W-5Fe-5Ni-6Mo) is shown in Comparative Example 2. In addition,
All compositions are% by volume.

Example 1 Tungsten powder and Mo ₂ NiB ₂ powder were blended in the proportions shown in Example 1 of Table 2, mixed and pulverized in acetone with an attritor for 8 hours, and then dried in a nitrogen atmosphere. Grained. Next, this mixed powder was filled in a mold, and pressed by a hydraulic press in the up and down uniaxial direction at a pressure of 1.5 Ton / cm ^{2 to} obtain a green compact. This green compact was subjected to an argon atmosphere pressurization (gas pressure of 9.8 kg / cm ² ) at 1700
Heated for 30 minutes at a temperature of ° C. The sintered body was ground with a diamond grindstone or mirror-finished with a diamond paste, and the hardness, wear resistance and corrosion resistance shown in Table 3 were examined. Hardness is room temperature, 300 ℃ and 90
It was evaluated by Vickers hardness (Hv) at 0 ° C.
The measurement was performed at 5 points under a load of 5 kg, and the average value was obtained. Since SKD61 (nitriding treatment) of Comparative Example 1 has a very thin surface hardening phase, it was measured by micro Vickers (load 100 g). The wear resistance was evaluated by the Ohkoshi type wear test. The Ogoshi-type wear test is a method in which a test piece processed into a plate shape is pressed against a rotating ring to cause friction, and the volume of wear marks on the plate scraped by the ring is measured.
The smaller the wear volume, the better the wear resistance. The ring material was S35C, the test conditions were a friction distance of 200 m, a final load of 18.9 kg, and a friction speed of low speed (0.21 m / sec), medium speed (0.94 m / sec) and high speed (4.39 m / sec). Seconds). The corrosion resistance was evaluated by a dipping test in molten aluminum. In this test, after immersing the block in molten aluminum (ADC10,750 ° C.) for 8 hours, the depth at which the block was eroded from the surface by the molten aluminum was measured. Therefore, the smaller the erosion depth, the better the corrosion resistance.

The characteristics of Example 1 and Comparative Examples 1 and 2 are shown in Table 3. The hardness of Example 1 was higher than that of the sintered tungsten alloy of Comparative Example 2, and was about 1.5 times at 900 ° C. Next, the specific wear amount is much smaller than that of the SKD61 (nitriding treatment) of Comparative Example 1, especially on the medium and high speed sides, and is smaller than that of the sintered tungsten alloy of Comparative Example 2 over the entire speed range. Was excellent. It is considered that this is due to the fact that the hardness at normal temperature and high temperature became high and the adhesion resistance was improved. Regarding the corrosion resistance to molten aluminum, the SKD61 (nitriding treatment) of Comparative Example 1 has an erosion depth of 650 μm and the sintered tungsten alloy of Comparative Example 2 has an erosion depth of 1800 μm, whereas the alloy of Example 1 has no erosion. Not very good.

The bending strength of the alloy A of Example 1 is 85 k at room temperature.
It was g / mm ² , and the bending strength did not decrease up to 1000 ° C. Further, when the transverse rupture strength was measured, no deformation of the test piece was observed even at 1000 ° C. until it was broken, and the deformation resistance at high temperature was also excellent. The toughness value K _1C is 28.7M.
It had a very high Pa / mm ^0.5 and high toughness.

Example 2 Tungsten powder and Mo ₂ CoB ₂ powder were mixed in the proportions shown in Example 1 of Table 2, mixed and pulverized in acetone for 52 hours by a vibrating ball mill, and then dried in a nitrogen atmosphere. Granulated. Next, this mixed powder was filled in a graphite mold, and 200 kg / in an argon atmosphere (atmospheric pressure).
1550 while applying pressure in the upper and lower uniaxial directions with a pressure of cm ^2.
Heated at a temperature of ° C for 20 minutes. A block was cut out from this sintered body into a shape suitable for the test, and after grinding with a diamond grindstone or mirror finishing with diamond paste, the properties shown in Table 3 were examined.

Example 3 Tungsten powder and Mo ₂ FeB ₂ powder were mixed in the proportions shown in Example 3 of Table 2, and then mixed and pulverized, compacted and sintered in the same manner as in Example 1. However, the sintering atmosphere was atmospheric pressure.

The characteristics of the alloy A obtained in Examples 2 and 3 are shown in Table 3. Both the wear resistance and the wear resistance and the SKD61 (nitriding treatment) of Comparative Example 1 and the sintered tungsten alloy of Comparative Example 2 are higher. It had excellent corrosion resistance. The hardness was higher than that of the sintered tungsten alloy of Comparative Example 2.

Example 4 Tungsten powder, Mo ₂ NiB ₂ powder and TiB ₂
After mixing the powders in the proportions shown in Example 4 of Table 2, a sintered body was produced in the same manner as in Example 2. The hardness of Example 4 is higher than that of the sintered tungsten alloy of Comparative Example 2, 900 ° C.
Was about 3 times. Next, the specific wear amount is the SKD of Comparative Example 1.
The value was much smaller than that of 61 (nitriding treatment), especially on the medium and high speed sides, and was smaller than the sintered tungsten alloy of Comparative Example 2 over the entire speed range, and was excellent in wear resistance.
Further, there was no corrosion by molten aluminum and the corrosion resistance was very good. The transverse rupture strength was 140 kg / mm ² at room temperature, and the transverse rupture strength did not decrease up to 1000 ° C. Further, when the transverse rupture strength was measured, no deformation of the test piece was observed even at 1000 ° C. until it was broken, and the deformation resistance at high temperature was also excellent. Further, the toughness value K _1C is 8.5 MPa / mm ^0.5.
Met. Compared with the alloys A of Examples 1 to 3, the toughness was slightly lower, but the room temperature and high temperature hardness, the wear resistance and the transverse rupture strength were improved.

Example 5 Tungsten powder, Mo ₂ NiB ₂ powder and ZrB ₂
After mixing the powders in the proportions shown in Example 5 of Table 2, a sintered body was produced in the same manner as in Example 2.

Example 6 Tungsten powder, Mo ₂ CoB ₂ powder and TiB ₂
After mixing the powders in the proportions shown in Example 6 of Table 2, a sintered body was produced in the same manner as in Example 1.

Example 7 Tungsten powder, Mo ₂ NiB ₂ powder and TiB ₂
After mixing the powders in the proportions shown in Example 7 of Table 2, a sintered body was produced in the same manner as in Example 1. However, the sintering atmosphere was atmospheric pressure.

Example 8 Tungsten powder, Mo ₂ CoB ₂ powder and TiB ₂
After mixing the powders in the proportions shown in Example 8 of Table 2, a sintered body was produced in the same manner as in Example 1. However, the sintering atmosphere was atmospheric pressure.

Example 9 Tungsten powder, Mo ₂ NiB ₂ powder and ZrB ₂
After mixing the powders in the proportions shown in Example 9 of Table 2, a sintered body was produced in the same manner as in Example 1. However, sintering was performed in a vacuum.

Example 10 Tungsten powder, W ₂ NiB ₂ powder, W ₂ CoB ₂ powder and TiB ₂ powder were mixed in the proportions shown in Example 10 of Table 2 and then sintered in the same manner as in Example 2. Was produced.

Example 11 Tungsten powder, WCoB powder, MoCoB powder and TaB ₂ powder were mixed in the proportions shown in Example 11 of Table 2, and then a sintered body was produced in the same manner as in Example 2.

Example 12 Tungsten powder, W ₂ FeB ₂ powder, WFeB powder and CrB ₂ powder were mixed in the proportions shown in Example 12 of Table 2, and then a sintered body was prepared in the same manner as in Example 2. ..

The characteristics of the alloy B obtained in Examples 4 to 12 are shown in Table 3. The wear resistance is lower than that of SKD61 (nitriding treatment) of Comparative Example 1 and the sintered tungsten alloy of Comparative Example 2. It was also excellent in corrosion resistance. The hardness was much higher than that of the sintered tungsten alloy of Comparative Example 2. Compared with the alloys A of Examples 1 to 3, the toughness was slightly lower, but the normal temperature and high temperature hardness were higher, and the wear resistance and transverse rupture strength were improved.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

As described above, the high corrosion resistance and wear resistance boride-based tungsten-based alloy of the present invention is a new material having high room temperature and high temperature hardness and excellent corrosion resistance and wear resistance. It can be applied to many industrial fields such as thermocouple protection tube for measuring temperature of molten metal, ladle for die casting machine, evaporating dish of acid or alkali solution, sleeve for molten metal bending die casting machine, plunger chip, die, extrusion die.

Claims (3)

[Claims] 1. Mo ₂ FeB ₂ , Mo ₂ CoB ₂ , Mo
₂ NiB ₂ , W ₂ FeB ₂ , W ₂ CoB ₂ , W ₂ NiB
₂ , 1 to 30% by volume of ternary compound boride powder selected from MoCoB, WFeB and WCoB (hereinafter,% is volume%), and the balance is tungsten powder and inevitable impurities. A high-corrosion and wear-resistant boride-based tungsten-based alloy, which is a sintered body obtained by molding and sintering powder. 2. Mo ₂ FeB ₂ , Mo ₂ CoB ₂ , Mo
₂ NiB ₂ , W ₂ FeB ₂ , W ₂ CoB ₂ , W ₂ NiB
₂ , 1 to 20% of one or more ternary compound boride powder selected from MoCoB, WFeB and WCoB, and MxB
At least one selected from the binary boride powders represented by y (where M represents Ti, Zr, Ta, Nb, Cr, V, and x = 1 to 2, y = 1 to 4). 1 to 2 above
A high corrosion-resistant and wear-resistant boride-based tungsten-based alloy, which is a sintered body obtained by molding and sintering a mixed powder of 0% and the balance of tungsten powder and inevitable impurities. 3. MxBy is TiB ₂ , ZrB ₂ , TaB
_2, CrB 2 of at least one or more kinds selected from among ₂
The high-corrosion and wear-resistant boride-based tungsten-based alloy according to claim 2, which is an original boride.