JPS6057499B2 - hard sintered alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hard sintered alloy comprising a hard phase mainly composed of a complex boride containing Fe and a binder phase that binds the hard phase. It relates to hard sintered alloys.

Conventionally, hard materials include WC-based cemented carbide, stellite,
High speed steel etc. exist. Recently, hard sintered alloys having iron borides and iron complex borides as hard phases have been developed as materials to replace these materials. No. 127818, Special Publication No. 56-
No. 8904 and Japanese Patent Publication No. 56-15773. The hard sintered alloys disclosed in these proposals include iron boride or iron boride and Cr, MO, W, Ti, V,
Among boride-forming elements such as Nb, Ta, Hf, Zr, and CO. A hard phase consisting of any one or more borides and/or complex borides, and Fe, Cr, Ni, MO, W, Ti
, V, Nb, Ta, Hf, Zr, Cu and other metals and/
or a binder phase consisting of one or more types of alloys containing these.

Furthermore, boride forms a hard phase; the material is MB or M2B
(hereinafter, M represents metal), complex boride is MxNyB (
Hereinafter, M and N represent complex boride metals. x and Y are composed of an intermetallic compound having a structure such that M and N represent stoichiometric values necessary to form a compound.
In Ku Special Publication No. 56-15773, further A],
Hard sintered alloys with improved hardness and toughness have been proposed by limiting the Si and 0 contents.The purpose of the present invention is to improve the excellent corrosion resistance of the hard sintered alloys disclosed in these proposals. The object of the present invention is to provide a hard sintered alloy that maintains oxidation resistance and wear resistance, and has even better mechanical strength, toughness, and stability thereof.

The present invention will be explained in detail below.

In the present invention, at least 10% (hereinafter % represents weight %)
A hard sintered alloy comprising 40 to 95% of a hard phase made of a complex boride containing Fe and a binder phase that binds the hard phase, the hard sintered alloy having a B content of 3 ~8%, Cr
Content: 35% or less, Ni content: 35% or less, AI content: 2.85% or less, Si content: 0.03 to 4.75%, C
The content is 0.95% or less, the O content is 2.3% or less,
The main point is that the MO and/or W content is within a range that satisfies the atomic ratio of (MO and/or W)/B from 0.75 to 1.25, with the remainder being Fe and unavoidable impurities. Pertains to hard sintered alloys.

The hard sintered alloy (hereinafter referred to as sintered alloy) has the main constituent elements as described above, and in particular (MO and/or W).
)/B atomic ratio in the range of 0.75 to 1.25, the hardness is in the range of RA8O to 93, and is 175 to 300k.
It stably exhibits a high anti-resistance force of 91wd.

Why does setting the atomic ratio of (MO and/or W)/B around 1 result in higher anti-deposition strength and less variation?
Although the reason is not clear, a more detailed investigation shows that the complex boride containing Fe that forms the hard phase is mainly MO2F.
eB2 or WFeB type or a mixed boride thereof, and some other LMl. It was found that it was composed of B, MxNyB type boride. Furthermore, especially W
If the content is large, W2FeB? Complex borides were also observed. MO2Fe8, WFeB or W2F'EB2
In complex borides of type MOl:. It is observed that W partially substitutes with each other, and Fe partially substitutes with the elements Cr, Ni, and CO.

Therefore, in the following, we will include forms in which MO or w of these three types of complex borides is partially substituted, forms in which Fe is partially substituted with Cr, Ni, and CO, MO2FeB2, WFeB,
These will be collectively referred to as W2Fe type 8 complex borides.

In order to form a hard phase mainly composed of these MO2FeB2, WFeB, and W2FeB2 type complex borides, at least 10% of Fe must be included in the hard phase. The main point is that Fe and Fe-containing compounds were used in this sintered alloy because the Fe-containing complex boride sintered body exhibits sufficiently high hardness and toughness, and the reason why Fe and Fe-containing compounds were used When added in an appropriate amount, it exhibits excellent corrosion resistance, heat resistance, and oxidation resistance similar to that of stainless steel; boride powder containing mainly Fe can be easily produced industrially; and Fe is an abundant resource. This is because it is available and inexpensive.

The hardness of the sintered alloy depends on the amount of complex boride serving as the hard phase, the amount of the binder phase, and the hardness of the binder phase.

The hardness of the sintered alloy is in the range of RA from 80 to 93. To achieve a hardness of RA8O or higher, the amount of hard phase must be at least 40%.
I need. On the other hand, when the amount of hard phase exceeds 95%, the hardness is RA93, but the anti-destructive strength is 175 kg'ml.
The following is true. Therefore, the amount of hard phase should be in the range of 40 to 95%. B, which is a hard phase forming element, forms a hard phase with a lower limit of 40
3% is required for 95% formation and 8% is required for 95% hard phase formation.

Therefore, the limited range of B is 3 to 8%. Like B, MO and W are elements that form a complex boride that becomes a hard phase;
The atomic ratio of MO and/or W)/B is 0.75 to 1.
25, the sintered alloy has a hardness of RA8O to 93 and a hardness of 175 to 300k91i.
It stably exhibits high anti-deposition strength.

Furthermore, the atomic ratio of (MO and/or W)/B is 0.9
When it is set to 0 to 1.20, even higher anti-deposition strength can be obtained.
Therefore, the content of MO and/or W is in a range that satisfies the atomic ratio (MO and/or W)/B of 0.75 to 1.25s, preferably 0.90 to 1.20. Cr not only improves the corrosion resistance, heat resistance, and oxidation resistance of the sintered alloy, but when used in combination with Ni, it also has the effect of making the hard alloy nonmagnetic by austenitizing the binder phase. have

When applying a sintered alloy to applications that require mechanical strength and wear resistance but do not require corrosion resistance, it is not necessary to specifically include Cr in the sintered alloy, but it is usually necessary to incorporate Cr in conjunction with these properties. Therefore, when corrosion resistance is required, it is preferable that Cr be contained at a lower limit of 0.5%. On the other hand, if the Cr content exceeds 35%, although it is excellent in terms of corrosion resistance, heat resistance, and oxidation resistance, the mechanical strength decreases and the anti-destructive strength becomes 175k91i or less. Therefore, the Cr content is 35% or less, preferably 0.5 to 35%.
shall be. Like Cr, Ni is an element useful for corrosion resistance and oxidation resistance, and is also an element required when the structure of the binder phase is an austenitic nonmagnetic material.

In order to achieve these objectives, reach the objectives by up to 35%. CO is a hard phase MO2FeB2,W
FeB, W2FeB2 is an element that can mainly replace Fe in the boride, and when the bonding phase is a ferrite phase,
It has the effect of increasing the red-hot hardness of the binder phase, and this effect is observed when added at 0.5%.

However, when it exceeds 35%, the transverse rupture strength becomes 175k91i or less. Therefore, the upper limit is set at 35%. Cu is an element added for the purpose of improving the thermal conductivity and corrosion resistance of the sintered alloy, and an effect is seen when added at 0.1%, and when it exceeds 35%, the hardness and transverse rupture strength decrease. causes a decrease.

Therefore, the Cu content is set to 35% or less. ■b of the periodic table
Ti, Zr, Hf of the group and ■, Nb, Ta of the b group,
Each metal is substituted with MO or W in the MO2FeB2, WFeB, W2FeB2 type complex boride, and a portion is consumed for alloying in the binder phase.

These group (1) a and Va group metals not only improve the hardness of the sintered alloy but also have the effect of preventing coarsening of crystal grains during liquid phase sintering. Although these metals are generally expensive elements, they exhibit great effects when added in small amounts. Therefore, these group IIb and group Vb metals are effective when the total amount of each metal is 5%.However, considering the cost, the total amount of each metal is 1%.
Within the range of 5%, satisfactory hardness and transverse rupture strength can be obtained. Therefore, the total amount of these metals should be 15% or less. C increases the reduction of oxides and the hardness of the binder phase.
This element is effective in increasing the hardness of the sintered alloy as a whole, but even if it exceeds 0.95%, the hardness does not improve and the transverse rupture strength begins to decrease.

Therefore, the C content is set to 0.95% or less. Al is mixed in from the raw material powder and reacts with B) and O, resulting in A
Monoboride and Al oxide are likely to be formed, and in particular, aluminum oxide inhibits the sinterability of the sintered alloy.

Therefore, it is preferable that the amount of Al contained in the sintered alloy is as small as possible, but if it is 1% or less, its influence is relatively small. However, if the incorporation of O into the sintered alloy is prevented as much as possible, and the N content is 2.85% or less, the damage caused by crabs can be considerably reduced. Therefore, the content should be 2.85% or less. Since zero reacts with B, Cr, Al, Si, etc. to form oxides, which impairs sinterability and causes a decrease in transverse rupture strength and an increase in variation, it is better to reduce its amount as much as possible.

However, if the amount is 2.3% or less, the effect is relatively small, and therefore the O content is set to 2.3% or less. S1 is an element that is mainly mixed in from the raw material powder.

This Si has the effect of improving the sinterability of the sintered alloy, increasing the density, and, as a result, improving the mechanical properties of the sintered alloy. However, if it is less than 0.03%, the effect will be small, and if it exceeds 4.75%, the sintered alloy will become brittle. Therefore, the Si content is 0.03 to 4.7
5%. In addition, as disclosed in the above-mentioned Japanese Patent Application Publication No. 2003-120022, the sintered alloy is produced by using Fe-B or Fe-B alloy powder prepared by water or gas atomization as a boron source, or in some cases by using Fe-B or Fe-B alloy powder prepared by water or gas atomization. Ferroboron powder, Ni
, Cr, W, Ti, MO, etc. or B
Using simple powders, these and MO, W, Ti, V, Fe, C
Blending elemental metal powder such as r, Ni, CO, Cu, etc. or alloy powder containing two or more of these to a predetermined composition, and if necessary, mixing carbon powder or carbide,
The mixed powder is wet-pulverized in an organic solvent using a vibrating ball mill, dried, granulated, and molded, and the molded product is subjected to liquid-phase sintering in a non-oxidizing atmosphere.

By using the liquid phase sintering method, the main sintered alloy is approximately 10
The density will be 0%. To prevent oxidation during sintering, vacuum,
It is important to perform sintering in a non-oxidizing atmosphere such as a reducing gas or an inert gas. Liquid phase sintering is usually 1
5 to 9 cycles at 100 to 1400°C; Sintering temperature is 11
If it is less than 0, a sufficient amount of liquid phase will not appear, so sintering will not proceed sufficiently, resulting in a sintered body with many pores. On the other hand, 14
When the temperature exceeds 00°C, although liquid phase sintering progresses sufficiently, the crystal grains become enlarged and the transverse rupture strength decreases. Also, if the sintering time is less than 1/5, sufficient densification will not be achieved,
On the other hand, even after 90 minutes, there is no improvement in strength commensurate with the passage of time. In some cases, the strength may decrease. Therefore, it is not necessary to take more than 9 sintering times. The liquid phase sintering method has been described for the purpose of reducing pores in the sintered alloy as much as possible, but in order to achieve this purpose, not only the liquid phase sintering method but also the hot isostatic pressing method, hot isostatic pressing method, hot isostatic pressing method, etc. Breath method,
The purpose can also be fully achieved by the electric current sintering method.

This will be explained below using examples.

The compositions of the materials used in Examples and Comparative Examples are shown in Table 1 and Table 2.
Those shown in Table 3 were used.

r Example 1 Ferroboron powder A: 20.2%, ferrotungsten powder: 69.2%, Cr powder: 2.1%, Ni powder:
1.1%, carbonyl Fe powder: 7.1%, C powder: 0.3
%, wet milled for 28 hours in an iron vibrating ball mill (the same applies to the following examples), dried, granulated, shaped, and sintered in vacuum at 1300°C.

Example 2 Ferroboron powder B: 9.3%, ferrotungsten powder:
22.2%, W powder: 27.4%, Cr powder: 1.1%, N
i゛ powder: 2.0%, WB powder: 25.0%, carbonyl F
E-powder: 12.7% and C-powder: 0.3% were blended, wet-pulverized for 2 hours in a vibrating ball mill, dried, granulated, molded, and sintered at 1275° C. in vacuum.

Example 3 B-containing alloy powder A: 31.1%, MO powder: 35.5%, N
Blend I powder: 2.1%, carbonyl Fe powder: 31.0%, and C powder: 0.3%, wet-pulverize in a vibrating ball mill for 2F@, dry and granulate, then shape, and in a vacuum at 1225°C. Sintered with

Example 4 B-containing alloy powder C: 44.6%, MO powder: 51.2%, N
I powder: 1.1%, carbonyl Fe powder: 2.8%, C powder:
0.3% and placed in a vibrating ball mill with 2FgI! After wet pulverization, dry granulation, molding, and sintering at 1225° C. in vacuum.

Example 5 Ferroboron powder A: 27.0%, MO powder: 39.1%,
Cr8: 3.1%, Ni powder: 1. l%, MOB powder: 29
．． 1%, carbonyl Fe powder: 0.3%, C powder: 0.3%
were mixed, wet-pulverized for two cycles in a vibrating ball mill, dried, granulated, molded, and sintered in vacuum at 1275°C.

Example 6 B-containing alloy powder C: 2&1%, ferrotungsten powder: 3
8.0%, MO powder: 16.7%, Cr powder: 0.5%, N
I powder: 0.5%, MOB powder: 16.0%, C powder: 0.2
% and placed in a vibrating ball mill for 2S! Wet grinding between
After dry granulation, it was shaped and sintered at 1275° C. in vacuum.

Example 7B-containing alloy powder C: 32.3%, MO powder: 28.
0%, Cr powder: 0.6%, Ni powder: 2.1%, carbonyl Fe powder: 36.7%, C powder: 0.3%, wet milled for 2S1 in a vibrating ball mill, and dried. After granulation, it was molded and sintered at 12500C in vacuum.

Example 8 B-containing alloy powder C: 44.6%, MO powder: 47.1%, N
I powder: 2.1%, carbonyl Fe powder: 5.9%, C powder:
0.3%, wet milling for 2Fn in a vibrating ball mill, dry granulation, molding, and sintering at 1275° C. in vacuum.

Example 9 B-containing alloy powder C: 32.3%, MO powder: 44.8%, C
R powder: 0.6%, Ni powder: 2.1%, carbonyl Fe powder: 19.9%, C powder: 0.3% were blended, wet pulverized for 2 hours in a vibrating ball mill, and dried and granulated. Post-forming and in vacuum 1
It was sintered at 275°C.

Example 10 Ferroboron powder A: 27.6%, MO powder: 50.6%,
Cr powder: 2.3%, Ni powder 2.0%, MOB powder: 15.
0%, carbonyl Fe powder: 2.2%, C powder: 0.3%, and milled in a vibrating ball mill for 2S! After wet pulverization, dry granulation, molding, and sintering at 1275° C. in vacuum.

Example 11 B-containing alloy powder A: 32.0%, MO powder: 39.0%, C
R powder: 6.5%, Ni powder: 2.0%, carbonyl Fe powder: 20.2%, C powder: 0.3% were blended, wet pulverized in a vibrating ball mill for two times, and then dried and granulated. Post-forming and in vacuum 1
It was sintered at 275°C.

Example 12 B-containing alloy powder B: 43.4%, MO powder: 34.3%, C
R powder: 21.0%, Ni powder: 1.0%, C powder: 0.3%
were blended, wet milled for 2S1 in a vibrating ball mill, dried, granulated, shaped, and sintered at 1275°C in vacuum.

Example 13 Ferroboron powder A: 30.3%, MO powder: 4
1.9%, Cr powder: 2.1%, Ni powder: 25.4%, C
Powder: 0.3% was blended, wet-pulverized for two cycles in a vibrating ball mill, dried and granulated, molded, and sintered at 1200° C. in vacuum.

Example 14B containing alloy powder C: 40.7%, ferrotitanium powder: 9.5%, MO powder: 46.6%, Ni powder: 1.1%
, carbonyl Fe powder: 1.8%, and C powder: 0.3%, wet milled in a vibrating ball mill for 28 hours, dried, granulated, molded, and sintered at 1300° C. in vacuum.

Example 15 B-containing alloy powder C: 42.0%, ferrovanadium powder: 7
．． 3%, MO powder: 50.4%, and C powder: 0.3%, wet-pulverized in a vibrating ball mill for 2 hours, dried, granulated, formed, and sintered at 1275° C. in vacuum.

Example 16B containing alloy powder C: 25.0%, MO powder: 28
．． 5%, Ni powder: 1.1%, C9 powder: 19.0%, MO
Powder B: 25.3%, carbonyl Fe powder: 0.8%, and powder C: 0.3% were blended, wet-pulverized in a vibrating ball mill for 2 turbines, dried and granulated, then molded, and heated at 1225°C in vacuum. Sintered with

Example 17 B-containing alloy powder C: 25.0%, MO powder: 28.5%, C
r powder: 0.9%, Ni powder: 1.0%, Cu powder: 19.0
%, MOB powder: 25.3%, C powder: 0.3%, and put it in a vibrating ball mill for 2S! After wet pulverization, dry granulation, molding, and sintering at 1200° C. in vacuum.

Comparative Example 1 Ferrobon powder A: 35.0%, MO powder: 30.0%, C
R powder: 3.0%, Ni powder: 3.0%, carbonyl Fe powder: 28.7%, C powder: 0.3% were blended, wet milled for 280V in a vibrating ball mill, and after dry granulation. It was molded and sintered at 1200°C in vacuum.

Comparative Example 2 B-containing alloy powder B: 42.0%, MO powder: 54.7%, N
I powder: 3.0% and C powder: 0.3% were blended, wet-pulverized for two times in a vibrating ball mill, dried, granulated, molded, and sintered at 1275° C. in vacuum.

Comparative Example 3 B-containing alloy powder D: 43.0%, B-containing alloy powder E: 16.
0%, MO powder: 25.0%, Cr powder: 14.6%, Ni
1.0% of powder and 0.4% of C powder were blended, wet-pulverized in a vibrating ball mill for 2 hours, dried and granulated, then molded, and crushed in a vacuum for 12 hours.
It was sintered at 25°C.

) The chemical analysis values of the sintered alloys prepared based on the above Examples 1 to 17 and Comparative Examples 1 to 3, (MO and/or
Table 4 shows the atomic ratio of W)/B, amount of hard phase, hardness, and transverse rupture strength.

Examples 1 to 5 correspond to claim 1, and B
The content, amount of hard phase, hardness, and transverse rupture strength are shown.

Examples 6 to 10 correspond to claim 1,
(MO and/or W)/B atomic ratio and amount of hard phase,
Hardness and transverse rupture strength are shown.

Examples 11 to 13 correspond to claim 1, and particularly show the amount of hard phase, hardness, and transverse rupture strength when relatively large amounts of Cr and Ni are contained.

Examples 14 to 17 correspond to claim 3, and show the amount of hard phase, hardness, and resistance when containing Ti of group a, V of group a, CO, O*, and Cu, respectively. The rupture force was shown. Note that Example 13 was shown as an example of a sintered alloy intended for nonmagnetic properties.

Comparative Examples 1 and 3 are cases where the atomic ratio of (MO and/or W)/B is small.

Comparative Example 2 shows a case where the atomic ratio of (MO and/or W)/B is large. It can be seen that the present invention exhibits clearly superior transverse rupture strength when compared with these comparative examples.

Claims (1)

[Scope of Claims] 1 A hard sintered alloy comprising 40 to 95% by weight (hereinafter % is weight%) of a hard phase made of a complex boride containing Fe and a binder phase that binds the hard phase, Complex boride is MxNyB
type (hereinafter, M and N are metals, X and Y represent the stoichiometric values necessary for M and N to form a compound), M is Mo and/or W, and N is It is composed of Fe and one or more elements selected from Cr, Ni, and the proportion of Fe in the hard phase is 10 to 22% of the total hard phase, and the binder phase is Fe and Cr, Ni, Si, and one or more elements selected from C, and the content of the one or more selected elements is greater than or equal to C.
r0.5-35%Ni0.5-35%Si0.03-4.75%C0.05-0.95%, and in addition, the hard sintered alloy contains 2.85% Al as an impurity element. Hereinafter, O is 2.3% or less,
and a hard sintered alloy consisting of 3 to 8% B and the balance Fe and unavoidable impurities, and the Mo/and/or W content is 0.75 in the atomic ratio of (Mo and/or W)/B.
1.25. 2. The hard sintered alloy according to claim 1, wherein the Mo and/or W content is within a range satisfying an atomic ratio of (Mo and/or W)/B from 0.90 to 1.20. 3 40 to 95% hard phase consisting of complex boride containing Fe
and a binder phase that binds the hard phase, the complex boride is of the MxNyB type, and M is selected from Mo and/or W and Ti, V, Nb, Ta, Hf, and Zr. N is composed of Fe and one or more elements selected from Cr, Ni, and Co, and the proportion of Fe in the hard phase is 10 to 10% of the total hard phase.
22%, the bonded phase is Fe, and Cr, Ni, Si
, C, Co, Cu, Ti, V, Nb, Ta, Hf, Zr
The content of the selected one or more elements is Cr0.5-35% Ni0.5-35% Si0.03 with respect to the hard sintered alloy. ~4.75% C0.05~0.95% Co0.5~35% Cu0.1~35% Total of Ti, V, Nb, Ta, Hf, and Zr is 0.5~1
In addition, the hard sintered alloy has Al as an impurity element of 2.85% or less, O of 2.3% or less, and B of 3 to 8%, with the balance consisting of Fe and unavoidable impurities. A hard sintered alloy with a Mo and/or W content of (Mo and/or W)/B atomic ratio of 0.75
1.25. 4. The hard sintered alloy according to claim 3, wherein the Mo and/or W content is within a range satisfying the atomic ratio of (Mo and/or W)/B from 0.90 to 1.20.