CN102492886B - Tungsten aluminum carbide-iron-nickel hard alloy and preparation method thereof - Google Patents

Abstract

The invention provides a tungsten carbide aluminum-iron nickel hard alloy, which comprises tungsten carbide aluminum, iron and nickel; wherein, the molar ratio of iron and nickel is 1:5-5:1. The preparation method of the tungsten carbide aluminum-iron-nickel hard alloy is as follows: mixing tungsten carbide aluminum powder, iron powder and nickel powder to obtain a mixture; cold pressing the mixture to obtain a green compact; The blank is vacuum sintered to obtain tungsten carbide aluminum-iron-nickel hard alloy. In the present invention, iron and nickel are added to tungsten carbide aluminum at a molar ratio of 1:5 to 5:1, so that the tungsten carbide aluminum alloy has high density, high microhardness and high bending strength, which is comparable to that of cobalt-added tungsten carbide aluminum alloy. Comparable performance. Because iron and nickel are widely distributed in nature, easy to obtain materials, and low in cost, the tungsten carbide aluminum-iron-nickel hard alloy prepared by the present invention not only has high density, high microhardness and high bending strength, but also has low cost and is economical and applicable .

Description

A kind of tungsten carbide aluminum-iron-nickel hard alloy and preparation method thereof

technical field

The invention belongs to the field of metal materials, in particular to a tungsten carbide aluminum-iron-nickel hard alloy and a preparation method thereof.

Background technique

Tungsten carbide is a black hexagonal crystal with high hardness, which is similar to diamond. Pure tungsten carbide is brittle, and if it is mixed with a small amount of metals such as titanium, cobalt or aluminum, the brittleness can be reduced. Therefore, it has become a trend to add other metals to tungsten carbide to improve its performance.

Aluminum is often used as an additive metal due to its light weight, oxidation resistance, and good ductility. Tungsten carbide aluminum cemented carbide made by adding aluminum to tungsten carbide is an emerging technical material researched and developed in recent years. Tungsten carbide aluminum is a substitutional solid solution formed by part of aluminum atoms entering the tungsten lattice in the tungsten carbide lattice. Alloy, which not only has the high hardness and high wear resistance of tungsten carbide, but also has the light weight, oxidation resistance and excellent ductility of aluminum. The alloy has high hardness (microhardness greater than 25GPa), high bending strength (bending strength above 1500MPa) and low density (density of rich aluminum alloy can reach 3.0g/cm ³ ), and is developing into a new type of high hardness, high strength , good processability, high oxidation resistance temperature of the new hard alloy, the material is expected to be used in mechanical processing tools, glass cutting, forging dies, drawing dies, rolls, oil well drilling tools, mining drilling tools, excavation drilling tools and electrical contact materials etc. have been applied.

The traditional preparation method of tungsten carbide aluminum cemented carbide uses tungsten carbide powder as raw material and is prepared by powder metallurgy sintering process. However, due to the high melting point and high temperature resistance of tungsten carbide aluminum cemented carbide, the requirements for sintering conditions are more stringent. And it is difficult to achieve its high-density sintering. In order to reduce the sintering conditions and obtain a high-density alloy sintered body, the prior art discloses a method for preparing a tungsten carbide-aluminum sintered body using cobalt as a sintering agent, such as a Chinese patent with application number 200610016994. Alloy sintered body. In this patent, a tungsten carbide aluminum cemented carbide sintered body is prepared by vacuum hot pressing sintering technology with tungsten carbide aluminum powder as raw material and cobalt as sintering agent. It has high density, high microhardness and high bending strength. However, cobalt is a rare metal with high cost and difficult to meet the requirements of economic development.

Contents of the invention

The technical problem solved by the present invention is to provide a tungsten carbide aluminum-iron-nickel hard alloy, which has performance equivalent to that of tungsten carbide aluminum-cobalt hard alloy, high density, high microhardness and high bending strength, but the cost is relatively high. Low.

The invention provides a tungsten carbide aluminum-iron nickel hard alloy, which comprises tungsten carbide aluminum, iron and nickel; wherein, the molar ratio of iron and nickel is 1:5-5:1.

Preferably, the ratio of the mass of tungsten carbide aluminum to the total mass of iron and nickel is 5-15:1.

Preferably, the molar ratio of iron to nickel is 1:3-3:1.

Preferably, the aluminum tungsten carbide has an atomic ratio shown in formula (I):

(W _1-x Al _x )C (I);

In formula (I), 0.10≤x≤0.86.

The present invention also provides a preparation method of tungsten carbide aluminum-iron-nickel hard alloy, comprising the following steps:

Mix tungsten carbide aluminum powder, iron powder and nickel powder to obtain a mixture;

cold pressing the mixture to obtain a green compact;

The compact is vacuum sintered to obtain tungsten carbide aluminum-iron-nickel hard alloy.

Preferably, the pressure of the cold pressing is 400MPa-500MPa.

Preferably, the vacuum sintering temperature is 1300°C-1500°C.

Preferably, the vacuum sintering time is 0.5h-2h.

Preferably, the vacuum degree of the vacuum sintering is less than 1×10 ^-3 Pa.

Preferably, it also includes: polishing the obtained tungsten carbide aluminum-iron-nickel hard alloy.

Compared with the prior art, the present invention uses tungsten carbide aluminum powder, iron powder and nickel powder as raw materials to prepare tungsten carbide aluminum-iron-nickel hard alloy through vacuum high-temperature sintering technology. Nickel has good mechanical strength, ductility and corrosion resistance; iron has high hardness, good ductility, plasticity and thermal conductivity, iron and nickel are added to tungsten carbide at a molar ratio of 1:5 to 5:1 Aluminum can make tungsten carbide aluminum alloy have high density, high microhardness and high bending strength, which has comparable performance with cobalt-added tungsten carbide aluminum alloy. Since iron and nickel are widely distributed in nature, materials are easy to obtain, and the cost is low, the tungsten carbide aluminum-iron-nickel hard alloy prepared by the present invention not only has high density, high microhardness and high bending strength, but also has low cost and is economical and applicable .

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

The embodiment of the invention discloses a tungsten carbide aluminum-iron nickel hard alloy, which comprises tungsten carbide aluminum, iron and nickel; wherein, the molar ratio of iron and nickel is 1:5-5:1.

The ratio of the mass of tungsten carbide aluminum to the total mass of iron and nickel is 5-15:1, preferably 7-12:1.

The aluminum tungsten carbide preferably has an atomic ratio shown in formula (I):

(W _1-x Al _x )C (I);

In formula (I), preferably x satisfies 0.10≤x≤0.86, more preferably x satisfies 0.20≤x≤0.70.

In the present invention, aluminum tungsten carbide is the hard phase, and iron and nickel are the sintering agents. Nickel is a hard and malleable metal with a melting point of 1453°C. Nickel has strong corrosion resistance and is mostly used in alloy manufacturing and metal plating to increase the ductility and corrosion resistance of the substrate. Iron is a flexible and malleable metal with high hardness, good ductility, plasticity and thermal conductivity. In the present invention, iron and nickel are used as sintering agents, and iron and nickel are added to tungsten carbide aluminum at a molar ratio of 1:5 to 5:1 so that the sintering system can obtain a suitable sintering temperature and sintering atmosphere, and improve the sintering performance. Speed, thereby improving the strength of the tungsten carbide aluminum-iron-nickel cemented carbide sintered body, so that the tungsten-aluminum-iron-nickel cemented carbide sintered body has good metallurgical properties. In the present invention, the molar ratio of iron to nickel is 1:5-5:1, preferably 1:3-3:1, more preferably 3:1, 1:1 or 3:1.

The invention also discloses a preparation method of tungsten carbide aluminum-iron-nickel hard alloy, comprising the following steps:

Mix tungsten carbide aluminum powder, iron powder and nickel powder to obtain a mixture;

cold pressing the mixture to obtain a green compact;

The compact is vacuum sintered to obtain tungsten carbide aluminum-iron-nickel hard alloy.

In the present invention, the raw material for preparing tungsten carbide aluminum-iron nickel hard alloy includes tungsten carbide aluminum powder. The aluminum tungsten carbide powder preferably has an atomic ratio shown in formula (I):

(W _1-x Al _x )C (I);

In formula (I), preferably x satisfies 0.10≤x≤0.86, more preferably x satisfies 0.20≤x≤0.70. The present invention has no special limitation on the source of the aluminum tungsten carbide powder, which can be prepared according to the method disclosed in Chinese patent CN01129544.9. The raw materials for preparing tungsten carbide aluminum-iron-nickel cemented carbide in the present invention also include iron powder and nickel powder, and there is no special limitation on the source of the iron powder and nickel powder.

The mixing is firstly mixing iron powder and nickel powder according to the molar ratio of 1:5 to 5:1, the molar ratio of iron and nickel is preferably 1:3 to 3:1, more preferably 3:1, 1:1 or 3:1; then the mixture of tungsten carbide aluminum powder, iron powder and nickel powder is mixed in a mass ratio of 5-15:1, preferably in a mass ratio of 7-12:1.

The present invention is not particularly limited to the method for mixing, can use the method well-known to those skilled in the art, as: mix powder or The mixture is mechanically mixed evenly. For mixing, dry mixing and wet mixing methods well known to those skilled in the art can be used. The wet mixing liquid medium can be liquid substances such as alcohol, acetone or water. The present invention is preferably wet mixing, and the medium is preferably alcohol.

After the mixture is obtained, it is cold-pressed in a mold according to a method well known to those skilled in the art to obtain a compact; the pressure of the cold-press is preferably 400MPa-500MPa, more preferably 430MPa-470MPa.

After the compact is obtained, it is vacuum sintered to obtain tungsten carbide aluminum-iron-nickel hard alloy. In the present invention, the vacuum sintering adopts a vacuum sintering device, and the vacuum condition is increased while applying temperature during the sintering process, so as to promote the combination and bond formation between metal particles, and realize the densification and sintering of the powder. Since the temperature in the alloy sintering process is generally high, vacuum high-temperature sintering can not only inhibit the oxidation behavior of particles during sintering, but also ensure the uniformity of shrinkage during sintering. The vacuum sintering method has simple process, convenient operation and large production capacity. During the vacuum sintering process, the vacuum degree is less than 1×10 ^-3 Pa, preferably 1×10 ^-4 Pa to 1×10 ^-3 Pa; the sintering temperature is 1300°C to 1500°C, preferably 1400°C to 1450°C; The time is 0.5h to 2h, preferably 1h to 1.5h.

The tungsten carbide aluminum-iron nickel cemented carbide obtained through sintering exists in the form of a sintered body, and various products can be obtained after polishing, grinding, forging and other processing of the tungsten carbide aluminum-iron nickel cemented carbide.

After the tungsten carbide aluminum-iron nickel hard alloy was obtained, X-ray diffraction analysis was carried out on it. The results showed that the tungsten carbide aluminum-iron nickel hard alloy was very stable in the process of vacuum high temperature sintering, no decomposition, good crystallization, and no It forms intermetallic compounds with iron and nickel, and the finally obtained tungsten carbide aluminum-iron-nickel hard alloy has a stable structure and a significantly improved crystallinity.

Density measurement and SEM analysis of the obtained tungsten carbide-aluminum-iron-nickel hard alloy show that the density of tungsten carbide-aluminum-iron-nickel hard alloy is very high.

The relative density, microhardness and bending strength of the obtained tungsten carbide aluminum-iron-nickel hard alloy were measured, and the results showed that the obtained tungsten carbide aluminum-iron-nickel hard alloy had high density, high microhardness and high bending strength .

The invention uses tungsten carbide aluminum powder, iron powder and nickel powder as raw materials to prepare tungsten carbide aluminum-iron nickel hard alloy through vacuum high-temperature sintering technology. Nickel has good mechanical strength, ductility and corrosion resistance; iron has high hardness, good ductility, plasticity and thermal conductivity, iron and nickel are added to tungsten carbide at a molar ratio of 1:5 to 5:1 Aluminum can make tungsten carbide aluminum alloy have high density, high microhardness and high bending strength, which has comparable performance with cobalt-added tungsten carbide aluminum alloy. Since iron and nickel are widely distributed in nature, materials are easy to obtain, and the cost is low, the tungsten carbide aluminum-iron-nickel hard alloy prepared by the present invention not only has high density, high microhardness and high bending strength, but also has low cost and is economical and applicable . At the same time, the preparation method of the tungsten carbide aluminum-iron-nickel hard alloy provided by the invention has simple process and convenient operation, and can be used for mass production.

In order to further understand the present invention, the tungsten carbide aluminum-iron-nickel cemented carbide provided by the present invention and its preparation method are described below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

Example 1

30 grams of (W _0.5 Al _0.5 ) C powder and 3 grams of iron powder and nickel powder were wet mixed to obtain a mixture, wherein the molar ratio of iron powder and nickel powder was 3:1. After the mixture is cold-pressed at 450MPa, it is sintered under vacuum conditions of 1×10 ^-3 Pa～1×10 ^-4 Pa, the sintering temperature is 1500°C, and the sintering time is 1h to obtain tungsten carbide aluminum-iron-nickel cemented carbide Sintered body. The sintered body is polished to obtain tungsten carbide aluminum-iron-nickel hard alloy.

The X-ray diffraction analysis of the obtained tungsten carbide aluminum-iron-nickel hard alloy shows that the tungsten carbide aluminum-iron-nickel hard alloy is very stable during the vacuum high-temperature sintering process, does not decompose, crystallizes well, and does not interact with iron , nickel forms an intermetallic compound, and the final obtained tungsten carbide aluminum-iron-nickel cemented carbide has a stable structure and a significantly improved crystallinity.

Density measurement and SEM analysis of the obtained tungsten carbide-aluminum-iron-nickel hard alloy show that the density of tungsten carbide-aluminum-iron-nickel hard alloy is very high.

The relative density, fiber hardness and bending strength of tungsten carbide aluminum-iron-nickel hard alloy were measured. The results showed that the obtained tungsten carbide-iron-nickel hard alloy had a relative density of 99% and a microhardness of 2100Kg/mm ² , the bending strength is 1552MPa.

Example 2

30 g of (W _0.5 Al _0.5 ) C powder and 3 g of iron powder and nickel powder were wet mixed to obtain a mixture, wherein the molar ratio of iron powder and nickel powder was 1:1. After the mixture is cold-pressed at 450MPa, it is sintered under vacuum conditions of 1×10 ^-3 Pa to 1×10 ^-4 Pa, the sintering temperature is 1470°C, and the sintering time is 1h to obtain tungsten carbide aluminum-iron-nickel cemented carbide Sintered body. After the sintered body is polished, the tungsten carbide aluminum-iron-nickel hard alloy is obtained.

The X-ray diffraction analysis of the obtained tungsten carbide aluminum-iron-nickel hard alloy shows that the tungsten carbide aluminum-iron-nickel hard alloy is very stable during the vacuum high-temperature sintering process, does not decompose, crystallizes well, and does not interact with iron , nickel forms an intermetallic compound, and the final obtained tungsten carbide aluminum-iron-nickel cemented carbide has a stable structure and a significantly improved crystallinity.

Density measurement and SEM analysis of the obtained tungsten carbide-aluminum-iron-nickel hard alloy show that the density of tungsten carbide-aluminum-iron-nickel hard alloy is very high.

Carry out relative density, fiber hardness and flexural strength to tungsten carbide aluminum-iron-nickel hard alloy and measure, and measurement result shows, the relative density of the obtained tungsten carbide-iron-nickel hard alloy is 98%, microhardness is 2010Kg/ mm ² , the bending strength is 1466MPa.

Example 3

A mixture of 30 grams of (W _0.5 Al _0.5 )C powder and 3 grams of iron powder and nickel powder was wet mixed to obtain a mixture, wherein the molar ratio of iron powder and nickel powder was 1:3. After the mixture is cold-pressed at 450MPa, it is sintered under a vacuum condition of 1×10 ^-3 Pa to 1×10 ^-4 Pa, the sintering temperature is 1400°C, and the sintering time is 1h to obtain tungsten carbide aluminum-iron-nickel cemented carbide Sintered body. After the sintered body is polished, the tungsten carbide aluminum-iron-nickel hard alloy is obtained.

The X-ray diffraction analysis of the obtained tungsten carbide aluminum-iron-nickel hard alloy shows that the tungsten carbide aluminum-iron-nickel hard alloy is very stable during the vacuum high-temperature sintering process, does not decompose, crystallizes well, and does not interact with iron , nickel forms an intermetallic compound, and the final obtained tungsten carbide aluminum-iron-nickel cemented carbide has a stable structure and a significantly improved crystallinity.

Density measurement and scanning electron microscope analysis of tungsten carbide aluminum-iron nickel cemented carbide show that the density of tungsten carbide aluminum-iron nickel cemented carbide is very high.

The relative density, fiber hardness and bending strength of tungsten carbide aluminum-iron-nickel hard alloy are measured, and the measurement results show that the relative density of the obtained tungsten carbide-iron-nickel hard alloy is 98%, and the microhardness is 1970Kg/ mm ² , the bending strength is 1417MPa.

Example 4

30 g of (W _0.5 Al _0.5 ) C powder and 4 g of iron powder and nickel powder were wet mixed to obtain a mixture, wherein the molar ratio of iron powder and nickel powder was 3:1. After the mixture is cold-pressed at 450MPa, it is sintered under vacuum conditions of 1×10 ^-3 Pa to 1×10 ^-4 Pa, the sintering temperature is 1390°C, and the sintering time is 1h to obtain tungsten carbide aluminum-iron-nickel cemented carbide Sintered body. After the sintered body is polished, the tungsten carbide aluminum-iron-nickel hard alloy is obtained.

The X-ray diffraction analysis of the obtained tungsten carbide aluminum-iron-nickel hard alloy shows that the tungsten carbide aluminum-iron-nickel hard alloy is very stable during the vacuum high-temperature sintering process, does not decompose, crystallizes well, and does not interact with iron , nickel forms an intermetallic compound, and the final obtained tungsten carbide aluminum-iron-nickel cemented carbide has a stable structure and a significantly improved crystallinity.

Density measurement and scanning electron microscope analysis of tungsten carbide aluminum-iron nickel cemented carbide show that the density of tungsten carbide aluminum-iron nickel cemented carbide is very high.

Carry out relative density, fiber hardness and flexural strength to tungsten carbide aluminum-iron-nickel hard alloy to measure, and measurement result shows, the relative density of the obtained tungsten carbide-iron-nickel hard alloy is 99%, microhardness is 1948Kg/ mm ² , the bending strength is 1630MPa.

Example 5

30 g of (W _0.5 Al _0.5 )C powder and 5 g of iron powder and nickel powder were wet-mixed to obtain a mixture, wherein the molar ratio of iron powder and nickel powder was 3:1. After the mixture is cold-pressed at 450MPa, it is sintered under a vacuum condition of 1×10 ^-3 Pa to 1×10 ^-4 Pa, the sintering temperature is 1380°C, and the sintering time is 1h to obtain tungsten carbide aluminum-iron-nickel cemented carbide Sintered body. After the sintered body is polished, the tungsten carbide aluminum-iron-nickel hard alloy is obtained.

The X-ray diffraction analysis of the obtained tungsten carbide aluminum-iron-nickel hard alloy shows that the tungsten carbide aluminum-iron-nickel hard alloy is very stable in the vacuum high-temperature sintering process, does not decompose, crystallizes well, and does not interact with iron , nickel forms an intermetallic compound, and the final obtained tungsten carbide aluminum-iron-nickel cemented carbide has a stable structure and a significantly improved crystallinity.

Density measurement and SEM analysis of the obtained tungsten carbide-aluminum-iron-nickel cemented carbide showed that the density of tungsten carbide-aluminum-iron-nickel cemented carbide was very high.

Carry out relative density, fiber hardness and flexural strength to tungsten carbide aluminum-iron-nickel hard alloy to measure, measure result shows, the relative density of the obtained tungsten carbide-iron-nickel hard alloy is 98%, microhardness is 1846Kg/ mm ² , the bending strength is 1745MPa.

Comparative example 1

Mix 9 grams of (W _0.5 Al _0.5 )C powder with 1.50 grams of cobalt powder, put it into a graphite grinding tool, and sinter it under a vacuum condition of 1×10 ^-3 Pa. The sintering temperature is 1500°C, the pressure is 20MPa, and the sintering time is for 15 minutes to obtain a tungsten carbide aluminum-cobalt alloy sintered body. The tungsten carbide aluminum-cobalt alloy sintered body is polished to obtain the tungsten carbide aluminum-cobalt alloy. The relative density, fiber hardness and bending strength of the tungsten carbide aluminum-cobalt alloy were measured. The results showed that the obtained tungsten carbide aluminum-cobalt alloy had a relative density of 99%, a microhardness of 1876Kg/mm ² and a bending strength of 1130MPa .

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. a preparation method of tungsten carbide aluminum-iron-nickel carbide, comprising the following steps: Mix tungsten carbide aluminum powder, iron powder and nickel powder to obtain a mixture, wherein firstly the iron powder and nickel powder are mixed according to the molar ratio of 1:3 to 3:1, and then the tungsten carbide aluminum powder and the iron powder and nickel powder are mixed The mixture is mixed according to the mass ratio of 5-15:1; cold pressing the mixture to obtain a green compact; The compact is vacuum sintered to obtain tungsten carbide aluminum-iron-nickel hard alloy. 2. The preparation method according to claim 1, characterized in that, the pressure of the cold pressing is 400MPa-500MPa. 3. The preparation method according to claim 1, characterized in that the temperature of the vacuum sintering is 1300°C-1500°C. 4. The preparation method according to claim 1, characterized in that the vacuum sintering time is 0.5h-2h. 5. The preparation method according to claim 1, characterized in that the vacuum degree of the vacuum sintering is less than 1×10 ⁻³ Pa. 6. The preparation method according to any one of claims 1-5, further comprising: polishing the obtained tungsten carbide aluminum-iron nickel cemented carbide.