CN102268566B - High conductivity and high wear resistance copper-molybdenum alloy material and preparation method thereof - Google Patents

Abstract

A copper-molybdenum alloy material with high conductivity and high wear resistance, which is composed of matrix alloy: Cu, friction component: Al ₂ O ₃ , lubricating component: MoS ₂ , high-temperature component: Mo and copper, and Al ₂ O ₃ , The powders of MoS ₂ , Mo and copper are mixed according to the proportion, and put into the stainless steel grinding tank of the high-energy ball mill to make the mixed powder material; the mixed powder material is sent to the press, pre-pressed into a billet, and the billet is sent to Put it into a cold isostatic press for pressing, and send the statically pressed blank into a vacuum sintering furnace for sintering to obtain a product. In the present invention, the mass fraction ranges of the above-mentioned components are determined on the basis of a large number of experiments. Experiments have proved that ingredients within this range can make the reaction go smoothly and achieve the best material performance.

Description

A kind of copper-molybdenum alloy material with high conductivity and high wear resistance and preparation method thereof

technical field

The invention relates to a copper-based composite material, in particular to a copper-molybdenum alloy material with high conductivity and high wear resistance and a preparation method thereof.

Background technique

With the progress and development of science and technology, high-speed, high-current electric friction materials have been widely used, such as in the field of rail transit, various switches of power transmission and transformation systems, various conductive contacts of communication systems, and industrial controllers. Various contactors, plug and unplug conductive parts, etc. This kind of friction-conductive friction material has the following characteristics: frictional contact and conductive contact coexist, service life, reliability and electrical conductivity are required to be equal, and the material is required to have the function of friction-conduction integration at the same time.

In the current-carrying friction pair, there are problems such as friction and wear and poor conductive contact. The friction of materials will cause energy loss, friction heating and other problems, which will deteriorate the performance of materials and reduce the life of related products. Wear and tear can cause material loss, reduced service life, and reduced contact reliability. It is difficult to meet the basic requirements for the service life of materials under high-life and no-copy service conditions. Poor conductive contact can cause problems such as reduced conductive efficiency and reduced reliability. Poor conductive contact can increase the off-line rate of guide rail/slider. For example, the off-line rate of foreign high-speed railways is less than 5%. However, due to the design of wires/sliders and line management in my country, the current off-line rate is as high as 15%, and the current quality is low. Restrict the effective power of the electric locomotive to play.

Arcing is one of the other main characteristics of current-carrying friction and wear. There is a strong correlation between arcing and friction and wear characteristics: arc damage leads to damage to the contact surface, resulting in a substantial reduction in surface integrity and uniformity; incomplete surface contact will lead to significant deterioration of electrical contact performance, making The contact resistance increases, and the tendency of arcing increases, which in turn reduces the performance of the surface material and promotes the further deterioration of the friction and wear performance. Therefore, improving the performance of friction/current-carrying materials must continuously improve the surface contact state. The addition of solid lubricants to the metal matrix can improve the friction and wear properties of friction/current-carrying materials.

Copper has high electrical conductivity, thermal conductivity and excellent processing performance, but the melting point, room temperature strength and high temperature strength of pure copper are low, which makes it difficult to meet the requirements of harsh working conditions. The traditional method to improve the strength of copper alloy is the alloying method. For example, Cu-Be alloy QBe2 can obtain a tensile strength of 1350MPa after 48% cold deformation after aging, but the electrical conductivity is only 19.5% IACS.

Existing copper alloys are difficult to balance high conductivity and high strength, and composite strengthening not only does not significantly reduce the conductivity of the copper matrix, but also improves the room temperature and high temperature properties of the matrix, becoming a high-strength, high-conductivity copper-based composite material. main means of reinforcement. The main methods are:

(1) Al ₂ O ₃ dispersion strengthened copper alloy

Add directly to the copper matrix or in-situ generate dispersed second phase particles through a certain process, comprehensively utilize the deformation strengthening and the dispersion strengthening of the second phase particles to obtain high material strength, and at the same time reduce the solid solution in the copper matrix as much as possible The content of solute atoms and impurity atoms in the state makes it a new type of copper-based composite material with a conductivity close to that of pure copper. Among them, Al ₂ O ₃ reinforced particles not only do not significantly reduce the conductivity of the matrix, but also are used emphatically because of their remarkable room-temperature and high-temperature performance of the reinforced matrix. However, as the amount of Al ₂ O3 particles increases, the electrical conductivity of the material decreases significantly while the wear resistance increases.

(2) Graphite/copper self-lubricating material

Based on copper-based powder metallurgy materials, graphite materials that are prone to shear are added to form a continuous/self-generated lubricating film on the friction surface, which improves the contact behavior and significantly improves the current-carrying and friction and wear properties. The research shows that the friction coefficient stability, current-carrying efficiency and current-carrying stability of graphite copper materials are significantly higher than those of ordinary copper-based materials. However, copper and graphite are incompatible with each other, and no chemical reaction occurs even at 1280 ° C. In addition, the specific gravity of copper and graphite is quite different, resulting in uneven mixing of materials during molding. The combination of copper and graphite is a pseudo-alloy, and there are many defects in the material interface, which seriously restricts the improvement of its strength and lubricating performance. In addition, copper/graphite self-lubricating materials have low flexural strength and poor toughness, especially when the temperature is greater than or equal to 300°C, the matrix strength and wear resistance decrease significantly.

(3) MoS ₂ /copper-based self-lubricating materials

During the sintering process under the protection of hydrogen, the lubricating component MoS ₂ in the copper matrix composite reacts with the matrix copper to form copper molybdenum sulfide, Cu sulfide and metal Mo; and with the increase of MoS ₂ content, the sintered products have change regularly. Because the Cu-MoS ₂ composite material contains molybdenum disulfide, it can fully provide and supplement solid lubricant, so that the repair and damage process of the lubricating film can reach a dynamic balance; in addition, the Cu sulfide has a good chemical affinity with the matrix material , the solid lubricating film formed by it and the matrix particles are easily bonded together, which increases the mechanical engagement between the solid lubricating film and the matrix, makes the solid lubricating film and the matrix have better adhesion, higher bonding strength, and is not easy to break and fall off.

(4) Molybdenum-copper alloy

Molybdenum metal and its alloys have excellent physical, chemical and mechanical properties. It has: high melting point, high temperature strength, low expansion coefficient, low specific heat, good thermal conductivity, excellent corrosion resistance and high temperature wear resistance, Excellent thermal shock resistance and thermal fatigue resistance. Molybdenum is one of the elements with the best electrical conductivity and thermal conductivity ratio in metals except gold, silver, copper and other metals, so it has become a very promising application in high-tech fields such as electronics industry, defense industry, aerospace industry, nuclear industry, etc. Advanced materials have become an important raw material and an irreplaceable strategic material in the national economy, and have broad development prospects.

Utilizing the excellent properties of copper and molybdenum, traditional Mo-Cu alloys are used as vacuum contact heads, conductive heat dissipation elements, solid dynamic seals, ribs for sliding friction, water-cooled electrode heads for high-temperature furnaces, and electrical machining electrodes in the electronics industry. widely used. These alloys mainly include molybdenum-based alloys such as Mo-30Cu and Mo-50Cu. Because the Mo-Cu alloy with low expansion coefficient and Cu with high thermal conductivity is prepared by powder metallurgy method, it is a pseudo alloy, and the alloy is mainly composed of molybdenum and the copper content is low, so the conductivity of the alloy is higher than that of pure copper. Dropped a lot.

It can be seen from the above research that the copper-based alloys and molybdenum alloys currently studied cannot meet the following performance indicators: the tensile strength of the alloy material is >400MPa, the hardness is >90HB, and under the conditions of high-speed sliding and high current (speed greater than 300m/s , current greater than 1kA) material friction coefficient <0.2, electrical conductivity ≥ 70% IACS. Among various copper-based and molybdenum-based materials, materials with such excellent high conductivity and high wear resistance have not been reported. Therefore, it is necessary and urgent to develop a copper-molybdenum alloy with high electrical conductivity and high wear resistance.

Contents of the invention

The object of the present invention is to provide a copper-molybdenum alloy with high electrical conductivity and high temperature wear resistance. Friction components, lubricating components and high temperature components are dispersed in the alloy. To reduce wear, anti-wear effect.

The technical scheme adopted by the present invention to achieve the above object is: a high-conductivity and high-wear-resistant copper-molybdenum alloy material, the raw material is composed of matrix alloy: Cu, friction component: Al ₂ O ₃ , lubricating component: MoS ₂ , high-temperature component : Composition of Mo, the mass fraction of each material is: Al ₂ O ₃ 0.1-0.5%, MoS ₂ 0.1-0.5%, Mo 1-5%, and the rest is copper. In the prepared alloy, Al ₂ O ₃ , MoS ₂ and Mo are evenly distributed in the copper matrix.

Cu powder containing Al ₂ O ₃ , MoS ₂ and Mo powder reduction raw materials prepared by redox within the high-conductivity and high-wear-resistant copper-molybdenum alloy, through high-energy ball milling mechanical alloying, pre-pressing, cold isostatic pressing, and vacuum reduction sintering prepared by the process.

The specific preparation method is as follows:

1. Powders of Al ₂ O ₃ with a mass fraction of 0.1-0.5%, MoS ₂ with a mass fraction of 0.1-0.5%, Mo with a mass fraction of 1-5%, and copper with a mass fraction of 94-98.8% are prepared according to After the ratio is prepared, put it into the stainless steel grinding tank of the high-energy ball mill, mix and grind for 5-25 hours, operate in vacuum, the vacuum degree is not less than 10 ^-2 Pa, and dry the argon gas protection to obtain the mixed powder material;

2. Send the mixed powder material into the press, pre-press it into a billet, and hold the pressure for 8-15 minutes;

3. Send the pre-pressed billet into the cold isostatic press for pressing at a pressure of 180-220MPa and keep the pressure for 8-20min;

4. Send the billets statically pressed in step 3 into a vacuum sintering furnace for sintering, the sintering temperature is 950-1050°C, the sintering time is 1-2h, hydrogen protection, the heating rate is 10°C/min, and the product is obtained.

The beneficial effects of the present invention are:

1. In the present invention, the mass fraction ranges of the above-mentioned components are determined on the basis of a large number of experiments. Experiments have proved that the ingredients within this range can make the reaction proceed smoothly and make the material performance the best.

2. The high-conductivity and high-wear-resistant copper-molybdenum alloy prepared by the present invention has the following components: the mass fraction of Al ₂ O ₃ is 0.1-0.5%, the mass fraction of MoS ₂ is 0.1-0.5%, and the mass fraction of Mo It is 1-5%, and the rest is Cu.

3. The prepared highly conductive and wear-resistant copper-molybdenum alloy material has excellent performance: tensile strength ≥ 400MPa, hardness ≥ 90HB, under the conditions of high-speed sliding and high current (speed greater than 300m/s, current greater than 1kA) material friction coefficient < 0.2, conductivity ≥ 70% IACS. The preparation and production process is simple and easy to control, and the enhanced particle size and uniform distribution.

4. In the highly conductive and wear-resistant copper-molybdenum alloy material prepared by the present invention, the Al ₂ O ₃ phase plays an anti-wear effect, the MoS ₂ phase plays a wear-reducing effect, and the Mo phase is fine and uniformly dispersed in the Cu matrix, both It does not form a network structure that has a large negative impact on conductivity, and can give full play to the dispersion strengthening effect of the Mo phase. The prepared alloy has excellent comprehensive physical and mechanical properties, so the invention has very broad application prospects.

Detailed ways

A copper-molybdenum alloy material with high conductivity and high wear resistance. The raw material is composed of matrix alloy: Cu, friction component: Al ₂ O ₃ , lubricating component: MoS ₂ and high temperature component: Mo. _In the prepared alloy, the mass fraction of _Al2O3 is 0.1-0.5%, the mass fraction of _MoS2 is 0.1-0.5%, the mass fraction of Mo is 1-5%, and the rest is copper. In the prepared alloy, Al ₂ O ₃ , MoS ₂ and Mo are evenly distributed in the copper matrix.

Cu powder containing Al ₂ O ₃ , MoS ₂ and Mo powder reduction raw materials prepared by redox within the high-conductivity and high-wear-resistant copper-molybdenum alloy, through high-energy ball milling mechanical alloying, pre-pressing, cold isostatic pressing, and vacuum reduction sintering prepared by the process.

The specific preparation method is as follows:

1. Powders of Al ₂ O ₃ with a mass fraction of 0.1-0.5%, MoS ₂ with a mass fraction of 0.1-0.5%, Mo with a mass fraction of 1-5%, and copper with a mass fraction of 94-98.8% are prepared according to After the ratio is prepared, put it into the stainless steel grinding tank of the high-energy ball mill, mix and grind for 5-25 hours, operate in vacuum, the vacuum degree is not less than 10 ^-2 Pa, and dry the argon gas protection to obtain the mixed powder material;

2. Send the mixed powder material into the press, pre-press it into a billet, and hold the pressure for 8-15 minutes;

3. Send the pre-pressed billet into the cold isostatic press for pressing at a pressure of 180-220MPa and keep the pressure for 8-20min;

4. Send the billets statically pressed in step 3 into a vacuum sintering furnace for sintering, the sintering temperature is 950-1050°C, the sintering time is 1-2h, hydrogen protection, the heating rate is 10°C/min, and the product is obtained.

Example 1

A copper-molybdenum alloy material with high conductivity and high wear resistance and its preparation method: _the raw materials used are: Cu powder containing _Al2O3 , _MoS2 powder, and pure molybdenum powder; the specific mass fraction of each component is as follows Down:

Al ₂ O ₃ : 0.1%

MoS ₂ : 0.1%

Mo: 1%

The rest is Cu, and the impurity content is <0.1%.

Put the above-mentioned powders mixed in proportion into the stainless steel grinding tank of the high-energy ball mill, and mix and run for 15 hours. During the powder mixing and grinding process, vacuum operation, vacuum degree 10 ^-2 Pa, filled with dry Ar gas for protection, rotation speed 1400r/ min;

The mixed powder after high-energy ball milling is pre-pressed under a 100T press, and the pressure is maintained for 10 minutes;

The pre-pressed blank is pressed on a cold isostatic press with a pressure of 180 MPa and a pressure hold of 10 minutes;

Sinter in a vacuum sintering furnace with a sintering temperature of 950°C, a sintering time of 1.5h, a vacuum of 10 ^-2 Pa, hydrogen protection, a heating rate of 10°C/min, and release from the furnace to obtain the product.

Example 2

This example prepares a highly conductive and wear-resistant copper-molybdenum alloy material. The raw materials used are: Cu powder containing _Al2O3 , _MoS2 powder, and pure molybdenum powder; the specific proportions of the mass fractions _of each component are as follows:

Al ₂ O ₃ : 0.2%

MoS ₂ : 0.2%

Mo: 2%

The rest is Cu, and the impurity content is less than 0.1%.

Put the above-mentioned powders mixed in proportion into the stainless steel grinding tank of the high-energy ball mill, and mix and run for 20 hours. During the powder mixing and grinding process, vacuum operation, vacuum degree 10 ^-3 Pa, filled with dry Ar gas for protection, rotation speed 1500r/ min;

The mixed powder after high-energy ball milling is pre-pressed under a 100T press, and the pressure is maintained for 10 minutes;

The pre-pressed blank is pressed on a cold isostatic press with a pressure of 200 MPa and a pressure hold of 10 minutes;

Sinter in a vacuum sintering furnace at a sintering temperature of 1000°C, a sintering time of 2h, a vacuum of 10 ^-3 Pa, hydrogen protection, and a heating rate of 10°C/min.

Example 3

This example prepares a highly conductive and wear-resistant copper-molybdenum alloy material. The raw materials used are: Cu powder containing _Al2O3 , _MoS2 powder, and pure molybdenum powder; the specific proportions of the mass fractions _of each component are as follows:

Al ₂ O ₃ : 0.3%

MoS ₂ : 0.3%

Mo: 3%

The rest is Cu, and the impurity content is less than 0.1%.

Put the above proportioned powder into the stainless steel grinding tank of the high-energy ball mill, and mix and run for 22 hours. During the powder mixing and grinding process, vacuum operation, vacuum degree 10 ^-3 Pa, filled with dry Ar gas for protection, rotation speed 1600r/min ;

The mixed powder after high-energy ball milling is pre-pressed under a 100T press, and the pressure is maintained for 12 minutes;

The pre-pressed blank is pressed on a cold isostatic press with a pressure of 200 MPa and a pressure hold of 15 minutes;

Sinter in a vacuum sintering furnace at a sintering temperature of 1050°C, a sintering time of 2h, a vacuum of 10 ^-3 Pa, hydrogen protection, and a heating rate of 10°C/min, and the product is obtained.

Example 4

This example prepares a highly conductive and wear-resistant copper-molybdenum alloy material. The raw materials used are: Cu powder containing _Al2O3 , _MoS2 powder, and pure molybdenum powder; the specific proportions of the mass fractions _of each component are as follows:

Al ₂ O ₃ : 0.3%

_MoS2 : 0.5%

Mo: 5%

The rest is Cu, and the impurity content is less than 0.1%.

Put the above proportioned powder into the stainless steel grinding tank of the high-energy ball mill, and mix and run for 24 hours. During the powder mixing and grinding process, vacuum operation, vacuum degree 10 ^-3 Pa, filled with dry Ar gas for protection, rotation speed 1600r/min ;

The mixed powder after high-energy ball milling is pre-pressed under a 100T press, and the pressure is maintained for 15 minutes;

The pre-pressed blank is pressed on a cold isostatic press with a pressure of 220 MPa and a pressure hold of 15 minutes;

Sinter in a vacuum sintering furnace at a sintering temperature of 1050°C, a sintering time of 2h, a vacuum of 10 ^-3 Pa, hydrogen protection, and a heating rate of 10°C/min, and the product is obtained.

Claims (2)

1. A copper-molybdenum alloy material with high conductivity and high wear resistance, characterized in that: the raw material is composed of matrix alloy: Cu, friction component: Al ₂ O ₃ , lubricating component: MoS ₂ , high temperature component: Mo, each The mass fraction of raw materials is: Al ₂ O ₃ 0.1-0.5%, MoS ₂ 0.1-0.5%, Mo 1-5%, and the rest is copper; Al ₂ O ₃ , MoS ₂ and Mo in the prepared alloy are evenly distributed in the copper matrix . 2. the preparation method of a kind of highly conductive high wear-resistant copper-molybdenum alloy material according to claim 1, is characterized in that the steps are as follows: 1. Powders of Al ₂ O ₃ with a mass fraction of 0.1-0.5%, MoS ₂ with a mass fraction of 0.1-0.5%, Mo with a mass fraction of 1-5%, and copper with a mass fraction of 94-98.8% are prepared according to After the ratio is prepared, put it into the stainless steel grinding tank of the high-energy ball mill, mix and grind for 5-25 hours, operate in vacuum, the vacuum degree is not less than 10 ^-2 Pa, and dry the argon gas protection to obtain the mixed powder material; 2. Send the mixed powder material into the press, pre-press it into a billet, and hold the pressure for 8-15 minutes; 3. Send the pre-pressed billet into the cold isostatic press for pressing at a pressure of 180-220MPa and keep the pressure for 8-20min; 4. Send the billets statically pressed in step 3 into a vacuum sintering furnace for sintering, the sintering temperature is 950-1050°C, the sintering time is 1-2h, hydrogen protection, the heating rate is 10°C/min, and the product is obtained.