Preparation method of diamond-enhanced high-entropy alloy composite coating
Technical Field
The invention belongs to surface treatment of metal materials, and particularly relates to a method for preparing a diamond-enhanced high-entropy alloy composite coating by cladding.
Background
Mechanical products such as agricultural machines and mining machines often work in harsh abrasive environments, and therefore, their equipment components are subjected to large abrasive wear, which is essentially caused by cutting minute amounts of swarf from the surface of the material. From the abrasive dust obtained in the abrasive wear test in the laboratory, it was observed that it was spiral, curved, etc. like the chips of cutting work, and thus such wear could be solved by increasing the surface hardness. In order to reduce abrasive wear caused by scouring of materials and hard particles on equipment parts, a layer of wear-resistant material is often coated on the surfaces of the equipment parts to improve hardness, so that the equipment parts can be protected. The wear-resistant coating technology can obtain a coating with excellent performance (such as high hardness, wear resistance, corrosion resistance and the like) on the surface of a substrate. The method for preparing the coating comprises thermal spraying, cladding, sputtering, vapor deposition and the like, wherein the thermal spraying process needs special equipment and skilled operation technology, and the coating is relatively thin and has high large-area construction efficiency. Cladding is realized by adding cladding materials on the surface of a base material, melting the cladding materials together with a thin layer on the surface of the base material by using a high-energy beam and then solidifying the cladding materials, and forming a material-adding cladding layer which is metallurgically bonded with the base body on the surface of the base layer. The temperature of the base material is low during sputtering and vapor deposition, and a vacuum environment is needed, so the binding force of the coating is small, the cost is high, and the technology is not suitable for large-size parts. The diamond has extremely high wear resistance, corrosion resistance and low friction coefficient, and the price of the diamond is greatly reduced along with the development of the manufacturing technology of the diamond, so that the diamond can be used for preparing a wear-resistant coating and improving the wear resistance of the coating. The diamond has higher surface energy and is easy to be thermally damaged, so that common metal materials are difficult to wet, and the diamond is easy to graphitize at high temperature, the performance of the diamond is reduced, and the quality of a coating is finally reduced. A cladding technology is adopted to prepare a coating which is chemically and metallurgically combined with a matrix and has higher hardness and wear resistance, on the basis, Cr contained in a cladding material is used as an active element, the connection strength of diamond and the coating can be improved after diamond abrasive particles are pressed in, the diamond is a reinforcing phase, the hardness of the coating is further improved, and finally the wear resistance of parts and components is improved. The coating can not bear large impact load because of containing brittle diamond, and avoids the working condition of larger impact.
According to the invention, abrasive particles are pressed into the coating on the heated cladding layer by using pressure on the cladding layer with similar brazing filler metal components to form the diamond-enhanced high-entropy alloy wear-resistant coating.
Disclosure of Invention
The invention aims to solve the problem of improving the wear resistance and corrosion resistance of a steel matrix, firstly, a coating containing an active element Cr is induction-clad on the surface of the steel matrix, diamond particles are pressed into the medium-temperature coating while the coating has better plasticity after heating, a small amount of reaction is carried out between the diamond and the active element Cr between the coatings at a higher temperature to form carbide, the connection strength between the diamond and the coating is improved, the diamond becomes a reinforcing phase, and the hardness of the coating is further enhanced. Finally, the wear-resistant coating of the diamond enhanced high-entropy alloy is formed.
The method for preparing the diamond enhanced high-entropy alloy composite coating comprises the following process steps:
the method comprises the following steps of firstly, pretreating the surface of a low-carbon steel workpiece, namely polishing the surface by using a grinding wheel or abrasive paper to remove rust, burrs and fins, and removing oil stains on the surface by using acetone.
Step two, ball-milling and mixing mixed powder of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si according to a proportion, wherein the purity of Cu simple substance metal powder is 99.5-100%, and the particle size of the powder is 30-300 mu m; wherein the Ni-Cr-B-Si comprises the following components in percentage by mass: 14-17, B: 2.5-4.5, Si: 3-4.5, C: 0.6-0.9, and the balance of Ni; the Fe-Cr-B-Si comprises the following components in percentage by mass: 12-15, B: 2.5-4.5, Si: 3-4.5, C: 0.6-1.0, and the balance of Fe; the Co-Cr-B-Si comprises the following components in percentage by mass: 15-18, B: 2.5-4.5, Si: 3-4.5, C: 0.5-0.8, and the balance of Co; wherein the mass percentages of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si are as follows: 23-28: 23-27: 22-27: 23 to 28. Ball-milling and mixing by adopting a steel ball-milling tank, wherein the mass ratio of grinding balls to mixed powder is 2.5-3.5: 1, sealing, opening a vacuum valve, vacuumizing for 20-30 minutes, putting the ball-milling tank into a planetary ball mill, rotating at 280-350 r/min, inverting at 32-45 Hz, ball-milling and mixing for 60-80 minutes, and finally preparing high-entropy alloy powder;
thirdly, adopting the high-entropy alloy powder prepared in the second induction heating cladding step on the surface of the steel matrix, wherein the power of an induction power supply is 1 kW-4 kW, the working frequency is 550 kHz-2 MHz, and the heating current is 10A-15A, and preparing a high-entropy alloy coating after cladding, wherein the thickness of the coating is 50-750 mu m;
and step four, after the high-entropy alloy coating is heated under the protection of inert gas, pressing diamonds with the grain size of 3-35 microns on the surface of the high-entropy alloy coating, arranging the diamonds on the surface of the coating according to the area proportion of 30-50%, keeping the temperature of the coating at 320-420 ℃, pressing the diamonds into the coating under the action of the pressure of 180-260 MPa, and continuously preserving the heat for 5-8 min.
And step five, cooling to obtain the diamond enhanced high-entropy alloy coating.
The invention has the beneficial effects that:
(1) the diamond has excellent wear resistance and corrosion resistance, and the diamond is pressed into the medium-temperature coating, so that the graphitization of the diamond caused by high temperature in the cladding process is avoided, and the connection strength of the coating to the diamond is improved by carbide formed by a small amount of interface reaction between the diamond and the coating. In addition, in the cooling process, because the thermal expansion coefficient of the coating is large, compression stress to the diamond is formed due to cold contraction, and the connection strength of the diamond can be further improved.
(2) The coating is formed by induction cladding with mature Ni-Cr-B-Si, Fe-Cr-B-Si and Co-Cr-B-Si, and the high-entropy alloy coating with enhanced carbide is formed, which is beneficial to improving the wear resistance and corrosion resistance of the coating.
(3) Adopts self-fluxing alloy powder of Ni-Cr-B-Si, Fe-Cr-B-Si and Co-Cr-B-Si which are applied in a large quantity to carry out cladding, thereby being beneficial to reducing the cost.
Detailed Description
Example 1:
the method comprises the following steps of firstly, pretreating the surface of a 20 steel workpiece, namely polishing the surface with sand paper to remove rust, burrs and flashes, and removing oil stains on the surface with acetone;
step two, ball-milling and mixing Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si mixed powder according to a certain proportion to prepare high-entropy alloy powder; wherein the purity of the Cu elemental metal powder is 99.5-100%, and the particle size of the powder is 30-300 μm; wherein the Ni-Cr-B-Si comprises the following components in percentage by mass: 14-17, B: 2.5-4.5, Si: 3-4.5, C: 0.6-0.9, and the balance of Ni; the Fe-Cr-B-Si comprises the following components in percentage by mass: 12-15, B: 2.5-4.5, Si: 3-4.5, C: 0.6-1.0, and the balance of Fe; the Co-Cr-B-Si comprises the following components in percentage by mass: 15-18, B: 2.5-4.5, Si: 3-4.5, C: 0.5-0.8, and the balance of Co; wherein the mass percentages of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si are as follows: 23: 23: 27: 27. the ball milling and mixing are carried out by adopting a steel ball milling tank, the mass ratio of the milling balls to the mixed powder is 2.5: 1, a vacuum valve is opened after the sealing and the vacuum pumping is carried out for 20 minutes, then the ball milling tank is placed into a planetary ball mill, the rotating speed is 350 r/min, the inversion frequency is 45 Hz, and the ball milling and mixing time is 60 minutes.
Thirdly, cladding the high-entropy alloy powder prepared in the second step on the surface of the steel substrate by adopting induction heating, wherein the power of an induction power supply is 4kW, the working frequency of the induction heating is 550 kHz, and the induction heating current is 15A, and a high-entropy alloy coating is prepared after cladding, and the thickness of the coating is 550 microns;
and step four, heating the high-entropy alloy coating to 320-350 ℃ under the protection of inert gas, pressing diamonds with the grain size of 3-20 microns on the surface of the high-entropy alloy coating, arranging the diamonds on the surface of the coating according to the area proportion of 30%, pressing the diamonds into the coating under the action of 260MPa pressure, and continuously preserving heat for 5 min.
And step five, cooling to obtain the diamond enhanced high-entropy alloy coating.
Experiments show that the coating obtained after the induction cladding on the surface of the steel matrix has smooth appearance, basically has no defects of pores, cracks and the like, has fine coating structure grains, and is distributed with fine Cr in the FCC high-entropy alloy matrix7C3After the diamond is pressed in, the surface of the coating is basically uniform, and carbides are formed on the surface of the diamond through the observation of a scanning electron microscope, so that the coating can improve the wear resistance of the wear-resistant particles. Because the diamond has excellent wear resistance and hardness, the wear resistance of the carbon steel 20 steel is improved by more than 6.5 times after the coating is prepared.
Example 2:
the method comprises the following steps of firstly, pretreating the surface of a 45 steel workpiece, namely polishing the surface by using a grinding wheel or abrasive paper to remove rust, burrs and fins, and removing oil stains on the surface by using acetone;
step two, ball-milling and mixing mixed powder of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si according to a proportion, wherein the purity of Cu simple substance metal powder is 99.5-100%, and the particle size of the powder is 30-300 mu m; wherein the Ni-Cr-B-Si comprises the following components in percentage by mass: 14-17, B: 2.5-4.5, Si: 3-4.5, C: 0.6-0.9, and the balance of Ni; the Fe-Cr-B-Si comprises the following components in percentage by mass: 12-15, B: 2.5-4.5, Si: 3-4.5, C: 0.6-1.0, and the balance of Fe; the Co-Cr-B-Si comprises the following components in percentage by mass: 15-18, B: 2.5-4.5, Si: 3-4.5, C: 0.5-0.8, and the balance of Co; wherein the mass percentages of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si are as follows: 28: 23: 22: 23. ball-milling and mixing are carried out by adopting a steel ball-milling tank, the mass ratio of the milling balls to the mixed powder is 3.5: 1, a vacuum valve is opened after sealing, vacuum pumping is carried out for 30 minutes, then the ball-milling tank is placed into a planetary ball mill, the rotating speed is 280 r/min, the inversion frequency is 32 Hz, and the ball-milling and mixing time is 60 minutes. And preparing the high-entropy alloy powder.
Thirdly, adopting the high-entropy alloy powder prepared in the second induction heating cladding step on the surface of the steel matrix, wherein the power of an induction power supply is 1 kW, the working frequency of induction heating is 2MHz, the induction heating current is 10A, and preparing a high-entropy alloy coating after cladding, wherein the thickness of the coating is 50 microns;
and step four, heating the high-entropy alloy coating to 320-340 ℃ under the protection of inert gas, pressing diamonds with the grain size of 10-15 microns into the surface of the high-entropy alloy coating, arranging the diamonds on the surface of the coating according to 40% of area proportion, pressing the diamonds into the coating under the action of 260MPa, and continuously preserving heat for 5 min.
And step five, cooling to obtain the diamond enhanced high-entropy alloy coating.
Experiments show that the coating obtained after induction cladding has smooth appearance, basically has no defects of pores, cracks and the like, has fine coating structure grains, and is distributed with fine Cr in an FCC high-entropy alloy matrix7C3After the diamond is pressed in, the surface of the coating is basically uniform, carbides are formed on the surface of the diamond through observation of a scanning electron microscope, the coating can improve the wear resistance of wear-resistant particles, and the wear resistance of the carbon steel 45 steel is improved by more than 4.9 times after the coating is prepared due to the fact that the diamond has excellent wear resistance and hardness.
Example 3:
the method comprises the following steps of firstly, pretreating the surface of a Q235 steel workpiece, namely polishing the surface by using a grinding wheel or abrasive paper to remove rust, burrs and fins, and removing oil stains on the surface by using acetone;
step two, ball-milling and mixing Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si mixed powder according to a certain proportion to prepare high-entropy alloy powder; wherein the purity of the Cu elemental metal powder is 99.5-100%, and the particle size of the powder is 30-300 μm; wherein the Ni-Cr-B-Si comprises the following components in percentage by mass: 14-17, B: 2.5-4.5, Si: 3-4.5, C: 0.6-0.9, and the balance of Ni; the Fe-Cr-B-Si comprises the following components in percentage by mass: 12-15, B: 2.5-4.5, Si: 3-4.5, C: 0.6-1.0, and the balance of Fe; the Co-Cr-B-Si comprises the following components in percentage by mass: 15-18, B: 2.5-4.5, Si: 3-4.5, C: 0.5-0.8, and the balance of Co; wherein the mass percentages of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si are as follows: 25: 25: 25: 25. the ball milling and mixing are carried out by adopting a steel ball milling tank, the mass ratio of the milling balls to the mixed powder is 3: 1, a vacuum valve is opened after sealing, the vacuum pumping is carried out for 25 minutes, then the ball milling tank is placed into a planetary ball mill, the rotating speed is 300 r/min, the inversion frequency is 40 Hz, and the ball milling and mixing time is 70 minutes.
Thirdly, adopting the high-entropy alloy powder prepared in the second induction heating cladding step on the surface of the steel matrix, wherein the power of an induction power supply is 2kW, the work frequency of induction heating is 1MHz, and the induction heating current is 12A, and manufacturing a high-entropy alloy coating after cladding, wherein the thickness of the coating is 750 mu m;
and step four, heating the high-entropy alloy coating to 400-420 ℃ under the protection of inert gas, pressing diamonds with the grain size of 25-35 mu m into the surface of the coating, arranging the diamonds on the surface of the coating according to 50% of area proportion, pressing the diamonds into the coating under the action of 200MPa pressure, and continuously preserving heat for 6 min.
And step five, cooling to obtain the diamond enhanced high-entropy alloy coating.
Experiments show that the high-entropy alloy of the face-centered cubic solid solution with smooth coating appearance, basically no defects such as air holes and cracks and the like, and fine Cr is distributed in the matrix of the high-entropy alloy7C3After the diamond is pressed in, the surface of the coating is basically uniform, and carbides are formed on the surface of the diamond through the observation of a scanning electron microscope, so that the wear resistance of the material can be improved. Because the diamond has excellent wear resistance and hardness, the wear resistance of the prepared coating is improved by 6.2 times after the wear resistance test.
Example 4:
the method comprises the following steps of firstly, pretreating the surface of a Q255 steel workpiece, namely polishing the surface with sand paper to remove rust, burrs and flashes, and removing oil stains on the surface with acetone;
and step two, ball-milling and mixing the mixed powder of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si according to a proportion to prepare the high-entropy alloy powder. Wherein the purity of the Cu simple substance metal powder is 99.5-100%, and the particle size of the powder is 30-300 μm; wherein the Ni-Cr-B-Si comprises the following components in percentage by mass: 14-17, B: 2.5-4.5, Si: 3-4.5, C: 0.6-0.9, and the balance of Ni; the Fe-Cr-B-Si comprises the following components in percentage by mass: 12-15, B: 2.5-4.5, Si: 3-4.5, C: 0.6-1.0, and the balance of Fe; the Co-Cr-B-Si comprises the following components in percentage by mass: 15-18, B: 2.5-4.5, Si: 3-4.5, C: 0.5-0.8, and the balance of Co; wherein the mass percentages of Cu, Ni-Cr-B-Si, Co-Cr-B-Si and Fe-Cr-B-Si are as follows: 23: 28: 22: 27. the ball milling and mixing are carried out by adopting a steel ball milling tank, the mass ratio of the milling balls to the mixed powder is 3.1: 1, a vacuum valve is opened after the sealing and the vacuum pumping is carried out for 26 minutes, the ball milling tank is placed into a planetary ball mill, the rotating speed is 310 r/min, the inversion frequency is 30 Hz, and the ball milling and mixing time is 70 minutes.
Thirdly, cladding the high-entropy alloy powder prepared in the second step on the surface of the steel matrix by adopting induction heating, wherein the power of an induction power supply is 3kW, the working frequency of the induction heating is 1MkHz, and the induction heating current is 12.5A, and manufacturing a high-entropy alloy coating after cladding, wherein the thickness of the coating is 500 mu m;
and step four, heating the high-entropy alloy coating to 350-360 ℃ under the protection of inert gas, pressing diamonds with the particle size of 5-15 microns on the surface of the high-entropy alloy coating, arranging the diamonds on the surface of the coating according to 40% of area proportion, pressing the diamonds into the coating under the action of the pressure of 240MPa, and continuously preserving heat for 6 min.
And step five, cooling to obtain the diamond enhanced high-entropy alloy coating.
Experiments show that the FCC high-entropy alloy with smooth coating appearance, basically no defects such as air holes, cracks and the like and fine coating structure grains is obtained after induction cladding on the surface of a steel matrix, and Cr is refined by ball milling and mixing alloy powder7C3So that Cr is present7C3The coating is dispersed and distributed, the surface of the coating is basically uniform after the diamond is pressed in, and carbides are formed on the surface of the diamond through the observation of a scanning electron microscope, so that the coating can improve the wear resistance of wear-resistant particles. Because the diamond has excellent wear resistance and hardness, the wear resistance of the carbon steel Q255 steel is improved by more than 6.1 times after the coating is prepared.