A laser cladding copper-based composite coating resistant to high temperature wear and its preparation method

Abstract

The present invention relates to a laser cladding copper-based composite coating resistant to high temperature wear. By mass percentage, the coating is composed of 30.0 - 60.0% nickel-coated graphite powder, 6.8 - 11.9% Ni powder, 1.2 - 2.1% Al powder, 0.4 - 0.7% Fe powder, 0.4 - 0.7% Cr powder, 0.4 - 0.7% Mn powder, 0.4 - 0.7% rare earth oxide, and the balance Cu powder. Meanwhile, the present invention also discloses a preparation method of the coating. The preparation process of the present invention is simple and has high production efficiency. The obtained coating has the characteristics of high bonding strength with the substrate, high hardness, high temperature resistance, stable friction coefficient from room temperature to 500 °C, and excellent wear resistance, and is suitable for being used as an anti-wear coating for mechanical sliding parts under harsh conditions such as high temperature and high speed.

Description

Technical Field

[0001] The present invention relates to the technical field of metal coatings, and particularly relates to a laser cladding copper-based composite coating with high temperature wear resistance and a preparation method thereof. Background Art

[0002] Copper alloys and their composites are widely used due to their excellent electrical conductivity, thermal conductivity, mechanical properties and machining properties, such as in the fields of new energy vehicles, high-speed railways, aerospace, etc. Among them, copper-nickel alloys have high mechanical properties, corrosion resistance and high temperature softening resistance, and can be used as high-strength parts under complex and harsh working conditions. However, due to the poor tribological properties of copper-nickel alloys, they cannot meet the requirements of harsh working conditions such as high temperature, high speed and heavy load, which greatly limits their application range. Therefore, it is of great engineering application value to design and prepare wear-resistant copper-based composites that can serve in high temperature environments based on copper-nickel alloys.

[0003] As an important material processing method, laser cladding technology has the advantages of dense coating structure, fine grains and small heat affected zone of the substrate, and is widely used to improve the wear resistance, corrosion resistance and oxidation resistance of materials. Patent CN117364077A discloses a copper-based laser cladding coating and a preparation method thereof. The coating is composed of 48-67% Cu, 28-47% Cr, 3-7% TiO 2 and 0.4-0.8% CeO 2 by mass percentage, and has high hardness and wear resistance, with an average hardness of 160-220 HV and a mass wear rate of 9-17 mg / km. Patent CN117070936A discloses a preparation method of a laser cladding copper-based wear-resistant medium entropy alloy coating. The hardness of the coating reaches 392 HV through solid solution strengthening of elements such as Ni, Cr, Fe and in-situ self-generated Cu 6.5 Sn reinforcing phase, but its high temperature wear resistance is not disclosed. Patent CN114892167A discloses a laser cladding high melting point particle reinforced copper alloy coating. This preparation method uses a large amount of rare metals such as W, Mo, Ta, Nb, which has the disadvantages of high cost and low economic efficiency, and its high temperature wear resistance is not disclosed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a laser cladding copper-based composite coating with high temperature wear resistance and excellent performance in high temperature environments.

[0005] Another technical problem to be solved by the present invention is to provide a preparation method of the laser cladding copper-based composite coating with high temperature wear resistance.

[0006] To solve the above problems, the present invention discloses a high temperature wear resistant laser cladding copper-based composite coating, characterized in that the coating is composed, by mass percentage, of 30.0-60.0% nickel-coated graphite powder, 6.8-11.9% Ni powder, 1.2-2.1% Al powder, 0.4-0.7% Fe powder, 0.4-0.7% Cr powder, 0.4-0.7% Mn powder and 0.4-0.7% rare earth oxide and the remainder Cu powder.

[0007] The friction coefficient of the coating at room temperature to 500 °C is 0.39-0.55, and the wear rate is (0.34-6.69)×10 - 5 mm 3 / Nm.

[0008] The method for preparing a high temperature wear resistant laser cladding copper-based composite coating as described above is characterized in that: first, weighing is performed according to the ratio, and then Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, rare earth oxide and nickel-coated graphite powder are mixed evenly by a planetary ball mill, the obtained mixed powder is dried and then fed into a powder feeder, and laser cladding is performed on the treated metal substrate surface, and naturally cooled after cladding is completed to obtain a high temperature wear resistant laser cladding copper-based composite coating.

[0009] The Cu powder, Ni powder, Al powder, Fe powder, Cr powder and Mn powder are all spherical powders, and the powder purity is ≥99.8%, and the particle size is 45-75 μm.

[0010] The rare earth oxide is CeO 2 Powder, purity ≥99.9%, particle size 15~25 μm.

[0011] The particle size of the nickel-coated graphite powder is 45-90 μm; the mass percentage of graphite in the nickel-coated graphite powder is 25%.

[0012] The ball milling conditions refer to using a polytetrafluoroethylene ball mill and silicon nitride grinding balls, ball milling for 2 to 4 hours at a ball-to-material mass ratio of 0.5:1 and a rotation speed of 150 to 200 r / min.

[0013] The drying process is carried out at a temperature of 80-100°C and for a time of 1 hour.

[0014] The treated metal substrate is prepared by the following method: grinding the steel surface with silicon carbide sandpaper to remove the oxide layer, then sandblasting with aluminum oxide shot blasting to roughen the steel surface, and finally cleaning the steel surface with anhydrous ethanol and drying it.

[0015] The conditions for the laser cladding refer to a laser power of 0.6 - 0.9 kW, an overlapping rate of 40 - 60%, a scanning speed of 800 - 1000 mm / min, a powder feeding rate of 6 - 8 g / min, both the shielding gas and the carrier gas being argon, and the shielding gas flow rate being 10 - 20 L / min.

[0016] The present invention has the following advantages compared with the prior art:

[0017] 1. The present invention prepares a copper-based composite coating metallurgically bonded to the substrate on the surface of the steel by the laser cladding method. This coating has the advantages of high bonding strength, fine grains, and low porosity.

[0018] 2. By adding alloying elements Ni, Al, Fe, Cr, and Mn, the present invention improves the high-temperature mechanical properties of the coating. At the same time, adding graphite improves the tribological properties of the coating, and adding CeO 2 powder improves the forming quality and comprehensive properties of the coating.

[0019] 3. By adjusting the material formula and process parameters, the present invention can control the coating properties. The prepared high-temperature resistant friction and wear copper-based composite coating has a stable friction coefficient and excellent wear resistance from room temperature to 500 °C.

[0020] 4. The process of the present invention is simple, has high production efficiency, and broad application prospects. It is suitable for surface coating of mechanical moving parts under harsh conditions such as high temperature and high speed, such as key components like plain sliding bearings, bushings, and axle bushes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following further elaborates on the specific embodiments of the present invention with reference to the drawings.

[0022] Figure 1 It is the Vickers hardness of the laser cladding copper-based composite coating with high temperature wear resistance prepared in Examples 1 - 3 of the present invention.

[0023] Figure 2 It is the wear rate of the laser cladding copper-based composite coating with high temperature wear resistance prepared in Example 2 of the present invention at 25 °C, 300 °C, and 500 °C.

[0024] Figure 3 It is the friction coefficient of the laser cladding copper-based composite coating with high temperature wear resistance prepared in Example 3 of the present invention at 25 °C, 300 °C, and 500 °C. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] A laser cladding copper-based composite coating with high temperature and wear resistance. By mass percentage (g / g), the coating is composed of 30.0 - 60.0% nickel-coated graphite powder, 6.8 - 11.9% Ni powder, 1.2 - 2.1% Al powder, 0.4 - 0.7% Fe powder, 0.4 - 0.7% Cr powder, 0.4 - 0.7% Mn powder, 0.4 - 0.7% rare earth oxide, and the balance Cu powder. The friction coefficient of the coating at room temperature to 500 °C is 0.39 - 0.55, and the wear rate is (0.34 - 6.69)×10 -5 mm 3 / Nm.

[0026] Its preparation method: First, weigh according to the ratio. Then, mix the Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, rare earth oxide, and nickel-coated graphite powder evenly with a planetary ball mill. The ball milling conditions refer to using a polytetrafluoroethylene ball milling tank and silicon nitride grinding balls, and ball milling for 2 - 4 hours under the condition that the mass ratio of balls to materials (g / g) is 0.5:1 and the rotation speed is 150 - 200 r / min. The obtained mixed powder is dried at 80 - 100 °C for 1 hour and then sent to a powder feeder, and laser cladding is carried out on the surface of the treated metal substrate. The laser power is 0.6 - 0.9 kW, the overlapping rate is 40 - 60%, the scanning speed is 800 - 1000 mm / min, the powder feeding rate is 6 - 8 g / min, the protective gas and the carrier gas are both argon, and the flow rate of the protective gas is 10 - 20 L / min. After the cladding is completed, it is naturally cooled to obtain the laser cladding copper-based composite coating with high temperature and wear resistance.

[0027] Among them: The Cu powder, Ni powder, Al powder, Fe powder, Cr powder, and Mn powder are all spherical powders, and the powder purity is ≥99.8%, and the particle size is 45 - 75 μm.

[0028] The rare earth oxide is CeO 2 powder, with a purity ≥99.9% and a particle size of 15 - 25 μm.

[0029] The particle size of the nickel-coated graphite powder is 45 - 90 μm; the mass percentage of graphite in the nickel-coated graphite powder is 25%.

[0030] The treated metal substrate is prepared by the following method: Use silicon carbide sandpaper to polish the surface of the steel to remove the oxide layer, then use alumina shot peening for sandblasting treatment to roughen the surface of the steel, and finally clean and dry the surface of the steel with anhydrous ethanol to obtain it.

[0031] Example 1

[0032] A laser cladding copper-based composite coating with high temperature wear resistance, which is composed of 30.0 g of nickel-coated graphite powder, 11.9 g of Ni powder, 2.1 g of Al powder, 0.7 g of Fe powder, 0.7 g of Cr powder, 0.7 g of Mn powder and 0.7 g of CeO 2 powder and 53.2 g of Cu powder.

[0033] Its preparation method:

[0034] First, weigh according to the ratio, and then mechanically mix the Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, CeO 2 powder and nickel-coated graphite powder by a planetary ball mill. The mass ratio of balls to materials (g / g) is 0.5:1, the rotation speed is 200 r / min, and the ball milling mixing time is 3 hours. The obtained mixed powder is dried at 100 °C for 1 hour and then fed into a powder feeder, and laser cladding is carried out on the surface of the treated metal substrate. The laser power is 0.8 kW, the overlapping rate is 50%, the scanning speed is 800 mm / min, the powder feeding rate is 8 g / min, and argon is used as the protective gas and carrier gas, and the protective gas flow rate is 15 L / min. After the cladding is completed, it is naturally cooled to obtain a laser cladding copper-based composite coating with high temperature wear resistance.

[0035] Perform performance tests on the obtained coating:

[0036]

Hardness

[0037] The results show that the Vickers hardness of the copper-based composite coating is 553.7 HV 0.2 , as Figure 1 shown.

[0038]

High-temperature tribological properties

[0039] Example 2

[0040] A laser-clad copper-based composite coating with high temperature wear resistance, which is composed of 40.0 g of nickel-coated graphite powder, 10.2 g of Ni powder, 1.8 g of Al powder, 0.6 g of Fe powder, 0.6 g of Cr powder, 0.6 g of Mn powder, 0.6 g of CeO 2 powder and 45.6 g of Cu powder.

[0041] Its preparation method:

[0042] First, weigh according to the ratio, and then use a planetary ball mill to mechanically mix the Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, CeO 2 powder and nickel-coated graphite powder. The mass ratio of balls to materials (g / g) is 0.5:1, the rotation speed is 200 r / min, and the ball milling mixing time is 3 hours. The obtained mixed powder is dried at 100 °C for 1 hour and then sent to a powder feeder, and laser cladding is carried out on the surface of the treated metal substrate. The laser power is 0.7 kW, the overlapping rate is 50%, the scanning speed is 900 mm / min, the powder feeding rate is 7 g / min, and argon is used as the protective gas and carrier gas, and the flow rate of the protective gas is 15 L / min. After the cladding is completed, it is naturally cooled to obtain the laser-clad copper-based composite coating with high temperature wear resistance.

[0043] The obtained coating is subjected to hardness testing and high-temperature tribological performance testing, and the testing methods are the same as those in Example 1.

[0044] The Vickers hardness of this copper-based composite coating is 643.7 HV 0.2 , as Figure 1 shown; the friction coefficient of this coating is 0.44 - 0.48 at 25 °C to 500 °C, and the wear rate is (0.34 - 1.19) × 10 -5 mm 3 / Nm, as Figure 2 shown.

[0045] Example 3

[0046] A laser-clad copper-based composite coating with high temperature wear resistance, which is composed of 60.0 g of nickel-coated graphite powder, 6.8 g of Ni powder, 1.2 g of Al powder, 0.4 g of Fe powder, 0.4 g of Cr powder, 0.4 g of Mn powder, 0.4 g of CeO 2 powder and 30.4 g of Cu powder.

[0047] Its preparation method:

[0048] First, weigh according to the ratio, and then use a planetary ball mill to mechanically mix the Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, CeO 2The powder and nickel-coated graphite powder are mechanically mixed using a planetary ball mill with a ball-to-powder mass ratio (g / g) of 0.5:1, a rotation speed of 150 r / min, and a ball milling mixing time of 4 hours. The obtained mixed powder is dried at 100 °C for 1 hour and then fed into a powder feeder, and laser cladding is performed on the surface of the treated metal substrate. The laser power is 0.6 kW, the overlap rate is 50%, the scanning speed is 1000 mm / min, the powder feeding rate is 6 g / min, and argon is used as the shielding gas and carrier gas with a shielding gas flow rate of 20 L / min. After the cladding is completed, it is naturally cooled to obtain a laser cladded copper-based composite coating with high temperature wear resistance.

[0049] The obtained coating is subjected to hardness testing and high temperature tribological property testing, and the testing methods are the same as those in Example 1.

[0050] The Vickers hardness of the copper-based composite coating is 737.1 HV 0.2 , as Figure 1 shown; the friction coefficient of the coating is 0.39 - 0.44 from 25 °C to 500 °C, as Figure 3 shown, and the wear rate is (1.09 - 5.66)×10 -5 mm 3 / Nm.

Claims

1. A high temperature wear resistant laser cladding copper-based composite coating, characterized in that: The coating is composed of 30.0-60.0% nickel-coated graphite powder, 6.8-11.9% Ni powder, 1.2-2.1% Al powder, 0.4-0.7% Fe powder, 0.4-0.7% Cr powder, 0.4-0.7% Mn powder, 0.4-0.7% rare earth oxide and the balance Cu powder by mass percentage; the particle size of the nickel-coated graphite powder is 45-90 μm; the mass percentage of graphite in the nickel-coated graphite powder is 25%; The preparation method of the composite coating comprises the following steps: firstly weighing according to a proportion, then uniformly mixing Cu powder, Ni powder, Al powder, Fe powder, Cr powder, Mn powder, rare earth oxide and nickel-coated graphite powder with a planetary ball mill, feeding the obtained mixed powder into a powder feeder after drying, and laser cladding is performed on the surface of the treated metal substrate, and naturally cooling is performed after the cladding is completed, so as to obtain a laser cladding copper-based composite coating resistant to high temperature wear.

2. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The friction coefficient of the coating is 0.39-0.55 at room temperature to 500 °C, and the wear rate is (0.34-6.69)×10 -5 mm 3 / Nm.

3. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The Cu powder, Ni powder, Al powder, Fe powder, Cr powder and Mn powder are all spherical powders, and the powder purity is ≥99.8%, and the particle size is 45-75 μm.

4. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The rare earth oxide is CeO2 powder with a purity of ≥99.9% and a particle size of 15-25 μm.

5. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The ball milling conditions refer to using a polytetrafluoroethylene ball mill and silicon nitride grinding balls, ball milling for 2 to 4 hours at a ball-to-material mass ratio of 0.5:1 and a rotation speed of 150 to 200 r / min.

6. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The drying process is carried out at a temperature of 80-100°C and for a time of 1 hour.

7. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The treated metal substrate is prepared by the following method: grinding the steel surface with silicon carbide sandpaper to remove the oxide layer, then sandblasting with aluminum oxide shot blasting to roughen the steel surface, and finally cleaning the steel surface with anhydrous ethanol and drying it.

8. The high temperature wear resistant laser cladding copper-based composite coating according to claim 1, characterized in that: The laser cladding conditions are as follows: the laser power is 0.6-0.9 kW, the overlap rate is 40-60%, the scanning speed is 800-1000 mm / min, the powder feeding rate is 6-8 g / min, the shielding gas and the carrier gas are both argon, and the shielding gas flow rate is 10-20 L / min.

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