Composite powder and its preparation method and application

Abstract

The present invention discloses a composite powder, its preparation method, and application. The composite powder comprises the following raw materials in the following percentages by mass: 60% to 90% Ni60 and 10% to 30% SiC. The composite powder provided herein can be applied to an alloy surface to produce a composite coating that improves the alloy's wear resistance and oxidation resistance. This provides the theoretical basis and technical support for the long-term application of Inconel 718 high-temperature alloy as a key moving component in harsh operating conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating materials, and in particular relates to a composite powder and a preparation method and application thereof. Background Art

[0002] Nickel-based superalloys refer to high-temperature alloys with nickel as the matrix (the content is generally greater than 50%) and high strength and good corrosion resistance in the range of 650℃ to 1000℃. With the continuous research on nickel-based superalloys, their application in industrial production is becoming more and more extensive. 80% of the high-strength alloys used in the aerospace field are nickel-based alloys, accounting for 50% of the materials used in aircraft engines. Among nickel-based superalloys, Inconel718 alloy is a precipitation-strengthened nickel-based superalloy. Its usage has reached more than 60% of the total use of superalloys. It is widely used in aviation, aerospace, energy, chemical industry and other fields. It is also used to manufacture some core components in industrial production, such as engine blades, turbine disks, compressor disks, casings and fasteners. However, due to the long-term use of Inconel718 alloy in high-temperature and high-pressure environments, it will inevitably fail due to wear. If it is directly scrapped, the production cost of the parts will increase. Therefore, it is crucial to study its wear resistance and friction reduction and use surface modification technology to improve its tribological properties.

[0003] At present, a variety of surface technologies are widely used at home and abroad to improve the tribological properties of nickel-based high-temperature alloys, such as laser cladding, plasma spraying, physical vapor deposition, chemical vapor deposition, nitriding and shot peening. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a composite powder, which can be used to prepare a composite coating on the surface of an alloy to improve the wear resistance and oxidation resistance of the alloy.

[0005] The present invention also provides a method for preparing the composite powder.

[0006] The invention also provides a method for preparing the composite coating.

[0007] The present invention also provides a composite coating prepared by the above preparation method.

[0008] The present invention also provides a coated product.

[0009] The present invention also provides an application.

[0010] According to a first aspect of the present invention, a composite powder is provided. The composite powder includes the following raw materials in the following mass percentages: 60% to 90% Ni60 and 10% to 30% SiC.

[0011] The Ni60 powder is the most widely used type of high-hardness Ni-Cr-B-Si self-fluxing alloy powder, and has excellent comprehensive performance. Its corrosion resistance, oxidation resistance, heat resistance, wear resistance and impact toughness are all good. In addition, Ni60 has a low melting point and a wide solid-liquid phase temperature range, and has a strong wetting ability on a variety of substrates and particles. Ni6 powder with strong wetting ability can form good contact with the substrate, thereby improving the adhesion of the composite coating prepared from the composite powder.

[0012] The silicon carbide has a hexagonal crystal structure, high hardness, good chemical stability and excellent wear resistance, and can be widely used in fields such as surface modification; SiO2 formed after SiC oxidation will form a protective film, which can limit the penetration of external oxygen or corrosive media and enhance its corrosion and oxidation resistance at high temperatures.

[0013] In some embodiments of the present invention, the composite powder further comprises Ti3SiC2.

[0014] The Ti3SiC2 is a typical ternary layered MAX phase ceramic, which not only has the good electrical conductivity, thermal conductivity and high toughness of metals, but also has excellent properties of ceramics such as high thermal stability, high melting point and high yield strength. It is prone to interlayer sliding at high temperatures and produces lubrication properties.

[0015] In some preferred embodiments of the present invention, the mass percentage of Ti3SiC2 in the composite powder is 1% to 20%.

[0016] In some more preferred embodiments of the present invention, the mass percentage of Ti3SiC2 in the composite powder is 5% to 10%.

[0017] In some preferred embodiments of the present invention, the particle size of the Ti3SiC2 is 40 to 60 μm.

[0018] In some more preferred embodiments of the present invention, the particle size of the Ti3SiC2 is 45-50 μm.

[0019] In some more preferred embodiments of the present invention, the particle size of the Ti3SiC2 is 48 μm.

[0020] In some embodiments of the present invention, the mass percentage of Ni60 in the composite powder is 70% to 80%.

[0021] In some embodiments of the present invention, the particle size of the Ni60 is 30-120 μm.

[0022] In some preferred embodiments of the present invention, the particle size of the Ni60 is 48-106 μm.

[0023] In some embodiments of the present invention, the mass percentage of SiC in the composite powder is 15% to 25%.

[0024] In some preferred embodiments of the present invention, the mass percentage of SiC in the composite powder is 20%.

[0025] In some embodiments of the present invention, the SiC has a particle size of 40 to 60 μm.

[0026] In some preferred embodiments of the present invention, the particle size of the SiC is 45-50 μm.

[0027] In some more preferred embodiments of the present invention, the SiC has a particle size of 48 μm.

[0028] According to a second aspect of the present invention, a method for preparing the composite powder according to the first aspect of the present invention is proposed, the preparation method comprising the following steps: mixing the components in the composite powder and then ball milling the mixture to obtain the composite powder.

[0029] In some embodiments of the present invention, the ball milling time is 1 to 3 hours.

[0030] In some preferred embodiments of the present invention, the ball milling time is 1.5 to 2.5 hours.

[0031] In some more preferred embodiments of the present invention, the ball milling time is 2 hours.

[0032] In some embodiments of the present invention, the rotation speed of the ball mill is 500-700 r / min.

[0033] In some preferred embodiments of the present invention, the rotation speed of the ball mill is 550-650 r / min.

[0034] In some more preferred embodiments of the present invention, the rotation speed of the ball mill is 600 r / min.

[0035] In some embodiments of the present invention, the preparation method further comprises the step of drying the composite powder after ball milling.

[0036] In some preferred embodiments of the present invention, the drying time is 2 to 6 hours.

[0037] In some more preferred embodiments of the present invention, the drying time is 3 to 5 hours.

[0038] In some more preferred embodiments of the present invention, the drying time is 4 hours.

[0039] In some preferred embodiments of the present invention, the drying temperature is 40-80°C.

[0040] In some more preferred embodiments of the present invention, the drying temperature is 50-70°C.

[0041] In some more preferred embodiments of the present invention, the drying temperature is 60°C.

[0042] According to a third aspect of the present invention, a composite coating is provided. The composite coating is prepared using the composite powder as described in the first aspect of the present invention.

[0043] According to a fourth aspect of the present invention, a method for preparing the composite coating according to the third aspect of the present invention is provided, the method comprising the following steps:

[0044] The composite powder is coated on the surface of the substrate to obtain the product.

[0045] In some embodiments of the present invention, the substrate comprises a nickel-based high-temperature alloy.

[0046] In some preferred embodiments of the present invention, the nickel-based high-temperature alloy includes Inconel 718 alloy.

[0047] In some embodiments of the present invention, the coating method includes laser cladding.

[0048] In some preferred embodiments of the present invention, the laser power of the laser cladding is 700-900W.

[0049] In some more preferred embodiments of the present invention, the laser power of the laser cladding is 800W.

[0050] In some preferred embodiments of the present invention, the diameter of the laser spot of the laser cladding is 1 to 3 mm.

[0051] In some more preferred embodiments of the present invention, the diameter of the laser spot of the laser cladding is 1.5 to 2 mm.

[0052] In some more preferred embodiments of the present invention, the laser spot diameter of the laser cladding is 1.8 mm.

[0053] In some preferred embodiments of the present invention, the defocus amount of the laser cladding is -30 to -10 mm.

[0054] In some more preferred embodiments of the present invention, the defocus amount of the laser cladding is -20 mm.

[0055] In some preferred embodiments of the present invention, the scanning speed of the laser cladding is 3 to 7 mm / s.

[0056] In some more preferred embodiments of the present invention, the scanning speed of the laser cladding is 5 mm / s.

[0057] In some preferred embodiments of the present invention, the powder feeding rate of the laser cladding is 10 to 17 g / min.

[0058] In some more preferred embodiments of the present invention, the powder feeding rate of the laser cladding is 13.5 g / min.

[0059] In some preferred embodiments of the present invention, the overlap rate of the laser cladding is 40% to 60%.

[0060] In some more preferred embodiments of the present invention, the overlap rate of the laser cladding is 50%.

[0061] According to a fifth aspect of the present invention, a coated product is provided, the coated product comprising a substrate and a coating;

[0062] The coating includes: a coating prepared from the composite powder as described in the first aspect of the present invention or a composite coating as described in the third aspect of the present invention.

[0063] In some embodiments of the present invention, the substrate comprises a nickel-based high-temperature alloy.

[0064] In some preferred embodiments of the present invention, the nickel-based high-temperature alloy includes Inconel 718 alloy.

[0065] According to a sixth aspect of the present invention, it is proposed to use the composite powder as described in the first aspect of the present invention or the composite coating as described in the third aspect of the present invention in surface modification of nickel-based alloys.

[0066] In some embodiments of the present invention, the nickel-based alloy includes Inconel 718 alloy.

[0067] The present invention has at least the following beneficial effects:

[0068] 1) The composite powder provided by the present invention can be used to prepare a composite coating with wear-reducing and oxidation-resistant properties. Coating the composite coating on a substrate can improve the wear resistance and oxidation resistance of the substrate, thereby better meeting its practical application requirements;

[0069] 2) The composite coating provided by the present invention is a wear-resistant and oxidation-resistant composite coating prepared on the surface of Inconel718 high-temperature alloy using laser cladding technology, with Ni60, SiC ceramics and ternary layered solid lubricant Ti3SiC2 powder as raw materials. The present invention provides the theoretical basis and technical support for the long-term application of Inconel718 high-temperature alloy as a key moving component under harsh working conditions. The coating material and its preparation process are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0071] Figure 1 This is a graph showing the average microhardness test results of the composite coatings obtained in Examples 1 to 3 in the test examples of the present invention;

[0072] Figure 2 The electron microscope results for characterizing the cross-sectional morphology of the composite coatings obtained in Examples 1, 4 and 5 in the test examples of the present invention are shown; wherein, Figure 2 (a) is the composite coating obtained in Example 1, Figure 2 (b) is the composite coating obtained in Example 4, Figure 3 (c) is the composite coating prepared in Example 5, and the scale bar is 100 μm;

[0073] Figure 3 The XRD results of the composite coatings obtained in Examples 1, 4 and 5 of the present invention are shown in FIG. 1 , wherein C1 refers to Example 1, C2 refers to Example 4, and C3 refers to Example 5.

[0074] Figure 4 Graph showing the microhardness of the composite coatings obtained in Examples 1, 4, and 5 of the present invention; wherein C1 refers to Example 1, C2 refers to Example 4, and C3 refers to Example 5;

[0075] Figure 5 Graphs showing the friction coefficients of the composite coatings obtained in Examples 1, 4, and 5 and the control group (Inconel 718 alloy) in the test examples of the present invention; FIG. A shows the friction coefficient at room temperature, FIG. B shows the friction coefficient at 600° C., C1 refers to Example 1, C2 refers to Example 4, and C3 refers to Example 5;

[0076] Figure 6 Graph showing the wear rate and average friction coefficient of the composite coatings obtained in Examples 1, 4, and 5 and the control group (Inconel 718 alloy) in the test examples of the present invention; wherein C1 refers to Example 1, C2 refers to Example 4, and C3 refers to Example 5;

[0077] Figure 7The wear surface morphology of the composite coatings obtained in Examples 1, 4 and 5 and the control group (Inconel718 alloy) at room temperature in the test examples of the present invention is shown in FIG. Figure 7 (a1) to (d1) are the wear surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5, respectively, with a scale of 200 μm. Figure 7 (a2) to (d2) are typical wear area morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5, respectively, with a scale of 20 μm.

[0078] Figure 8 The wear surface morphology of the composite coatings obtained in Examples 1, 4 and 5 and the control group (Inconel718 alloy) at 600°C is shown in the test example of the present invention; wherein, Figure 7 (a1) to (d1) are the wear surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5, respectively, with a scale of 200 μm. Figure 7 (a2) to (d2) are typical wear area morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5, respectively, with a scale of 20 μm.

[0079] Figure 9 Graph showing the oxidation kinetics of the composite coatings obtained in Examples 1 and 5 and the control group (Inconel 718 alloy) in the test examples of the present invention; wherein C1 refers to Example 1, and C3 refers to Example 5;

[0080] Figure 10 The XRD results of the oxidized surfaces of the composite coatings obtained in Examples 1, 4 and 5 and the control group (Inconel718 alloy) in the test examples of the present invention are shown; wherein C1 refers to Example 1, C2 refers to Example 4, and C3 refers to Example 5;

[0081] Figure 11 These are the oxidized surface morphologies of the composite coatings obtained in Examples 1, 4 and 5 and the control group (Inconel718 alloy) after oxidation in the test examples of the present invention; wherein, (a1) to (d1) are respectively oxidized surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4 and 5 after oxidation, with a scale of 100 μm; (a2) to (d2) are respectively typical oxidized surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4 and 5 after oxidation, with a scale of 20 μm. DETAILED DESCRIPTION

[0082] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0083] Materials and Definitions

[0084] In the following examples, the Ni60 powder used has a particle size of 48 to 106 μm and was purchased from Hebei Guifa Alloy Wear-Resistant Materials Co., Ltd.; the SiC powder used has a particle size of 48 μm and was purchased from Shanghai Naio Nano Technology Co., Ltd.; the Ti3SiC2 powder used has a particle size of 48 μm and was purchased from Shanghai Naio Nano Technology Co., Ltd.; and the Inconel718 alloy used was purchased from Shenzhen Yishengbai Metal Materials.

[0085] Example 1

[0086] This embodiment provides a composite powder comprising 80 wt% Ni60 and 20 wt% SiC. This embodiment also uses the composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology. The preparation method of the composite powder and the composite coating specifically includes the following steps:

[0087] 1) Preparation of composite powder:

[0088] ① Use an electronic balance to weigh Ni60 powder and SiC powder according to the ratio and mix them to obtain a mixed powder;

[0089] ② Place the mixed powder in a ball mill (DECO-PBM-V-0.4L) and ball mill for 2 hours at a speed of 600 r / min. Place the ball-milled mixed powder at a constant temperature of 60°C and dry it for 4 hours to obtain a composite powder.

[0090] 2) Preparation of composite coating:

[0091] ① Matrix pretreatment: Use 80-mesh, 200-mesh, and 400-mesh sandpaper to polish the Inconel718 alloy matrix to remove surface impurities;

[0092] ② A fiber laser (YLS-300) with a laser output power of 800W was used to melt the composite powder obtained in step 1) onto the substrate surface in a synchronous powder feeding manner to obtain a composite coating; the laser beam output spot was The scanning speed is 5 mm / s, the defocus is -20 mm, the powder feeding rate is 13.5 g / min, and the overlap rate is 50%.

[0093] Example 2

[0094] This embodiment provides a composite powder, which includes 90wt% Ni60 and 10wt% SiC. This embodiment also uses the composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology. The preparation method of the composite powder and the composite coating is the same as that in Example 1, except that the mixing ratio of the composite powder is adjusted to 90wt% Ni60 and 10wt% SiC.

[0095] Example 3

[0096] This embodiment provides a composite powder, which includes 70wt% Ni60 and 30wt% SiC. This embodiment also uses the composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology. The preparation method of the composite powder and the composite coating is the same as that in Example 1, except that the mixing ratio of the composite powder is adjusted to 70wt% Ni60 and 30wt% SiC.

[0097] Example 4

[0098] This embodiment provides a composite powder, which includes 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that in Example 1, except that the mixing ratio of the composite powder is adjusted to 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2.

[0099] Example 5

[0100] This embodiment provides a composite powder, which includes 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that in Example 1, except that the mixing ratio of the composite powder is adjusted to 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2.

[0101] Example 6

[0102] This embodiment provides a composite powder, which includes 80wt% Ni60 and 20wt% SiC. This embodiment also uses the composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology. The preparation method of the composite powder and the composite coating is the same as that in Example 1, except that the laser output power of the fiber laser is adjusted to 1000W.

[0103] Example 7

[0104] This embodiment provides a composite powder, which includes 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that of Example 6, except that the mixing ratio of the composite powder is adjusted to 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2.

[0105] Example 8

[0106] This embodiment provides a composite powder, which includes 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that of Example 6, except that the mixing ratio of the composite powder is adjusted to 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2.

[0107] Example 9

[0108] This embodiment provides a composite powder, which includes 80wt% Ni60 and 20wt% SiC. This embodiment also uses the composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology. The preparation method of the composite powder and the composite coating is the same as that in Example 1, except that the laser output power of the fiber laser is adjusted to 1200W.

[0109] Example 10

[0110] This embodiment provides a composite powder, which includes 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that of Example 9, except that the mixing ratio of the composite powder is adjusted to 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2.

[0111] Example 11

[0112] This embodiment provides a composite powder, which includes 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2; this embodiment also uses the above-mentioned composite powder to prepare a composite coating on the surface of Inconel718 alloy by laser cladding technology; the preparation method of the above-mentioned composite powder and composite coating is the same as that of Example 9, except that the mixing ratio of the composite powder is adjusted to 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2.

[0113] Test example

[0114] This test example tested the tribological properties of the composite coatings prepared in Examples 1 to 11, including friction coefficient, wear rate, hardness, cross-sectional morphology, and XRD patterns. The specific test methods and test results are as follows:

[0115] 1. Detection of friction coefficient and wear rate of composite coatings with different SiC contents:

[0116] In order to determine the more preferred SiC content, this test example tested the friction coefficient and wear rate of the composite coatings prepared in Examples 1 to 3. The proportions of the composite powders used in Examples 1 to 3 are shown in Table 1.

[0117] Table 1 Proportions of composite powders used in Examples 1 to 3

[0118]

[0119] The test methods and results of the above friction coefficient and wear rate are as follows:

[0120] 1) Tribological performance tests were conducted using a ball-on-disc high-temperature friction and wear tester (HT-1000, purchased from Lanzhou Zhongke Kaihua Technology Development Co., Ltd.). The test parameters are shown in Table 2; the obtained friction coefficients are shown in Table 3.

[0121] Table 2 Friction and wear parameters

[0122]

[0123] 2) The width and depth of the surface marks of the samples after the wear test were measured using the MT-500 probe-type material surface wear scar measuring instrument (purchased from Lanzhou Zhongke Kaihua Technology Development Co., Ltd.), and the wear rate (WR, mm) was calculated according to the following formula: 3 (N·m)):

[0124] WR= V

[0125] Fl; where WR represents the wear rate of the sample; V represents the total volume lost by the sample after the room temperature and high temperature wear tests, in mm; F ​​represents the load specified in the test, in N; l represents the total distance traveled by the ball during the sliding process, in m; the obtained wear rates are shown in Table 3.

[0126] Table 3 Friction coefficient and wear rate results of composite coatings with different SiC contents

[0127]

[0128] The results in Table 3 show that the composite coating composed of 20wt% SiC and 80wt% Ni60 (Example 1) exhibits superior wear resistance and friction reduction, achieving the lowest coefficient of friction and wear rate at both room temperature and 600°C. Therefore, the present invention further adds the MAX phase Ti3SiC2 to this formulation to investigate the synergistic effect of the ceramic and lubricating phases on improving the performance of the composite coating.

[0129] 2. Detect the performance of the composite coating prepared under different laser powers:

[0130] In order to determine the more preferred laser cladding conditions, this test example conducted preliminary performance tests on the composite coatings prepared in Examples 1 and 4 to 11. Since the hardness of the coating has a significant impact on the tribological properties, the preliminary microhardness test results were used to screen the laser power used for laser cladding. The ratios of the composite powders and the laser powers used in Examples 1 and 4 to 11 are shown in Table 4.

[0131] The specific detection method is as follows: the test starts from the top of the cladding layer, and points are made every 100μm along the longitudinal direction (i.e., the depth direction) of the coating until the substrate, and then 5 more points are made to calculate the substrate hardness; the horizontal direction is measured three times every 100μm and the average value is taken to obtain the longitudinal microhardness value; the results are as follows Figure 1 As shown; wherein, the composite powder of 80wt% Ni60 and 20wt% SiC is recorded as C1, the composite powder of 75wt% Ni60, 20wt% SiC and 5wt% Ti3SiC2 is recorded as C2, and the composite powder of 70wt% Ni60, 20wt% SiC and 10wt% Ti3SiC2 is recorded as C3.

[0132] Table 4 Ratio of composite powders used in Examples 4 to 11 and laser power

[0133]

[0134] Depend on Figure 1It can be seen that when laser cladding is performed with a laser power of 800 W, the microhardness of the composite coating obtained is the highest. Therefore, a laser power of 800 W is selected as the optimal parameter, and subsequent specific performance tests are only carried out on the composite coating prepared with a laser power of 800 W (Examples 1, 4, and 5).

[0135] 3. Micromorphology characterization of composite coating:

[0136] In this test example, the composite coatings prepared in Examples 1, 4 and 5 were subjected to microscopic morphology characterization and phase analysis.

[0137] 1) Observation of cross-sectional morphology of composite coating:

[0138] The cross-sectional morphologies of the composite coatings prepared in Examples 1, 4, and 5 were observed using an electron microscope. Figure 2 shown; among them, Figure 2 (a) is the composite coating obtained in Example 1, Figure 2 (b) is the composite coating obtained in Example 4, Figure 2 (c) is the composite coating prepared in Example 5.

[0139] Depend on Figure 2 It can be seen that the fusion lines between the composite coatings provided in Examples 1, 4 and 5 and the substrate are all wavy lines, indicating that the coatings are heated evenly and a good metallurgical bond is formed between the coatings and the Inconel718 alloy substrate. The composite coatings obtained in Examples 1, 4 and 56 have no obvious defects such as macro cracks inside.

[0140] 2) X-ray diffraction (XRD) pattern analysis of composite coating:

[0141] X-ray diffraction was performed on the composite coatings obtained in Examples 1, 4 and 5, and the results were as follows: Figure 2 As shown; wherein, "C1" refers to the composite coating obtained in Example 1, "C2" refers to the composite coating obtained in Example 4, and "C3" refers to the composite coating obtained in Example 5.

[0142] Depend on Figure 3 It can be seen that the composite coatings prepared in Examples 1, 4 and 5 have similar compositions, all of which are composed of metal compounds FeNi, CrNi, Ni3Si and Cr 23 C6 composition; in addition, (Ni 82 Ti 18 ) 0.04 The lack of Ti3SiC2 element may be due to the low content of added Ti3SiC2 and its decomposition during the laser cladding process. It can be seen that the target composite coating can be obtained by the preparation method provided by the present invention.

[0143] 4. Microhardness test of composite coating:

[0144] In this test example, the microhardness of the composite coatings prepared in Examples 1, 4 and 5 was characterized respectively.

[0145] The specific detection method is as follows: the test starts from the top of the cladding layer, and points are made every 100μm along the longitudinal direction (i.e., the depth direction) of the coating until the substrate, and then 5 more points are made to calculate the substrate hardness; the horizontal direction is measured three times every 100μm and the average value is taken to obtain the longitudinal microhardness value; the results are as follows Figure 4 As shown; wherein, "C1" refers to the composite coating obtained in Example 1, "C2" refers to the composite coating obtained in Example 4, and "C3" refers to the composite coating obtained in Example 5.

[0146] Depend on Figure 4 It can be seen that the hardness of the composite coating obtained in Example 1 is calculated to be 951.4HV 0.5 , which is about 4 times that of the substrate; while the average microhardness of the composite coatings obtained in Examples 4 and 5 is 442.4HV 0.5 and 366.1HV 0.5 , compared to the substrate (238.3HV 0.5 ) increased by 1.5 to 1.8 times, which shows that the composite coating provided by the present invention can effectively improve the hardness of the substrate.

[0147] The reasons why the composite powder provided by the present invention can be used to prepare a high-hardness composite coating mainly include the following three aspects:

[0148] ①The strong convection in the molten pool makes the hard phase and intermetallic compounds evenly distributed in the cladding layer, resulting in dispersion strengthening in the coating;

[0149] ②The fast cooling rate of laser cladding leads to the formation of solid solution strengthening, and the large undercooling degree leads to fine grain strengthening;

[0150] ③The particularity of the Ti3SiC2 structure improves the performance of the composite coating.

[0151] In addition, from Figure 4 The results also show that the microhardness of the composite coatings obtained in Examples 4 and 5 gradually decreases; Figure 3 Analysis of the XRD results shows that the increase of Ti3SiC2 in the coating promotes the diffusion of Fe and Ni elements in the matrix into the coating, which increases the dilution rate of the coating; at the same time, the carbon content decreases, that is, the content of hard phase carbides such as Cr7C3 decreases, resulting in a relatively loose coating structure and reduced density, which further leads to a decrease in microhardness.

[0152] 5. Tribological performance test of composite coating:

[0153] In this test example, the tribological properties of the composite coatings prepared in Examples 1, 4 and 5 were tested, including friction coefficient and wear rate. For specific testing methods, please refer to the description in Part 1 of this test example. The obtained friction coefficient curve is shown in FIG. Figure 5 The wear rate and average friction coefficient are shown in Figure 6 As shown; wherein, "C1" refers to the composite coating obtained in Example 1, "C2" refers to the composite coating obtained in Example 4, and "C3" refers to the composite coating obtained in Example 5.

[0154] Depend on Figure 5 It can be seen that at room temperature and high temperature (600° C.), the friction coefficients of the composite coatings obtained in Examples 1, 4 and 5 are greatly improved relative to the substrate.

[0155] Depend on Figure 6 It can be seen that at room temperature, the friction coefficient of the Inconel718 alloy substrate is the highest (0.937), and it also fluctuates greatly in the friction test; the composite coatings obtained in Examples 1, 4, and 5 have a stronger ability to resist wear due to the increase in hardness, and the friction coefficients are reduced to varying degrees; and the composite coating obtained in Example 5 has a lower friction coefficient than the composite coating of Example 4 due to the addition of a larger amount of the lubricating phase Ti3SiC2. At room temperature, the wear resistance of the composite coatings of Examples 1, 4, and 5 is significantly improved; among them, the composite coating with both SiC and Ti3SiC2 added has a lower wear rate. The wear rate of the coating of Example 4 at room temperature is 2.51×10 -5 mm3 / (N·m), the coating wear rate of Example 5 is 2.13×10 - 5 mm3 / (N·m). At 600℃, the wear rate of the coating of Example 4 is 7.59×10 -5 mm3 / (N·m), the wear rate of the coating in Example 5 is 3.57×10 -5 mm3 / (N·m).

[0156] The above results show that the addition of Ti3SiC2 as a lubricating phase significantly improves the tribological properties of the material surface and makes the coating have better friction reduction properties; the hard particles SiC in the composite coating greatly improve the hardness of the coating and reduce the wear on the grinding balls and the coating.

[0157] 6. Macroscopic morphology and local area characterization of wear scars of composite coatings:

[0158] In order to more intuitively observe the excellent wear resistance of the composite coating provided by the present invention, this test example characterized the wear scar macromorphology and local area of ​​the Inconel718 alloy substrate and the composite coatings prepared in Examples 1, 4 and 5 under different temperature conditions.

[0159] 1) Macromorphology and local area characterization of wear scars of composite coatings at room temperature:

[0160] The surfaces of the Inconel 718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5 after being polished using a ball-on-disc high-temperature friction and wear tester HT-1000 in Part 1 of this test example were observed using a scanning electron microscope (SEM, model TESCAN MIRA 4), and photographed and recorded. The results are shown in FIG. Figure 7 shown; among them, Figure 7 (a1) to (d1) are the wear surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4 and 5, respectively; Figure 7 (a2) to (d2) are typical wear area morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4, and 5, respectively;

[0161] An energy spectrum analyzer (Xplore 30, Aztec one, Oxford) was used to scan a typical area to obtain the element distribution pattern on the surface. The results are shown in Table 5.

[0162] Table 5 Energy spectrum analysis (EDS) results of typical wear areas at room temperature

[0163]

[0164] Depend on Figure 7 From Table 5, we can see that:

[0165] ①The wear scar width of the Inconel718 alloy substrate is the largest, the surface deformation is serious, and it is very rough, indicating that its tribological performance is poor; the substrate shows furrows, severe plastic deformation and more broken particles at room temperature, which produces greater friction resistance and increases the friction coefficient of the substrate; when the substrate is worn, an oxide film is generated on its wear surface, but because the oxide film is discontinuous and loose, it is easily damaged and falls off during friction with the Si3N4 grinding ball (i.e., the grinding ball in the aforementioned ball-on-disc high-temperature friction and wear tester), and has no protective effect; in summary, the wear mechanism of the Inconel718 alloy substrate at room temperature is mainly abrasive wear, adhesive wear and plastic deformation.

[0166] ② A large amount of white grinding debris appeared on the surface of the composite coating obtained in Example 1, which was in powdery and granular form, and flaky shedding occurred. Due to the load applied to the Si3N4 ceramic ball, stress concentration occurred at the contact point with the coating, which easily led to plastic deformation and caused the coating surface material to be squeezed and shedding.

[0167] ③ The worn surface of the composite coating obtained in Example 4 is distributed with broken hard particles and adhesion traces. During the wear process, the broken particles distributed on the coating surface are easily dislodged by repeated squeezing by the counter-grinding balls, forming abrasive wear between the counter-grinding balls and the coating surface. Due to the load applied to the counter-grinding rod, the local stress on the contact surface is sufficient to cause plastic deformation, destroying the oxide film and lubricating film on this surface. The soft solid solution on the coating surface directly contacts the counter-grinding ball surface, resulting in adhesion. During the subsequent continued sliding, the adhesion points are sheared off and form wear debris. The EDS results in Table 5 show that the O content in the typical worn area of ​​the composite coating obtained in Example 4 is 11.72%, and the C content is 13.93%, indicating the presence of small amounts of oxides and metal carbides in this area.

[0168] ④ The composite coating obtained in Example 5 has obvious plastic deformation and plowing on the worn surface. Although the hardness of the coating is improved compared to the substrate, it is still much lower than that of the Si3N4 counter-grinding ball. The coating surface is subjected to vertical pressure and shear force from the counter-grinding ball, resulting in certain plastic deformation. The counter-grinding ball and hard grinding debris easily scratch the coating surface during the friction process, thereby forming plowing. The coating surface has peeling and plastic deformation. Due to the characteristics of rapid melting and rapid solidification of laser cladding, there is a large residual stress inside the coating. During the friction process, stress concentration occurs when the coating surface is subjected to vertical load. When the stress exceeds the material strength limit, microcracks will be generated. With the cyclic action of the external load, the microcracks continue to expand, and eventually the coating surface will flake off, and the lubricating phase in the coating will appear on the worn surface. The lubricating phase in the coating forms a lubricating film during friction contact. During the wear process, the counter-grinding ball is in direct contact with the lubricating film, and the lubricating film is in direct contact with the coating. Therefore, wear only occurs between the counter-grinding ball and the lubricating film, and between the coating and the lubricating film, significantly reducing the wear rate and friction coefficient of the coating.

[0169] 2) Macromorphology and local characterization of wear scars of composite coatings at 600°C:

[0170] The specific test methods for characterizing the macroscopic morphology and local area of ​​the wear scar of the composite coating under 600°C conditions refer to the characterization methods under room temperature conditions mentioned above. The results are as follows Figure 8 and as shown in Table 6; among them, Figure 8 (a1) to (d1) are the wear surface morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4 and 5, respectively; Figure 8 (a2) to (d2) are typical wear area morphologies of the Inconel718 alloy substrate and the composite coatings provided in Examples 1, 4 and 5, respectively.

[0171] Table 6 EDS results of typical wear areas at 600℃

[0172]

[0173]

[0174] Depend on Figure 8 From Table 6, we can see that:

[0175] ①Since the hardness of Si3N4 grinding balls is higher than that of Inconel718 matrix, during the friction process, the Inconel718 surface is in direct contact with the Si3N4 ball, and a certain amount of plastic deformation occurs under the cutting and extrusion of the grinding balls and hard particles, resulting in local fracture and shedding of surface materials; at the same time, there are hard protruding particles on the Inconel718 matrix, which will cause two-body abrasive wear on the Inconel718 matrix; under the dual action, wider furrows appear on the matrix surface, generating greater furrow resistance and shear resistance; from Figure 8 It can be seen that compared with the wear morphology at room temperature, no obvious scratches and plowing phenomena appear on the worn surface of the composite coating;

[0176] ② The surface of the composite coating obtained in Example 1 showed slight plowing grooves and a small amount of white wear debris. EDS showed that the mass ratio of the C element was 3.43%, indicating that the 20wt% SiC coating had less carbide hard phase detached, and its surface suffered from slight abrasive wear and oxidative wear.

[0177] ③ The composite coating obtained in Example 4 had no broken particles on its surface, but slight flaking and tearing occurred locally, indicating that the coating had undergone adhesive wear. The oxygen content in the characteristic region of the coating was the highest at 6.93%.

[0178] ④ The O content of the composite coating obtained in Example 5 was the highest at 22.77%, indicating that the shedding of the coating at 600°C was mainly due to the shedding of the oxide film. Under the protection of the oxide film, the hard phase carbide basically did not peel off from the coating surface; obvious stratification occurred on the coating surface, indicating that the density of the oxide film was good at 600°C, which slowed down the direct contact between the grinding ball and the coating surface and played a good wear-resistant role.

[0179] 7. Anti-oxidation performance test of composite coating:

[0180] 1) XRD pattern analysis of oxidized surface:

[0181] The oxidation resistance of the Inconel718 alloy substrate and the composite coatings prepared in Example 1 and Example 5 were tested using a Kejing single-temperature zone tube furnace (OTF-1200X). The test steps were strictly in accordance with the oxidation weight gain method in the standard "Test Method for Determination of Oxidation Resistance of Steel and High-Temperature Alloys". The specific test method is as follows:

[0182] ① Place the prepared test piece in a quartz boat, and then put it into a Kejing single-temperature zone tube furnace. Set the temperature to 800℃ and the heating rate to 10℃ / min. Perform a high-temperature oxidation test on the sample for 100 hours.

[0183] ② Use an electronic balance with an accuracy of 0.0001 to record the weight increase of the substrate and composite coating at 1h, 4h, 7h, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h and 100h during the constant temperature oxidation process;

[0184] ③ After the oxidation test, the oxidation products of the substrate and the C3 composite coating with the best oxidation resistance (ie, Example 5) were detected using an X-ray diffractometer (XRD, Japan Smartlab SE), and the substrate and C1 (ie, Example 1) were used as controls using a scanning electron microscope (SEM, TESCAN MIRA4) and an energy dispersive spectrometer (EDS, Xplore30.Aztec one) to analyze the surface oxidation micromorphology and element distribution; the results are shown in Figure 2. Figure 9 and Figure 10 shown.

[0185] Depend on Figure 9 It can be seen that the oxide on the substrate surface is mainly Cr2O3, while the composite coating obtained in Example 1 has more types of oxides. In addition to Cr2O3, there are also metal oxides such as Fe2O3, TiO2, and SiO2. The composite coating obtained in Example 5 mainly detects the diffraction peak of SiO2.

[0186] 2) Oxidation kinetics curve analysis of composite coating:

[0187] The oxidation kinetics curve is drawn with oxidation time as the horizontal axis and oxidation weight gain per unit area of ​​the coating as the vertical axis. The results are as follows: Figure 10 shown.

[0188] Depend on Figure 10 It can be seen that the weight of all samples increases with the extension of oxidation time. The calculation of the weight gain per unit surface area shows that within 100 h, the weight of the substrate and the composite coatings obtained in Examples 1, 4 and 5 increased by 56.4 mg / cm 2 , 49.2mg / cm 2 , 46.8mg / cm 2 and 41.2 mg / cm 2 Under the same oxidation conditions, the weight gain of the coating is less than that of the substrate, and the oxidation amount of Inconel718 high-temperature alloy and the coating increases with the extension of oxidation time.

[0189] 3) Surface morphology characterization of the oxidation composite coating:

[0190] The oxidized surface morphology was observed using SEM (TESCAN MIRA4), and the characteristic areas were scanned. The element content distribution was studied by EDS (Xplore 30. Aztec one). The results are shown in the figure. Figure 11 and as shown in Table 7.

[0191] Table 7 EDS results of typical oxidation morphologies of the substrate, composite coatings obtained in Examples 1, 4 and 5

[0192]

[0193]

[0194] Depend on Figure 11 From Table 7, we can see that:

[0195] ① Figure 11 Figures a1 and a2 show the overall morphology of the substrate surface and a magnified view of a local area, respectively. The substrate surface material is fragmented, lacking a smooth, dense oxide film. This is due, in part, to the significant difference in thermal expansion coefficients between the material and the oxide, which causes cracks on the substrate surface and subsequent shedding. Furthermore, the sample underwent multiple hot and cold cycles from 800°C to room temperature. As the temperature increased, an oxide film gradually formed on the surface. During this process, the oxide film was subject to tensile stress from the substrate, while the substrate was subject to compressive stress from the oxide film. The forces acting in opposite directions during cooling are reversed. In this case, if the applied stress exceeds the oxide film's tolerance limit, the film will crack or peel.

[0196] Figure a2 shows that the tiny lamellar material (such as area B) contains the highest Cr and O contents, at 64.62% and 27.40%, respectively. This is speculated to be Cr oxide. Point C shows a massive material with a high C content of 53.70%, possibly a hard phase carbide. The matrix's other metal contents are not high, primarily consisting of chromium oxide.

[0197] ② Figure 11 Figures b1 and b2 shown in the figure are the overall morphology and local area magnification of the surface of the composite coating obtained in Example 1, respectively; the oxidized surface of the composite coating obtained in Example 1 shows a layered structure, and different layered areas are selected for analysis. As shown in Figure b2, point D is the lower area of ​​the surface, where the O content is relatively low, only 4.00%. It is speculated that this is an area not covered by the oxide film and is still mainly composed of high-content iron-nickel compounds; point E is mainly composed of Cr (53.01%) and O (33.69%), which should be CrO2; the element distribution at point F is basically the same as that at E, indicating that the surface of the coating is covered with a layer of Cr oxide.

[0198] ③ Figure 11Figures c1 and c2 shown in the figure are the overall morphology and local area enlarged views of the surface of the composite coating obtained in Example 4, respectively; Figures d1 and d2 are the overall morphology and local area enlarged views of the surface of the composite coating obtained in Example 5, respectively; observing the oxidized surface morphology of the two coatings (Examples 4 and 5) with the addition of Ti3SiC2, the surface of the composite coating obtained in Example 4 is completely covered with an oxide film, and the G shown in Figure c2 is the particulate matter on its surface, where Si element (33.77%) and O element (39.40%) are present, indicating that they are SiO2; those at H and I are mainly iron and chromium oxides; in comparison, the surface of the composite coating obtained in Example 5 is smoother, indicating that the oxide film generated by the composite coating provided by the present invention after high-temperature oxidation is relatively uniform, and can effectively prevent further oxidation of the material surface.

[0199] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A composite coating, characterized in that: The composite coating is prepared using a composite powder, which includes the following raw materials in percentage by mass: 1% to 20% Ti3SiC2, 60% to 90% Ni60, and 15% to 25% SiC. The composite powder is prepared by the following preparation method: mixing the components in the composite powder and then ball milling the mixture to obtain the composite coating; The preparation method of the composite coating comprises the following steps: coating the composite powder on the surface of a substrate to obtain the composite coating; the coating method comprises laser cladding; the laser power of the laser cladding is 700-900 W; the laser spot diameter of the laser cladding is 1-3 mm; the defocus amount of the laser cladding is -30--10 mm; the scanning speed of the laser cladding is 3-7 mm / s; the powder feeding rate of the laser cladding is 10-17 g / min; and the overlap rate of the laser cladding is 40%-60%. The substrate comprises a nickel-based high-temperature alloy; The particle size of the Ni60 is 30-120 μm; The particle size of the SiC is 40-60 μm; The particle size of the Ti3SiC2 is 40-60 μm.

2. A coated product, characterized in that The coated product includes a substrate and a coating; The coating is the composite coating according to claim 1.

3. Use of the composite coating as claimed in claim 1 in surface modification of nickel-based alloys.

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