A preparation method and application of self-lubricating cemented carbide coating

Abstract

The present invention relates to the technical field of surface coatings, and specifically to a method for preparing a self-lubricating cemented carbide coating and its application. The present invention solves the problem of poor durability of the coating. The method for preparing the self-lubricating cemented carbide coating in the present invention comprises pre-treating a substrate, fixing the treated substrate, forming a Cr bonding layer and a hard layer on the surface of the treated substrate by an arc ion plating process, and then forming a lubricating layer on the hard layer by a plasma spraying process, and finally obtaining a self-lubricating cemented carbide coating. The present invention improves the bonding strength of the coating by treating the substrate with plasma cleaning, then controls the impact parameters of the Cr bonding layer and the thickness of the hard layer to improve the hardness of the coating, controls the impact parameters of the hard layer to reduce the wear rate of the coating, reduces the friction coefficient of the coating by changing the amount of lubricating material and the parameters of ball milling, and finally controls the parameter conditions of the plasma spraying process and the thickness of the lubricating layer to improve the corrosion resistance of the coating.

Description

Technical Field

[0001] The invention relates to the technical field of surface coatings, in particular to a preparation method of a self-lubricating hard alloy coating and application thereof. Background Art

[0002] Self-lubricating alloy coating technology has gradually developed in recent years. It can effectively solve the problems of hardness, wear resistance or poor lubricity of the substrate surface, and is widely used in the surface protection of cutting tools, bearings and instrument components. Self-lubricating alloy coatings generally include materials such as molybdenum disulfide or soft metals. These materials have low shear strength and can reduce the friction coefficient by adhering to the substrate surface, so they have good lubricity. With the continuous improvement of the requirements of the times, some self-lubricating alloy coatings cannot take into account wear resistance, hardness and lubricity, and are gradually being eliminated in the industry.

[0003] The method of preparing self-lubricating alloy coating also has an important influence on the performance of the coating. Arc ion plating and plasma spraying technology are the main technologies for preparing coatings at this stage. Among them, arc ion plating technology has a high metal ionization rate, strong film density and strong adhesion, which is suitable for industrial large-area workpiece coating; plasma spraying technology has good material density during the spraying process, strong coating adhesion, good uniformity, and less thermal impact on the substrate, reducing the risk of substrate deformation or damage.

[0004] Patent CN115044901B discloses an ordered microporous wear-resistant self-lubricating coating and its preparation method. The invention uses laser cladding technology to directly form an ordered microporous nickel-based hard coating on the surface of a titanium alloy substrate, and then uses high-temperature infiltration technology to melt the soft metal lubricant SnAg alloy and the negative expansion material ZrW as a regulator. 2 O 8 Infiltrate the nickel-based hard coating micropores to form a new wear-resistant self-lubricating coating. However, the laser cladding technology and high-temperature infiltration technology in the invention have high requirements for the substrate, which can easily cause deformation and damage to the substrate. At the same time, the deposition efficiency is low, which will affect the adhesion and adhesion of the coating, and ultimately cause the coating to have insufficient hardness and poor wear resistance.

[0005] In summary, today's self-lubricating alloy coatings still have shortcomings such as poor wear resistance and poor corrosion resistance, which results in poor coating durability and seriously affects industrial production efficiency.

[0006] Therefore, a preparation method and application of a self-lubricating cemented carbide coating are proposed. Summary of the invention

[0007] The purpose of the present invention is to design a preparation method and application of a self-lubricating cemented carbide coating. The preparation method of the self-lubricating cemented carbide coating includes pre-treating a substrate, fixing the treated substrate, forming a Cr bonding layer and a hard layer on the surface of the treated substrate by an arc ion plating process, and then forming a lubricating layer on the hard layer by a plasma spraying process, and finally obtaining a self-lubricating cemented carbide coating. The present invention improves the bonding strength of the coating by plasma cleaning the substrate and controlling the parameter conditions of the substrate on the workpiece rotating rack; improves the hardness of the coating by controlling the impact parameters of the Cr bonding layer, the thickness of the Cr bonding layer and the hard layer; reduces the wear rate of the coating by controlling the impact parameters of the hard layer and the element percentage of the hard layer; reduces the friction coefficient of the coating by changing the amount of graphene powder, molybdenum powder and nickel alloy, as well as the rotation speed and time of ball milling; and improves the corrosion resistance of the coating by controlling the parameter conditions of the plasma spraying process and the thickness of the lubricating layer.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a method for preparing a self-lubricating cemented carbide coating, the method comprising the following steps:

[0010] S1 polishes the surface of the substrate, and then performs plasma cleaning on it after ultrasonic treatment for 5 hours to obtain a treated substrate;

[0011] S2: fix the treated substrate on the workpiece rotating rack in the coating chamber, adjust the rotation speed of the workpiece rotating rack to 3rpm-7rpm, make the treated substrate face the target surface horizontally at a distance of 100cm, and heat the coating chamber to 400℃-600℃;

[0012] S3 introduces argon gas, adjusts the gas pressure A1, adjusts the substrate bias voltage B1, turns on the Cr target, adjusts the target current C1, and impacts the treated substrate with Cr ions to form a Cr bonding layer;

[0013] S4: turn off the argon gas, introduce nitrogen gas, adjust the gas pressure A2, adjust the substrate bias voltage B2, turn on the AlCrTiB target, adjust the target current C2, form an AlCrTiBN film as a hard layer on the Cr bonding layer, and turn off the nitrogen gas and the arc ion plating device;

[0014] S5: mixing and ball-milling 6-10 parts of graphene powder, 1-4 parts of molybdenum powder and 47-51 parts of nickel alloy to obtain a lubricating material;

[0015] S6: spraying the lubricating material onto the surface of the hard layer through a plasma spraying process to form a lubricating layer, and obtaining the self-lubricating cemented carbide coating after cooling.

[0016] Preferably, the plasma cleaning process in S1 is: plasma etching the substrate under atmosphere D at a temperature of 450°C-650°C.

[0017] Preferably, the atmosphere D is one or two of argon, nitrogen and hydrogen.

[0018] Preferably, the gas pressure A1 in S3 is 0.8Pa-1.4Pa; the substrate bias voltage B1 is -150V to -300V; the target current C1 is 50A-80A; and the thickness of the Cr bonding layer is 3nm-9nm.

[0019] Preferably, the gas pressure A2 in S4 is 1.5Pa-2.1Pa; the substrate bias voltage B2 is -200V to -350V; and the target current C2 is 65A-95A.

[0020] Preferably, the AlCrTiB target in S4 is formed by splicing a pure Al target, a pure Cr target, a pure Ti target and a pure B target.

[0021] Preferably, the thickness of the hard layer in S4 is 30 μm-50 μm; the atomic percentage of elements in the hard layer is: Al 26%-28%, Cr 5%-7%, Ti 12%-14%, B 0.8%-1%, and the rest is N.

[0022] Preferably, the chemical composition of the nickel alloy in S5 includes: 87.7% Ni, 9.2% Cr, 2.8% Si and 0.3% C; the rotation speed of the ball mill is 480rpm-520rpm; and the ball milling time is 12h-18h.

[0023] Preferably, the process parameters of the plasma spraying in S6 are: spraying power 36KW-40KW, spray gun moving speed 30mm / s-90mm / s, spraying distance 80mm-120mm; the thickness of the lubricating layer is 5μm-20μm.

[0024] Another aspect of the present invention provides an application of a self-lubricating cemented carbide coating, wherein the self-lubricating cemented carbide coating is prepared by any one of the above-mentioned preparation methods; the self-lubricating cemented carbide coating can be used for surface protection of cutting tools, bearings and instrument components.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention improves the adhesion of the coating by treating the substrate with plasma cleaning and controlling the parameter conditions of the substrate on the workpiece rotating rack. Plasma cleaning can remove dirt, grease, oxides or other pollutants on the surface of the substrate, and can effectively improve the adhesion of the substrate surface, so that the coating and the substrate are more closely combined; controlling the conditions of plasma cleaning, the rotation speed of the workpiece rotating rack and the temperature of the coating chamber can prepare for subsequent coating, so that the coating can be closely combined with the substrate, and will not fall off in the later stage, thereby improving the durability of the coating.

[0027] 2. Improve the hardness of the coating by controlling the impact parameters of the Cr bonding layer, the thickness of the Cr bonding layer and the hard layer. Impacting a layer of Cr bonding layer on the surface of the substrate can make the hard layer and the substrate bond more tightly, thereby improving the hardness of the coating; the air pressure condition will affect the deposition speed, improve the adhesion of the Cr bonding layer, make the Cr bonding layer more compact and increase the hardness; suitable parameter conditions can improve the deposition quality and the strength of the Cr bonding layer; suitable Cr bonding layer thickness can make the hard layer have good bonding with the substrate, and suitable hard layer thickness can keep the hardness of the coating at the maximum.

[0028] 3. Reduce the wear rate of the coating by controlling the impact parameters of the hard layer and the percentage of elements in the hard layer. The gas pressure conditions of arc ion plating will affect the deposition speed, improve the adhesion of the hard layer, make the hard layer denser, and thus improve the wear resistance of the coating; introducing elements such as Al, Cr, and Ti into the hard layer can significantly improve the wear resistance of the coating, and the atomic percentage of the hard layer elements will affect the overall hardness of the hard layer, thereby improving the wear resistance of the coating.

[0029] 4. Reduce the friction coefficient of the coating by changing the amount of graphene powder, molybdenum powder and nickel alloy, as well as the speed and time of ball milling. Adding graphene powder to nickel alloy can effectively improve the lubricity of the lubricating layer. This is because in the layered structure of graphene, the van der Waals force between the layers is weak, so graphene has very good interlayer sliding performance. This unique structure enables graphene to provide lubrication on the friction interface and reduce friction; the mechanism of action of molybdenum powder is similar to that of graphene, and its interlayer van der Waals force is weak, which makes it have good lubrication performance, thereby reducing friction; the particle size of the lubricating material is controlled by the speed and time of ball milling, so that the particle distribution of the subsequent lubricating layer is relatively uniform, the density is strong, and the friction coefficient is reduced.

[0030] 5. Improve the corrosion resistance of the coating by controlling the parameters of the plasma spraying process and the thickness of the lubricating layer. The power of plasma spraying will affect the melting effect of the lubricating material. Properly increasing the spraying power can enable the spraying particles to obtain higher energy, so that they can spread and solidify better, form a denser coating structure, reduce the pores and defects in the coating, and thus improve the corrosion resistance of the lubricating layer; the lubricating layer can effectively block the contact between the external corrosive medium and the coating substrate, and to a certain extent, it also plays a sealing role, which can prevent external moisture, dust, impurities, etc. from entering the interior of the substrate, thereby reducing the occurrence of corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the self-lubricating cemented carbide coating designed for the present invention.

[0032] Figure 2 This is a friction coefficient graph of Example 44, Example 48, Examples 50-51, Examples 53-58, Example 60 and Comparative Examples 6-8 of the present invention.

[0033] In the figure: 1. Lubricating layer; 2. Hard layer; 3. Cr bonding layer; 4. Matrix. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention provides a method for preparing a self-lubricating cemented carbide coating, such as Figure 1 As shown, the self-lubricating cemented carbide coating consists of a lubricating layer 1, a hard layer 2, and a Cr bonding layer 3. Figure 1-Figure 2 , the technical solution is as follows:

[0036] Example 1

[0037] S1 polishes the surface of the substrate, ultrasonicates it for 5 hours, and then plasma etches the substrate in an argon atmosphere at a temperature of 450° C. to obtain a treated substrate;

[0038] S2: fix the treated substrate on the workpiece rotating rack in the coating chamber, adjust the rotation speed of the workpiece rotating rack to 3 rpm, make the treated substrate face the target surface horizontally at a distance of 100 cm, and heat the coating chamber to 400° C.;

[0039] S3 introduces argon gas, adjusts the gas pressure to 0.8 Pa, adjusts the substrate bias voltage to -150 V, turns on the Cr target, adjusts the target current to 50 A, and impacts the treated substrate with Cr ions to form a Cr bonding layer with a thickness of 3 nm;

[0040] S4: turn off the argon gas, introduce nitrogen gas, adjust the gas pressure to 1.5 Pa, adjust the substrate bias voltage to -200 V, turn on the AlCrTiB target, adjust the target current to 65 A, form an AlCrTiBN film as a hard layer on the Cr bonding layer, the hard layer thickness is 30 μm, turn off the nitrogen gas and the arc ion plating device;

[0041] S5: 6 parts of graphene powder, 1 part of molybdenum powder and 47 parts of nickel alloy are mixed and ball-milled at a ball-milling speed of 480 rpm for 12 hours to obtain a lubricating material;

[0042] S6 sprays the lubricating material onto the surface of the hard layer through a plasma spraying process, with a spraying power of 36KW, a spray gun moving speed of 30mm / s, and a spraying distance of 80mm to form a lubricating layer with a thickness of 5μm. After cooling, the self-lubricating cemented carbide coating is obtained.

[0043] Example 2-12

[0044] Referring to the parameter conditions of the preparation method in Example 1, the specific differences are shown in Table 1.

[0045] Table 1 Parameter conditions of Examples 1-12

[0046]

[0047] Comparative Example 1

[0048] The parameters and conditions of the preparation method in Example 1 are referred to, except that plasma cleaning is not performed.

[0049] Comparative Example 2

[0050] The parameters of the preparation method in Example 1 are referred to, except that the rotation speed of the workpiece rotating rack is 30 rpm and the temperature of the coating chamber is 800°C.

[0051] Comparative Example 3

[0052] The parameters and conditions of the preparation method in Example 1 are referred to, except that the rotation speed of the workpiece rotating rack is 1 rpm and the temperature of the coating chamber is 200°C.

[0053] Example 13 Bonding Strength Test

[0054] The bonding strength of Examples 1-12 and Comparative Examples 1-3 was tested by a pull-off test, and the results are shown in Table 2.

[0055] Table 2 Bonding strength test of Examples 1-12 and Comparative Examples 1-3

[0056]

[0057] It can be found from Table 2 that in Comparative Example 1, plasma cleaning is not performed and the adhesion of the coating is poor. This is because plasma cleaning can remove dirt, grease, oxides or other contaminants on the surface of the substrate, and can effectively improve the adhesion of the substrate surface, so that the coating and the substrate are more closely combined; in Comparative Examples 2-3, the rotation speed of the workpiece turntable is too high or too low and the temperature of the coating chamber is too high or too low, which will affect the adhesion of the coating. The adhesion of the coating is significantly reduced. This is because the rotation speed is too fast or too slow and the temperature is too high or too low, which will cause uneven distribution of the coating, thereby reducing the adhesion of the coating, and the coating is easy to fall off, affecting the durability of the coating. In Examples 1-12, when the atmosphere of plasma cleaning is changed, the cleaning temperature, the rotation speed of the workpiece turret and the temperature of the coating chamber remain unchanged, the cleaning effect is best under the argon and nitrogen atmospheres, and the adhesion of the coating is the strongest. At this time, the adhesion of Example 4 is 52.9MPa; when the atmosphere of plasma cleaning is argon and nitrogen, the cleaning temperature is changed, the rotation speed of the workpiece turret and the temperature of the coating chamber remain unchanged, the adhesion of the coating is strongest at a cleaning temperature of 550°C, and the adhesion of Example 7 is 54.7MPa; when the atmosphere of plasma cleaning is argon and nitrogen, the cleaning temperature is 550°C, the rotation speed of the workpiece turret is changed, and the temperature of the coating chamber remains unchanged, the adhesion of the coating is the strongest at a cleaning temperature of 550°C, and the adhesion of Example 7 is 54.7MPa. The adhesion is strongest when the rotation speed of the workpiece turntable is 5rpm, and the adhesion of Example 9 is 56.6MPa at this time; when the atmosphere of plasma cleaning is argon and nitrogen, the cleaning temperature is 550°C, the rotation speed of the workpiece turntable is 5rpm, when the temperature of the coating chamber is changed, the adhesion of the coating first increases and then decreases. When the temperature of the coating chamber is 500°C, the adhesion of the coating is strongest, and the adhesion of Example 11 is 58.2MPa at this time. This is because controlling the conditions of plasma cleaning, the rotation speed of the workpiece turntable and the temperature of the coating chamber can prepare for subsequent coating, so that the coating can be tightly combined with the substrate, and will not fall off in the later stage, thereby improving the durability of the coating.

[0058] Examples 14-27

[0059] Referring to the parameter conditions of the preparation method in Example 11, the difference lies in that the process parameters for preparing the Cr bonding layer, the thickness of the Cr bonding layer and the hard layer are changed. The specific differences are shown in Table 3.

[0060] Table 3 Parameter conditions of Example 11 and Examples 14-27

[0061]

[0062] Comparative Example 4

[0063] Refer to the parameter conditions of the preparation method in Example 11, except that the thickness of the Cr bonding layer is 30 nm and the thickness of the hard layer is 100 μm.

[0064] Comparative Example 5

[0065] Refer to the parameter conditions of the preparation method in Example 11, except that the thickness of the Cr bonding layer is 1 nm and the thickness of the hard layer is 5 μm.

[0066] Example 28 Vickers hardness test

[0067] The Vickers hardness of Example 11, Examples 14-27 and Comparative Examples 4-5 was tested by Vickers hardness test, and the results are shown in Table 4.

[0068] Table 4 Vickers hardness test of Example 11, Examples 14-27 and Comparative Examples 4-5

[0069]

[0070] It can be found from Table 4 that in Comparative Example 4, the thickness of the hard layer is relatively high, and the Vickers hardness of the coating also increases with the increase in thickness. This is because, in general, the greater the thickness, the stronger the hardness. However, an overly thick hard layer will cause internal stress, which is prone to cracking, peeling, and other phenomena, and the durability is not strong; in Comparative Example 5, the thickness of the Cr bonding layer and the hard layer is very thin, and it is difficult to have a strong Vickers hardness, and the durability of the coating is poor. In Example 11 and Examples 14-27, when the gas pressure A1 is changed, the substrate bias B1, the target current C1, the thickness of the Cr bonding layer and the hard layer remain unchanged, the hardness of the coating is the largest when the gas pressure A1 is 1.0Pa. At this time, the Vickers hardness of Example 14 is 794HV. This is because the gas pressure conditions affect the deposition speed, improve the adhesion of the Cr bonding layer, make the Cr bonding layer more dense, and increase the hardness; when the gas pressure A1 is 1.0Pa, the substrate bias B1 is changed, the target current C1, the thickness of the Cr bonding layer and the hard layer remain unchanged When the substrate bias voltage B1 is -250V, the Vickers hardness of the coating is the largest, and the Vickers hardness of Example 18 is 923HV, because the substrate bias voltage will affect the internal stress of the Cr bonding layer. When the internal stress is too large, the Cr bonding layer will cause curling. At the same time, the substrate bias voltage will also affect the hardness of the coating; when the air pressure A1 is 1.0Pa, the substrate bias voltage B1 is -250V, the target current C1 is changed, and the thickness of the Cr bonding layer and the hard layer remains unchanged, the hardness of the coating is the largest when the target current C1 is 60A, and the Vickers hardness of Example 20 is 987HV , because the size of the target current will affect the stability of the arc, thereby affecting the quality of deposition, and ultimately affecting the hardness of the Cr bonding layer; when the gas pressure A1 is 1.0Pa, the substrate bias B1 is -250V, the target current C1 is 60A, the thickness of the Cr bonding layer is changed, and the thickness of the hard layer remains unchanged, the hardness of the coating is the maximum when the thickness of the Cr bonding layer is 5nm, and the Vickers hardness of Example 23 is 1075HV; when the gas pressure A1 is 1.0Pa, the substrate bias B1 is -250V, the target current C1 is 60A, the thickness of the Cr bonding layer is changed, and the thickness of the hard layer remains unchanged, the hardness of the coating is the maximum when the thickness of the Cr bonding layer is 5nm, and the Vickers hardness of Example 23 is 1075HV; The thickness is 5nm. When the thickness of the hard layer is changed, the hardness of the coating is the largest when the thickness of the hard layer is 40μm. The Vickers hardness of Example 26 is 1120HV. This is because a layer of Cr bonding layer is impacted on the surface of the substrate, which can make the hard layer and the substrate bond more tightly, thereby improving the hardness of the coating. The appropriate thickness of the Cr bonding layer can make the hard layer and the substrate have good bonding force. The appropriate thickness of the hard layer can keep the hardness of the coating at the maximum, but an excessively thick hard layer also has a certain impact on the coating, and the durability of the coating is not strong.

[0071] Examples 29-45

[0072] Referring to the parameter conditions of the preparation method in Example 26, the difference lies in that the process parameters for preparing the hard layer and the atomic percentage of the hard layer elements are changed. The specific differences are shown in Table 5.

[0073] Table 5 Parameters and conditions of Example 26 and Examples 29-45

[0074]

[0075] Example 46 Wear rate test

[0076] Example 26 and Examples 29-45 were subjected to wear tests, and the mass changes before and after wear were measured to calculate the wear rate. The results are shown in Table 6.

[0077] Table 6 Wear rate test of Example 26 and Examples 29-45

[0078]

[0079] It can be found from Table 6 that in Examples 26 and Examples 29-45, when the gas pressure A2 is changed, the substrate bias B2, the target current C2 and the atomic percentage of the hard layer elements remain unchanged, the wear rate is lowest when the gas pressure A2 is 1.9 Pa, and the wear rate of Example 30 is 0.76 mg / h, because the gas pressure conditions of arc ion plating will affect the deposition speed, improve the adhesion of the hard layer, and make the hard layer more compact, thereby improving the wear resistance of the coating, thereby reducing the wear rate; when the gas pressure A2 is 1.9 Pa, the substrate bias B2 is changed, the target current C2 and the atomic percentage of the hard layer elements remain unchanged, the wear rate is lowest when the substrate bias B2 is -300 V, and the wear rate of Example 33 is 0.69 mg / h, because the substrate bias will affect The internal stress of the hard layer, when the internal stress is too large, will cause cracking of the hard layer, and the substrate bias will also affect the wear rate of the coating; when the gas pressure A2 is 1.9Pa, the substrate bias B2 is -300V, the target current C2 is changed, and the atomic percentage of the hard layer elements remains unchanged, the wear rate is lowest when the target current C2 is 75A, and the wear rate of Example 35 is 0.64mg / h, because the size of the target current will affect the stability of the arc, thereby affecting the quality of deposition, and ultimately affecting the wear rate of the coating; when the gas pressure A2 is 1.9Pa, the substrate bias B2 is -300V, the target current C2 is 75A, the percentage of the Al element is changed, and the percentages of other elements remain unchanged, the wear of the coating first decreases and then increases. When the percentage of the Al element is 2 7%, the wear rate of the coating is the lowest, and the wear rate of Example 38 is 0.60 mg / h; when the gas pressure A2 is 1.9 Pa, the substrate bias B2 is -300 V, the target current C2 is 75 A, the percentage of Al element is 27%, the percentage of Cr element is changed, and the percentage of other elements remains unchanged, the percentage of Cr element is 6%, and the wear rate of the coating is the lowest, and the wear rate of Example 40 is 0.55 mg / h; when the gas pressure A2 is 1.9 Pa, the substrate bias B2 is -300 V, the target current C2 is 75 A, the percentage of Al element is 27%, the percentage of Cr element is 6%, the percentage of Ti element is changed, and the percentage of B element remains unchanged, the wear of the coating first decreases and then increases, and when the percentage of Ti element is 13% , the wear rate of the coating is the lowest, and the wear rate of Example 42 is 0.49 mg / h; when the gas pressure A2 is 1.9 Pa, the substrate bias B2 is -300 V, the target current C2 is 75 A, the percentage of Al element is 27%, the percentage of Cr element is 6%, and the percentage of Ti element is 13%, when the percentage of B element is changed, the wear of the coating first decreases and then increases. When the percentage of B element is 0.9%, the wear rate of the coating is the lowest, and the wear rate of Example 44 is 0.45 mg / h. This is because the introduction of elements such as Al, Cr, and Ti into the hard layer can significantly improve the wear resistance of the coating, and the atomic percentage of the hard layer elements will affect the overall hardness of the hard layer, thereby improving the wear resistance of the coating and reducing the wear rate of the coating.

[0080] Examples 47-60

[0081] Referring to the parameter conditions of the preparation method in Example 44, the difference is that the amounts of graphene powder, molybdenum powder and nickel alloy, as well as the speed and time of ball milling are changed. The specific differences are shown in Table 7.

[0082] Table 7 Parameter conditions of Example 44 and Examples 47-60

[0083]

[0084] Comparative Example 6

[0085] Refer to the parameter conditions of the preparation method in Example 44, except that the lubricating material only contains 49 parts of nickel alloy.

[0086] Comparative Example 7

[0087] Refer to the parameter conditions of the preparation method in Example 44, except that the ball milling speed is 100 rpm and the ball milling time is 5 h.

[0088] Comparative Example 8

[0089] Refer to the parameter conditions of the preparation method in Example 44, except that the ball milling speed is 800 rpm and the ball milling time is 25 h.

[0090] Example 61 Friction coefficient test

[0091] The friction coefficients of Example 44, Examples 47-60 and Comparative Examples 6-8 were tested according to ASTM G133-2005 standard. The results are shown in Table 8. The friction coefficients of Example 44, Example 48, Examples 50-51, Examples 53-58, Example 60 and Comparative Examples 6-8 are shown in Table 8. Figure 2 shown.

[0092] Table 8 Friction coefficient test of Example 44, Examples 47-60 and Comparative Examples 6-8

[0093]

[0094] From Table 8 and Figure 2It can be found that in Comparative Example 6, only nickel alloy is added as a lubricating material, and the friction coefficient of the coating is very high, reaching 0.56, indicating that a single nickel alloy cannot effectively reduce the friction coefficient of the coating, and other substances need to be added to further improve the performance; in Comparative Examples 7-8, the rotation speed and time of ball milling will also affect the friction coefficient of the coating. Too fast or too slow rotation speed and too long or too short time will increase the friction coefficient of the coating. In Examples 44 and 47-60, when the amount of graphene powder is changed, the amount of molybdenum powder and nickel alloy, the rotation speed and time of ball milling remain unchanged, the friction coefficient of the coating first decreases and then increases. When the amount of graphene powder is 8 parts, the friction coefficient of the coating is the lowest. The friction coefficient of Example 48 is 0.26. Adding graphene powder to nickel alloy can effectively improve the lubricity of the lubricating layer. This is because in the layered structure of graphene, the van der Waals force between the layers is weak, so graphene has very good Good interlayer sliding performance, this unique structure enables graphene to provide lubrication on the friction interface and reduce friction; when the amount of graphene powder is 8 parts, the amount of molybdenum powder is changed, the amount of nickel alloy, the speed and time of ball milling remain unchanged, the friction coefficient of the coating is the lowest when the amount of molybdenum powder is 2 parts, and the friction coefficient of Example 51 is 0.22. Molybdenum powder is added to the lubricating material because the action mechanism of molybdenum powder is similar to that of graphene, and its interlayer van der Waals force is weak, so it has good lubrication performance, thereby reducing Less friction, lowering the friction coefficient; when the amount of graphene powder is 8 parts, the amount of molybdenum powder is 2 parts, the amount of nickel alloy is changed, and the speed and time of ball milling remain unchanged, the friction coefficient of the coating is lowest when the amount of nickel alloy is 49 parts, and the friction coefficient of Example 54 is 0.19; when the amount of graphene powder is 8 parts, the amount of molybdenum powder is 2 parts, and the amount of nickel alloy is 49 parts, the speed of ball milling is changed, and the time of ball milling remains unchanged, the friction coefficient of the coating is lowest when the speed of ball milling is 500rpm, and Example The friction coefficient of Example 56 is 0.16; when the amount of graphene powder is 8 parts, the amount of molybdenum powder is 2 parts, the amount of nickel alloy is 49 parts, and the ball mill speed is 500rpm, when the ball milling time is changed, the friction coefficient of the coating first decreases and then increases. When the ball milling time is 14h, the friction coefficient of the coating is the smallest. The friction coefficient of Example 58 is 0.13. The particle size of the lubricating material is controlled by the ball milling speed and time, so that the particle distribution of the subsequent lubricating layer is relatively uniform, the density is strong, and the friction coefficient is reduced.

[0095] Examples 62-71

[0096] Referring to the parameter conditions of the preparation method in Example 58, the difference lies in that the parameter conditions of the plasma spraying process and the thickness of the lubricating layer are changed. The specific differences are shown in Table 9.

[0097] Table 9 Parameters and conditions of Example 58 and Examples 62-71

[0098]

[0099] Example 72 Corrosion resistance test

[0100] The corrosion resistance test was carried out according to GB / T 7998-2023 standard to test the final corrosion depth. The results are shown in Table 10.

[0101] Table 10 Corrosion resistance test of Example 58 and Examples 62-71

[0102]

[0103] It can be found from Table 10 that in Examples 58 and 62-71, when the spraying power is changed, the spray gun moving speed, the spraying distance and the thickness of the lubricating layer remain unchanged, the corrosion resistance of the coating increases first and then decreases. When the spraying power is 38KW, the corrosion resistance of the coating is the strongest, and the corrosion depth of Example 62 is 18.9μm. This is because the power of plasma spraying will affect the melting effect of the lubricating material. Too low power will cause the lubricating material to be incompletely melted, and the lubricating material will fall off after spraying. When the spraying power is 38KW, the spray gun moving speed is changed, and the spraying distance is 38KW. When the coating distance and the thickness of the lubricating layer remain unchanged, the corrosion resistance of the coating is strongest when the spray gun moves at a speed of 50 mm / s. The corrosion depth of Example 64 is 17.8 μm. Because the movement speed of the spray gun is too fast or too slow may cause uneven lubricating layer. Fast movement may cause incomplete deposition of the lubricating layer, resulting in local voids or inconsistent thickness. If the spray gun moves too slowly, it may cause local overheating, too thick lubricating layer or warping, cracks and other problems, thereby affecting the corrosion resistance of the coating. When the spraying power is 38KW and the spray gun moves at a speed of 50 mm / s, when the spraying distance is changed and the thickness of the lubricating layer remains unchanged, the corrosion resistance of the coating increases first and then decreases. When the spraying distance is 100 mm, the corrosion resistance of the coating is the strongest. The corrosion depth of Example 67 is 16.9 μm. Because the spraying distance also has a great influence on the compactness of the lubricating layer, when the spray gun distance is too far, the sprayed material will be cooled in the air in advance, which may lead to insufficient melting of the lubricating material, poor compactness, and easy appearance of pores and cracks in the coating. When the distance is too close, due to overheating during the spraying process, the lubricating material may be too melted, forming It forms a loose structure, affecting the corrosion resistance; when the spraying power is 38KW, the spray gun moving speed is 50mm / s, and the spraying distance is 100mm, when the thickness of the lubricating layer is changed, the corrosion resistance of the coating is strongest when the thickness of the lubricating layer is 15μm. The corrosion depth of Example 70 is 13.6μm. The lubricating layer also plays a sealing role to a certain extent, which can prevent external moisture, dust, impurities, etc. from entering the interior of the substrate, thereby reducing the occurrence of corrosion. When the lubricating layer is too thin, the sealing is poor, which may cause pollutants to enter, causing corrosion, pollution and failure.

[0104] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a self-lubricating cemented carbide coating, characterized in that: The preparation method of the self-lubricating cemented carbide coating comprises the following steps: S1 polishes the surface of the substrate, ultrasonicates it for 5 hours, and then plasma etches the substrate under atmosphere D at a temperature of 450° C. to 650° C., wherein the atmosphere D is one or two of argon, nitrogen and hydrogen, to obtain a treated substrate; S2: fix the treated substrate on the workpiece rotating rack in the coating chamber, adjust the rotation speed of the workpiece rotating rack to 3rpm-7rpm, make the treated substrate face the target surface horizontally at a distance of 100cm, and heat the coating chamber to 500°C; S3: Open the arc ion plating device, introduce argon gas, adjust the gas pressure A1 to 0.8Pa-1.4Pa, adjust the substrate bias voltage B1 to -150V--300V, turn on the Cr target, adjust the target current C1 to 50A-80A, and impact the treated substrate with Cr ions to form a Cr bonding layer, the thickness of the Cr bonding layer is 3nm-9nm; S4: turn off the argon gas, introduce nitrogen gas, adjust the gas pressure A2 to 1.5Pa-2.1Pa, adjust the substrate bias voltage B2 to -200V to -350V, turn on the AlCrTiB target, which is composed of pure Al target, pure Cr target, pure Ti target and pure B target; adjust the target current C2 to 65A-95A, form an AlCrTiBN film on the Cr bonding layer as a hard layer, turn off the nitrogen gas and the arc ion plating device; the thickness of the hard layer is 30μm-50μm; the atomic percentage of the elements in the hard layer is: Al 26%-28%, Cr 5%-7%, Ti 12%-14%, B 0.8%-1%, and the rest is N; S5: 6-10 parts of graphene powder, 1-4 parts of molybdenum powder and 47-51 parts of nickel alloy are mixed and ball-milled to obtain a lubricating material; the chemical composition of the nickel alloy includes: 87.7% Ni, 9.2% Cr, 2.8% Si and 0.3% C; the rotation speed of the ball mill is 480rpm-520rpm; the time of the ball mill is 12h-18h; S6 sprays the lubricating material onto the surface of the hard layer through a plasma spraying process to form a lubricating layer. The parameters of the plasma spraying process are: spraying power 36KW-40KW, spray gun moving speed 30mm / s-90mm / s, spraying distance 80mm-120mm; the thickness of the lubricating layer is 5μm-20μm; after cooling, the self-lubricating cemented carbide coating is obtained.

2. Application of a self-lubricating cemented carbide coating, characterized in that: The self-lubricating cemented carbide coating is prepared by the preparation method described in claim 1; the self-lubricating cemented carbide coating is used for surface protection of cutting tools and instrument components.

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