A small capacitance insulating coating and its preparation method and use

Abstract

The present invention relates to a small-capacitance insulating coating and a preparation method and use thereof, in order to solve the defect that the existing insulating coating has a large capacitance and is not conducive to the blocking of high-frequency shaft current, and specifically relates to the field of surface coating processing technology, wherein the small-capacitance insulating coating comprises a coating body and grooves distributed in an array on the coating body; the spacing between adjacent grooves is 85-250 μm; the depth of the grooves is 10-30 μm; the opening equivalent circle diameter of the grooves is 55-160 μm. The small-capacitance insulating coating provided by the present invention reduces the capacitance of the insulating coating by designing the surface of the insulating coating and setting grooves with specific distribution on the surface of the insulating coating, thereby ensuring that a good blocking effect can still be achieved under high-frequency shaft current.

Description

Technical Field

[0001] The present invention relates to the technical field of surface coating processing, and relates to a small-capacitance insulating coating and a preparation method and use thereof, and in particular to a small-capacitance insulating coating for high-frequency shaft current and a preparation method and use thereof. Background Art

[0002] During the operation of the motor system, the bearing is a key component in the motor system, and its safety performance is related to the safety and stability of the entire system. When the bearing roller runs at high speed on the lubricating oil film, since the oil film is an insulating layer and is very thin, a bearing capacitance will be formed in the bearing. For example, the high du / dt of the common-mode voltage output by the inverter will induce high-frequency charging and discharging currents in the motor parasitic capacitance and the bearing capacitance. Whenever the insulated gate bipolar transistor IGBT is turned on or off, this common-mode current will be triggered. Although the capacitive charging and discharging current itself will not cause harm to the bearing, the charging and discharging process will cause charging voltages at both ends of the oil film between the roller and the inner and outer rings of the bearing. When the charging voltage exceeds the oil film breakdown voltage value, the energy stored in the capacitor will be released through the bearing, causing the variable frequency speed regulation motor to discharge the gap between the inner and outer rings (including the oil film) capacitor, that is, the EDM current, and generate discharge sparks at the same time. Long-term shaft currents will cause pitting of the bearing, which will then bring noise and vibration, causing early failure of the bearing.

[0003] One of the current solutions to this problem is to use insulating bearings instead of ordinary bearings at both ends of the motor main shaft. Insulating bearings are a general term for bearings that can prevent current from passing through and have insulating properties. By integrating insulation properties into the bearing, the problem of shaft current corrosion is fundamentally solved. The surface of the outer or inner ring of the insulating bearing has an insulating coating of several hundred microns to 2 mm thick, which can withstand a voltage of at least 1000V. Compared with other insulation methods, such as shaft or housing insulation, hybrid ceramic deep groove ball bearings, etc., it is more cost-effective and highly reliable.

[0004] For example, CN115181928A discloses a bearing outer ring coating, a preparation method thereof, and an insulating bearing, wherein the preparation method comprises: spraying metal material and ceramic material on the outer surface of the bearing outer ring in sequence, thereby forming a base metal layer and a ceramic layer stacked in sequence, immersing the sprayed bearing outer ring in a sealing agent, and sealing the pores in the ceramic layer. The present invention provides a preparation process for a ceramic spray-coated insulating bearing, wherein an ordinary bearing is subjected to a simple spraying treatment to form an insulating bearing, a metal material is used as a base, and a ceramic material is sprayed, and the pores of the spray layer are filled by the penetration effect of the sealing agent, thereby improving the insulating effect of the insulating bearing.

[0005] However, since the current insulating layer is very thin and has a large capacitance, it is not conducive to blocking high-frequency shaft currents. At the same time, due to the limitations of the preparation process of the insulating coating, the thickness of the coating is limited. Therefore, reducing the capacitance of the insulating layer in the insulating bearing is an urgent problem that needs to be solved to strengthen the application of the insulating shaft layer in blocking high-frequency shaft currents. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a low-capacitance insulating coating and a preparation method and use thereof, so as to solve the defect that the existing insulating coating has a large capacitance and is not conducive to high-frequency shaft current isolation.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a low-capacitance insulating coating, the low-capacitance insulating coating comprising a coating body and grooves arrayed on the coating body;

[0009] The spacing between adjacent grooves is 85-250 μm; the depth of the groove is 10-30 μm; and the opening equivalent circle diameter of the groove is 55-160 μm.

[0010] The low-capacitance insulating coating provided by the present invention reduces the capacitance of the insulating coating by designing the surface of the insulating coating and arranging grooves with specific distribution on the surface of the insulating coating, thereby ensuring that a good barrier effect can still be achieved under high-frequency shaft current.

[0011] As a preferred technical solution of the present invention, the opening shape of the groove includes one of circular, hexagonal or rhombus shapes, or a combination of at least two of them.

[0012] As a preferred technical solution of the present invention, the small capacitor insulating coating comprises an insulating material and a sealing material;

[0013] Preferably, the sealing material in the small capacitor insulating coating has a mass percentage of 1-2%.

[0014] As a preferred technical solution of the present invention, the insulating material includes aluminum oxide and / or titanium oxide.

[0015] Preferably, the sealing material comprises a resin material.

[0016] In a second aspect, the present invention provides a method for preparing the small capacitance insulating coating as described in the first aspect, the preparation method comprising:

[0017] The substrate is sequentially subjected to sandblasting treatment, insulating layer setting, first sealing treatment, first smoothing treatment, groove formation, second smoothing treatment and second sealing treatment to obtain a small-capacitance insulating coating.

[0018] As a preferred technical solution of the present invention, the pressure of the sandblasting treatment is 0.1-0.6 MPa.

[0019] The distance between the sandblasting port and the substrate during the sandblasting process is 30-120 mm.

[0020] In the sandblasting process, the angle between the sandblasting port and the surface of the substrate is 70-90°.

[0021] The sand grains used in the sandblasting process include 24-46# alumina white corundum sand grains.

[0022] The surface roughness Ra of the product obtained by the sandblasting treatment is 2-4 μm.

[0023] The insulating layer is provided by atmospheric plasma spraying.

[0024] As a preferred technical solution of the present invention, the first sealing comprises placing the product obtained after setting the insulating layer in a sealing material and sequentially performing a first vacuum treatment and a first pressure-maintaining treatment, and then performing a first heat-maintaining treatment.

[0025] The absolute vacuum degree of the first vacuum treatment is 50-500Pa.

[0026] The holding time of the first vacuum treatment is 5-10 minutes.

[0027] The relative atmospheric pressure of the first pressure-maintaining treatment is 0.2-0.3 MPa.

[0028] The holding time of the first pressure-maintaining treatment is 60-90 minutes.

[0029] The heating rate of the first heat preservation treatment is 5-12°C / min.

[0030] The insulation temperature of the first insulation treatment is 120-130°C.

[0031] The insulation time of the first insulation treatment is 1-5h.

[0032] As a preferred technical solution of the present invention, the first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to be 0.1-0.4 μm.

[0033] The grooves are formed by laser engraving or pitting.

[0034] The second smoothing treatment includes removing 0.01-0.015 mm from the surface of the product obtained after the grooves are formed.

[0035] The second sealing comprises placing the product obtained by the second smoothing treatment in a sealing material and sequentially performing a second vacuum treatment and a second pressure-keeping treatment, and then performing a second heat-keeping treatment.

[0036] The absolute vacuum degree of the second vacuum treatment is 50-500 Pa; and the holding time of the second vacuum treatment is 5-10 min.

[0037] The relative atmospheric pressure of the second pressure-maintaining treatment is 0.2-0.3 MPa; and the holding time of the second pressure-maintaining treatment is 60-90 min.

[0038] The heating rate of the second heat preservation treatment is 5-12°C / min; the heat preservation temperature of the second heat preservation treatment is 120-130°C; and the heat preservation time of the second heat preservation treatment is 1-5h.

[0039] As a preferred technical solution of the present invention, the insulating layer is provided by atmospheric plasma spraying;

[0040] The current in the atmospheric plasma spraying is 300-650A; the voltage in the atmospheric plasma spraying is 40-80V; the flow rate of the auxiliary gas in the atmospheric plasma spraying is 1-15L / min; the scanning speed in the atmospheric plasma spraying is 140-160m / min; the powder feeding amount in the atmospheric plasma spraying is 20-150g / min; the powder feeding carrier gas flow rate in the atmospheric plasma spraying is 2-12L / min; the main gas flow rate in the atmospheric plasma spraying is 25-75L / min; the main gas pressure in the atmospheric plasma spraying is 0.3-0.8MPa; the auxiliary gas pressure in the atmospheric plasma spraying is 0.5-0.8MPa; the distance between the nozzle and the substrate in the atmospheric plasma spraying is 100-250mm; the angle between the nozzle and the substrate surface in the atmospheric plasma spraying is 70-90°; the temperature of the substrate surface in the atmospheric plasma spraying is 50-150℃;

[0041] The groove is formed by laser engraving.

[0042] In a third aspect, the present invention provides a use of the low-capacitance insulating coating as described in the first aspect, wherein the use comprises using the low-capacitance insulating coating as a coating for a bearing.

[0043] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0044] The present invention reduces the effective contact area with the bearing sleeve at the microscopic level by laser engraving on the coating of the insulating bearing, while not changing the overall shape of the insulating bearing at the macroscopic level, so it will not affect its mechanical properties and mechanical properties. As the number of engraved cells (pits) increases, the equivalent contact area is reduced at the microscopic level, and the equivalent capacitance of the insulating bearing is ultimately reduced. Compared with other technical solutions, the present invention effectively increases the blocking effect of the capacitor on alternating current, also called capacitive reactance, by reducing the equivalent capacitance of the insulating bearing. This makes the insulating coating of this solution more suitable for use in high-frequency alternating current environments, reduces the erosion and destructive effects of the EDM effect of the bearing on the bearing raceway, and greatly improves the performance and life of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a SEM photo of the surface of the product after the groove is formed in Example 1 of the present invention;

[0046] Figure 2 is a schematic diagram of the texture pattern of the surface of the insulating coating after the groove is formed in Example 1 of the present invention;

[0047] Figure 3 This is a SEM photograph of the surface after the second smoothing treatment after the grooves are formed in Example 1 of the present invention.

[0048] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0049] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0050] This embodiment provides a small capacitance insulating coating, the small capacitance insulating coating comprising a coating body and grooves distributed in an array on the coating body;

[0051] Among them, the spacing between adjacent grooves is 85-250μm, for example, it can be 85μm, 90μm, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 240μm or 250μm, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0052] In the present invention, the spacing between adjacent grooves is the distance between the center points of adjacent grooves.

[0053] Among them, the depth of the groove is 10-30μm, for example, it can be 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, 22μm, 24μm, 26μm, 28μm or 30μm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0054] Among them, the opening equivalent circle diameter of the groove is 55-160μm, for example, it can be 55μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm or 160μm, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0055] The opening shape of the groove includes one or a combination of at least two of a circle, a hexagon or a rhombus.

[0056] Wherein, the small capacitance insulating coating comprises insulating material and sealing material.

[0057] Wherein, the insulating material includes aluminum oxide and / or titanium oxide.

[0058] Exemplarily, when the insulating material uses aluminum oxide and titanium oxide, the mass percentage includes: 90-98% aluminum oxide, and the balance is titanium oxide. The mass percentage of aluminum oxide can be, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97% or 98%, etc., but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0059] Wherein, the sealing material comprises a resin material.

[0060] Exemplarily, the resin material includes epoxy resin, silicone resin and other commonly used sealing resin materials in the art, wherein the epoxy resin is such as epoxy resin e-51 and the like.

[0061] Among them, the sealing material in the small capacitor insulating coating has a mass percentage of 1-2%, for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8% or 2%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0062] In the present invention, the capacitance of the small capacitance insulating coating is ≤115pF.

[0063] Furthermore, the present invention provides a method for preparing the aforementioned small capacitance insulating coating, the preparation method comprising:

[0064] The substrate is sequentially subjected to sandblasting treatment, insulating layer setting, first sealing treatment, first smoothing treatment, groove formation, second smoothing treatment and second sealing treatment to obtain a small-capacitance insulating coating.

[0065] In the present invention, the material of the substrate used in the preparation process can be directly selected according to the material of the bearing, or other materials can be selected according to specific needs, for example, such as GCr15, 42CrMo, 40Cr and other materials.

[0066] In the present invention, the substrate may be selectively cleaned before each process to remove debris, stains and other substances that may affect subsequent processes from the previous process. For example, water or alcohol may be used for cleaning.

[0067] Specifically, the pressure of the sandblasting treatment is 0.1-0.6 MPa, for example, it can be 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa or 0.6 MPa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0068] Specifically, the distance between the sandblasting port and the substrate in the sandblasting process is 30-120 mm, for example, it can be 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm or 120 mm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0069] Specifically, the angle between the sandblasting port and the surface of the substrate in the sandblasting process is 70-90°, for example, it can be 70°, 72°, 74°, 76°, 78°, 80°, 82°, 84°, 86°, 88° or 90°, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0070] Specifically, the sand grains used in the sandblasting process include 24-46# alumina white corundum sand grains.

[0071] Specifically, the surface roughness Ra of the substrate obtained by sandblasting is 2-4μm, for example, it can be 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm or 4μm, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0072] Specifically, the insulating layer is provided by atmospheric plasma spraying.

[0073] Exemplarily, when the insulating layer is provided by atmospheric plasma spraying:

[0074] The current in the atmospheric plasma spraying is 300-650A, for example, it can be 300A, 350A, 400A, 450A, 500A, 550A, 600A or 600A, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0075] The voltage of the atmospheric plasma spraying is 40-80V, for example, it can be 40V, 45V, 50V, 55V, 60V, 65V, 70V, 75V or 80V, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0076] The flow rate of the auxiliary gas (which may be hydrogen or helium or other commonly used auxiliary gases in the art) in the atmospheric plasma spraying is 1-15 L / min, for example, 1 L / min, 2 L / min, 4 L / min, 6 L / min, 8 L / min, 10 L / min, 12 L / min, 14 L / min or 15 L / min, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0077] The scanning speed in the atmospheric plasma spraying is 140-160 m / min, for example, it can be 140 m / min, 142 m / min, 144 m / min, 146 m / min, 148 m / min, 150 m / min, 152 m / min, 154 m / min, 156 m / min, 158 m / minu or 160 m / min, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0078] The powder feeding rate in the atmospheric plasma spraying is 20-150 g / min, for example, it can be 20 g / min, 30 g / min, 40 g / min, 50 g / min, 60 g / min, 70 g / min, 80 g / min, 90 g / min, 100 g / min, 110 g / min, 120 g / min, 130 g / min, 140 g / min or 150 g / min, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0079] The flow rate of the powder delivery carrier gas (argon or nitrogen or other commonly used carrier gases in the art) in the atmospheric plasma spraying is 2-12 L / min, for example, it can be 2 L / min, 4 L / min, 6 L / min, 8 L / min, 10 L / min or 12 L / min, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0080] The flow rate of the main gas (argon or other commonly used main gas in the art) in the atmospheric plasma spraying is 25-75 L / min, for example, it can be 25 L / min, 30 L / min, 35 L / min, 40 L / min, 45 L / min, 50 L / min, 55 L / min, 60 L / min, 65 L / min, 70 L / min or 75 L / min, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0081] The main gas pressure in the atmospheric plasma spraying is 0.3-0.8 MPa, for example, it can be 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa or 0.8 MPa, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0082] The auxiliary gas pressure in the atmospheric plasma spraying is 0.5-0.8 MPa, for example, it can be 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa or 0.8 MPa, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0083] The distance between the nozzle and the substrate in the atmospheric plasma spraying is 100-250 mm, for example, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, 220 mm, 240 mm or 250 mm, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0084] The angle between the nozzle and the substrate surface in the atmospheric plasma spraying is 70-90°, for example, it can be 70°, 72°, 74°, 76°, 78°, 80°, 82°, 84°, 86°, 88° or 90°, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0085] The temperature of the substrate surface during the atmospheric plasma spraying is 50-150°C, for example, 50°C, 60°C, 80°C, 100°C, 120°C, 140°C or 150°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0086] Specifically, the first sealing comprises placing the product obtained after providing the insulating layer in a sealing material, performing a first vacuum treatment and a first pressure-maintaining treatment in sequence, and then performing a first heat-maintaining treatment.

[0087] Among them, the absolute vacuum degree of the first vacuum treatment is 50-500Pa, for example, it can be 50Pa, 100Pa, 150Pa, 200Pa, 250Pa, 300Pa, 350Pa, 400Pa, 450Pa or 500Pa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0088] The holding time of the first vacuum treatment is 5-10 min, for example, it can be 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min or 10 min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0089] Among them, the relative atmospheric pressure of the first pressure-maintaining treatment is 0.2-0.3 MPa, for example, it can be 0.2 MPa, 0.22 MPa, 0.24 MPa, 0.26 MPa, 0.28 MPa or 0.3 MPa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0090] Among them, the holding time of the first pressure-maintaining treatment is 60-90 minutes, for example, it can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes or 90 minutes, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0091] Among them, the heating rate of the first insulation treatment is 5-12℃ / min, for example, it can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min or 12℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0092] Among them, the insulation temperature of the first insulation treatment is 120-130°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0093] The insulation time of the first insulation treatment is 1-5h, for example, 1h, 2h, 3h, 4h or 5h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0094] Among them, the first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.1-0.4μm, for example, it can be 0.1μm, 0.15μm, 0.2μm, 0.25μm, 0.3μm, 0.35μm or 0.4μm, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0095] In the present invention, the first smoothing treatment can be performed by grinding, polishing, or other methods to reduce the surface roughness of the material, as long as the specified roughness requirement is met.

[0096] Exemplarily, the first smoothing process includes sequential grinding and polishing operations.

[0097] Among them, the grinding operation includes grinding the ceramic coating with a 180-330 mesh diamond grinding wheel, the grinding wheel linear speed is 4000-5500 SFPM, the workpiece linear speed is 50-120 SFPM, the grinding wheel step is 0.05-0.09 grinding wheel width / rev, the feed amount is 0.002-0.01mm, and the surface roughness Ra of the ground product is 0.4-1μm.

[0098] The polishing operation includes polishing the workpiece surface using a 30 μm or 45 μm diamond film polishing belt, with a removal amount of 0.005-0.01 mm and a surface roughness Ra of the product obtained after polishing of 0.1-0.4 μm.

[0099] Specifically, the groove is formed by laser engraving or pitting.

[0100] For example, when the groove is formed by laser engraving, the focal length of the light spot is set to 5-15 mm, the laser beam scanning rate is set to 200-500 mm / s, the laser beam power is set to 20-80 W, the engraving angle is set to 85-90 °, the engraving program, the engraving depth is set to 10-30 μm, and the number of dots (cells) is set to 20-150 / mm. 2, cell shape, select Ar or CO2 gas as the gas for protecting the environment and cooling effect, etc. After completing the setting of parameters, the engraving of the insulating bearing is completed. The engraving equipment includes a laser machine, a laser (the laser can be one of a carbon dioxide laser, a Nd:YAG laser, a fiber laser or a semiconductor laser) and a two-dimensional workbench. The laser engraving adopts a three-dimensional dynamic control laser machine and a two-dimensional workbench linkage method to engrave on the workpiece with a laser; the laser engraving parameters are input through a data keyboard and completed by a human-machine interface computer control method. During operation, the workpiece to be processed is fixed on the two-dimensional workbench in a direction parallel to the horizontal plane. A rotating motor and a flip motor are provided on the workbench, which can make the bearing rotate and deflect 360° along the axis. The laser head on the laser machine is aligned with the workpiece on the two-dimensional workbench, and the pattern and program to be engraved are input through the keyboard. The machine is started, and the laser engraving of the insulating bearing workpiece can be quickly completed.

[0101] Specifically, the second smoothing treatment includes removing 0.01-0.015 mm from the surface of the product obtained after the groove is formed, for example, it can be 0.01 mm, 0.011 mm, 0.012 mm, 0.013 mm, 0.014 mm or 0.015 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0102] Specifically, the second sealing comprises placing the product obtained by the second smoothing treatment in a sealing material and sequentially performing a second vacuum treatment and a second pressure-keeping treatment, and then performing a second heat-keeping treatment.

[0103] Among them, the absolute vacuum degree of the second vacuum treatment is 50-500Pa, for example, it can be 50Pa, 100Pa, 150Pa, 200Pa, 250Pa, 300Pa, 350Pa, 400Pa, 450Pa or 500Pa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0104] The holding time of the second vacuum treatment is 5-10 min, for example, it can be 5 min, 5.5 min, 6 min, 6.5 min, 7 min, 7.5 min, 8 min, 8.5 min, 9 min, 9.5 min or 10 min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0105] Among them, the relative atmospheric pressure of the second pressure-maintaining treatment is 0.2-0.3 MPa, for example, it can be 0.2 MPa, 0.22 MPa, 0.24 MPa, 0.26 MPa, 0.28 MPa or 0.3 MPa, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0106] Among them, the holding time of the second pressure-maintaining treatment is 60-90 minutes, for example, it can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes or 90 minutes, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0107] Among them, the heating rate of the second insulation treatment is 5-12℃ / min, for example, it can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min or 12℃ / min, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0108] Among them, the insulation temperature of the second insulation treatment is 120-130°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0109] The insulation time of the second insulation treatment is 1-5h, for example, 1h, 2h, 3h, 4h or 5h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0110] Furthermore, the present invention provides a use of the aforementioned low-capacitance insulating coating, which includes using the low-capacitance insulating coating as a coating for a bearing.

[0111] Further, in order to illustrate the good use effect that can be achieved by providing a small capacitance insulating coating in the present invention, an actual example is used for illustration, as follows:

[0112] Example 1

[0113] This embodiment provides a small capacitance insulating coating, the small capacitance insulating coating comprising a coating body and grooves arrayed and distributed on the coating body;

[0114] The spacing between adjacent grooves is 150 μm; the depth of the groove is 30 μm; the opening equivalent circle diameter of the groove is 100 μm; the opening shape of the groove is hexagonal;

[0115] The small capacitor insulating coating comprises insulating material and sealing material; the sealing material in the small capacitor insulating coating contains 1.5% by mass; the insulating material is alumina; and the sealing material is epoxy resin e-51.

[0116] The preparation process is as follows:

[0117] The substrate is sequentially subjected to sandblasting, insulating layer setting, first sealing, first smoothing, groove formation, second smoothing and second sealing to obtain a low-capacitance insulating coating;

[0118] The material of the substrate used is GCr15;

[0119] The pressure of the sandblasting treatment is 0.35MPa; the distance between the sandblasting port and the substrate in the sandblasting treatment is 70mm; the angle between the sandblasting port and the substrate surface in the sandblasting treatment is 80°; the sand grains used in the sandblasting treatment are 24# alumina white corundum sand grains; the surface roughness Ra of the substrate obtained by the sandblasting treatment is 3μm;

[0120] The insulating layer is provided by atmospheric plasma spraying;

[0121] The first sealing comprises placing the product with the insulating layer in the sealing material and performing the first vacuum treatment and the first pressure-keeping treatment in sequence, and then performing the first heat-keeping treatment; the absolute vacuum degree of the first vacuum treatment is 150Pa; the holding time of the first vacuum treatment is 6min; the relative atmospheric pressure of the first pressure-keeping treatment is 0.27MPa; the holding time of the first pressure-keeping treatment is 70min; the heating rate of the first heat-keeping treatment is 7°C / min; the heat-keeping temperature of the first heat-keeping treatment is 125°C; the heat-keeping time of the first heat-keeping treatment is 2h;

[0122] The first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.2 μm;

[0123] The groove is formed by laser engraving;

[0124] The second smoothing treatment includes removing 0.012 mm from the surface of the product obtained after the groove is formed;

[0125] The second sealing comprises placing the product obtained by the second smoothing treatment in a sealing material and sequentially performing a second vacuum treatment and a second pressure-keeping treatment, and then performing a second heat-keeping treatment; the absolute vacuum degree of the second vacuum treatment is 300 Pa; the holding time of the second vacuum treatment is 6 minutes; the relative atmospheric pressure of the second pressure-keeping treatment is 0.25 MPa; the holding time of the second pressure-keeping treatment is 80 minutes; the heating rate of the second heat-keeping treatment is 8°C / min; the heat-keeping temperature of the second heat-keeping treatment is 125°C; the heat-keeping time of the second heat-keeping treatment is 2 hours;

[0126] Among them, the SEM photos of the product surface after the groove is formed are as follows Figure 1 As shown, the schematic diagram of the texture pattern of the insulating coating surface after the groove is formed is as follows Figure 2 As shown, the surface SEM photo of the product obtained after the second smoothing treatment is as follows Figure 3 shown.

[0127] Example 2

[0128] This embodiment provides a small capacitance insulating coating, the small capacitance insulating coating comprising a coating body and grooves arrayed and distributed on the coating body;

[0129] The spacing between adjacent grooves is 200 μm; the depth of the groove is 20 μm; the opening equivalent circle diameter of the groove is 120 μm; the opening shape of the groove is circular;

[0130] The small capacitor insulating coating comprises insulating material and sealing material; the sealing material in the small capacitor insulating coating contains 1.8% by mass; the insulating material contains 98% by mass of aluminum oxide and 2% by mass of titanium oxide; the sealing material is epoxy resin e-51.

[0131] The preparation process is as follows:

[0132] The substrate is sequentially subjected to sandblasting, insulating layer setting, first sealing, first smoothing, groove formation, second smoothing and second sealing to obtain a low-capacitance insulating coating;

[0133] The material of the substrate used is 42CrMo;

[0134] The pressure of the sandblasting treatment is 0.4 MPa; the distance between the sandblasting port and the substrate during the sandblasting treatment is 90 mm; the angle between the sandblasting port and the substrate surface during the sandblasting treatment is 85°; the sand grains used in the sandblasting treatment are 46# alumina white corundum sand grains; the surface roughness Ra of the substrate obtained by the sandblasting treatment is 3.5 μm;

[0135] The insulating layer is provided by atmospheric plasma spraying;

[0136] The first sealing includes placing the product with the insulating layer in the sealing material and performing the first vacuum treatment and the first pressure-keeping treatment in sequence, and then performing the first heat-keeping treatment; the absolute vacuum degree of the first vacuum treatment is 300Pa; the holding time of the first vacuum treatment is 8min; the relative atmospheric pressure of the first pressure-keeping treatment is 0.25MPa; the holding time of the first pressure-keeping treatment is 80min; the heating rate of the first heat-keeping treatment is 9°C / min; the heat-keeping temperature of the first heat-keeping treatment is 128°C; the heat-keeping time of the first heat-keeping treatment is 3h;

[0137] The first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.3 μm;

[0138] The groove is formed by laser engraving;

[0139] The second smoothing treatment includes removing 0.014 mm from the surface of the product obtained after the groove is formed;

[0140] The second sealing includes placing the product obtained by the second smoothing treatment in a sealing material and performing a second vacuum treatment and a second pressure holding treatment in sequence, and then performing a second heat preservation treatment; the absolute vacuum degree of the second vacuum treatment is 150Pa; the holding time of the second vacuum treatment is 8min; the relative atmospheric pressure of the second pressure holding treatment is 0.28MPa; the holding time of the second pressure holding treatment is 70min; the heating rate of the second heat preservation treatment is 10℃ / min; the heat preservation temperature of the second heat preservation treatment is 122℃; the heat preservation time of the second heat preservation treatment is 3h.

[0141] Example 3

[0142] This embodiment provides a small capacitance insulating coating, the small capacitance insulating coating comprising a coating body and grooves arrayed and distributed on the coating body;

[0143] The spacing between adjacent grooves is 85 μm; the depth of the groove is 10 μm; the opening equivalent circle diameter of the groove is 55 μm; the opening shape of the groove is a rhombus;

[0144] The small capacitor insulating coating comprises insulating material and sealing material; the sealing material in the small capacitor insulating coating has a mass percentage of 1%; the insulating material comprises, by mass percentage: 95% aluminum oxide and 5% titanium oxide; the sealing material is epoxy resin e-51.

[0145] The preparation process is as follows:

[0146] The substrate is sequentially subjected to sandblasting, insulating layer setting, first sealing, first smoothing, groove formation, second smoothing and second sealing to obtain a low-capacitance insulating coating;

[0147] The material of the substrate used is 40Cr;

[0148] The pressure of the sandblasting treatment is 0.1 MPa; the distance between the sandblasting port and the substrate during the sandblasting treatment is 30 mm; the angle between the sandblasting port and the surface of the substrate during the sandblasting treatment is 90°; the sand grains used in the sandblasting treatment are 24# alumina white corundum sand grains; the surface roughness Ra of the substrate obtained by the sandblasting treatment is 2 μm;

[0149] The insulating layer is provided by atmospheric plasma spraying;

[0150] The first sealing comprises placing the product with the insulating layer in the sealing material and performing the first vacuum treatment and the first pressure-keeping treatment in sequence, and then performing the first heat-keeping treatment; the absolute vacuum degree of the first vacuum treatment is 50Pa; the holding time of the first vacuum treatment is 10min; the relative atmospheric pressure of the first pressure-keeping treatment is 0.2MPa; the holding time of the first pressure-keeping treatment is 90min; the heating rate of the first heat-keeping treatment is 5°C / min; the heat-keeping temperature of the first heat-keeping treatment is 120°C; the heat-keeping time of the first heat-keeping treatment is 5h;

[0151] The first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.1 μm;

[0152] The groove is formed by laser engraving;

[0153] The second smoothing treatment includes removing 0.01 mm from the surface of the substrate obtained after the groove is formed;

[0154] The second sealing includes placing the product obtained by the second smoothing treatment in a sealing material and performing a second vacuum treatment and a second pressure holding treatment in sequence, and then performing a second heat preservation treatment; the absolute vacuum degree of the second vacuum treatment is 500Pa; the holding time of the second vacuum treatment is 5min; the relative atmospheric pressure of the second pressure holding treatment is 0.3MPa; the holding time of the second pressure holding treatment is 60min; the heating rate of the second heat preservation treatment is 12°C / min; the heat preservation temperature of the second heat preservation treatment is 130°C; the heat preservation time of the second heat preservation treatment is 1h.

[0155] Example 4

[0156] This embodiment provides a small capacitance insulating coating, the small capacitance insulating coating comprising a coating body and grooves arrayed and distributed on the coating body;

[0157] The spacing between adjacent grooves is 250 μm; the depth of the groove is 20 μm; the opening equivalent circle diameter of the groove is 160 μm; the opening shape of the groove is a square;

[0158] The small capacitor insulating coating comprises insulating material and sealing material; the sealing material in the small capacitor insulating coating contains 2% by mass; the insulating material contains 90% aluminum oxide and 10% titanium oxide by mass; the sealing material is epoxy resin e-51.

[0159] The preparation process is as follows:

[0160] The substrate is sequentially subjected to sandblasting, insulating layer setting, first sealing, first smoothing, groove formation, second smoothing and second sealing to obtain a low-capacitance insulating coating;

[0161] The material of the substrate used is GCr15;

[0162] The pressure of the sandblasting treatment is 0.6MPa; the distance between the sandblasting port and the substrate during the sandblasting treatment is 120mm; the angle between the sandblasting port and the substrate surface during the sandblasting treatment is 70°; the sand grains used in the sandblasting treatment are 46# alumina white corundum sand grains; the surface roughness Ra of the substrate obtained by the sandblasting treatment is 4μm;

[0163] The insulating layer is provided by atmospheric plasma spraying;

[0164] The first sealing includes placing the product with the insulating layer in the sealing material and performing the first vacuum treatment and the first pressure-keeping treatment in sequence, and then performing the first heat-keeping treatment; the absolute vacuum degree of the first vacuum treatment is 500Pa; the holding time of the first vacuum treatment is 5min; the relative atmospheric pressure of the first pressure-keeping treatment is 0.3MPa; the holding time of the first pressure-keeping treatment is 60min; the heating rate of the first heat-keeping treatment is 12°C / min; the heat-keeping temperature of the first heat-keeping treatment is 130°C; the heat-keeping time of the first heat-keeping treatment is 1h;

[0165] The first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.4 μm;

[0166] The groove is formed by laser engraving;

[0167] The second smoothing treatment includes removing 0.015 mm from the surface of the product obtained after the groove is formed;

[0168] The second sealing comprises placing the product obtained by the second smoothing treatment in a sealing material and performing a second vacuum treatment and a second pressure holding treatment in sequence, and then performing a second heat preservation treatment; the absolute vacuum degree of the second vacuum treatment is 50Pa; the holding time of the second vacuum treatment is 10min; the relative atmospheric pressure of the second pressure holding treatment is 0.2MPa; the holding time of the second pressure holding treatment is 90min; the heating rate of the second heat preservation treatment is 5°C / min; the heat preservation temperature of the second heat preservation treatment is 120°C; the heat preservation time of the second heat preservation treatment is 5h.

[0169] Comparative Example 1

[0170] The only difference from Example 1 is that the small capacitor insulating coating is a smooth coating, that is, no grooves are formed during the preparation process.

[0171] Comparative Example 2

[0172] The only difference from Example 1 is that the spacing between adjacent grooves in the small capacitance insulating coating is 50 μm.

[0173] Comparative Example 3

[0174] The only difference from Example 1 is that the spacing between adjacent grooves in the small capacitance insulating coating is 300 μm.

[0175] Comparative Example 4

[0176] The only difference from Example 1 is that the depth of the grooves in the small capacitance insulating coating is 5 μm.

[0177] Comparative Example 5

[0178] The only difference from Example 1 is that the depth of the grooves in the small capacitor insulating coating is 40 μm.

[0179] Comparative Example 6

[0180] The only difference from Example 1 is that the opening equivalent circle diameter of the groove in the small capacitor insulating coating is 40 μm.

[0181] In the above embodiments and comparative examples, the current in the atmospheric plasma spraying is 500A; the voltage of the atmospheric plasma spraying is 60V; the flow rate of the auxiliary gas (hydrogen) in the atmospheric plasma spraying is 10L / min; the scanning speed in the atmospheric plasma spraying is 150m / min; the powder feeding amount in the atmospheric plasma spraying is 80g / min; the flow rate of the powder feeding carrier gas (argon) in the atmospheric plasma spraying is 8L / min; the flow rate of the main gas (argon) in the atmospheric plasma spraying is 50L / min; the main gas pressure in the atmospheric plasma spraying is 0.5MPa; the auxiliary gas pressure in the atmospheric plasma spraying is 0.6MPa; the distance between the nozzle and the substrate in the atmospheric plasma spraying is 150mm; the angle between the nozzle and the surface of the substrate in the atmospheric plasma spraying is 80°; the temperature of the substrate surface in the atmospheric plasma spraying is 100°C.

[0182] The small capacitance insulating coatings obtained in the examples and comparative examples were tested for capacitance using a capacitance meter, and the results are shown in Table 1 below.

[0183] Table 1

[0184] Capacitance / pF Example 1 40 Example 2 70 Example 3 100 Example 4 115 Comparative Example 1 380 Comparative Example 2 200 Comparative Example 3 220 Comparative Example 4 280 Comparative Example 5 40 (Coating cracks) Comparative Example 6 200

[0185] As can be seen from Table 1, in the solution provided by the present invention, the effective contact area with the bearing sleeve is reduced microscopically by laser engraving on the coating of the insulating bearing, while the overall shape of the insulating bearing will not be changed macroscopically, so its mechanical properties and mechanical properties will not be affected. Within a certain numerical range of the equivalent diameter of the cell pits and the pit spacing, as the number of engraved cells increases, the contact area A is reduced microscopically, and the equivalent capacitance of the insulating bearing is finally reduced. According to the capacitance calculation formula: C = ε0ε r A / d. Where C represents the capacitance of the capacitor, in Farad (F); ε0 represents the dielectric constant of the medium, ε r is the relative dielectric constant of the material; A represents the area of ​​the capacitor plate; d represents the distance between the capacitor plates, that is, the coating thickness.

[0186] (2) Compared with other technical solutions, the present invention effectively increases the resistance of the capacitor to alternating current, that is, the capacitive reactance, by reducing the equivalent capacitance of the insulating bearing. This makes the insulating coating of Example 1 more suitable for use in high-frequency alternating current environments, reduces the erosion and damage of the bearing's EDM effect on the bearing raceway, and greatly improves the performance and life of the bearing. The larger the capacitance, the easier it is for alternating current to pass through the capacitor, and the smaller the resistance of the capacitor; the higher the frequency of alternating current, the easier it is for alternating current to pass through the capacitor, which means that the higher the frequency, the smaller the resistance of the capacitor. Using Xc=1 / (2πfC), the capacitive reactance is inversely proportional to the capacitance and also inversely proportional to the frequency. If the capacitive reactance is represented by Xc, the capacitance is represented by C, and the frequency is represented by f.

[0187] (3) In Comparative Example 1, a smooth coating surface is used, which is the current technical solution, that is, the equivalent area A of the entire insulating coating is the actual coating surface area, so the final capacitance value C is the largest. In Comparative Example 2, the spacing of the grooves is too small, and the lubricating oil in the coating grooves has a capillary diffusion effect, which makes the corresponding equivalent area A closer to the smooth surface, and does not contribute much to the reduction of capacitance C. In Comparative Example 3, the spacing of the grooves in the coating is too large, and the effective contact area increases, which makes the corresponding equivalent area A closer to the smooth surface, and does not contribute much to the reduction of capacitance C. In Comparative Example 4, because the depth of the grooves is too shallow, the lubricating oil in the coating grooves has a capillary diffusion effect, which makes the corresponding equivalent area A closer to the smooth surface, and does not contribute much to the reduction of capacitance. In Comparative Example 5, because the engraving depth is too deep, the processing difficulty increases, and the coating cracks. In Comparative Example 6, because the equal diameter is small, the effect of the pit is not obvious, which increases the effective contact area and does not contribute much to the reduction of capacitance C.

[0188] It is stated that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0189] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0190] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0191] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A low capacitance insulating coating, characterized in that: The small capacitance insulating coating comprises a coating body and grooves arrayed on the coating body; the capacitance of the small capacitance insulating coating is ≤115pF; The spacing between adjacent grooves is 85-250 μm; the depth of the groove is 10-30 μm; and the opening equivalent circle diameter of the groove is 55-160 μm.

2. The low capacitance insulating coating as claimed in claim 1, characterized in that: The opening shape of the groove includes one of a circle, a hexagon or a rhombus, or a combination of at least two of them.

3. The low capacitance insulating coating as claimed in claim 1, characterized in that: The small capacitance insulating coating comprises insulating material and sealing material; The sealing material in the small capacitor insulating coating has a mass percentage of 1-2%.

4. The low capacitance insulating coating as claimed in claim 3, characterized in that: The insulating material includes aluminum oxide and / or titanium oxide; The sealing material includes a resin material.

5. A method for preparing a small capacitance insulating coating as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises: The substrate is sequentially subjected to sandblasting treatment, insulating layer setting, first sealing treatment, first smoothing treatment, groove formation, second smoothing treatment and second sealing treatment to obtain a small-capacitance insulating coating.

6. The preparation method according to claim 5, characterized in that: The pressure of the sandblasting treatment is 0.1-0.6MPa; The distance between the sandblasting port and the substrate during the sandblasting process is 30-120 mm; The angle between the sandblasting port and the substrate surface during the sandblasting process is 70-90°; The sand grains used in the sandblasting process include 24-46# alumina white corundum sand grains; The surface roughness Ra of the substrate obtained by the sandblasting is 2-4 μm; The insulating layer is provided by atmospheric plasma spraying.

7. The preparation method according to claim 5, characterized in that: The first sealing comprises placing the product obtained after providing the insulating layer in a sealing material and sequentially performing a first vacuum treatment and a first pressure-maintaining treatment, and then performing a first heat-maintaining treatment; The absolute vacuum degree of the first vacuum treatment is 50-500Pa; The holding time of the first vacuum treatment is 5-10 minutes; The relative atmospheric pressure of the first pressure-maintaining treatment is 0.2-0.3 MPa; The holding time of the first pressure-maintaining treatment is 60-90 minutes; The heating rate of the first heat preservation treatment is 5-12°C / min; The insulation temperature of the first insulation treatment is 120-130°C; The insulation time of the first insulation treatment is 1-5h.

8. The preparation method according to claim 5, characterized in that: The first smoothing treatment includes controlling the surface roughness Ra of the product obtained after the first sealing to 0.1-0.4 μm; The groove is formed by laser engraving or pitting; The second smoothing treatment includes removing 0.01-0.015 mm from the surface of the product obtained after the groove is formed; The second sealing comprises placing the product obtained by the second smoothing treatment in a sealing material and sequentially performing a second vacuum treatment and a second pressure-keeping treatment, and then performing a second heat-keeping treatment; The absolute vacuum degree of the second vacuum treatment is 50-500 Pa; the holding time of the second vacuum treatment is 5-10 min; The relative atmospheric pressure of the second pressure-maintaining treatment is 0.2-0.3 MPa; the holding time of the second pressure-maintaining treatment is 60-90 min; The heating rate of the second heat preservation treatment is 5-12°C / min; the heat preservation temperature of the second heat preservation treatment is 120-130°C; and the heat preservation time of the second heat preservation treatment is 1-5h.

9. The preparation method according to claim 5, characterized in that: The insulating layer is provided by atmospheric plasma spraying; The current in the atmospheric plasma spraying is 300-650A; the voltage in the atmospheric plasma spraying is 40-80V; the flow rate of the auxiliary gas in the atmospheric plasma spraying is 1-15L / min; the scanning speed in the atmospheric plasma spraying is 140-160m / min; the powder feeding amount in the atmospheric plasma spraying is 20-150g / min; the powder feeding carrier gas flow rate in the atmospheric plasma spraying is 2-12L / min; the main gas flow rate in the atmospheric plasma spraying is 25-75L / min; the main gas pressure in the atmospheric plasma spraying is 0.3-0.8MPa; the auxiliary gas pressure in the atmospheric plasma spraying is 0.5-0.8MPa; the distance between the nozzle and the substrate in the atmospheric plasma spraying is 100-250mm; the angle between the nozzle and the substrate surface in the atmospheric plasma spraying is 70-90°; the temperature of the substrate surface in the atmospheric plasma spraying is 50-150℃; The groove is formed by laser engraving.

10. A use of the small capacitance insulating coating according to any one of claims 1 to 4, characterized in that: The use includes using the low-capacitance insulating coating as a coating for a bearing.

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