Insulating paint composition, insulating paint and preparation method thereof, and insulating coating

Abstract

The invention provides an insulating paint composition, an insulating paint and a preparation method thereof, and an insulating coating. The insulating coating composition is prepared from the following components in parts by weight: 50 to 60 parts of glass powder, 5 to 10 parts of mica mineral material, 5 to 10 parts of hexagonal boron nitride, 5 to 10 parts of SiO2 aerogel, 3 to 5 parts of bentonite and 2 to 12 parts of high-temperature-resistant filler, wherein the glass powder is prepared from the following components in parts by weight: 30 to 40 parts of SiO2, 20 to 30 parts of BaO, 15 to 20 parts of Al2O3, 5 to 10 parts of B2O3, 1 to 3 parts of Li2O, 1 to 3 parts of La2O3, 1 to 3 parts of Y2O3, 2 to 5 parts of CaO and 1 to 3 parts of Co2O3; the high-temperature-resistant filler comprises MgO and ZrO2. The insulating coating prepared from the insulating paint composition has good insulating property, high temperature resistance and oxidation resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular, to an insulating coating composition, an insulating coating, a preparation method thereof, and an insulating coating layer. Background Art

[0002] Sensor components often need to work in high-temperature environments, especially in industries such as metallurgy, chemical engineering, and aerospace. The use of sensors in high-temperature environments has become the norm. However, metal materials such as steel and iron are prone to oxidation reactions at high temperatures. The generated oxide layer not only reduces the mechanical properties of the metal but may also affect the sensitivity and signal transmission of the sensor, resulting in a decline or even failure of the equipment performance. To protect the performance of these easily oxidized metals in high-temperature environments, a high-temperature resistant and anti-oxidation coating is usually coated on the metal surface. At the same time, to ensure the normal operation of the sensor at high temperatures, the coating is also required to have good insulation properties.

[0003] Currently, existing high-temperature resistant and anti-oxidation coatings mostly use materials such as metal oxides, ceramics, or carbides. Although these materials can provide certain anti-oxidation protection, they can only exhibit high-temperature resistance and insulation properties on the surface of metals that are not easily oxidized. For metals that are easily oxidized, the coating cannot achieve excellent protection and high insulation properties for a long time. For example, although the alumina coating has good anti-oxidation performance at lower temperatures, its insulation performance at high temperatures is poor, and its bonding force with steel and iron is limited. In addition, the insulating coating prepared using environmentally unfriendly organic substances such as benzene has a relatively complex process and a not-high-enough high-temperature resistance. The coating often requires long-time sintering treatment at high temperatures, which not only has high energy consumption and expensive production costs but also has a complex process and is difficult to achieve large-scale industrial production. For sensor parts, it is more required that the coating can still maintain stable anti-oxidation and insulation properties after undergoing multiple high-temperature cycles.

[0004] Therefore, there is an urgent need to develop a high-temperature resistant and anti-oxidation insulating coating that can protect metals that are easily oxidized on the surface for a long time at a high temperature not exceeding 850°C. Summary of the Invention

[0005] The main object of the present invention is to provide an insulating coating composition, an insulating coating, a preparation method thereof, and an insulating coating layer to solve the problem of poor protection and high-temperature resistance of the existing coating for metals that are easily oxidized on the surface at high temperatures.

[0006] To achieve the above object, according to one aspect of the present invention, an insulating coating composition is provided. By weight, the insulating coating composition comprises: 50-60 parts of glass powder, 5-10 parts of mica mineral material, 5-10 parts of hexagonal boron nitride, 5-10 parts of SiO2 aerogel, 3-5 parts of bentonite, and 2-12 parts of high-temperature resistant filler; wherein, by weight, the glass powder comprises 30-40 parts of SiO2, 20-30 parts of BaO, 15-20 parts of Al2O3, 5-10 parts of B2O3, 1-3 parts of Li2O, 1-3 parts of La2O3, 1-3 parts of Y2O3, 2-5 parts of CaO, and 1-3 parts of Co2O3; the high-temperature resistant filler comprises MgO and ZrO2.

[0007] Further, by weight, the above insulating coating composition comprises: 52-58 parts of glass powder, 6-9 parts of mica mineral material, 6-9 parts of hexagonal boron nitride, 5-8 parts of SiO2 aerogel, 3-4 parts of bentonite, and 3-10 parts of high-temperature resistant filler.

[0008] Further, by weight, the high-temperature resistant filler comprises 1-3 parts of MgO and 1-3 parts of ZrO2; and / or, the high-temperature resistant filler further comprises 0.5-3 parts of cobalt black; and / or, the high-temperature resistant filler further comprises 0.5-3 parts of Cr2O3.

[0009] Further, the mass ratio of the glass powder to the high-temperature resistant filler is 53-57:5-10.

[0010] Further, the mica mineral material is selected from any one or more of phlogopite, muscovite, sericite, and synthetic mica, and the mass ratio of the mica mineral material to the hexagonal boron nitride is 6-9:6-8.

[0011] Further, by weight, the insulating coating composition further comprises 30-50 parts of solvent and 0.5-1 part of dispersant; and / or, the insulating coating composition further comprises 10-20 parts of binder; wherein, the solvent is water; and / or, the binder is a 2-5wt% aqueous solution of hydroxyethyl cellulose; and / or, the dispersant is a polyurethane dispersant.

[0012] According to another aspect of the present invention, an insulating coating is provided, which is obtained by mixing the insulating coating composition, and the insulating coating composition is the above-mentioned insulating coating composition.

[0013] According to still another aspect of the present invention, a preparation method of the above insulating coating is provided, and the preparation method comprises: successively ball-milling and standing the raw materials corresponding to the insulating coating to obtain the insulating coating.

[0014] According to another aspect of the present invention, an insulating coating is provided, which is obtained by sequentially drying and baking after an insulating paint is coated on the surface of a metal, and the insulating paint is the above-mentioned insulating paint.

[0015] Furthermore, the insulating coating protects the metal at a temperature of ≤850 °C; wherein, the protection time is 5000 - 20000 h, the metal is selected from any one or more of steel, iron, titanium alloy and titanium aluminide alloy, and the coating thickness of the insulating paint is 0.1 - 0.2 mm.

[0016] Applying the technical solution of the present invention, the insulating coating composition of the present application controls the components and their contents within the above ranges, enabling the insulating coating to have good insulating properties, good high-temperature resistance and anti-oxidation properties at temperatures not higher than 850 °C, and being able to achieve long-term protection, thus being better applied to the surface of metals prone to oxidation. Specifically, glass powder is one of the core components, which can effectively bind other components together to form a dense protective layer. During the high-temperature sintering process, the glass powder melts to form a continuous glass phase, which can seal the defects on the metal surface and prevent the intrusion of oxygen, thereby effectively preventing the oxidation of the metal. In addition, after cooling, the glass powder solidifies to form an enamel surface with a certain hardness, thus providing good mechanical protection and the ability to resist chemical erosion. Moreover, SiO2, BaO, Al2O3, and B2O3 in its composition can further improve the high-temperature resistance and insulating properties of the coating. The flaky structure of the mica mineral material helps to form a layered isolation layer, which can effectively isolate the current conduction, thereby enhancing the insulating effect of the coating and also improving the anti-oxidation ability. At the same time, mica can form a protective layer at high temperatures, further enhancing the anti-oxidation performance of the coating. Hexagonal boron nitride is a material with excellent high-temperature stability and insulating properties. In the insulating coating composition of the present application, it mainly acts as a reinforcing agent, which can significantly improve the high-temperature insulating properties and anti-oxidation ability of the coating. SiO2 aerogel is a nanomaterial with extremely low density and high porosity, which can effectively isolate the heat transfer, reduce the change of the temperature gradient on the metal surface when the environmental temperature changes, thereby effectively reducing the risk of coating peeling caused by too rapid instantaneous temperature change, and then extending the service life of the coating, and can also reduce the oxidation rate of the metal to a certain extent. At the same time, the high porosity and microstructure of the aerogel can enhance the insulating properties of the coating, and can maintain good insulating effects even under high-temperature and high-voltage conditions. The addition of bentonite is beneficial to improving the suspension performance and easy coating property of the coating. The high-temperature-resistant fillers ZrO2 and MgO both have high melting points and good heat-resistant properties, which can form a dense high-temperature phase in the coating, thereby enhancing the high-temperature stability of the coating. Since steel and pure iron will undergo obvious oxidation phenomena at temperatures above 300 °C, therefore, the coating formed by the insulating coating composition of the present application can be better used on the surfaces of steel and pure iron sensor components, and has good protective properties and a long protection time even at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specification drawings forming a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 Shows an optical photograph of the state of the insulating coating after enameling in Example 1 of the present application;

[0019] Figure 2 An optical photograph showing the insulating coating after enameling in Example 2 of the present application is shown;

[0020] Figure 3 An optical photograph showing the insulating coating after enameling in Example 3 of the present application is shown. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] As analyzed in the background technology of this application, there is a problem in the prior art that the coating has poor protection and high temperature resistance against metals whose surfaces are easily oxidized at high temperatures. In order to solve the above problems, this application provides an insulating coating composition, an insulating coating and a preparation method thereof, and an insulating coating.

[0023] In a typical embodiment of the present application, an insulating coating composition is provided, which comprises, by weight: 50 to 60 parts of glass powder, 5 to 10 parts of mica mineral material, 5 to 10 parts of hexagonal boron nitride, 5 to 10 parts of SiO2 aerogel, 3 to 5 parts of bentonite and 2 to 12 parts of high temperature resistant filler; wherein, by weight, the glass powder comprises 30 to 40 parts of SiO2, 20 to 30 parts of BaO, 15 to 20 parts of Al2O3, 5 to 10 parts of B2O3, 1 to 3 parts of Li2O, 1 to 3 parts of La2O3, 1 to 3 parts of Y2O3, 2 to 5 parts of CaO and 1 to 3 parts of Co2O3; the high temperature resistant filler comprises MgO and ZrO2.

[0024] The insulating coating composition of the present application controls the components and their contents within the above ranges, enabling the insulating coating to have good insulating properties, good high-temperature resistance and anti-oxidation properties at temperatures not higher than 850 °C, and being able to achieve long-term protection, so as to be better applied to the surface of metals prone to oxidation. Specifically, glass powder is one of the core components, which can effectively bind other components together to form a dense protective layer. The glass powder melts during the high-temperature sintering process to form a continuous glass phase, which can seal the defects on the metal surface and prevent the intrusion of oxygen, thereby effectively preventing the oxidation of the metal. In addition, the glass powder solidifies after cooling to form an enamel surface with a certain hardness, thus providing good mechanical protection and resistance to chemical erosion. Moreover, SiO2, BaO, Al2O3 and B2O3 in its composition can further improve the high-temperature resistance and insulating properties of the coating. The flaky structure of the mica mineral material helps to form a layered isolation layer, which can effectively isolate the current conduction, thereby enhancing the insulating effect of the coating and also improving the anti-oxidation ability. At the same time, mica can form a protective layer at high temperatures, further enhancing the anti-oxidation performance of the coating. Hexagonal boron nitride is a material with excellent high-temperature stability and insulating properties. In the insulating coating composition of the present application, it mainly acts as a reinforcing agent, which can significantly improve the high-temperature insulating properties and anti-oxidation ability of the coating. SiO2 aerogel is a nanomaterial with extremely low density and high porosity, which can effectively isolate the heat transfer, reduce the change of the temperature gradient on the metal surface when the environmental temperature changes, thereby effectively reducing the risk of coating peeling caused by too rapid instantaneous temperature change, and further extending the service life of the coating, and can also reduce the oxidation rate of the metal to a certain extent. At the same time, the high porosity and microstructure of the aerogel can enhance the insulating properties of the coating, and can maintain good insulating effects even under high-temperature and high-voltage conditions. The addition of bentonite is beneficial to improving the suspension performance and easy coating property of the coating. The high-temperature resistant fillers ZrO2 and MgO both have high melting points and good heat resistance, and can form a dense high-temperature phase in the coating, thereby enhancing the high-temperature stability of the coating. Since steel and pure iron will undergo obvious oxidation phenomena at temperatures above 300 °C, therefore, the coating formed by the insulating coating composition of the present application can be better used on the surfaces of steel and pure iron sensor parts, and has good protective performance and a long protection time even at high temperatures.

[0025] Preferably, the particle size of the solid components (glass powder, mica mineral material, hexagonal boron nitride, bentonite and high-temperature resistant filler) is 200 - 400 mesh.

[0026] In order to further improve the insulation, antioxidant and high-temperature resistance properties of the insulation coating, in one embodiment of the present application, by weight, the above insulation coating composition includes: 52 to 58 parts of glass powder, 6 to 9 parts of mica mineral material, 6 to 9 parts of hexagonal boron nitride, 5 to 8 parts of SiO2 aerogel, 3 to 4 parts of bentonite, and 3 to 10 parts of high-temperature resistant filler.

[0027] In order to further improve the high-temperature resistance property of the insulation coating, in one embodiment of the present application, by weight, the high-temperature resistant filler includes 1 to 3 parts of MgO and 1 to 3 parts of ZrO2; and / or, the high-temperature resistant filler further includes 0.5 to 3 parts of cobalt black; and / or, the high-temperature resistant filler further includes 0.5 to 3 parts of Cr2O3.

[0028] Cobalt black is a black powder composed of cobalt oxides, which forms a stable oxide layer at high temperatures, helping to enhance the anti-oxidation and corrosion resistance of the coating. Cr2O3 has good chemical stability and high-temperature antioxidant properties, helping to further improve the anti-oxidation performance of the coating and chemical stability at high temperatures. In addition, Cr2O3 also has certain insulation properties, helping to optimize the electrical characteristics of the coating.

[0029] Preferably, the mass ratio of MgO to ZrO2 in the high-temperature resistant filler is 1 to 2:2 to 3. MgO, as a stabilizer, helps to inhibit the phase transformation of ZrO2 (such as the transformation from the tetragonal phase to the monoclinic phase), thereby improving the toughness and strength of the coating. At the same time, the phase transformation toughening effect of ZrO2 combined with the grain boundary strengthening effect of MgO helps to further enhance the anti-cracking and spalling properties of the coating.

[0030] In one embodiment of the present application, the mass ratio of the glass powder to the high-temperature resistant filler is 53 to 57:5 to 10.

[0031] Preferably, controlling the mass ratio of the glass powder to the high-temperature resistant filler within the above range helps to melt into a dense film layer at about 400°C. At the same time, when the ambient temperature reaches above 800°C, a sufficient amount of high-temperature resistant filler helps to improve the high-temperature stability of the coating.

[0032] In one embodiment of the present application, the mica mineral material is selected from any one or more of phlogopite, muscovite, sericite and synthetic mica, and the mass ratio of the mica mineral material to the hexagonal boron nitride is 6 to 9:6 to 8.

[0033] Preferably, the type of the mica mineral material is within the above range, and the mass ratio of the mica mineral material to the hexagonal boron nitride is controlled within the above range. The hexagonal structure of the hexagonal boron nitride combined with the flaky structure of the mica mineral material helps to form a more complex microstructure, thereby enhancing the overall performance of the coating.

[0034] SiO2 aerogel has good toughness at both normal and high temperatures. Preferably, the mass ratio of SiO2 aerogel to high-temperature resistant filler is 5-7:5-10, which helps to further reduce the adverse effects of the relatively large brittleness of the high-temperature resistant filler on the coating and prevent the coating from cracking due to thermal stress.

[0035] In one embodiment of the present application, by weight, the insulating coating composition further comprises 30-50 parts of a solvent and 0.5-1 part of a dispersant; and / or, the insulating coating composition further comprises 10-20 parts of a binder; wherein, the solvent is water; and / or, the binder is an aqueous solution of 2-5 wt% hydroxyethyl cellulose; and / or, the dispersant is a polyurethane dispersant.

[0036] Preferably, solvents of the above types and contents help to uniformly disperse the solid components and other components in the coating, so that it has good fluidity during spraying or coating. Preferably, binders of the above types and contents help to enhance the binding force between the components in the coating and the adhesion between the coating and the metal substrate. Preferably, dispersants of the above types and contents help to improve the dispersibility of the solid components in the coating, thereby reducing the agglomeration of the solid components in the solution and then forming a uniform coating.

[0037] In another typical embodiment of the present application, an insulating coating is provided, which is obtained by mixing the insulating coating composition, and the insulating coating composition is the above-mentioned insulating coating composition.

[0038] The insulating coating comprising the above-mentioned insulating coating composition has good insulating properties, anti-oxidation properties and high-temperature resistance properties, so that it can be better applied to the surfaces of steel and pure iron sensor parts. The insulating coating of the present application can be coated on the surface of blanks at room temperature to 300°C. The insulating coating should be stored sealed in a cool and dry place. There will be slight precipitation after long-term placement, and it can be used just by stirring evenly.

[0039] In still another typical embodiment of the present application, a preparation method of the above-mentioned insulating coating is provided, and the preparation method comprises: successively ball-milling and standing the raw materials corresponding to the insulating coating to obtain the insulating coating.

[0040] Preferably, the raw materials corresponding to the above-mentioned insulating coating are ball-milled in a ball-milling tank to a D50 particle size of 1-10 μm and then left standing for 14 days to obtain the insulating coating. Among them, the ball-to-material ratio is 2-4:1, the rotation speed of ball-milling is 70-90 rpm, and the time of ball-milling is 10-20 h.

[0041] The insulating coating obtained by the above preparation method has good insulating properties, anti-oxidation properties and high-temperature resistance properties, so that it can be better applied to the surfaces of steel and pure iron sensor parts. The preparation process of this application is simple, can realize mass production, maintain good product consistency, and has a relatively low price.

[0042] In another typical embodiment of this application, an insulating coating is provided, which is obtained by sequentially drying and baking after the insulating coating is coated on the surface of a metal. It is characterized in that the insulating coating is the above-mentioned insulating coating.

[0043] The insulating coating including the above insulating coating has good insulating properties, anti-oxidation properties and high-temperature resistance properties. In addition, the preparation process of the insulating coating is simple, that is, the insulating coating is sprayed on the metal surface in any surface state at room temperature, and after the coating is naturally dried, it is baked, and after baking, it is naturally cooled to room temperature. In addition, it is preferably that the baking temperature is 750-1050 °C and the baking time is 10-15 min.

[0044] In an embodiment of this application, the insulating coating protects the metal at a temperature of ≤850 °C; wherein, the protection time is 5000-20000 h, the metal is selected from any one or more of steel, iron, titanium alloy and titanium aluminum alloy, and the coating thickness of the insulating coating is 0.1-0.2 mm. The metal can also be a superalloy, and the superalloy is an alloy that can work for a long time in a continuous high-temperature environment without significant performance degradation. Preferably, the superalloy is a nickel-based superalloy.

[0045] The insulating coating of this application can protect steel and pure iron, or other metals for a long time at a high temperature not higher than 850 °C, and can almost cover all metal types; at the same time, the coating has good high-temperature insulation properties and the characteristic of non-decay of the high-low temperature cycle performance of the experienced environment. In addition, the insulating coating of this application is a water-based coating and has the advantage of being green and environmentally friendly. Preferably, the dosage of the insulating coating is 0.25-0.35 kg / m 2 , which helps to achieve the above coating thickness on the metal surface, so as to better form an insulating coating.

[0046] The beneficial effects of this application will be further described below in conjunction with embodiments.

[0047] Example 1

[0048] By weight, the raw materials of the insulating paint include: 55 parts of glass powder, 8 parts of phlogopite, 7 parts of hexagonal boron nitride, 7 parts of SiO2 aerogel, 4 parts of bentonite, 2 parts of MgO, 2 parts of ZrO2, 1 part of Cr2O3, 40 parts of water, 15 parts of 3wt% aqueous solution of hydroxyethyl cellulose, and 0.6 part of polyurethane dispersant 7031. Among them, the glass powder includes 35 parts of SiO2, 25 parts of BaO, 18 parts of Al2O3, 8 parts of B2O3, 2 parts of Li2O, 2 parts of La2O3, 2 parts of Y2O3, 4 parts of CaO and 2 parts of Co2O3. The particle sizes of the glass powder, phlogopite, hexagonal boron nitride, bentonite, MgO, ZrO2 and Cr2O3 are 200 mesh.

[0049] The raw materials are ball-milled in a ball mill until the D50 particle size reaches 1 μm and then left standing for 14 days to obtain the insulating paint. Among them, the ball-to-material ratio is 3:1, the rotation speed of the ball mill is 80 rpm, and the ball-milling time is 15 h.

[0050] The insulating paint is sprayed on the surface of a 1Cr18Ni9Ti stainless steel sensor. After drying, it is calcined at 1050 °C for 10 min, and then naturally cooled after being taken out of the furnace, forming an insulating coating on the surface of the sensor.

[0051] Example 2

[0052] By weight, the raw materials of the insulating paint include: 50 parts of glass powder, 5 parts of phlogopite, 5 parts of hexagonal boron nitride, 5 parts of SiO2 aerogel, 3 parts of bentonite, 1 part of MgO, 1 part of ZrO2, 2 parts of high cobalt black, 30 parts of water, 10 parts of 2wt% aqueous solution of hydroxyethyl cellulose, and 0.5 part of polyurethane dispersant 7031. Among them, the glass powder includes 30 parts of SiO2, 20 parts of BaO, 15 parts of Al2O3, 5 parts of B2O3, 1 part of Li2O, 1 part of La2O3, 1 part of Y2O3, 2 parts of CaO and 1 part of Co2O3. The particle sizes of the glass powder, phlogopite, hexagonal boron nitride, bentonite, MgO, ZrO2 and Cr2O3 are 200 mesh.

[0053] The raw materials are ball-milled in a ball mill until the D50 particle size reaches 7 μm and then left standing for 14 days to obtain the insulating paint. Among them, the ball-to-material ratio is 2:1, the rotation speed of the ball mill is 70 rpm, and the ball-milling time is 20 h.

[0054] The insulating paint is sprayed on the surface of a TD4 electro-technical pure iron sensor. After drying, it is calcined at 750 °C for 15 min, and then naturally cooled after being taken out of the furnace, forming an insulating coating on the surface of the sensor.

[0055] Example 3

[0056] By weight, the raw materials of the insulating paint include: 60 parts of glass powder, 10 parts of phlogopite, 10 parts of hexagonal boron nitride, 10 parts of SiO2 aerogel, 5 parts of bentonite, 3 parts of MgO, 3 parts of ZrO2, 3 parts of high cobalt black, 50 parts of water, 20 parts of 5wt% aqueous solution of hydroxyethyl cellulose, and 1 part of polyurethane dispersant 7031. Among them, the glass powder includes 40 parts of SiO2, 30 parts of BaO, 20 parts of Al2O3, 10 parts of B2O3, 3 parts of Li2O, 3 parts of La2O3, 3 parts of Y2O3, 5 parts of CaO, and 3 parts of Co2O3. The particle sizes of the glass powder, phlogopite, hexagonal boron nitride, bentonite, MgO, ZrO2, and Cr2O3 are 200 mesh.

[0057] The raw materials are ball-milled in a ball mill until the D50 particle size reaches 10 μm and then left standing for 14 days to obtain the insulating paint. Among them, the ball-to-material ratio is 4:1, the rotation speed of the ball mill is 90 rpm, and the ball-milling time is 10 h.

[0058] The insulating paint is sprayed on the surface of a 2Cr13 stainless steel sensor. After drying, it is calcined at 750 °C for 15 min, and then naturally cooled after being taken out of the furnace to form an insulating coating on the surface of the sensor.

[0059] Example 4

[0060] The difference from Example 1 is that the total weight of the glass powder and the high-temperature resistant fillers (MgO, ZrO2, and Cr2O3) is 60 parts, and the mass ratio of the glass powder to the high-temperature resistant fillers is 53:7, and finally an insulating coating is obtained.

[0061] Example 5

[0062] The difference from Example 1 is that the total weight of the glass powder and the high-temperature resistant fillers (MgO, ZrO2, and Cr2O3) is 60 parts, and the mass ratio of the glass powder to the high-temperature resistant fillers is 58:2, and finally an insulating coating is obtained.

[0063] Example 6

[0064] The difference from Example 1 is that the total weight of the phlogopite and the hexagonal boron nitride is 15 parts, and the mass ratio of the phlogopite to the hexagonal boron nitride is 9:6, and finally an insulating coating is obtained.

[0065] Example 7

[0066] The difference from Example 1 is that the total weight of the phlogopite and the hexagonal boron nitride is 15 parts, and the mass ratio of the phlogopite to the hexagonal boron nitride is 6:9, and finally an insulating coating is obtained.

[0067] Example 8

[0068] The difference from Example 1 is that the total weight fraction of SiO2 aerogel and high-temperature resistant fillers (MgO, ZrO2, and Cr2O3) is 12 parts, and the mass ratio of SiO2 aerogel to high-temperature resistant fillers is 5:7, finally obtaining an insulating coating.

[0069] Example 9

[0070] The difference from Example 1 is that the total weight fraction of SiO2 aerogel and high-temperature resistant fillers (MgO, ZrO2, and Cr2O3) is 12 parts, and the mass ratio of SiO2 aerogel to high-temperature resistant fillers is 8:4, finally obtaining an insulating coating.

[0071] Example 10

[0072] The difference from Example 1 is that the total weight fraction of MgO and ZrO2 is 4 parts, and the mass ratio of MgO to ZrO2 is 1:3, finally obtaining an insulating coating.

[0073] Example 11

[0074] The difference from Example 1 is that the total weight fraction of MgO and ZrO2 is 4 parts, and the mass ratio of MgO to ZrO2 is 3:1, finally obtaining an insulating coating.

[0075] Comparative Example 1

[0076] The difference from Example 1 is that the main solid components are 50 wt.% Al2O3, 30 wt.% ZrO2, and 20 wt.% boric acid. The above raw materials are ball-milled in a ball mill until the D50 particle size reaches 0.3 μm and then left standing for 14 days to obtain an insulating coating. Among them, the ball-to-material ratio is 5:1, the rotation speed of ball milling is 80 rpm, and the ball milling time is 50 h.

[0077] The insulating coating is sprayed on the surface of a 1Cr18Ni9Ti stainless steel sensor. After drying, it is calcined at 1050 °C for 10 min, and then naturally cooled after being taken out of the furnace, forming an insulating coating on the surface of the sensor.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that, by weight fraction, the raw materials of the insulating coating include: 65 parts of glass powder, 4 parts of phlogopite, 4 parts of hexagonal boron nitride, 4 parts of SiO2 aerogel, 4 parts of bentonite, 0.5 part of MgO, 0.5 part of ZrO2, 4 parts of Cr2O3, 40 parts of water, 15 parts of hydroxyethyl cellulose aqueous solution, and 0.6 part of polyurethane dispersant 7031, finally obtaining an insulating coating.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that high-temperature resistant fillers (MgO, ZrO2, and Cr2O3) are not added, and an insulating coating is finally obtained.

[0082] Test method:

[0083] High-temperature resistance test: The coating is subjected to high-temperature resistance test at different temperatures not higher than 850 °C. If the coating does not burn off and flow at high temperature, it meets the requirements; if the coating burns off and flows at high temperature, it does not meet the requirements.

[0084] Anti-oxidation test: The coating is subjected to anti-oxidation test at 850 °C. After high temperature, the coating still adheres tightly to the metal surface. Measure the area of the oxide scale formed on the metal surface and calculate the proportion of the oxidized area.

[0085] Insulation test: For the sensor parts with an insulating coating on the surface, at 500 °C and 100 V, the resistance measured with the coil test is not less than 1 megohm.

[0086] Protection time test: For the sensor parts with an insulating coating on the surface, it is heated from room temperature to 500 °C in 2 h, kept at 500 °C for 5 - 6 h, and finally cooled to room temperature in air. In the process of one heat cycle, after one cycle, the anti-oxidation and insulation properties of the coating do not decay, and the longest protection time is tested.

[0087] The insulating coatings of the above examples and comparative examples are subjected to performance tests, and the test results are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] As can be seen from Table 1, the coating of Comparative Example 1 has low stability at high temperature, is difficult to sinter densely, and cannot play the role of metal protection and insulation for a long time. Due to the absence of high-temperature resistant fillers in the insulating coating of Comparative Example 3, the coating is prone to flow and burn off during the high-temperature sintering process, is difficult to sinter densely, and cannot play the role of metal protection and insulation for a long time.

[0092] Among them, Figure 1 is an optical photograph of the state of the insulating coating after baking in Example 1. As can be seen from Figure 1 it, the surface of the insulating coating in Example 1 is green at room temperature of 25 °C after baking, and the coating is uniform and dense, indicating that the coating in Example 1 of the present application can play a good role in protection and high-temperature insulation.

[0093] Figure 2 is an optical photograph of the state of the insulating coating after baking in Example 2. As can be seen from Figure 2It can be seen that after the insulating coating of Example 2 is fired, its surface is black at room temperature of 25°C, and the coating is uniform and dense, indicating that the coating of Example 2 of the present application can play a good role in protection and high-temperature insulation.

[0094] Figure 3 is an optical photograph of the state after the insulating coating of Example 3 is fired. From Figure 3 It can be seen that after the insulating coating of Example 3 is fired, its surface is black at room temperature of 25°C, and the coating is uniform and dense, indicating that the coating of Example 3 of the present application can play a good role in protection and high-temperature insulation.

[0095] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0096] By controlling the components and their contents of the insulating coating composition of the present application within the above ranges, the insulating coating can have good insulating properties, good high-temperature resistance and anti-oxidation properties at temperatures not higher than 850 °C, and can achieve long-term protection, so as to be better applied to the surface of metals that are prone to oxidation. Specifically, glass powder is one of the core components, which can effectively bind other components together to form a dense protective layer. During the high-temperature sintering process, the glass powder melts to form a continuous glass phase, which can seal the defects on the metal surface and prevent the intrusion of oxygen, thereby effectively preventing the oxidation of the metal. In addition, after cooling, the glass powder solidifies to form an enamel surface with a certain hardness, thus providing good mechanical protection and resistance to chemical erosion. Moreover, SiO2, BaO, Al2O3 and B2O3 in its composition can further improve the high-temperature resistance and insulating properties of the coating. The flaky structure of the mica mineral material helps to form a layered isolation layer, which can effectively isolate the current conduction, thereby enhancing the insulating effect of the coating and also improving the anti-oxidation ability. At the same time, mica can form a protective layer at high temperatures, further enhancing the anti-oxidation performance of the coating. Hexagonal boron nitride is a material with excellent high-temperature stability and insulating properties. In the insulating coating composition of the present application, it mainly acts as a reinforcing agent, which can significantly improve the high-temperature insulating properties and anti-oxidation ability of the coating. SiO2 aerogel is a nanomaterial with extremely low density and high porosity, which can effectively isolate the heat transfer, reduce the change of the temperature gradient on the metal surface when the environmental temperature changes, thereby effectively reducing the risk of coating peeling caused by too rapid instantaneous temperature change, and then extending the service life of the coating, and can also reduce the oxidation rate of the metal to a certain extent. At the same time, the high porosity and microstructure of the aerogel can enhance the insulating properties of the coating, and can maintain good insulating effects even under high-temperature and high-voltage conditions. The addition of bentonite is beneficial to improving the suspension performance and easy coating property of the coating. The high-temperature resistant fillers ZrO2 and MgO both have high melting points and good heat resistance, and can form a dense high-temperature phase in the coating, thereby enhancing the high-temperature stability of the coating. Since steel and pure iron will undergo obvious oxidation phenomena at temperatures above 300 °C, therefore, the coating formed by the insulating coating composition of the present application can be better used on the surfaces of steel and pure iron sensor parts, and has good protective performance and a long protection time even at high temperatures.

[0097] The above are only examples of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An insulating coating composition, characterized in that: In parts by weight, the insulating coating composition comprises: 50-60 parts of glass powder; 5-10 parts of mica mineral material; 5 to 10 parts of hexagonal boron nitride; 5-10 parts of SiO2 aerogel; 3-5 parts of bentonite; and 2 to 12 parts of high temperature resistant filler; Wherein, the glass powder includes, by weight, 30 to 40 parts of SiO2, 20 to 30 parts of BaO, 15 to 20 parts of Al2O3, 5 to 10 parts of B2O3, 1 to 3 parts of Li2O, 1 to 3 parts of La2O3, 1 to 3 parts of Y2O3, 2 to 5 parts of CaO and 1 to 3 parts of Co2O3; The high temperature resistant filler includes MgO and ZrO2.

2. The insulating coating composition according to claim 1, characterized in that: In parts by weight, the insulating coating composition comprises: 52 to 58 parts of the glass powder; 6 to 9 parts of the mica mineral material; 6 to 9 parts of hexagonal boron nitride; 5 to 8 parts of the SiO2 aerogel; 3 to 4 parts of the bentonite; and 3 to 10 parts of the high temperature resistant filler.

3. The insulating coating composition according to claim 1 or 2, characterized in that: In parts by weight, the high temperature resistant filler includes 1 to 3 parts of the MgO and 1 to 3 parts of the ZrO2; and / or, the high temperature resistant filler also includes 0.5 to 3 parts of high cobalt black; and / or, the high temperature resistant filler also includes 0.5 to 3 parts of Cr2O3.

4. The insulating coating composition according to any one of claims 1 to 3, characterized in that: The mass ratio of the glass powder to the high temperature resistant filler is 53-57:5-10.

5. The insulating coating composition according to any one of claims 1 to 4, characterized in that: The mica mineral material is selected from any one or more of phlogopite, muscovite, sericite and synthetic mica, and the mass ratio of the mica mineral material to hexagonal boron nitride is 6-9:6-8.

6. The insulating coating composition according to any one of claims 1 to 5, characterized in that: In parts by weight, the insulating coating composition further comprises 30 to 50 parts of a solvent and 0.5 to 1 part of a dispersant; and / or the insulating coating composition further comprises 10 to 20 parts of a binder; Wherein, the solvent is water; and / or the binder is a 2-5 wt % hydroxyethyl cellulose aqueous solution; and / or the dispersant is a polyurethane dispersant.

7. An insulating coating obtained by mixing an insulating coating composition, characterized in that: The insulating coating composition is the insulating coating composition according to any one of claims 1 to 6.

8. A method for preparing the insulating coating according to claim 7, characterized in that: The preparation method comprises: The raw materials corresponding to the insulating coating are ball-milled and left to stand in sequence to obtain the insulating coating.

9. An insulating coating, obtained by coating an insulating coating on a metal surface, followed by drying and calcining, characterized in that: The insulating coating is the insulating coating according to claim 7.

10. The insulating coating according to claim 9, characterized in that: The insulating coating protects the metal at a temperature of ≤850°C; wherein the protection time is 5000 to 20000 hours, the metal is selected from any one or more of steel, iron, titanium alloy and titanium aluminum alloy, and the coating thickness of the insulating coating is 0.1 to 0.2 mm.

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