A phosphate inorganic intumescent flame-retardant coating for a substation or converter station, and its preparation method and application

Abstract

The present invention discloses a phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station, and its preparation method and application. The raw materials of the coating include, by mass, 30-50 parts of phosphate, 10-20 parts of modified glass powder, 5-20 parts of inorganic flame retardant, 3-20 parts of filler, 5-10 parts of curing agent, and 3-10 parts of auxiliary agent; the modified glass powder is one or two of glass powder with a melting point of 500°C or 700°C, mixed with glass powder with a melting point of 350°C, and modified with a silane coupling agent. The phosphate inorganic intumescent flame-retardant coating prepared by the present invention can generate an intumescent flame-retardant carbon layer when burned at 1200°C, which can provide good fireproofing for the base material, has a heat resistance time of more than 60 minutes at 1200°C, and can be cured at room temperature. In addition, the coating formula is chromium-free, thereby improving the environmental friendliness of the phosphate intumescent flame-retardant coating.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature resistant coatings, and in particular to a phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station, and a preparation method and application thereof. Background Art

[0002] High-temperature resistant coatings generally refer to coatings that can be used in environments exceeding 200°C, without significant changes in performance, with the color remaining essentially the same and without defects such as cracks in the film. In short, coatings that can maintain their physical and mechanical properties at a stable level are called high-temperature resistant coatings. my country's substations (converter stations) are located in numerous locations, many of which are in harsh environments, requiring flame-retardant coatings to have excellent stability. High-temperature resistant coatings are widely used and promoted due to their excellent performance at high temperatures. They are widely used in petroleum cracking equipment, chimneys, high-temperature furnaces, heat exchangers, engines and their exhaust pipes, high-temperature steam pipes, etc. With the development of the global aviation and aerospace industries, people are paying more and more attention to high-temperature resistant coatings, and such coatings will be promoted to more industries and application fields.

[0003] Phosphate coatings are a type of coating that uses water-soluble phosphates as a binder and metal oxides as a curing agent. The pigments and fillers in these coatings are primarily inorganic, heat-resistant fillers, while the curing agent is primarily a metal oxide. Compared to organic coatings that use organic polymers as binders, inorganic coatings using heat-resistant phosphate binders offer the advantages of superior heat resistance and resistance to high-temperature oxidation. Organic polymers generally have poor heat resistance and cannot be used at high temperatures for long periods. Once phosphate coatings are applied and cured, a high-temperature resistant coating forms on the surface of the material. This coating system can withstand high-temperature airflow and can typically withstand temperatures of 650°C.

[0004] Chinese patent application publication number CN112266633A discloses a fire-retardant coating resistant to temperatures up to 1700°C and its preparation method. Using aluminum hydroxide, silicon dioxide, mica powder, magnesium oxide, double rare earth tantalate, and basalt fiber, the resulting fire-retardant coating can withstand temperatures up to 1700°C for 20 minutes, effectively filling a gap in domestic high-temperature-resistant coatings. Chinese patent application publication number CN115093725A discloses a fire-retardant coating composed of aluminum dihydrogen phosphate, zinc oxide, cerium oxide, gadolinium zirconate, polysiloxane, zirconium boride, pick powder, tungsten powder, chopped high-silica fiber, chromium trioxide, potassium chromate, a non-silicon defoamer, and deionized water. The coating is heat-resistant to 1800°C. Existing phosphate coatings primarily achieve their heat resistance through the synergistic combination of high-temperature-resistant inorganic fillers. Intumescent fire-retardant coatings are functional coatings that, when applied to a substrate, react with fire to form a char layer much thicker than the original coating, thereby reducing heat transfer to the substrate and improving the fire resistance of the protected substrate. Currently, intumescent flame-retardant coatings primarily achieve this charring effect through an intumescent flame retardant composed of an acid, carbon, and gas source. They are rarely used in phosphate-based flame-retardant coatings.

[0005] Chinese patent application document with publication number CN115418121A discloses an iron-based water-based high-temperature resistant insulating coating, its preparation method and application. The coating is composed of the following ingredients: 30 to 50 parts of low-melting point glass powder, 5 to 20 parts of inorganic aggregate, 0.5 to 5 parts of binder, 0.2 to 5 parts of dispersant, 0 to 5 parts of organic silicon film-forming aid, 0.5 to 5 parts of silica sol, and 35 to 60 parts of deionized water. The low-melting-point glass powder is LX-45, GT-50 and LX-680; or, the low-melting-point glass powder is LX-45, TY-906 and G-57; or, the low-melting-point glass powder is LX-45, TY-280, G-57 and LX-680; the initial melting temperature of the low-melting-point glass powder is 420°C to 600°C; it only uses water as a dispersion medium and does not contain volatile solvents. The preparation method is green and environmentally friendly, the sintering temperature is low (540 to 620°C), the damage to the substrate is small, and the organic components are small, avoiding the problems of coating powdering, decreased adhesion, coating shedding caused by the decomposition of organic matter at high temperature. However, its high-temperature resistance is still not very ideal, and the curing is divided into three temperature stages, and the curing procedure is relatively complicated. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to improve the high temperature resistance of phosphate coatings.

[0007] The present invention solves the above technical problems through the following technical means:

[0008] A phosphate inorganic intumescent flame-retardant coating for a substation or converter station, wherein the raw materials thereof include, by weight, 30-50 parts of phosphate, 10-20 parts of modified glass powder, 5-20 parts of inorganic flame retardant, 3-20 parts of filler, 5-10 parts of curing agent, and 3-10 parts of auxiliary agent;

[0009] The modified glass powder is prepared by mixing one or both of glass powder with a melting point of 500° C. and glass powder with a melting point of 700° C. with glass powder with a melting point of 350° C. and then modifying the mixture with a silane coupling agent.

[0010] Preferably, the phosphate is aluminum dihydrogen phosphate.

[0011] Preferably, the inorganic flame retardant is a mixture of one or more of magnesium hydroxide, aluminum hydroxide, magnesium carbonate, basic magnesium carbonate, and basic copper carbonate.

[0012] Preferably, the inorganic flame retardant is a mixture of one or more of magnesium hydroxide and aluminum hydroxide.

[0013] Preferably, the filler is a mixture of one or more of nano titanium dioxide, nano aluminum oxide, silicon carbide, kaolin, mica powder, and talc powder.

[0014] Preferably, the curing agent is a mixture of one or more of MgO, ZnO, and CuO.

[0015] Preferably, the curing agent is MgO.

[0016] Preferably, the auxiliary agent is a defoaming agent, an adhesion promoter, or a mixture of both.

[0017] Preferably, the defoaming agent is defoaming agent YS-T118.

[0018] Preferably, the adhesion promoter is one of SN 6797 adhesion promoter and 5140B water-based adhesion promoter, or a mixture of the two.

[0019] Preferably, the modified glass powder is obtained by mixing glass powder with a melting point of 350° C., glass powder with a melting point of 500° C., and glass powder with a melting point of 700° C., and then modifying the mixture with a silane coupling agent.

[0020] Preferably, the mass ratio of the glass powder with a melting point of 350° C., the glass powder with a melting point of 500° C., and the glass powder with a melting point of 700° C. is 1-2:1:1.

[0021] Preferably, the modified glass powder is obtained by mixing glass powder with a melting point of 350° C. and glass powder with a melting point of 500° C. and then modifying the mixture with a silane coupling agent.

[0022] Preferably, the mass ratio of the glass powder with a melting point of 350° C. to the glass powder with a melting point of 500° C. is 1:1-2.

[0023] Preferably, the silane coupling agent is silane coupling agent KH570.

[0024] Preferably, the preparation process of the modified glass powder includes the following steps: grinding glass powders of different melting points according to a ratio, sieving and mixing them by ball milling, mixing them with an ethanol / water mixed solution, adding a silane coupling agent and stirring evenly, heating to react, and drying to obtain the modified glass powder.

[0025] Preferably, the mass ratio of glass powder to silane coupling agent is 5:1.

[0026] Preferably, the mixture is heated to 60° C. and the reaction is carried out for 12 hours.

[0027] Preferably, the raw materials of the phosphate inorganic intumescent flame-retardant coating for the transformer substation or converter station further include water.

[0028] Preferably, the weight ratio of phosphate to water is 4-5:5-6.

[0029] Preferably, the melting range of the glass powder matches the temperature range of the gas generated by thermal decomposition of the inorganic flame retardant.

[0030] Preferably, the pyrolysis temperature range of the inorganic flame retardant matches the melting point range of the glass powder raw material; for example, magnesium hydroxide begins to decompose at 300°C, generates H2O (gas) at 350°C, and completes decomposition at 480°C; this matches the melting point range of glass powder, which has an initial melting point of 350°C and a half-melting point of 463°C. The temperature of the generated gas matches the temperature range where the glass powder begins to melt, and the entire pyrolysis process covers most of the glass powder melting range. This allows for gas expansion as the glass powder melts and flows, promoting the melting and flow of the glass powder for secondary film formation in the high-temperature zone. Furthermore, the thermal decomposition of magnesium hydroxide absorbs heat, improving the high-temperature resistance of the coating. The MgO generated simultaneously can achieve secondary solidification of aluminum dihydrogen phosphate in the high-temperature zone.

[0031] In the present invention, the initial melting temperature of the glass powder is adjusted to 350-700°C by compounding the glass powder. The melting range of 350-500°C in the compounded glass powder is utilized, and an inorganic flame retardant is preferably designed to achieve the effect of heat resistance of the carbon layer expansion in the low-temperature zone (350-500°C). The initial melting components of 500-700°C in the compounded glass powder are utilized to achieve secondary film formation in the high-temperature zone (500-700°C), thereby compensating for the mismatch between the thermal expansion coefficient of the high-temperature phosphate inorganic film-forming agent and the substrate, and ultimately achieving the purpose of heat resistance of 1200°C.

[0032] The present invention also provides a method for preparing the phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station, comprising the following steps:

[0033] S1. Grinding the modified glass powder, inorganic flame retardant, and filler, sieving, and ball milling to obtain a composite filler;

[0034] S2, prepare a phosphate aqueous solution, add the composite filler and additives in S1, and heat and stir;

[0035] S3. Add a curing agent to the product in S2 and stir to obtain the phosphate inorganic intumescent flame retardant coating for the transformer substation or converter station.

[0036] Preferably, the mass concentration of the phosphate aqueous solution is 40-50%.

[0037] The present invention also proposes an application of the phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station in the transformer substation or the converter station.

[0038] The present invention also provides a coating, which is prepared using the phosphate inorganic intumescent flame-retardant coating for transformer substations or converter stations.

[0039] The advantages of the present invention are:

[0040] The present invention uses phosphate as a film-forming agent and, based on melt foaming theory, synergistically prepares a phosphate inorganic intumescent flame-retardant coating by compounding an inorganic flame retardant with glass powder. High-temperature-resistant inorganic fillers can further improve the high-temperature resistance of the coating. A curing agent can achieve room-temperature curing of the phosphate coating, improving the coating's curing process. The addition of auxiliary defoaming agents and adhesion promoters improves the coating's adhesion and dispersibility. Through the synergistic action of phosphate, modified glass powder, inorganic flame retardant, high-temperature-resistant filler, curing agent, and auxiliary agents, the present invention can effectively improve the coating's intumescent flame-retardant effect and high-temperature resistance.

[0041] (1) The present invention is based on the principle of intumescent flame retardant and utilizes melt foaming theory. By matching the thermal decomposition temperature of the inorganic flame retardant with the melting point of the glass powder, the inorganic flame retardant is pyrolyzed to generate gas. At this time, the low-melting-point glass powder melts into liquid, and the gas expands to generate a carbon layer. In addition, the glass powders with different melting points can melt and flow at high temperatures (350-700°C) to play a secondary film-forming role. It realizes the preparation of phosphate inorganic intumescent flame-retardant coatings without using intumescent flame retardants, and improves the high-temperature resistance of conventional phosphate coatings through the intumescent carbon layer.

[0042] (2) The coating of the present invention has a simple preparation process. The functional fillers used in the coating are thoroughly mixed by grinding, screening, and ball milling the modified glass powder, inorganic flame retardant, and high-temperature resistant fillers. A phosphate aqueous solution is then added, and the temperature of the aqueous solution is controlled to allow for a full reaction between the filler and the phosphate.

[0043] (3) The phosphate inorganic intumescent flame-retardant coating prepared by the present invention can generate an intumescent flame-retardant carbon layer when burned at 1200°C, which can play a good fire-proof role on the base material and has a heat-resistant time of more than 60 minutes at 1200°C.

[0044] (4) The phosphate inorganic intumescent flame-retardant coating prepared by the present invention can be cured at room temperature, and the coating formula does not contain chromium elements, thereby improving the environmental friendliness of the phosphate inorganic intumescent flame-retardant coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a back temperature test diagram of the phosphate inorganic intumescent flame retardant coating prepared in Examples 1-4 of the present invention;

[0046] Figure 2 This is a digital image of the phosphate inorganic intumescent flame retardant coating and the carbon layer prepared in Example 1 of the present invention;

[0047] Figure 3 This is a scanning image of the expanded carbon layer of the phosphate inorganic intumescent flame-retardant coating prepared in Example 2 of the present invention;

[0048] Figure 4 This is a back temperature test diagram of the coatings prepared in Comparative Examples 1-7 of the present invention;

[0049] Figure 5 This is a digital image of the carbon layer of the coating prepared in Comparative Example 6 of the present invention;

[0050] Figure 6 This is a digital image of the carbon layer of the coating obtained in Comparative Example 7 of the present invention.

[0051] Figure 7 This is a digital image of the coating layer of the coating prepared in Comparative Example 9 of the present invention. DETAILED DESCRIPTION

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0053] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0054] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0055] In the following examples and comparative examples, the melting point of the glass powder is the temperature at which the glass powder begins to melt;

[0056] The glass powder with a melting point of 350°C is GT-35 low-melting-point glass powder, and the manufacturer is Anmi Micro-Nano New Materials (Guangzhou) Co., Ltd.

[0057] The glass powder with a melting point of 500°C is GT-50 low-melting-point glass powder, manufactured by Anmi Micro-Nano New Materials (Guangzhou) Co., Ltd.

[0058] The glass powder with a melting point of 700°C is GT-70 low-melting-point glass powder, and the manufacturer is Anmi Micro-Nano New Materials (Guangzhou) Co., Ltd.

[0059] The adhesion promoter SN 6797 was sourced from Foshan Keerle Building Materials Co., Ltd.

[0060] The defoaming agent YS-T118 is sourced from Beijing Kemite Technology Development Co., Ltd.

[0061] Example 1

[0062] A phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station. The raw materials thereof, in parts by mass, include 50 parts of aluminum dihydrogen phosphate, 10 parts of modified glass powder, 10 parts of magnesium hydroxide, 3 parts of nano-TiO2, 4 parts of nano-Al2O3, 10 parts of an MgO curing agent, and 3 parts of an adhesion promoter SN 6797.

[0063] The modified glass powder is prepared by compounding glass powders with melting points of 350°C, 500°C, and 700°C (the initial melting temperature of the glass powder) in a mass ratio of 1:1:1 and then modifying with silane. The specific preparation process includes the following steps:

[0064] (1) Grind glass powders of different melting points according to the ratio, sieve and mix them, and ball mill for 30 minutes;

[0065] (2) 10 parts by mass of the ball-milled glass powder was mixed with an ethanol / water mixed solution (volume ratio of ethanol:water = 8:2) at a mass fraction of 30%, and then 2 parts by mass of silane coupling agent KH570 was added and mechanically stirred for 30 minutes to ensure that the glass powder was mixed evenly;

[0066] (3) The uniformly mixed glass powder is kept constant at 60° C., reacted for 12 hours, and freeze-dried to obtain the modified glass powder.

[0067] The preparation process of phosphate inorganic intumescent flame retardant coating is as follows:

[0068] (1) Grinding modified glass powder, magnesium hydroxide, nano-TiO2, and nano-Al2O3 separately, sieving, and ball milling for 30 minutes to obtain a composite filler;

[0069] (2) preparing a 50% by mass aqueous solution of aluminum dihydrogen phosphate, adding the composite filler and adhesion promoter SN 6797 prepared in step (1), and stirring at 50° C. for 60 minutes;

[0070] (3) Add MgO and stir for 5 minutes to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which is then applied by brush. The substrate is stainless steel, and the coating thickness is 3 mm.

[0071] Example 2

[0072] A phosphate inorganic intumescent flame-retardant coating for a substation or a converter station. The raw materials thereof, in parts by mass, include 40 parts of aluminum dihydrogen phosphate, 12 parts of modified glass powder, 18 parts of magnesium hydroxide, 5 parts of nano-TiO2, 5 parts of nano-Al2O3, 8 parts of talc, 8 parts of a ZnO curing agent, 2 parts of an adhesion promoter SN 6797, and 2 parts of a defoaming agent YS-T118.

[0073] The modified glass powder is prepared by compounding glass powders with melting points of 350°C and 500°C (initiation temperature of glass powder) in a mass ratio of 1:2 and then modifying with silane. The specific preparation process is the same as that of Example 1.

[0074] The preparation process of phosphate inorganic intumescent flame retardant coating is as follows:

[0075] (1) Grinding modified glass powder, magnesium hydroxide, nano titanium dioxide, nano aluminum oxide, and talc powder separately, sieving, and ball milling for 30 minutes to obtain a composite filler;

[0076] (2) preparing a 40% by mass aqueous solution of aluminum dihydrogen phosphate, adding the composite filler, adhesion promoter SN 6797 and defoamer YS-T118 prepared in step (1), and stirring at 50° C. for 60 minutes;

[0077] (3) Add ZnO and stir for 5 minutes to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which is then applied by brush. The substrate is stainless steel, and the coating thickness is 3 mm.

[0078] Example 3

[0079] A phosphate inorganic intumescent flame-retardant coating for a substation or a converter station. The raw materials thereof, in parts by mass, include 45 parts of aluminum dihydrogen phosphate, 10 parts of modified glass powder, 15 parts of magnesium hydroxide, 6 parts of nano-titanium dioxide, 6 parts of talc powder, 6 parts of silicon carbide, 8 parts of a ZnO curing agent, 2 parts of an adhesion promoter SN 6797, and 2 parts of a defoaming agent YS-T118.

[0080] The modified glass powder is prepared by mixing glass powders with melting points of 350° C. and 500° C. in a mass ratio of 1:1 and then modifying with silane. The specific preparation process is the same as that of Example 1.

[0081] The preparation process of phosphate inorganic intumescent flame retardant coating is as follows:

[0082] (1) Grinding modified glass powder, magnesium hydroxide, nano-titanium dioxide, talc powder, and silicon carbide separately, sieving, and ball milling for 30 minutes to obtain a composite filler;

[0083] (2) preparing a 45% by mass aqueous solution of aluminum dihydrogen phosphate, adding the composite filler, adhesion promoter SN 6797 and defoamer YS-T118 prepared in step (1), and stirring at 50° C. for 60 min;

[0084] (3) Add ZnO and stir for 5 minutes to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which is then applied by brush. The substrate is stainless steel, and the coating thickness is 3.5 mm.

[0085] Example 4

[0086] A phosphate inorganic intumescent flame-retardant coating for a substation or a converter station. The raw materials thereof, in parts by mass, include 35 parts of aluminum dihydrogen phosphate, 15 parts of modified glass powder, 20 parts of magnesium hydroxide, 7 parts of nano-TiO2, 5 parts of talc, 5 parts of kaolin, 6 parts of MgO curing agent, 3 parts of adhesion promoter SN 6797, and 2 parts of defoaming agent YS-T118.

[0087] The modified glass powder is prepared by compounding glass powders with melting points of 350° C., 500° C., and 700° C. in a mass ratio of 2:1:1 and then modifying with silane. The specific preparation process is the same as that of Example 1.

[0088] The preparation process of phosphate inorganic intumescent flame retardant coating is as follows:

[0089] (1) Grinding modified glass powder, magnesium hydroxide, nano titanium dioxide, talc, and kaolin separately, sieving, and ball milling for 30 minutes to obtain a composite filler;

[0090] (2) preparing a 35% by mass aqueous solution of aluminum dihydrogen phosphate, adding the composite filler, adhesion promoter SN 6797 and defoamer YS-T118 prepared in step (1), and stirring at 50° C. for 60 minutes;

[0091] (3) Add MgO and stir for 5 minutes to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which is then applied by brush. The substrate is stainless steel, and the coating thickness is 4 mm.

[0092] Comparative Example 1

[0093] The only difference from Example 1 is that the raw materials do not contain modified glass powder. The raw materials, in parts by mass, include 50 parts of aluminum dihydrogen phosphate, 20 parts of magnesium hydroxide, 3 parts of nano-TiO2, 4 parts of nano-Al2O3, 10 parts of MgO curing agent, and 3 parts of adhesion promoter SN 6797.

[0094] According to the preparation process of the inorganic phosphate intumescent flame retardant coating in Example 1, the modified glass powder was removed to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which was then applied by brush. The substrate was stainless steel, and the coating thickness was 3 mm.

[0095] Comparative Example 2

[0096] The only difference from Example 1 is that the raw materials do not contain magnesium hydroxide. The raw materials, by mass, include 50 parts of aluminum dihydrogen phosphate, 20 parts of modified glass powder, 3 parts of nano-TiO2, 4 parts of nano-Al2O3, 10 parts of MgO curing agent, and 3 parts of adhesion promoter SN 6797.

[0097] The remaining steps and preparation method are the same as those in Example 1 (magnesium hydroxide is deleted accordingly) to obtain a uniformly mixed aluminum dihydrogen phosphate inorganic intumescent flame retardant coating, which is then applied by brush. The substrate is stainless steel, and the coating thickness is 3 mm.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that the glass powder is a glass powder with a single melting point, that is, the glass powder with a melting point of 350°C is used to replace the glass powders with melting points of 350°C, 500°C, and 700°C in the mass ratio of 1:1:1 in Example 1. The remaining steps are consistent with Example 1.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that the glass powder is a glass powder with a single melting point, that is, the glass powder with a melting point of 500°C is used to replace the glass powders with melting points of 350°C, 500°C, and 700°C in the mass ratio of 1:1:1 in Example 1. The remaining steps are consistent with Example 1.

[0102] Comparative Example 5

[0103] The difference from Example 1 is that the glass powder is a glass powder with a single melting point, that is, the glass powder with a melting point of 700°C is used to replace the glass powders with melting points of 350°C, 500°C, and 700°C in the mass ratio of 1:1:1 in Example 1. The remaining steps are consistent with Example 1.

[0104] Comparative Example 6

[0105] The only difference from Example 1 is that during the preparation of the modified glass powder, the milled glass powder was directly freeze-dried without the reaction process of step (2) and step (3). Experimental phenomenon: The glass powder agglomerated and had poor dispersibility.

[0106] Comparative Example 7

[0107] The difference from Example 1 lies in the different glass powder compounding ratios. Glass powders with melting points of 500°C and 700°C in a mass ratio of 1:1 are used instead of the glass powders with melting points of 350°C, 500°C, and 700°C in a mass ratio of 1:1:1 in Example 1. The remaining steps are the same as in Example 1.

[0108] Comparative Example 8

[0109] The difference from Example 4 is that the ratios of aluminum dihydrogen phosphate, modified glass powder, and magnesium hydroxide are different. The raw materials, by mass, include 60 parts of aluminum dihydrogen phosphate, 15 parts of modified glass powder, 20 parts of magnesium hydroxide, 7 parts of nano-TiO2, 5 parts of talc, 5 parts of kaolin, 6 parts of MgO curing agent, 3 parts of adhesion promoter SN 6797, and 2 parts of defoaming agent YS-T118. The remaining steps are the same as in Example 4.

[0110] Comparative Example 9

[0111] The difference from Example 4 lies in the different ratios of aluminum dihydrogen phosphate, modified glass powder, and magnesium hydroxide. The raw materials, by mass, include 25 parts aluminum dihydrogen phosphate, 15 parts modified glass powder, 20 parts magnesium hydroxide, 7 parts nano-TiO2, 5 parts talc, 5 parts kaolin, 6 parts MgO curing agent, 3 parts adhesion promoter SN 6797, and 2 parts defoaming agent YS-T118. The remaining steps are consistent with Example 4.

[0112] The phosphate inorganic intumescent flame retardant coatings obtained in Examples 1-4 were compared with the phosphate coatings obtained in Comparative Examples 1-8. An acetylene burner was used to provide a stable fire source at 1200°C. The coatings were applied to a stainless steel substrate. A thermocouple was used to record the back surface temperature of the plate after burning the twelve coatings at 1200°C for 30-60 minutes (burning for 30 minutes, the final stable temperature was higher than 300°C, and no more burning occurred). The relevant data obtained are shown in Tables 1 and 2. Figures 1-6 shown.

[0113] Table 1 Back surface temperature of twelve phosphate coatings

[0114]

[0115] From Table 1 and Figure 1-6It can be seen that the carbon layer of the aluminum dihydrogen phosphate coating with modified glass powder and inorganic flame retardant expanded, and the backside temperature was significantly lower than the control. In the 300-500°C range, the inorganic flame retardant pyrolyzes to generate a large amount of gas, causing the low-melting-point glass powder to melt and flow, which in turn causes the carbon layer to expand. The compounded glass powder melts and forms a secondary film at different temperatures, repairing cracks that develop when filling the aluminum dihydrogen phosphate at high temperatures. The refinement of the high-temperature resistant filler increases the density of the coating matrix in the high-temperature range, improving the coating's high-temperature resistance.

[0116] Figure 1 Figure 2 shows the backside temperature curves of the aluminum dihydrogen phosphate inorganic intumescent flame-retardant coatings prepared in Examples 1-4. The backside temperature curve represents the backside temperature at the center of the coating exposed to fire. The final stable center temperature maintained on the backside of the coatings in Examples 1-4 was below 300°C.

[0117] Figure 2 These are digital images of the aluminum dihydrogen phosphate inorganic intumescent flame-retardant coating prepared in Example 1 before and after the burning test. The coating surface is dense and has no obvious cracks. After burning, the carbon layer expands with air, but the carbon layer still maintains structural integrity and does not fall off.

[0118] Figure 3 This is a scan of the expanded carbon layer of the aluminum dihydrogen phosphate inorganic intumescent flame-retardant coating prepared in Example 2. The macroscopic carbon layer of the coating is expanded, and the microscopic morphology of the carbon layer is porous.

[0119] Figure 4The following are experimental diagrams of the back temperature of the coatings prepared in Comparative Examples 1-7. The blank sample represents the back temperature of the substrate without coating. The back temperature results of Comparative Examples 1-7 are shown in Table 1. In Comparative Example 1, since no modified glass powder was added, Mg(OH)2 pyrolyzed and produced gas, causing the carbon layer to expand. However, the high-temperature film-forming adhesion of aluminum dihydrogen phosphate decreased, and the high-temperature resistance of the coating was inferior to that of Example 1. In Comparative Example 2, since no Mg(OH)2 gas generating agent was added, the carbon layer of the coating had a low expansion multiple, and its high-temperature insulation performance was inferior to that of Example 1. The glass powder in Comparative Examples 3-5 has a single melting point, and after the glass powder melts and flows, it has a certain high-temperature film-forming effect and a better insulation effect. When the glass frit melted at 350°C, it melted too quickly, causing meltthrough and cracking in the coating, resulting in lower high-temperature resistance compared to Example 1. When the glass frit melted at 500°C, the initial temperature of the melt flow failed to cover the gasification and decomposition process of Mg(OH)2, leading to cracking in the coating. When the glass frit melted at 700°C, the melt flow temperature was too high, preventing secondary film formation in the high-temperature zone and compensating for the thermal expansion coefficient mismatch between the aluminum dihydrogen phosphate film-forming agent and the metal substrate. Therefore, the heat resistance of coatings containing single-melting-point glass frit was inferior to that of composite glass frit. In Comparative Example 6, the composite glass powder was not modified with silane, and the coating had excellent high-temperature resistance. However, the composite glass powder had poor dispersibility, which also resulted in the coating's high-temperature insulation performance being worse than that of Example 1. In Comparative Example 7, only glass powders with melting points of 500°C and 700°C were compounded. Because the melting range of the glass powder did not match the temperature range of the gas generated by the thermal decomposition of the inorganic flame retardant, the coating's carbon layer had a low expansion multiple, poor high-temperature insulation performance compared to Example 1, and cracks appeared in the coating. In Comparative Example 8, the content of the aluminum dihydrogen phosphate film-forming agent was increased, the ratio of glass powder to inorganic flame retardant was relatively reduced, and the flame retardant expansion effect was reduced. In Comparative Example 9, the content of the aluminum dihydrogen phosphate film-forming agent was reduced, resulting in poor coating effect, slagging, and difficulty in film formation.

[0120] Figure 5 The carbon layer of the phosphate inorganic coating prepared in Comparative Example 6 has an incomplete appearance due to poor dispersion of the glass powder, and the high-temperature secondary film-forming effect is poor.

[0121] Figure 6 The carbon layer of the phosphate inorganic flame retardant coating prepared in Comparative Example 7 has poor secondary film-forming effect and cracks in the carbon layer due to the mismatch between the characteristic temperatures of the glass powder and the inorganic flame retardant.

[0122] Figure 7 The coating of the phosphate inorganic coating prepared in Comparative Example 9 had poor film-forming properties due to the low proportion of film-forming agent, resulting in coating slagging.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station, characterized by: The raw materials include, by weight: 30-50 parts of phosphate, 10-20 parts of modified glass powder, 5-20 parts of inorganic flame retardant, 3-20 parts of filler, 5-10 parts of curing agent, and 3-10 parts of auxiliary agent; The modified glass powder is prepared by mixing one or both of glass powder with a melting point of 500°C and glass powder with a melting point of 700°C with glass powder with a melting point of 350°C and then modifying with a silane coupling agent. The phosphate is aluminum dihydrogen phosphate; and the inorganic flame retardant is magnesium hydroxide.

2. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 1, characterized in that: The filler is a mixture of one or more of nano titanium dioxide, nano aluminum oxide, silicon carbide, kaolin, mica powder and talc powder.

3. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 1, characterized in that: The curing agent is a mixture of one or more of MgO, ZnO and CuO.

4. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 1, characterized in that: The auxiliary agent is a defoaming agent, an adhesion promoter or a mixture of both.

5. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 4, characterized in that: The defoaming agent is defoaming agent YS-T118.

6. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 4, characterized in that: The adhesion promoter is 5140B water-based adhesion promoter.

7. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 1, characterized in that: The modified glass powder is prepared by mixing glass powder with a melting point of 350° C., glass powder with a melting point of 500° C., and glass powder with a melting point of 700° C. and then modifying the mixture with a silane coupling agent.

8. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 7, characterized in that: The mass ratio of the glass powder with a melting point of 350°C, the glass powder with a melting point of 500°C, and the glass powder with a melting point of 700°C is 1-2:1:

1.

9. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or converter station according to claim 1, characterized in that: The modified glass powder is prepared by mixing glass powder with a melting point of 350° C. and glass powder with a melting point of 500° C. and then modifying the mixture with a silane coupling agent.

10. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 9, characterized in that: The mass ratio of the glass powder with a melting point of 350°C to the glass powder with a melting point of 500°C is 1:1-2.

11. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 1, characterized in that: The silane coupling agent is silane coupling agent KH570.

12. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 1, characterized in that: The preparation process of the modified glass powder includes the following steps: grinding glass powders of different melting points according to a ratio, sieving and mixing them by ball milling, mixing them with an ethanol / water mixed solution, adding a silane coupling agent and stirring them evenly, heating to react, and drying to obtain the modified glass powder.

13. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 12, characterized in that: The mass ratio of glass powder to silane coupling agent is 5:

1.

14. The phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 12, characterized in that: The mixture was heated to 60°C and reacted for 12 hours.

15. A method for preparing a phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to any one of claims 1 to 14, characterized in that: The following steps are involved: S1. Grinding the modified glass powder, inorganic flame retardant, and filler, sieving, and ball milling to obtain a composite filler; S2, prepare a phosphate aqueous solution, add the composite filler and additives in S1, and heat and stir; S3. Add a curing agent to the product in S2 and stir to obtain the phosphate inorganic intumescent flame retardant coating for the transformer substation or converter station.

16. The method for preparing the phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to claim 15, characterized in that: The mass concentration of the phosphate aqueous solution is 40-50%.

17. Use of the phosphate inorganic intumescent flame-retardant coating for a transformer substation or a converter station according to any one of claims 1 to 14 in a transformer substation or a converter station.

18. A coating, characterized in that: The invention is prepared by using the phosphate inorganic intumescent flame retardant coating for a transformer substation or a converter station according to any one of claims 1 to 14.

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