Inorganic nano ceramic coating coated on outer wall of heating tube of hot water storage container and application of inorganic nano ceramic coating

Abstract

The invention relates to the field of inorganic nano-ceramic coatings, in particular to an inorganic nano-ceramic coating coated on the outer wall of a heating tube of a hot water storage container and application of the inorganic nano-ceramic coating. A three-component water-based inorganic nano ceramic coating is adopted, a component A comprises sol prepared from water, silicon dioxide, magnesium aluminum silicate and potassium silicate, a component B is methyltrimethoxysilane, and a component C comprises filler prepared from water, isopropanol, copper chromite black, aluminum oxide, zirconium dioxide and ferroferric oxide. According to the water-based inorganic nano ceramic coating with the three matched components, the spraying thickness of the coating is accurately controlled through a cold spraying coating technology, the coating is crosslinked into bonds and cured into a film on the surface of the heating tube, and a solid micron-sized film which is firm in adhesion, tough in combination, continuous and compact is formed on the surface of the heating tube and serves as the inorganic nano ceramic coating on the outer wall of the heating tube. The invention mainly solves the problem of long-term corrosion prevention of the stainless steel heating tube for the heat storage water tank container, improves the corrosion prevention effect of the heating tube, and has high temperature resistance and scale resistance.

Description

Technical Field

[0001] The present invention relates to the field of inorganic nano-ceramic coatings, and specifically to an inorganic nano-ceramic coating applied to the outer wall of a heating tube of a hot water storage container and its application, which is mainly used for the anti-corrosion of industrial, commercial, and civil hot water storage tanks or water containers that need to heat water. Background Art

[0002] At present, the heating tubes used in hot water storage tank containers are heating tubes made of heat-resistant stainless steel. Some heating tubes adopt an enamel surface treatment process. There are uncertain micro-cracks on the enamel surface, the enamel coating is not dense, and it is difficult for the enamel to completely cover the metal. The cations and anions in water will penetrate the metal of the heating tube itself, and the corrosion protection effect is poor; it is easy to oxidize, change color and fall off after high temperature, has high brittleness, the coating life is low, and it is easy to scale.

[0003] Market research feedback shows that after industrial and commercial users use it for ≥2 years, the current material technology solutions for heating tubes are mainly 310S heat-resistant stainless steel, Incoloy 800 alloy, and heating tubes with enamel coated on their outer surfaces. The metal material heating tubes are exposed and soaked in water. The disadvantage is that a potential difference is easily formed with the ions in the water, and corrosion damage is likely to occur; for the heating tubes with enamel coating, the enamel itself has low density, and microscopically, the surface shows a pinhole morphology. Pitting corrosion occurs locally quickly after soaking in a ferric chloride solution. After pitting corrosion occurs, the corrosion protection effect becomes worse, and the enamel coating will fall off in a short period; it is easy to fall off after being used at a high temperature of about 600°C. The anti-corrosion protection ability of the coating after high-temperature use is reduced, and the service life is low. After using for more than 2 years, the heating is slow, and the scale reduces the heating efficiency in the later stage.

[0004] After searching for patents on heating tubes with coatings, the technical solution closer to the present invention is an enamel protection coating heating tube. For example: The invention patent with the publication number CN1645972A proposes an enamel coating heating tube for an electric water heater and its manufacturing method. Coating an enamel coating on the surface of a metal tube shell has opened up a new way for the anti-corrosion and anti-scaling of electric water heaters; the utility model patent with the publication number CN218735054U proposes an enamel heating tube and a water heater. The enamel layer is sintered after being coated with enamel powder containing TiO2, and at least part of the enamel layer and / or the metal sleeve is formed with a concave structure for preventing scale accumulation. Summary of the Invention

[0005] The purpose of the present invention is to provide an inorganic nano-ceramic coating applied to the outer wall of a heating tube of a hot water storage container and its application, mainly to solve the long-term anti-corrosion problem of stainless steel heating tubes used in hot water storage tank containers. The heating device in the water tank container is soaked in water for heating for a long time. The inorganic nano-ceramic coating will isolate the cations and anions in the water, playing a role in anti-corrosion, high temperature resistance, anti-scaling and self-cleaning.

[0006] The technical solution of the present invention is as follows:

[0007] An inorganic nano-ceramic coating applied to the outer wall of the heating tube of a hot water storage container, which uses a three-component water-based inorganic nano-ceramic coating. Component A includes a sol prepared from water, silicon dioxide, aluminum magnesium silicate, and potassium silicate. Component B is methyltrimethoxysilane. Component C includes a filler prepared from water, isopropanol, copper chromite black, aluminum oxide, zirconium dioxide, and iron oxide. Among them:

[0008] By weight percentage, the components in the sol of Component A account for as follows: water 50 - 60%, silicon dioxide 20 - 30%, aluminum magnesium silicate 5 - 10%, potassium silicate 2 - 10%;

[0009] By weight percentage, the components in the filler of Component C account for as follows: water 2 - 5%, isopropanol 50 - 60%, copper chromite black 20 - 30%, aluminum oxide 1 - 5%, zirconium dioxide 0.1 - 0.5%, iron oxide 5 - 10%;

[0010] The weight ratio of Component A, Component B, and Component C is 1:0.8 - 1.2:1 - 2.

[0011] For the inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container, the silicon dioxide uses particles of 20 - 30 nanometers, and the aluminum oxide, zirconium dioxide, and iron oxide use particles of less than 500 nanometers.

[0012] Regarding the application of the inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container, the three-component water-based inorganic nano-ceramic coating is coated through a cold spraying coating technology, precisely controlling the spraying thickness of the coating, crosslinking and bonding on the surface of the heating tube to cure into a film, forming a solid micron-level film with firm adhesion, strong and tough combination, and continuous density on the surface of the heating tube. The film thickness is 20 - 30 microns, serving as the inorganic nano-ceramic coating on the outer wall of the heating tube.

[0013] Regarding the application of the inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container, the preparation process of the inorganic nano-ceramic coating includes the following steps:

[0014] Step 1, sandblasting treatment:

[0015] The surface of the heating tube is evenly treated with 80-mesh emery, and the surface sand is blown clean;

[0016] Step 2, aging treatment:

[0017] (1) Add Component B to Component A, and under room temperature conditions, place it on an aging machine for aging, set the rotation speed at 90 - 120 revolutions per minute, and age for more than 2 hours;

[0018] (2) After mixing Component A and Component B, quickly place it on a rolling machine for aging until aging is complete;

[0019] (3) The matured Component A and Component B are stored at room temperature for use in the coating preparation process;

[0020] Step 3: Coating preparation:

[0021] When preparing the coating, first place Component C on a maturator at room temperature for maturation, set the rotation speed at 90 - 120 revolutions per minute, and mature for 1 hour until uniform, ensuring no sedimentation or caking; then add the matured Component A and Component B to Component C, mix evenly and filter through a 300 - mesh screen for use in spraying;

[0022] Step 4: Spraying process:

[0023] (1) Preheat the heating tube to ensure that the surface temperature of the heating tube is 50 - 70 °C during spraying;

[0024] (2) Coating spraying: The spray gun nozzle diameter is 1 - 2 mm, the spraying pressure is 0.4 - 0.6 MPa, and the spraying distance is 20 - 30 cm;

[0025] Step 5: Baking and sintering.

[0026] For the application of the inorganic nano - ceramic coating on the outer wall of the heating tube of the hot water storage container, when performing coating spraying in Step 4, at room temperature, filter the three - component water - based inorganic nano - ceramic coating through a 300 - mesh filter screen for spraying, and control the spraying thickness within 20 - 30 μm.

[0027] For the application of the inorganic nano - ceramic coating on the outer wall of the heating tube of the hot water storage container, when performing baking and sintering in Step 5, the sintering furnace is divided into two temperature zones: the low - temperature zone temperature is set at 140 - 160 °C and sintered for 10 - 15 minutes; the high - temperature zone is set at 250 - 320 °C and sintered for 10 - 15 minutes.

[0028] The design concept of the present invention is:

[0029] Due to the large differences in water quality for industrial, commercial, and civil use in different regions, and the heating tube serving in a complex hot - cold cycle environment for a long time, pitting corrosion often occurs during use. In severe cases, problems such as perforation of the heating tube, leakage of electricity and water may occur. The important reason for the corrosion resistance of stainless steel is that there is a protective oxide film Cr2O3 on the surface, which is normally in a dynamic equilibrium state of dissolution and repair. When stainless steel is in an erosive anion (such as Cl - , Br - , SO4 2- ) and oxidant (Fe 3 + , Cu 2+ , Hg 2+)In the coexisting medium, the balance is disrupted, dissolution prevails, and the passive film on the surface undergoes local dissolution, bringing the medium into contact with the metal matrix, thereby causing pitting corrosion on its surface. The occurrence of pitting corrosion causes the local position of the metal to change from the passive state to the active state. The metal surface inside the corrosion pit is in the active state and has a relatively negative potential; the metal surface outside the corrosion pit is in the passive state and has a relatively positive potential. Thus, an active-passive micro-galvanic corrosion cell is formed inside and outside the corrosion pit. The cell has a large cathode-small anode area ratio structure, and the anodic current density is very high, accelerating the development of the corrosion pit. Therefore, the stainless steel heating tube is prone to pitting corrosion diffusion by itself when immersed in tap water, resulting in the rupture of the tube wall. In addition, the precipitation of scale such as calcium carbonate forms a thick layer of scale on the surface of the heating tube, affecting the heating efficiency.

[0030] The three-component waterborne inorganic nano-ceramic coating used in the present invention can be applied by ordinary spraying or electrostatic spraying through the cold spraying process, accurately controlling the coating spraying rate, and forming a uniform, dense and firm coating film on the surface of the heating tube, blocking the medium that causes metal corrosion, achieving a long-term corrosion resistance effect, and not showing oxidation and peeling under the extreme high-temperature conditions of the heating tube.

[0031] The present invention mainly improves the corrosion resistance of the heating tube. Compared with the enamel coating which is generally 100 - 150 microns thick, the coating thickness is reduced by more than 80% significantly, improving the heating efficiency; enhancing the anti-fouling ability; the high-temperature resistance has a long-term service temperature above 600 °C, and the coating on the surface of the heating tube does not peel off or break after being used under the high-temperature limit condition.

[0032] The advantages and beneficial effects of the present invention are:

[0033] 1. After the nano-protective layer on the surface of the inorganic nano-ceramic coating heating tube of the present invention is cured on the surface of the metal substrate, a nano-scale composite oxide ceramic protective film is formed, preventing the stainless steel heating tube from contacting with chloride ions and sulfate ions in the solution, and reducing the occurrence of pitting corrosion and stress corrosion. Through the verification of the ferric chloride corrosion resistance test on the inorganic nano-ceramic coating heating tube, compared with the bare stainless steel tube and the enamel-treated stainless steel tube, their failure times are increased from 10 hours and 360 hours to 1200 hours respectively, and its anti-corrosion performance is more than 3 times that of the stainless steel heating tube with an enamel protective layer.

[0034] 2. The surface of the inorganic nano-ceramic coating heating tube of the present invention is smoother and has a lower surface energy, with the surface energy being lower than 20 dynes; the inorganic nano-ceramic coating increases the nucleation work required for the formation of crystal nuclei and reduces the nucleation rate of crystal embryos, which can effectively avoid the formation of scale on the surface of the heating tube. At the same time, the scale on the surface of the inorganic nano-ceramic coating heating tube is loose and not easily attached, and during the heating process, tiny water vapor bubbles are continuously generated on its surface, giving a force for the scale to peel off. The force generated by the bubbles is greater than the force of the scale attaching to the surface of the heating tube, so the scale will peel off from the heating tube. Therefore, the inorganic nano-ceramic coating has the function of anti-scaling and self-cleaning.

[0035] 3. The present invention can solve the problems of the current enamel coating being not dense, the process being complex, the enameling temperature being high, and environmental pollution, etc. The water-based inorganic nano-ceramic coating has high density and does not corrode or fall off during the whole life cycle when applied to the heating tube. The cold spraying process is adopted, with a simple process, a low curing temperature, and a low process cost; an environmentally friendly water-based coating is used, which is more environmentally friendly; the inorganic nano-ceramic coating of the present invention has excellent high-temperature resistance, and the coating does not fall off during short-time heating under anhydrous conditions. Brief Description of the Drawings

[0036] Figure 1 is the process flow chart for preparing the inorganic nano-ceramic coating of the present invention.

[0037] Figures 2 - 3 is the morphology diagram of the heating tube with the inorganic nano-ceramic coating of the present invention. Among them, Figure 2 is the microscopic tissue morphology of the surface of the inorganic nano-ceramic coating, Figure 3 is the macroscopic photo of the heating tube with the coating of this solution. Detailed Description of the Invention

[0038] In the specific implementation process, the present invention uses a three-component water-based inorganic nano-ceramic coating. The three-component water-based inorganic nano-ceramic coating is coated by the cold spraying technology, and the spraying thickness of the coating is precisely controlled. It cross-links and bonds on the surface of the heating tube to form a film, forming a solid micron-scale film on the surface of the heating tube that adheres firmly, combines strongly, and is continuously dense. The thickness of the film is 20 - 30 microns, serving as the inorganic nano-ceramic coating on the outer wall of the heating tube to make its surface corrosion-resistant, anti-scaling and self-cleaning, high-temperature resistant, etc. multifunctional.

[0039] Next, the present invention will be further elaborated in detail through the drawings and embodiments.

[0040] Example 1

[0041] In the three-component water-based inorganic nano-ceramic coating of this example, the silicon dioxide uses particles with a scale of 20 - 30 nanometers, and the C component uses metal oxide particles with a scale of 200 - 300 nanometers. Its ratio is roughly as follows:

[0042]

[0043]

[0044] Among them, component A and component C are uniformly mixed according to their respective component ratios. Component B is a single-component silicone. The weight ratio of component A, component B, and component C is 1:1:2.

[0045] As Figure 1 shown, the process flow for preparing the inorganic nano-ceramic coating in this embodiment is as follows:

[0046] 1. Sandblasting treatment:

[0047] The surface of the heating tube is uniformly treated with 80-mesh carborundum, and the surface sand is blown clean with high-pressure gas. After the surface of the heating tube is sandblasted, the surface roughness is 2.5 - 3 μm.

[0048] 2. Aging treatment:

[0049] (1) Add component B to component A, and age it on an aging machine at room temperature. Set the rotation speed to 100 revolutions per minute and age for 6 hours.

[0050] (2) After mixing component A and component B, quickly place them on a rolling machine for aging until complete aging.

[0051] (3) The aged component A and component B are stored in a room-temperature environment for use in the coating preparation process.

[0052] 3. Coating preparation:

[0053] When preparing the coating, first age component C on an aging machine at room temperature. Set the rotation speed to 100 revolutions per minute and age for 1 hour until uniform, ensuring no sedimentation or caking; then add the aged component A and component B to component C, mix them uniformly, and filter with a 300-mesh screen for spraying use.

[0054] 4. Spraying process:

[0055] (1) Preheat the heating tube to ensure that the surface temperature of the heating tube is 60 °C during spraying;

[0056] If the temperature is too low, it will cause phenomena such as sagging and poor gloss; if the temperature is too high, it will cause the coating to wrinkle and become rough;

[0057] (2) Coating spraying: The spray gun nozzle diameter is 1.5 mm, the spraying pressure is 0.5 MPa, and the spraying distance is 25 cm;

[0058] At room temperature, filter the prepared coating with a 300-mesh filter screen and spray it, controlling the film thickness to be 20 - 30 μm.

[0059] 5. Baking and sintering:

[0060] The sintering furnace is divided into two temperature zones: the low-temperature zone is set at 150 °C and sintered for 10 minutes; the high-temperature zone is set at 300 °C and sintered for 15 minutes.

[0061] After the dehydration and condensation of siloxane, it undergoes a strong cross-linking reaction with nano-SiO2 particles to form a dense inorganic ceramic coating. A large number of silanol groups (-Si-OH) on the surface of nano-SiO2 particles are dehydrated and condensed to generate an inorganic network covalent bond connection structure of -Si-O-Si- / -Si-O-Me (siloxane bond), which has high coating mechanical strength, excellent adhesion and aging resistance.

[0062] The network structure formed by the dehydration and condensation of siloxane has a high adsorption effect. The surface of the nano-particles has the characteristics of insufficient coordination, a large specific surface area, and extremely strong physical and chemical activity, and has a high gloss.

[0063] The network structure formed by the dehydration and condensation of siloxane has a dense loading effect. The network structure carries components with high temperature resistance, wear resistance and impact resistance, fills the pores in the coating, and makes the coating more dense.

[0064] Such as Figure 2 、 Figure 3 As shown, the inorganic nano-ceramic coating of the embodiment of the present invention has a dense surface without pores and is corrosion-resistant and heat-resistant.

[0065] In this embodiment, a corrosion resistance test of a 3% ferric chloride solution was carried out on the heating tube of the inorganic nano-ceramic coating. Its failure time was more than 1200 hours. The coating did not peel off after long-term use at 600 °C for 1 h, and no scale adhered to the coating surface after soaking in tap water for 1 month.

[0066] Example 2

[0067] The difference from Example 1 is that in the three-component water-based inorganic nano-ceramic coating of this embodiment, the silica used is particles with a size of 20-30 nanometers, and the C component used is metal oxide particles with a size of 200-300 nanometers. Its ratio is roughly as follows:

[0068]

[0069] In this embodiment, the A component and the C component are uniformly mixed according to their respective component ratios. The B component is a single-component siloxane. The weight ratio of the A component, the B component, and the C component is 1:0.8:1.5.

[0070] Such as Figure 1 As shown, the process flow for preparing the inorganic nano-ceramic coating in this embodiment is as follows:

[0071] 1. Sandblasting treatment:

[0072] The surface of the heating tube is evenly treated with 80-mesh carborundum, and the surface sand is blown clean with high-pressure gas. After the surface of the heating tube is sandblasted, the surface roughness is 2.5 - 3 μm.

[0073] 2. Aging treatment:

[0074] (1) Add component B to component A, and place it on an aging machine at room temperature for aging. Set the rotation speed at 90 revolutions per minute and age for 8 hours.

[0075] (2) After mixing component A and component B, quickly place them on a rolling machine for aging until complete aging.

[0076] (3) The aged component A and component B are stored at room temperature for use in the coating preparation process.

[0077] 3. Coating preparation:

[0078] When preparing the coating, first place component C on an aging machine at room temperature for aging. Set the rotation speed at 90 revolutions per minute and age for 1 hour until uniform, ensuring no sedimentation or caking; then add the aged component A and component B to component C, mix evenly and filter with a 300-mesh screen for spraying use.

[0079] 4. Spraying process:

[0080] (1) Preheat the heating tube to ensure that the surface temperature of the heating tube is 50 °C during spraying;

[0081] If the temperature is too low, it will cause phenomena such as sagging and poor gloss; if the temperature is too high, it will cause the coating to wrinkle and become rough;

[0082] (2) Coating spraying: The spray gun orifice diameter is 1 mm, the spraying pressure is 0.4 MPa, and the spraying distance is 20 cm;

[0083] At room temperature, filter the prepared coating with a 300-mesh filter screen and spray it, controlling the film thickness at 20 - 30 μm.

[0084] 5. Baking and sintering:

[0085] The sintering furnace should be divided into two temperature zones: the low-temperature zone temperature is set at 140 °C and sintered for 15 minutes; the high-temperature zone is set at 280 °C and sintered for 15 minutes.

[0086] In this embodiment, a corrosion resistance test of 3% ferric chloride solution is carried out on the inorganic nano-ceramic coating heating tube. Its failure time is more than 1200 hours, the coating does not peel off after long-term use at 600 °C for 1 h, and no scale adheres to the coating surface after soaking in tap water for 1 month.

[0087] Example 3

[0088] The difference from Example 1 is that in the three-component waterborne inorganic nano-ceramic coating of this example, the silica is in the form of particles with a scale of 20-30 nanometers, and the C component is metal oxide particles with a size of 200-300 nanometers. The ratio is roughly as follows:

[0089]

[0090]

[0091] In this example, the A component and the C component are uniformly mixed according to their respective component ratios. The B component is a single-component silicone. The weight ratio of the A component, the B component, and the C component is 1:1.2:1.

[0092] As Figure 1 shown, the technological process for preparing the inorganic nano-ceramic coating in this example is as follows:

[0093] 1. Sandblasting treatment:

[0094] The surface of the heating tube is evenly treated with 80-mesh carborundum, and the surface sand is blown clean with high-pressure gas. After the surface of the heating tube is sandblasted, the surface roughness is 2.5-3 μm.

[0095] 2. Aging treatment:

[0096] (1) Add the B component to the A component, and age it on an aging machine at room temperature. Set the rotation speed to 120 revolutions per minute and age for 4 hours.

[0097] (2) After the A component and the B component are mixed, quickly place them on a rolling machine for aging until aging is complete.

[0098] (3) The aged A component and B component are stored at room temperature for use in the coating preparation process.

[0099] 3. Coating preparation:

[0100] When preparing the coating, first place the C component on an aging machine at room temperature for aging. Set the rotation speed to 120 revolutions per minute and age for 1 hour until it is uniform, ensuring no sedimentation or caking; then add the aged A component and B component to the C component, mix them evenly, and filter through a 300-mesh screen for spraying use.

[0101] 4. Spraying process:

[0102] (1) Preheat the heating tube to ensure that the surface temperature of the heating tube is 70 °C during spraying;

[0103] If the temperature is too low, it will cause phenomena such as sagging and poor gloss; if the temperature is too high, it will cause the coating to wrinkle and become rough;

[0104] (2) Coating spraying: The nozzle diameter of the spray gun is 2 mm, the spraying pressure is 0.6 MPa, and the spraying distance is 30 cm;

[0105] At room temperature, the prepared coating is filtered through a 300-mesh filter and sprayed, and the film thickness is controlled at 20 - 30 μm.

[0106] 5. Baking and sintering:

[0107] The sintering furnace is divided into two temperature zones: the low-temperature zone is set at 160 °C and sintered for 12 minutes; the high-temperature zone is set at 320 °C and sintered for 10 minutes.

[0108] In this embodiment, the inorganic nano-ceramic coating heating tube is verified by a corrosion resistance test with a 3% ferric chloride solution, and its failure time is more than 1200 hours. The coating does not peel off after 1 hour at a temperature of 600 °C, and no scale adheres to the coating surface after being soaked in tap water for 1 month.

[0109] The implementation results show that the present invention applies the inorganic nano-ceramic coating material to the surface of the heating tube of the hot water storage tank container, improving the anti-corrosion effect of the heating tube; the hydrophobic and low surface energy of the inorganic nano-ceramic coating surface improve the anti-scaling ability of the heating tube; the inorganic nano-ceramic coating has a high-temperature resistance effect, and the coating does not peel off after long-term use at 600 °C for 1 hour.

Claims

1. An inorganic nano-ceramic coating applied to the outer wall of the heating tube of a hot water storage container, characterized in that, A three-component waterborne inorganic nano-ceramic coating is adopted. Component A is a sol prepared from water, silicon dioxide, aluminum magnesium silicate, and potassium silicate. Component B is methyltrimethoxysilane. Component C is a filler prepared from water, isopropanol, copper chromite black, aluminum oxide, zirconium dioxide, and iron oxide. Among them: By weight percentage, the components in the sol of Component A account for as follows: water 50 - 60%, silicon dioxide 20 - 30%, aluminum magnesium silicate 5 - 10%, and potassium silicate 2 - 10%; By weight percentage, the components in the filler of Component C account for as follows: water 2 - 5%, isopropanol 50 - 60%, copper chromite black 20 - 30%, aluminum oxide 1 - 5%, zirconium dioxide 0.1 - 0.5%, and iron oxide 5 - 10%; The weight ratio of Component A, Component B, and Component C is 1:0.8 - 1.2:1 - 2.

2. The inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container according to claim 1, characterized in that, The silicon dioxide uses particles of 20 - 30 nanometers, and the aluminum oxide, zirconium dioxide, and iron oxide use particles of less than 500 nanometers.

3. Use of the inorganic nano-ceramic coating as claimed in any one of claims 1 to 2, which is applied to the outer wall of the heating tube of the hot water storage container, characterized in that, The three-component waterborne inorganic nano-ceramic coating is coated by cold spraying technology, precisely controlling the spraying thickness of the coating, crosslinking and bonding on the surface of the heating tube to form a film, and forming a solid micron-level film with firm adhesion, strong bonding, and continuous denseness on the surface of the heating tube. The film thickness is 20 - 30 microns, serving as the inorganic nano-ceramic coating on the outer wall of the heating tube.

4. The application of the inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container according to claim 3, characterized in that, The preparation process of the inorganic nano-ceramic coating includes the following steps: Step 1, sandblasting treatment: The surface of the heating tube is evenly treated with 80-mesh emery, and the surface sand is blown clean; Step 2, aging treatment: (1) Add Component B to Component A, and age it on an aging machine at room temperature, setting the rotation speed at 90 - 120 revolutions per minute and aging for more than 2 hours; (2) After mixing Component A and Component B, quickly place them on a rolling machine for aging until aging is complete; (3) The aged Component A and Component B are stored at room temperature for use in the coating preparation process; Step 3, coating preparation: When preparing the coating, first age Component C on an aging machine at room temperature, setting the rotation speed at 90 - 120 revolutions per minute and aging for 1 hour until it is uniform, ensuring no sedimentation and caking; then add the aged Component A and Component B to Component C, mix evenly and filter with a 300-mesh screen for spraying use; Step 4, spraying process: (1) Preheat the heating tube to ensure that the surface temperature of the heating tube is 50 - 70 °C during spraying; (2) Coating spraying: The spray gun orifice diameter is 1 - 2 mm, the spraying pressure is 0.4 - 0.6 MPa, and the spraying distance is 20 - 30 cm; Step 5, baking and sintering.

5. Use of the inorganic nano-ceramic coating applied to the outer wall of the heating pipe of the hot water storage container according to claim 4, characterized in that, When performing coating spraying in Step 4, at room temperature, filter and spray the three-component waterborne inorganic nano-ceramic coating with a 300-mesh filter screen, and control the spraying thickness within 20 - 30 μm.

6. Use of the inorganic nano-ceramic coating applied to the outer wall of the heating tube of the hot water storage container according to claim 4, characterized in that, When performing baking and sintering in Step 5, the sintering furnace has two temperature zones: the low-temperature zone temperature is set at 140 - 160 °C and sintered for 10 - 15 minutes; the high-temperature zone is set at 250 - 320 °C and sintered for 10 - 15 minutes.

Images