Environment-friendly multifunctional low-temperature firing enamel glaze as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of inorganic nonmetallic materials, and discloses an environment-friendly multifunctional low-temperature fired enamel glaze as well as a preparation method and application thereof. The enamel glaze material disclosed by the invention is prepared from the following raw materials in percentage by mass: 45 to 48 percent of SiO2, 10 to 15 percent of B2O3, 10 to 15 percent of kaolin, 13 to 17 percent of Na2CO3, 3 to 8 percent of spodumene, 8 to 12 percent of TiO2, 2 to 4 percent of ZrO2, 0 to 0.5 percent of Ag3PO4, 0 to 0.1 percent of graphite oxide, 1 to 3 percent of Fe2O3 / Cr2O3 composite nanoparticles, 0.5 to 1 percent of a sodium carboxymethyl cellulose aqueous solution and 2 to 4 percent of silica sol. The raw materials of the enamel glaze are environment-friendly and non-toxic, sintering can be completed at the temperature of 800 DEG C or below, and the enamel glaze has excellent corrosion resistance and wear resistance and meanwhile has broad-spectrum antibacterial and photocatalytic self-cleaning functions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic non-metallic materials, and particularly relates to an environmentally-friendly multifunctional low-temperature sintering enamel frit as well as a preparation method and application thereof. BACKGROUND

[0002] In the production and application field of enamel products, the performance of enamel frit as a core raw material directly determines the safety, practicality and environmental protection of the products. However, the traditional enamel frit widely used in the current market still has many key defects to be solved in the technical aspect, which are specifically as follows: 1) In the formula design of the traditional enamel frit, heavy metal compounds such as lead, cadmium and hexavalent chromium are often added to achieve specific adhesion, gloss and sintering effect. Such toxic substances have significant release risks in the whole life cycle of the production, use and disposal of enamel products. Especially when used in food contact scenarios (such as enamel tableware, kitchenware, etc.), heavy metals are easy to be precipitated in acidic, alkaline or high-temperature environments, and enter the human body through food, which poses a potential threat to human health.

[0003] 2) The sintering temperature of the traditional enamel frit is generally ≥ 850 ℃, and some special performance frits even need a high-temperature environment of 900-1050 ℃ to complete sintering. This high-temperature process not only puts high requirements on the high-temperature resistance of the production equipment (such as kiln), increases the cost of equipment purchase and maintenance, but also leads to high energy consumption. The traditional enamel frit with high energy consumption and high emission has been difficult to adapt to the development demand of green production, and has become an important bottleneck restricting the transformation and upgrading of the industry.

[0004] 3) One of the core advantages of enamel products is the corrosion resistance of the surface enamel layer. However, in complex use environments (such as contact with acidic solution, salt water, high-temperature and humid air, etc.), the enamel layer is easy to be chemically or electrochemically corroded, resulting in phenomena such as enamel peeling, rusting and cracking, which shortens the service life of the products. The defect of corrosion resistance limits the application of traditional enamel products in fields with high requirements for weather resistance and corrosion resistance, such as marine engineering and medical devices.

[0005] 4) With the upgrading of consumer demand for product performance and the expansion of application scenarios of enamel products, the single property of traditional enamel frit, which only provides basic decoration and protection functions, has been difficult to meet the market demand. For example, in the food field, consumers hope that enamel tableware has antibacterial function; in the field of building decoration, enamel plates used for external walls need to have self-cleaning function. However, the traditional enamel frit cannot realize the integration of functions such as antibacterial and self-cleaning, and is difficult to adapt to the development demand of emerging application scenarios.

[0006] Therefore, it is urgent to develop an environmentally-friendly, non-toxic, low-temperature sintering, corrosion-resistant and functionally composite enamel frit. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an environmentally friendly, multifunctional low-temperature fired enamel glaze, its preparation method and application, which addresses the shortcomings of the existing technology. The raw materials of the enamel glaze are environmentally friendly and non-toxic, can be sintered at a temperature below 800℃, have excellent corrosion resistance and wear resistance, and can also have broad-spectrum antibacterial and photocatalytic self-cleaning functions.

[0008] To address the technical problems proposed in this invention, this invention provides an environmentally friendly, multifunctional, low-temperature fired enamel glaze, comprising the following raw materials in weight percentages: SiO2 45-48%, B2O3 10-15%, kaolin 10-15%, Na2CO3 13-17%, spodumene 3-8%, TiO2 8-12%, ZrO2 2-4%, Ag3PO4 0-0.5%, graphite oxide (GO) 0-0.1%, Fe2O3 / Cr2O3 composite nanoparticles 1-3%, sodium carboxymethyl cellulose aqueous solution 0.5-1%, and silica sol 2-4%.

[0009] Preferably, the mass ratio of TiO2 to ZrO2 is 3:1 to 5:1.

[0010] Preferably, the mass ratio of ZrO2 to Ag3PO4 is 10:1 to 20:1.

[0011] In the above scheme, the particle size of SiO2 is 5~20μm and the purity is ≥99%.

[0012] In the above scheme, the particle size of B2O3 is 5~15μm and the purity is ≥99%.

[0013] In the above scheme, the kaolin has a particle size of 2~10μm and an Al2O3 content of ≥35%.

[0014] In the above scheme, the sodium carbonate has a particle size of 10~30μm and the purity of Na2CO3 is ≥98%.

[0015] In the above scheme, the spodumene has a particle size of 5~15μm and a Li2O content of ≥6%.

[0016] In the above scheme, the TiO2 is anatase type, with a particle size of 0.5~2μm and a purity of ≥99%.

[0017] In the above scheme, the particle size of ZrO2 is 20~50nm and the purity is ≥99%.

[0018] In the above scheme, the Ag3PO4 has a particle size of 0.1~1μm and a purity of ≥99.5%.

[0019] In the above scheme, the diameter of the graphite oxide sheets is 1~10μm and the thickness is 1~5nm.

[0020] In the above scheme, the particle size of the Fe2O3 / Cr2O3 composite nanoparticles is 50~200nm, and the molar ratio of Fe to Cr is 1:1~3:1.

[0021] In the above scheme, the preparation method of the Fe2O3 / Cr2O3 composite nanoparticles is as follows: dissolve the metal salt in water, add a complexing agent, heat and stir until a gel is formed, and then calcine to obtain Fe2O3 / Cr2O3 composite nanoparticles.

[0022] Furthermore, the metal salt includes iron salt and chromium salt, with a molar ratio of iron salt to chromium salt of 1:1 to 3:1.

[0023] Furthermore, the iron salt is one of ferric nitrate nonahydrate or ferric chloride.

[0024] Furthermore, the chromium salt is one of chromium nitrate nonahydrate and chromium chloride.

[0025] Furthermore, the mass ratio of the metal salt to water is 1:5 to 1:15.

[0026] Furthermore, the complexing agent is one of citric acid and oxalic acid.

[0027] Furthermore, the molar ratio of the complexing agent to the metal salt is 1.2:1 to 1.5:1.

[0028] Furthermore, the heating temperature is 80~90℃.

[0029] Furthermore, the calcination temperature is 500~600℃, and the calcination time is 2~4h.

[0030] In the above scheme, the mass concentration of the sodium carboxymethyl cellulose aqueous solution is 2-4%, and the viscosity is 800-1200 mPa·s.

[0031] In the above scheme, the solid content of the silica sol is 25-30%, and the pH value is 9-10.

[0032] This invention also provides a method for preparing an environmentally friendly, multifunctional low-temperature fired enamel glaze, comprising the following steps: 1) Kaolin and sulfuric acid solution are mixed, heated and stirred, and the product is washed and dried to obtain pretreated kaolin; 2) Add ZrO2 and Ag3PO4 to silica sol and disperse by ultrasonication to obtain slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene are mixed and pre-ground to obtain coarse powder; then TiO2, slurry A, graphite oxide and Fe2O3 / Cr2O3 composite nanoparticles are added and ground again to obtain glaze powder; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add water and stir to obtain enamel glaze slurry.

[0033] In the above scheme, the concentration of the sulfuric acid solution is 5~10wt%.

[0034] In the above scheme, the kaolin and sulfuric acid solution are mixed at a solid-liquid ratio of 1:5 to 1:10.

[0035] In the above scheme, the heating and stirring temperature is 60~80℃, and the time is 2~4h.

[0036] In the above scheme, the washing process uses water to achieve a neutral pH.

[0037] In the above scheme, the Al2O3 content of the pretreated kaolin is ≥38%.

[0038] In the above scheme, the ultrasonic dispersion time is 20~40 min.

[0039] In the above scheme, the grinding speed of the initial grinding is 200~300 rpm, and the grinding time is 2~4 hours.

[0040] In the above scheme, the particle size of the coarse powder is ≤10μm.

[0041] In the above scheme, the grinding speed for continued grinding is 400~500 rpm, and the grinding time is 1~2 hours.

[0042] In the above scheme, the particle size of the glaze powder is ≤3μm, and the mixing uniformity is ≥95%.

[0043] In the above scheme, the total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to water is 1:1.2 to 1:1.8, and the stirring time is 30 to 60 minutes.

[0044] This invention also provides an application of an environmentally friendly, multifunctional, low-temperature fired enamel glaze, comprising the following steps: spraying enamel glaze slurry onto the surface of a metal substrate, and performing two-stage sintering to obtain an enamel coating.

[0045] In the above scheme, the metal substrate is one of low-carbon steel, cast iron, stainless steel, and aluminum alloy.

[0046] In the above scheme, the coating thickness of the enamel glaze slurry is 80~150μm.

[0047] In the above scheme, the two-stage sintering includes pre-sintering and final sintering.

[0048] Furthermore, the pre-firing is carried out under a nitrogen atmosphere, the pre-firing temperature is 400~500℃, and the holding time is 20~40min.

[0049] Furthermore, the nitrogen flow rate is 5~10 L / min.

[0050] Furthermore, the heating rate of the preheating is 3~5℃ / min.

[0051] Furthermore, the final calcination is carried out in a weak oxidizing atmosphere, with a final calcination temperature of 750~800℃ and a holding time of 3~8 minutes.

[0052] Furthermore, the volume fraction of O2 in the weakly oxidizing atmosphere is 3-8%, with the remainder being nitrogen.

[0053] Furthermore, the heating rate for the final firing is 8~10℃ / min.

[0054] The main design features of this invention include: Regarding the composition of the enamel glaze, this invention uses SiO2-B2O3-Al2O3 as the basic glass network forming agent, and lowers the melting temperature through Na2O-Li2O synergistic fluxing, thereby enabling sintering at a lower temperature. Anatase TiO2 is introduced to achieve photocatalytic self-cleaning function, and nano-ZrO2 is introduced to synergistically enhance the wear resistance of the glaze surface. Nano-ZrO2 is uniformly distributed in the glaze layer as a hard reinforcing phase, protecting the relatively soft glass. The physical synergistic reinforcement between nano-ZrO2 and GO jointly constructs a highly wear-resistant and dense glaze layer structure. Ag3PO4 is used as an antibacterial agent; its combination with GO significantly improves antibacterial durability. GO has a large specific surface area and abundant oxygen-containing functional groups (such as carboxyl and hydroxyl groups), which can firmly support Ag3PO4 particles or Ag... + Ions can slowly and continuously release Ag-like substances. + This avoids the rapid consumption and inactivation of Ag3PO4, thus significantly extending the duration of the antibacterial effect. Innovatively, Fe2O3 / Cr2O3 composite nanoparticles are used as a colorant. By controlling the composite ratio, rich color expression can be achieved, while simultaneously improving the corrosion resistance of the glaze. The Fe2O3 / Cr2O3 composite nanoparticles form a highly inert and structurally stable protective phase in the glaze layer, and through the nano-filling effect, make the glaze layer denser, thereby significantly improving corrosion resistance.

[0055] In the preparation and application of enamel glazes, this invention employs acid washing of kaolin to significantly improve the purity of Al2O3 and enhance the chemical stability of the glaze; silica sol pretreatment of nano-ZrO2 and Ag3PO4 effectively prevents nanoparticle agglomeration and ensures uniform distribution of functional components; a two-stage gradient ball milling process of coarse and fine grinding achieves precise particle size control and uniform mixing of raw materials, laying the foundation for low-temperature firing; a two-stage sintering process is adopted. In the pre-firing stage, organic matter (including binder CMC) is gently removed under nitrogen, which prevents it from burning violently and generating gas during subsequent high-temperature sintering, thereby avoiding defects such as bubbles and pinholes in the glaze layer and ensuring a dense and smooth glaze surface; in the final firing stage, the glaze is melted under a weak oxidizing atmosphere, effectively preventing the functional components from oxidizing and failing, maintaining the stable valence state of Fe2O3 / Cr2O3 composite nanoparticles, ensuring uniform and durable glaze color, and reducing the risk of glaze cracking.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention completely eliminates lead, cadmium, and hexavalent chromium, and uses Fe2O3 / Cr2O3 composite nanoparticles to replace traditional cadmium sulfide selenide colorants, reducing the toxicity of heavy metals. It complies with GB 4806.10-2016 food contact coatings and coatings standards, and can be used in food contact scenarios such as tableware and kitchen utensils.

[0057] 2. This invention uses Li2O-B2O3 synergistic fluxing, and the firing temperature is ≤800℃, which is significantly lower than that of traditional processes, thereby reducing energy consumption and CO2 emissions. In addition, through gradient ball milling combined with staged firing process, the bonding strength between the glaze layer and the metal substrate is ≥30MPa, and the density and wear resistance of the glaze layer are improved by nano ZrO2, anatase TiO2 and GO synergistically.

[0058] 3. This invention achieves photocatalytic self-cleaning function by decomposing organic matter under ultraviolet light with TiO2, and achieves broad-spectrum antibacterial effect with Ag3PO4, with an inhibition rate of ≥99.9% against Escherichia coli and Staphylococcus aureus, and is resistant to high-pressure steam sterilization. This allows enamel glaze to go beyond providing basic decorative and protective functions and expand its application scenarios. Detailed Implementation

[0059] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0060] In the following examples, the raw materials used include: SiO2, particle size 5~20μm; B2O3, particle size 5~15μm; kaolin, particle size 2~10μm, Al2O3 content ≥35%; sodium carbonate, particle size 10~30μm; spodumene, particle size 5~15μm, Li2O content ≥6%; TiO2, anatase type, particle size 0.5~2μm; ZrO2, particle size 20~50nm; Ag3PO4, particle size 0.1~1μm; and graphite oxide, sheet diameter 1~10μm, 1~5nm.

[0061] Example 1 The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment comprises the following raw materials in weight percentage: SiO2 45.6%, B2O3 11%, kaolin 10.2%, Na2CO3 13.5%, spodumene 4.2%, TiO2 8.8%, ZrO2 2.2%, Ag3PO4 0.3%, graphite oxide 0.1%, Fe2O3 / Cr2O3 composite nanoparticles 1.3%, sodium carboxymethyl cellulose aqueous solution 0.6%, and silica sol 2.2%.

[0062] The sodium carboxymethyl cellulose aqueous solution has a mass concentration of 3% and a viscosity of 1000 mPa·s.

[0063] The silica sol has a solid content of 28% and a pH value of 9.5.

[0064] The preparation method of Fe2O3 / Cr2O3 composite nanoparticles is as follows: ferric nitrate nonahydrate and chromium nitrate nonahydrate are dissolved in deionized water at a Fe to Cr molar ratio of 2:1, the total mass ratio of ferric nitrate nonahydrate and chromium nitrate nonahydrate to deionized water is 1:8, citric acid is added (citric acid to metal ion molar ratio is 1.3:1), the mixture is heated to 85℃ and stirred until a gel is formed, and then calcined at 550℃ for 3 hours to obtain Fe2O3 / Cr2O3 composite nanoparticles with a particle size of 100nm.

[0065] The preparation method of the environmentally friendly multifunctional low-temperature fired enamel glaze in this embodiment includes the following steps: 1) Kaolin and an 8 wt% sulfuric acid solution were mixed at a solid-liquid ratio of 1:7, heated to 70°C, stirred and acid-washed for 3 hours, filtered, washed with deionized water until neutral, and dried to obtain pretreated kaolin with an Al2O3 content of 39%. 2) Add ZrO2 and Ag3PO4 to silica sol and sonicate for 30 min to obtain a uniformly dispersed slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene were mixed and ground in a planetary ball mill with zirconia balls as grinding balls at a ball-to-material ratio of 2:1 at 300 rpm for 2 hours to obtain coarse powder with a particle size ≤10μm; then TiO2, slurry A, graphite oxide and Fe2O3 / Cr2O3 composite nanoparticles were added and ground in a mill at 500 rpm for 1.5 hours to obtain glaze powder with a particle size ≤3μm and a mixing uniformity ≥95%; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add deionized water. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to the water is 1:1.5. Stir for 45 minutes to obtain the enamel glaze slurry.

[0066] The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment is applied to cookware. The application steps are as follows: Enamel slurry was sprayed onto the surface of a cast iron pot to a thickness of 100 μm. The pot was then sintered in a box furnace in two stages. First, it was pre-fired in a nitrogen atmosphere (nitrogen flow rate 8 L / min) by heating to 450 °C at 4 °C / min and holding for 30 min. Then, it was finally fired in a weak oxidizing atmosphere (O2 volume fraction 5%, the remainder being nitrogen) by heating to 780 °C at 8.5 °C / min and holding for 5 min. This process resulted in an enamel coating on the surface of the cast iron pot.

[0067] The material prepared in this embodiment was subjected to performance testing, and it exhibits excellent corrosion resistance, wear resistance, broad-spectrum antibacterial properties, and photocatalytic self-cleaning properties, wherein: Corrosion resistance: Tested according to GB / T 9989-2005 "Test for Chemical Corrosion Resistance of Enamel". Acid resistance: Boiling in a 4% (v / v) acetic acid solution for 30 minutes, the weight loss is 0.4 mg / dm³. 2 Alkali resistance: No visible corrosion was observed on the surface after boiling in a 2% sodium carbonate solution for 30 minutes.

[0068] Abrasion resistance: A 100mm × 100mm sample was tested using a Taber 5155 abrasion tester with a CS-10 grinding wheel. A load of 4.9 N was applied, and the coating surface was rubbed at a speed of 60 r / min. After 1000 revolutions, the average weight loss of the coating was 8 mg / cm³. 2 .

[0069] Antibacterial properties: Tested according to the film adhesion method in GB / T 21866-2008 "Determination of Antibacterial Properties and Antibacterial Effects of Antibacterial Coatings (Films)". The experimental bacteria were Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 6538), with a bacterial concentration of approximately 1×10⁻⁶. 5CFU / mL. The coated sample was brought into close contact with an agar plate containing the inoculated bacterial solution and incubated at 37°C and >90% relative humidity for 24 hours. The inhibition rate was then calculated. The results showed that the inhibition rate against both test bacteria was 99.95% after 24 hours.

[0070] Self-cleaning property (photocatalytic performance): Following the principle of ISO 10678:2010 "Fine ceramics (advanced ceramics, advanced industrial ceramics) — Determination of the catalytic activity of semiconductor photocatalytic materials in aqueous solution for the degradation of methylene blue", oleic acid was used as the target pollutant for testing. 0.1 mL of a 0.1 mol / L oleic acid-ethanol solution was uniformly coated onto the surface, and an oleic acid film was formed after the ethanol evaporated. The sample was placed in an ultraviolet photocatalytic reactor with a dominant wavelength of 365 nm and a light intensity of 1.0 mW / cm². 2 After 12 hours of vertical irradiation with ultraviolet light, the change in the area of ​​the characteristic peak of oleic acid on the coating surface was measured by Fourier transform infrared spectroscopy, and the oleic acid degradation rate was calculated to be 92%.

[0071] Bond strength: Tested according to ASTM C633-13, "Standard Test Method for Bond or Cohesive Strength of Thermally Sprayed Coatings". Using the tensile method and E-7 adhesive, the average bond strength between the enamel coating and the metal substrate was measured to be 32 MPa.

[0072] Example 2 The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment includes the following raw materials in weight percentage: SiO2 45%, B2O3 10.5%, kaolin 11.2%, Na2CO3 13.0%, spodumene 4.5%, TiO2 8%, ZrO2 3%, Fe2O3 / Cr2O3 composite nanoparticles 1.5%, sodium carboxymethyl cellulose aqueous solution 1.0%, and silica sol 2.3%.

[0073] The sodium carboxymethyl cellulose aqueous solution has a mass concentration of 2% and a viscosity of 800 mPa·s.

[0074] The silica sol has a solid content of 25% and a pH value of 9.0.

[0075] The preparation method of Fe2O3 / Cr2O3 composite nanoparticles is as follows: ferric chloride and chromium chloride are dissolved in deionized water at a molar ratio of Fe to Cr of 1:1, and the mass ratio of the total mass of ferric chloride and chromium chloride to the mass of deionized water is 1:10. Oxalic acid is added (the molar ratio of oxalic acid to the total metal ions is 1.2:1), and the mixture is heated to 80°C and stirred until a gel is formed. Then, it is calcined at 500°C for 4 hours to obtain Fe2O3 / Cr2O3 composite nanoparticles with a particle size of 150 nm.

[0076] The preparation method of the environmentally friendly multifunctional low-temperature fired enamel glaze in this embodiment includes the following steps: 1) Kaolin and a 9 wt% sulfuric acid solution were mixed at a solid-liquid ratio of 1:8, heated to 75°C, stirred, and acid-washed for 3.5 hours. After filtration, the mixture was washed with deionized water until neutral and dried to obtain pretreated kaolin with an Al2O3 content ≥38%. 2) Add ZrO2 to silica sol and sonicate for 35 min to obtain a uniformly dispersed slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene were mixed and ground in a planetary ball mill with zirconia balls as grinding balls at a ball-to-material ratio of 2:1 at 250 rpm for 3 hours to obtain coarse powder with a particle size ≤10μm; then TiO2, slurry A and Fe2O3 / Cr2O3 composite nanoparticles were added and ground at 400 rpm for 2 hours to obtain glaze powder with a particle size ≤3μm and a mixing uniformity ≥95%; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add deionized water. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to the water is 1:1.6. Stir for 50 min to obtain enamel glaze slurry.

[0077] The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment is applied to architectural enamel panels. The application steps are as follows: Enamel slurry was sprayed onto the surface of cold-rolled low-carbon steel sheet with a coating thickness of 120 μm. The sheet was then sintered in a box furnace in two stages. First, it was pre-fired in a nitrogen atmosphere (nitrogen flow rate 9 L / min) by heating to 400℃ at 5℃ / min and holding for 40 min. Then, it was finally fired in an atmosphere (O2 volume fraction 3%, the remainder nitrogen) by heating to 750℃ at 8℃ / min and holding for 8 min. The resulting enamel coating was used as an architectural enamel panel.

[0078] The material prepared in this embodiment was subjected to performance testing, and it exhibits excellent corrosion resistance, wear resistance, and photocatalytic self-cleaning properties, wherein: Self-cleaning property: Following the principle of ISO 10678:2010 "Determination of catalytic activity of semiconductor photocatalytic materials for the degradation of methylene blue in aqueous solution in fine ceramics (advanced ceramics, advanced industrial ceramics)," the contact angle was used as the indicator. A contact angle meter was used to measure the static contact angle of water on the coating surface at room temperature. The results showed that the surface contact angle was 8° under ultraviolet irradiation, indicating that ultraviolet light excited the photocatalytic reaction, decomposing organic pollutants on the surface and increasing the number of hydrophilic hydroxyl groups on the surface.

[0079] Weather resistance: QUV aging test was conducted according to ASTM G154-16 "Nonmetallic Materials - Fluorescent Ultraviolet Lamp Exposure Test Method". A UVA-340 lamp was used, and the cyclic conditions were: 8 hours of UV exposure at 60℃, followed by 4 hours of condensation at 50℃, for a total of 500 hours. The color difference before and after aging was measured using a colorimeter; the color difference ΔE = 1.2.

[0080] Salt spray resistance: Tested according to ASTM B117-19 "Salt spray test method". The coating sample was placed in a 5% sodium chloride solution at 35°C and continuously exposed for 2000 hours. The coating surface was inspected; no blistering, peeling, or other corrosion phenomena were observed.

[0081] Example 3 The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment comprises the following raw materials in weight percentage: SiO2 46.1%, B2O3 11.8%, kaolin 10.5%, Na2CO3 13.4%, spodumene 3.0%, TiO2 8.5%, ZrO2 2.0%, Ag3PO4 0.1%, graphite oxide 0.1%, Fe2O3 / Cr2O3 composite nanoparticles 1.2%, sodium carboxymethyl cellulose aqueous solution 0.8%, and silica sol 2.5%.

[0082] The sodium carboxymethyl cellulose aqueous solution has a mass concentration of 4% and a viscosity of 1200 mPa·s.

[0083] The silica sol has a solid content of 30% and a pH value of 10.0.

[0084] The preparation method of Fe2O3 / Cr2O3 composite nanoparticles is the same as in Example 1, except that the nonahydrate ferric nitrate and nonahydrate chromium nitrate are prepared in a Fe to Cr molar ratio of 1.5:1.

[0085] The preparation method of the environmentally friendly multifunctional low-temperature fired enamel glaze in this embodiment includes the following steps: 1) Kaolin and a 9 wt% sulfuric acid solution were mixed at a solid-liquid ratio of 1:10, heated to 65°C and stirred for 4 hours for acid washing. After filtration, the mixture was washed with deionized water until neutral and dried to obtain pretreated kaolin with an Al2O3 content ≥38%. 2) Add ZrO2 and Ag3PO4 to silica sol and sonicate for 36 min to obtain a uniformly dispersed slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene were mixed and ground in a planetary ball mill with zirconia balls as grinding balls at a ball-to-material ratio of 2:1 at 200 rpm for 4 h to obtain coarse powder with a particle size ≤10μm; then TiO2, slurry A, graphite oxide and Fe2O3 / Cr2O3 composite nanoparticles were added and ground for another 2 h at 420 rpm to obtain glaze powder with a particle size ≤3μm and a mixing uniformity ≥95%; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add deionized water. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to the water is 1:1.7. Stir for 40 min to obtain enamel glaze slurry.

[0086] The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment is applied to medical trays. The application steps are as follows: Enamel slurry was sprayed onto the surface of a stainless steel tray to a thickness of 80 μm. The tray was then sintered in a box furnace in two stages. First, it was pre-fired in a nitrogen atmosphere (nitrogen flow rate 6 L / min) by heating to 500℃ at 4℃ / min and holding for 20 min. Then, it was finally fired in a weak oxidizing atmosphere (8% O2 volume fraction, the remainder being nitrogen) by heating to 800℃ at 10℃ / min and holding for 3 min. This process resulted in an enamel coating on the surface of the stainless steel tray.

[0087] The material prepared in this embodiment was subjected to performance testing, and it exhibits excellent corrosion resistance, wear resistance, broad-spectrum antibacterial properties, and photocatalytic self-cleaning properties, wherein: Sterilization resistance: The coating sample was subjected to autoclaving testing according to a similar method to GB / T 25934.3-2010 "Sterilization of Medical and Health Products - Low-Temperature Steam Formaldehyde - Part 3: Development, Validation, and Routine Control Requirements for Sterilization Processes of Medical Devices". The coating sample was placed in an autoclave and sterilized 20 times at 121°C and 0.12 MPa. Each cycle lasted 30 minutes. The glaze was inspected; no cracks or peeling were found.

[0088] Disinfectant resistance: Tested according to GB / T 9274-1988 "Determination of resistance to liquid media for paints and varnishes". The coating sample was immersed in a 5% sodium hypochlorite solution at room temperature for 48 hours. The gloss was measured before and after immersion using a gloss meter, and the gloss retention rate was 87%.

[0089] Antibacterial properties: Tested according to the film adhesion method in GB / T21866-2008 "Determination of Antibacterial Properties and Antibacterial Effects of Antibacterial Coatings (Films)". The experimental bacteria were Escherichia coli (ATCC25922) and Staphylococcus aureus (ATCC6538), with a bacterial concentration of approximately 1×10⁻⁶. 5CFU / mL. The coated sample was brought into close contact with an agar plate containing the inoculated bacterial solution and incubated at 37°C and >90% relative humidity for 24 hours. The inhibition rate was then calculated. The results showed that the inhibition rate against both test bacteria was ≥99.9%.

[0090] Example 4 The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment comprises the following raw materials in weight percentage: SiO2 45.5%, B2O3 10%, kaolin 11.0%, Na2CO3 14.0%, spodumene 4.0%, TiO2 9.0%, ZrO2 2.7%, Ag3PO4 0.15%, graphite oxide 0.05%, Fe2O3 / Cr2O3 composite nanoparticles 1%, sodium carboxymethyl cellulose aqueous solution 0.6%, and silica sol 2.0%.

[0091] The sodium carboxymethyl cellulose aqueous solution has a mass concentration of 3% and a viscosity of 1000 mPa·s.

[0092] The silica sol has a solid content of 28% and a pH value of 9.5.

[0093] The preparation method of Fe2O3 / Cr2O3 composite nanoparticles is as follows: ferric nitrate nonahydrate and chromium nitrate nonahydrate are dissolved in deionized water at a Fe to Cr molar ratio of 3:1, the total mass ratio of ferric nitrate nonahydrate and chromium nitrate nonahydrate to deionized water is 1:10, oxalic acid is added (the total molar ratio of oxalic acid to metal ions is 1.2:1), the mixture is heated to 80℃ and stirred until a gel is formed, and then calcined at 500℃ for 4 hours to obtain Fe2O3 / Cr2O3 composite nanoparticles with a particle size of 170nm.

[0094] The preparation method of the environmentally friendly multifunctional low-temperature fired enamel glaze in this embodiment includes the following steps: 1) Kaolin and an 8wt% sulfuric acid solution were mixed at a solid-liquid ratio of 1:6, heated to 60℃ and stirred for 4 hours. After filtration, the mixture was washed with deionized water until neutral and dried to obtain pretreated kaolin with an Al2O3 content ≥38%. 2) Add ZrO2 and Ag3PO4 to silica sol and sonicate for 40 min to obtain a uniformly dispersed slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene were mixed and ground in a planetary ball mill with zirconia balls as grinding balls at a ball-to-material ratio of 2:1 at 220 rpm for 3.5 h to obtain coarse powder with a particle size ≤10μm; then TiO2, slurry A, graphite oxide and Fe2O3 / Cr2O3 composite nanoparticles were added and ground for another 2 h at 450 rpm to obtain glaze powder with a particle size ≤3μm and a mixing uniformity ≥95%; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add deionized water. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to the water is 1:1.4. Stir for 45 minutes to obtain the enamel glaze slurry.

[0095] The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment is applied to bipolar plates of new energy batteries. The application steps are as follows: Enamel slurry was sprayed onto the surface of 316L stainless steel to a thickness of 150μm. The coating was then sintered in a box furnace in two stages. First, pre-firing was carried out in a nitrogen atmosphere (nitrogen flow rate 7L / min), with the temperature increased to 480℃ at 3℃ / min and held for 35min. Then, final firing was carried out in a weak oxidizing atmosphere (O2 volume fraction 6%, the remainder being nitrogen), with the temperature increased to 790℃ at 9℃ / min and held for 6min. An enamel coating was obtained on the stainless steel surface and used as a bipolar plate for new energy batteries.

[0096] The material prepared in this embodiment was subjected to performance testing, and it exhibits excellent corrosion resistance, wear resistance, broad-spectrum antibacterial properties, and photocatalytic self-cleaning properties, wherein: Corrosion resistance: Following a similar method to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", a PEMFC environment was simulated. The coated samples were placed in a sulfuric acid solution at 80℃ and pH=3, and the corrosion current density was measured using an electrochemical workstation. Using a three-electrode system and a scan rate of 1 mV / s, the measured corrosion current density was 0.8 μA / cm². 2 This demonstrates that the enamel coating is dense and complete, effectively blocking corrosive media (H). + SO4 2- (etc.) penetrate the substrate surface.

[0097] Conductivity: Sheet resistance was tested according to ASTM D257-14, "Standard Test Method for DC Resistance or Conductivity of Insulating Materials". The four-probe method was used, and the sheet resistance was measured at room temperature; the sheet resistance was 8 mΩ·cm. 2 This indicates that the enamel forms a continuous conductive channel.

[0098] Example 5 The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment comprises the following raw materials in weight percentage: SiO2 46.0%, B2O3 11.5%, kaolin 10%, Na2CO3 13%, spodumene 3.5%, TiO2 9.5%, ZrO2 2.3%, Fe2O3 / Cr2O3 composite nanoparticles 1.6%, sodium carboxymethyl cellulose aqueous solution 0.5%, and silica sol 2.1%.

[0099] The sodium carboxymethyl cellulose aqueous solution has a mass concentration of 2% and a viscosity of 800 mPa·s.

[0100] The silica sol has a solid content of 25% and a pH value of 9.0.

[0101] The preparation method of Fe2O3 / Cr2O3 composite nanoparticles is the same as in Example 1, except that ferric nitrate nonahydrate and chromium nitrate nonahydrate are prepared in a Fe to Cr molar ratio of 2.5:1, and the particle size of the product is controlled at 50-200 nm to regulate the color development effect.

[0102] The preparation method of the environmentally friendly multifunctional low-temperature fired enamel glaze in this embodiment includes the following steps: 1) Kaolin and an 8wt% sulfuric acid solution were mixed at a solid-liquid ratio of 1:7, heated to 70℃ and stirred for 3 hours. After filtration, the mixture was washed with deionized water until neutral and dried to obtain pretreated kaolin with an Al2O3 content ≥38%. 2) Add ZrO2 to silica sol and sonicate for 30 minutes to obtain a uniformly dispersed slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene were mixed and ground in a planetary ball mill with zirconia balls as grinding balls at a ball-to-material ratio of 2:1 at 250 rpm for 1.8 h to obtain coarse powder with a particle size ≤10μm; then TiO2, slurry A and Fe2O3 / Cr2O3 composite nanoparticles were added and ground again at 480 rpm for 1.8 h to obtain glaze powder with a particle size ≤3μm and a mixing uniformity ≥95%; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add deionized water. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to the water is 1:1.8. Stir for 35 minutes to obtain the enamel glaze slurry.

[0103] The environmentally friendly, multifunctional, low-temperature fired enamel glaze of this embodiment is applied to artistic decoration. The application steps are as follows: Enamel slurry was sprayed onto the surface of cold-rolled low-carbon steel. Special color effects were achieved by controlling the particle size of Fe2O3 / Cr2O3 composite nanoparticles. The coating thickness was 100μm. The coating was sintered in a box furnace in two stages. First, it was pre-fired in a nitrogen atmosphere (nitrogen flow rate 10L / min) and heated to 500℃ at 5℃ / min, and held for 27min. Then, it was finally fired in a weak oxidizing atmosphere (O2 volume fraction 5%, the remainder nitrogen) and heated to 780℃ at 10℃ / min, and held for 8min. An enamel coating was obtained on the surface of cold-rolled low-carbon steel and used for artistic decoration.

[0104] The material prepared in this embodiment was subjected to performance testing, and it exhibits excellent corrosion resistance, wear resistance, and photocatalytic self-cleaning properties, wherein: Color rendering effect: The color gamut of the coating was measured using a spectrophotometer according to the CIE Lab colorimetric system. Compared with the standard color chart, the Lab color gamut expanded by 15%, indicating that the enamel layer has higher saturation and a wider range of lightness.

[0105] UV resistance: Tested according to ASTM G155-13 "Nonmetallic Materials - Xenon Lamp Exposure Test Method". Coated samples were placed in a xenon lamp aging chamber with an irradiance of 0.55 W / m², a black panel temperature of 65°C, and a relative humidity of 50% for a cumulative period of 1000 hours. The color difference before and after aging was measured using a colorimeter; the color difference ΔE = 1.8.

[0106] Abrasion resistance: A 100mm × 100mm sample was tested using a Taber 5155 abrasion tester with a CS-10 grinding wheel. A load of 4.9N was applied, and the coating surface was rubbed at a speed of 60 r / min. After 1000 revolutions, the average weight loss of the coating was 9 mg / cm³. 2 .

[0107] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An environmentally friendly, multifunctional low-temperature fired enamel glaze, characterized in that, The raw materials include the following percentages by mass: SiO2 45-48%, B2O3 10-15%, kaolin 10-15%, Na2CO3 13-17%, spodumene 3-8%, TiO2 8-12%, ZrO2 2-4%, Ag3PO4 0-0.5%, graphite oxide 0-0.1%, Fe2O3 / Cr2O3 composite nanoparticles 1-3%, sodium carboxymethyl cellulose aqueous solution 0.5-1%, and silica sol 2-4%.

2. The environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 1, characterized in that, The preparation method of the Fe2O3 / Cr2O3 composite nanoparticles is as follows: dissolve the metal salt in water, add a complexing agent, heat and stir until a gel is formed, and then calcine to obtain Fe2O3 / Cr2O3 composite nanoparticles.

3. The environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 2, characterized in that, The metal salt includes an iron salt and a chromium salt, wherein the iron salt is one of ferric nitrate nonahydrate or ferric chloride, and the chromium salt is one of chromium nitrate nonahydrate or chromium chloride; the complexing agent is one of citric acid or oxalic acid; the mass ratio of the metal salt to water is 1:5 to 1:15; the molar ratio of the complexing agent to the metal salt is 1.2:1 to 1.5:1; the heating temperature is 80 to 90°C; the calcination temperature is 500 to 600°C, and the calcination time is 2 to 4 hours.

4. The environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 1, characterized in that, The Fe2O3 / Cr2O3 composite nanoparticles have a particle size of 50-200 nm, wherein the molar ratio of Fe to Cr is 1:1-3:1; the sodium carboxymethyl cellulose aqueous solution has a mass concentration of 2-4% and a viscosity of 800-1200 mPa·s; the silica sol has a solid content of 25-30% and a pH value of 9-10; the graphene oxide sheets have a diameter of 1-10 μm and a thickness of 1-5 nm; the mass ratio of TiO2 to ZrO2 is 3:1-5:1; and the mass ratio of ZrO2 to Ag3PO4 is 10:1-20:

1.

5. The environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 1, characterized in that, The SiO2 has a particle size of 5-20 μm; the B2O3 has a particle size of 5-15 μm; the kaolin has a particle size of 2-10 μm and an Al2O3 content of ≥35%; the sodium carbonate has a particle size of 10-30 μm; the spodumene has a particle size of 5-15 μm and a Li2O content of ≥6%; the TiO2 is anatase type with a particle size of 0.5-2 μm; the ZrO2 has a particle size of 20-50 nm; and the Ag3PO4 has a particle size of 0.1-1 μm.

6. A method for preparing an environmentally friendly, multifunctional low-temperature fired enamel glaze as described in any one of claims 1 to 5, characterized in that, Includes the following steps: 1) Kaolin and sulfuric acid solution are mixed, heated and stirred, and the product is washed and dried to obtain pretreated kaolin; 2) Add ZrO2 and Ag3PO4 to silica sol and disperse by ultrasonication to obtain slurry A; 3) SiO2, B2O3, pretreated kaolin, Na2CO3 and spodumene are mixed and pre-ground to obtain coarse powder; then TiO2, slurry A, graphite oxide and Fe2O3 / Cr2O3 composite nanoparticles are added and ground again to obtain glaze powder; 4) Mix the glaze powder and sodium carboxymethyl cellulose aqueous solution, then add water and stir to obtain enamel glaze slurry.

7. The method for preparing the environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 6, characterized in that, The concentration of the sulfuric acid solution is 5-10 wt%; the kaolin and sulfuric acid solution are mixed at a solid-liquid ratio of 1:5 to 1:10; the heating and stirring temperature in step 1) is 60-80℃ and the time is 2-4 h; the Al2O3 content of the pretreated kaolin is ≥38%; the ultrasonic dispersion time is 20-40 min.

8. The method for preparing the environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 6, characterized in that, The initial grinding is performed at a speed of 200-300 rpm for 2-4 hours, with the coarse powder having a particle size ≤10 μm. The subsequent grinding is performed at a speed of 400-500 rpm for 1-2 hours, with the glaze powder having a particle size ≤3 μm and a mixing uniformity ≥95%. The total mass ratio of the glaze powder and sodium carboxymethyl cellulose aqueous solution to water is 1:1.2-1:1.8, and the stirring time is 30-60 minutes.

9. A method for applying an environmentally friendly, multifunctional low-temperature fired enamel glaze as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Enamel slurry is sprayed onto the surface of a metal substrate and sintered in two stages. Pre-firing is carried out in a nitrogen atmosphere at a temperature of 400-500℃ for 20-40 minutes. Final firing is carried out in a weak oxidizing atmosphere at a temperature of 750-800℃ for 3-8 minutes to obtain an enamel coating.

10. The application method of the environmentally friendly multifunctional low-temperature fired enamel glaze according to claim 9, characterized in that, The metal substrate is one of low-carbon steel, cast iron, stainless steel, and aluminum alloy; the coating thickness of the enamel slurry is 80~150μm; the heating rate of the pre-firing is 3~5℃ / min; the heating rate of the final firing is 8~10℃ / min; the volume fraction of O2 in the weak oxidizing atmosphere is 3~8%, with the remainder being nitrogen.