Metal product enamel technology capable of achieving uniform coloring

Abstract

The invention belongs to the technical field of enamel, and particularly relates to a metal product enamel technology capable of achieving uniform coloring. The invention aims to solve the problem that uniform coloring of various colors is difficult to realize in an existing enamel process. The preparation method comprises the following steps: mixing a glass forming agent, a fluxing agent, a stabilizer and a refining agent, and melting at high temperature to prepare a glass melt; performing water quenching cooling on the glass melt to obtain an enamel fine material, and performing grinding and magnetic separation to obtain basic enamel powder; metal oxide powder is dispersed in a dispersion medium to form a dyeing suspension, and then the dyeing suspension is mixed with basic enamel powder to form dyed enamel powder; after metal surface pretreatment, the dyed enamel powder is evenly printed on the metal surface through silk-screen printing, and an enamel blank is formed; and the enamel blank is subjected to staged low-temperature pre-sintering, high-temperature sintering and crystallization annealing processes, and finally the enamel product is obtained. The enamel product obtained by the enamel process provided by the invention has excellent color uniformity and pattern definition, and is high in application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of enamel, and particularly relates to an enamel process for metal products capable of uniform coloring. Background Art

[0002] As a process with a long history, the enamel technology endows products with gorgeous colors, excellent corrosion resistance and durability by melting glassy materials and attaching them to the metal surface. The existing enamel technology can fire enamel products with bright and lasting colors, high hardness, wear resistance and chemical corrosion resistance, and can create delicate artistic effects, which are widely used in artworks, jewelry, daily necessities and even industrial fields. However, the existing technology also faces problems such as high energy consumption, susceptibility to thermal shock, and complex process control. Especially in terms of the uniformity when multiple colors coexist, due to the melting characteristics of different color enamels, the mutual influence during the firing process, and the complexity of multi-layer superposition, it is difficult to obtain a multi-color enamel effect with highly consistent color, texture and luster in the same product or mass production, which has become a major bottleneck restricting the application of enamel technology in a wider range of fields.

[0003] Currently, it is still an important problem faced by the industry that it is difficult to achieve uniform coloring of multiple colors with the existing enamel process.

[0004] Therefore, an enamel process for metal products capable of uniform coloring is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an enamel process for metal products capable of uniform coloring. In the present invention, a glass former, a flux, a stabilizer and a refining agent are mixed and melted at high temperature to form a glass melt; the glass melt is quenched and cooled with water to obtain enamel fines, and after grinding and magnetic separation, basic enamel powder is obtained; metal oxide powder is dispersed in a dispersion medium to form a dyeing suspension, which is then mixed with the basic enamel powder to form dyed enamel powder; after the surface of the metal is pretreated, the dyed enamel powder is uniformly printed onto the metal surface by screen printing to form an enamel blank; the enamel blank undergoes a staged low-temperature pre-firing, high-temperature sintering and crystallization annealing process to finally obtain an enamel product.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An enamel process for metal products capable of uniform coloring, comprising the following steps:

[0008] Unless otherwise specified, the parts in the present invention all refer to parts by mass.

[0009] Mix a glass former, a flux, a stabilizer and a refining agent and melt them at high temperature to obtain a glass melt.

[0010] Among them, the glass former includes silica and boric acid, and the added mass ratio of silica to boric acid is 2.5:1 - 2; the fluxes include: sodium carbonate, potassium carbonate and lithium carbonate, and the added mass ratio of sodium carbonate, potassium carbonate and lithium carbonate is 2:2:1; the stabilizer is alumina, and the refining agent is potassium nitrate.

[0011] Heat the mixed glass former, fluxes, stabilizer and refining agent to 1200 - 1270 °C, stir at a stirring speed of 100 rpm during the melting process, and keep it for 60 - 120 min to obtain a glass melt.

[0012] Among them, the added mass ratio of the glass former, fluxes and stabilizer is: 5:2 - 3.2:1 - 1.5, and the addition amount of the refining agent is 0.25% of the total mass of the glass melt.

[0013] Pour the glass melt into water at 10 - 20 °C to quickly break it into fine particles to obtain enamel fines.

[0014] After grinding and magnetic separation of the enamel fines, basic enamel powder is obtained.

[0015] Uniformly disperse the metal oxide powder in the dispersion medium to obtain a dyed suspension.

[0016] Among them, the metal oxide is selected according to the color required for the enamel, and the corresponding relationship is: zirconium oxide powder is selected for blue, chromium oxide powder and copper oxide powder are selected for green, and the added amount ratio is 1:1; iron oxide powder is selected for red; manganese oxide powder is selected for purple; magnetite powder is selected for black; tin oxide powder is selected for white.

[0017] Among them, the dispersion medium is a mixture of deionized water and isopropanol; the added mass ratio of the metal oxide powder, deionized water and isopropanol is 50:80:40.

[0018] Disperse and mix 25 - 40 parts of the dyed suspension with 35 parts of the basic enamel powder to obtain dyed enamel powder.

[0019] Pretreat the surface of the metal product, and uniformly print the dyed enamel powder onto the surface by screen printing to obtain an enamel blank.

[0020] Subject the enamel blank to staged low-temperature pre-sintering to obtain crude enamel;

[0021] After high-temperature sintering of the crude enamel, continue with crystallization annealing to obtain an enamel product.

[0022] Preferably, the process of grinding and magnetic separation is: grind the enamel fines to 200 mesh at a water-to-material ratio of 0.5 - 1, and then perform magnetic separation at a magnetic field intensity of 0.1 - 0.5 tesla to remove magnetic impurities to obtain basic enamel powder.

[0023] Preferably, the pre-treatment process is as follows: after degreasing, water washing and acid pickling the surface of the metal product, sandblasting treatment is carried out; the screen printing process is as follows: cover the screen with the preset pattern on the metal product, apply the dyed enamel powder onto the screen according to the color of the pattern design, and make the dyed enamel powder transfer to the surface of the metal product through the mesh holes to obtain an enamel blank.

[0024] Among them, the degreasing process is: soak and rinse the metal product in a 40 g / L sodium carbonate aqueous solution at 60 °C for 10 min; the water washing process is: soak the degreased metal product in water for 2 min and wash away the residual alkali solution; the acid pickling process is: after soaking the water-washed metal product in dilute sulfuric acid with a volume concentration of 10% at a treatment temperature of 70 °C for 15 min, wash it with water again; the sandblasting treatment process is: after drying the acid-pickled metal product, use white corundum with a mesh size of 150 and a sandblasting pressure of 0.5 MPa and a sandblasting angle of 45° for treatment.

[0025] Preferably, the process of staged low-temperature pre-sintering is: after drying the enamel blank, preheat it at 75 - 90 °C for 30 min, then heat it up to 200 °C at a heating rate of 10 °C / min, keep it warm for 2 hours, and then heat it up to 300 °C at a heating rate of 10 °C / min and keep it warm for 1 hour to obtain crude enamel.

[0026] Preferably, the process of high-temperature sintering is: heat the crude enamel up to 850 - 950 °C at a heating rate of 15 - 20 °C / min, keep it warm for 10 min, and then cool it to 500 °C at a cooling rate of 15 °C / min.

[0027] Preferably, the process of crystallization annealing is: keep the crude enamel after high-temperature sintering at a treatment temperature of 500 °C, maintain it for 3 - 5 hours, and then cool it to 25 °C at a cooling rate of 1 °C / min to obtain an enamel product.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The basic material of the enamel coating is constructed by the basic enamel powder composed of the compounded glass former, flux, stabilizer and refining agent, and with the help of the pre-treatment of the surface of the metal product and the screen printing process, an enamel coating with excellent bonding strength is obtained. On the basis of having high hardness and wear resistance characteristics, the fine dispersion of the enamel color is ensured, and good color uniformity of the enamel product is ensured.

[0030] 2. By compounding metal oxide powders with base enamel powders, and leveraging the bridging oxygen structure of the borosilicate glass matrix and the ionic polarization effect provided by the fluxes, the metal oxides are uniformly distributed within the glass phase through staged low-temperature pre-sintering and high-temperature sintering, resulting in a uniform color distribution in the enamel products and significantly reducing the color deviation phenomenon.

[0031] 3. With the help of the staged low-temperature pre-sintering process, the organic carriers in the dispersion medium of the metal oxide powders are decomposed in stages, and further through high-temperature sintering, a dense metal ion distribution network is formed under the synergistic migration of lithium ions in the fluxes. Further, through the crystallization annealing process, alumina stabilizer is used as the nucleation center to form β-phase eutectics, establishing a multi-scale crystal intertwined structure, which greatly improves the hardness and color durability of the enamel products while eliminating the thermal expansion stress.

[0032] 4. By high-temperature melting and water quenching cooling, the internal stress of the base enamel powder is increased, avoiding the local agglomeration of the silicon-oxygen network during the subsequent high-temperature sintering process, and eliminating the bubbles inside the enamel glaze layer by means of the decomposition of the fluxes, ensuring the precise control of the distribution range of the metal oxide powders, improving the boundary clarity of the pattern, and guaranteeing a highly uniform color distribution on the enamel products. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a process flow chart of the enamel process provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions of the present invention will be clearly and completely described below through some embodiments and experimental examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Refer to Figure 1 As shown in the process flow chart, the present invention provides an enamel process for metal products with uniform coloring, and the technical solutions are as follows:

[0036] Example 1

[0037] Mix the glass former, fluxes, stabilizer and fining agent and melt them at high temperature to obtain a glass melt.

[0038] Among them, the glass former includes silica and boric acid, and the mass ratio of silica to boric acid added is 2.5:1; the fluxes include sodium carbonate, potassium carbonate and lithium carbonate, and the mass ratio of sodium carbonate, potassium carbonate and lithium carbonate added is 2:2:1; the stabilizer is alumina, and the fining agent is potassium nitrate.

[0039] Heat the mixed glass former, flux, stabilizer and fining agent to 1200 °C, stir at a stirring speed of 100 rpm during the melting process, and keep it for 60 min to obtain a glass melt.

[0040] Among them, the added mass ratio of the glass former, flux and stabilizer is 5:2:1, and the addition amount of the fining agent is 0.25% of the total mass of the glass melt.

[0041] Pour the glass melt into water at 10 °C to quickly break it into fine particles to obtain enamel fines.

[0042] Grind the enamel fines to 200 mesh at a water-to-material ratio of 0.5, and then perform magnetic separation under a magnetic field strength of 0.1 Tesla to remove magnetic impurities to obtain basic enamel powder.

[0043] Uniformly disperse the metal oxide powder in the dispersion medium to obtain a dyeing suspension.

[0044] Among them, the metal oxide is selected according to the color required for the enamel. For firing blue and white, therefore, zirconia powder and tin oxide powder are selected to prepare the corresponding dyeing suspensions respectively.

[0045] Among them, the dispersion medium is a mixture of deionized water and isopropanol; the added mass ratio of the metal oxide powder, deionized water and isopropanol is 50:80:40.

[0046] Disperse and mix 25 parts of the dyeing suspension with 35 parts of the basic enamel powder to obtain the dyed enamel powder.

[0047] After degreasing, water washing and acid pickling the surface of the metal product, perform sandblasting treatment; the process of screen printing is: cover the screen with the preset pattern on the metal product, apply the dyed enamel powder onto the screen according to the color of the pattern design, and make the dyed enamel powder transfer to the surface of the metal product through the mesh holes to obtain an enamel blank.

[0048] Among them, the degreasing process is: soak and rinse the metal product in a 40 g / L sodium carbonate aqueous solution at 60 °C for 10 min; the water washing process is: soak the degreased metal product in water for 2 min and wash away the residual alkali solution; the acid pickling process is: soak the water-washed metal product in dilute sulfuric acid with a volume concentration of 10% at a treatment temperature of 70 °C for 15 min, and then wash with water again; the sandblasting treatment process is: after drying the acid-pickled metal product, use white corundum with 150 meshes at a sandblasting pressure of 0.5 MPa and a sandblasting angle of 45° for treatment.

[0049] After drying the enamel blank, it is preheated at 75°C for 30 minutes, then heated at a rate of 10°C / min to 200°C and held for 2 hours, and then heated at a rate of 10°C / min to 300°C and held for 1 hour to obtain the crude enamel.

[0050] The process of high-temperature sintering is as follows: The crude enamel is heated at a rate of 15°C / min to 850°C, held for 10 minutes, and then cooled at a rate of 15°C / min to 500°C; the crude enamel after high-temperature sintering is maintained at a treatment temperature of 500°C for 3 hours and then cooled to 25°C at a cooling rate of 1°C / min to obtain the enamel product.

[0051] In Examples 1-5, the water quenching temperature is 10°C; in Examples 6-10, the water quenching temperature is 15°C; in Examples 11-20, the water quenching temperature is 15°C

[0052] In Examples 1-5, the holding time at the high-temperature melting temperature is 60 minutes; in Examples 6-10, the holding time at the high-temperature melting temperature is 80 minutes; in Examples 11-15, the holding time at the high-temperature melting temperature is 100 minutes; in Examples 16-20, the holding time at the high-temperature melting temperature is 120 minutes.

[0053] Compared with Example 1, in Examples 2-20, other operating parameters are different, the colors used are also different, and the process steps are exactly the same. The changes in parameters and color selections are summarized in Tables 1 and 2.

[0054] Table 1 Changes in operating parameters of Examples 1-20 (I)

[0055]

[0056] Table 2 Changes in operating parameters of Examples 1-20 (II) and color selections

[0057]

[0058] The selection of colors can be carried out arbitrarily according to the pattern requirements, and these examples are only used as verification standards for color uniformity and pattern fineness.

[0059] Comparative Example 1

[0060] Different from Example 1, the acid leaching pretreatment step is omitted, and only degreasing and water washing are carried out, and other process parameters are the same.

[0061] Comparative Example 2

[0062] Different from Example 1, phosphoric acid with an equal molar concentration is used instead of sulfuric acid during the acid leaching process, and other process parameters are the same.

[0063] Comparative Example 3

[0064] Different from Example 1, no stabilizer was added, and other process parameters were the same.

[0065] Comparative Example 4

[0066] Different from Example 6, lithium carbonate was not added to the flux, and other process parameters were the same.

[0067] Comparative Example 5

[0068] Different from Example 6, only the first-stage pre-sintering was carried out during the staged low-temperature pre-sintering, and other process parameters were the same.

[0069] Comparative Example 6

[0070] Different from Example 6, the temperature of the high-temperature sintering was reduced to 800 °C, and other process parameters were the same.

[0071] Comparative Example 7

[0072] Different from Example 11, the magnetic field strength during the magnetic separation process was reduced to 0.05 Tesla, and other process parameters were the same.

[0073] Comparative Example 8

[0074] Different from Example 11, the mass ratio of water to isopropanol in the dispersion medium was changed to 1:1, and other process parameters were the same.

[0075] Comparative Example 9

[0076] Different from Example 11, the cooling rate of the crystallization annealing was adjusted to 5 °C / min, and other process parameters were the same.

[0077] Comparative Example 10

[0078] Different from Example 16, the temperature of the water quenching cooling was changed to 50 °C, and other process parameters were the same.

[0079] Comparative Example 11

[0080] Different from Example 16, the addition amount of the flux was changed to 0.1% of the total mass of the glass melt, and other process parameters were the same.

[0081] Comparative Example 12

[0082] Different from Example 16, the temperature during the high-temperature melting process was reduced to 1100 °C, and other process parameters were the same.

[0083] Experimental Example 1

[0084] The color uniformity and Mohs hardness of the enamel products prepared in Examples 1-5 and Comparative Examples 1-3 were tested, and the relevant data are summarized in Table 3.

[0085] The test method for color uniformity was as follows: The Lab values of the same-color points on the surface of the enamel product spaced 2 cm apart were measured using a color difference meter. 10 groups of points were randomly selected and their respective △E values were calculated, and the average value of these △E values was taken as the color uniformity of the sample.

[0086] The test method for Mohs hardness was as follows: The hardness of the surface of the enamel product was determined using a Mohs hardness tester, and the range between two standard values was taken as the Mohs hardness of the enamel product.

[0087] Table 3 Color uniformity and Mohs hardness of the enamel products prepared in Examples 1-5 and Comparative Examples 1-3

[0088] △E Mohs hardness Example 1 0.8 6-7 Example 2 0.9 6-7 Example 3 0.8 6-7 Example 4 0.9 6-7 Example 5 1.0 6-7 Comparative Example 1 1.4 5-6 Comparative Example 2 2.2 5-6 Comparative Example 3 3.7 6-7

[0089] As shown in the color uniformity and Mohs hardness data in Table 3, the color uniformity of the enamel products in Examples 1-5 (△E value is 0.8-1.0) is significantly better than that in Comparative Examples 1-3 (△E value is 1.4-3.7), and the Mohs hardness of the examples stably reaches 6-7 levels. In Comparative Example 1, the acid leaching pretreatment was omitted, resulting in a decrease in color uniformity, with a △E value of 1.4 and a Mohs hardness of 5-6. In Comparative Example 2, phosphoric acid was used instead of sulfuric acid for acid leaching, and the color uniformity decreased significantly, with a △E value of 2.2 and a Mohs hardness of 5-6. In Comparative Example 3, no stabilizer was added, and the color uniformity decreased significantly, with a △E value of 3.7 and a Mohs hardness of 6-7. The above results show that the pretreatment of the metal surface, the selection of acid during acid leaching, and the addition of stabilizer act together to significantly improve the bonding strength, color uniformity, and hardness of the enamel coating. The pretreatment provides a clean and rough bonding surface for the enamel layer through steps such as degreasing, water washing, acid leaching, and sandblasting; sulfuric acid acid leaching can effectively remove the oxides on the metal surface; the stabilizer improves the structural stability and color uniformity of the enamel layer by promoting crystal growth. The synergistic effect of these processes and methods is the key to obtaining high-performance enamel products.

[0090] Experimental Example 2

[0091] The color uniformity of different color regions of the enamel products prepared in Examples 6-10 and Comparative Examples 4-6 was tested, and the relevant results are summarized in Table 4.

[0092] The test method for color uniformity refers to Experimental Example 1.

[0093] Table 4 Color uniformity of the enamel products prepared in Examples 6-10 and Comparative Examples 4-6

[0094] ΔE in the blue region ΔE in the green region Example 6 0.7 0.9 Example 7 0.8 0.8 Example 8 0.8 1.0 Example 9 0.8 0.9 Example 10 1.0 0.8 Comparative Example 4 3.2 2.7 Comparative Example 5 2.4 4.5 Comparative Example 6 3.8 1.7

[0095] As shown in the color uniformity data in Table 4, the color uniformity ΔE values of the enamel products prepared in Examples 6 - 10 in the blue region are 0.7 - 1.0, and the color uniformity ΔE values in the green region are 0.8 - 1.01. In Comparative Example 4, lithium carbonate was not added, the ΔE value in the blue region was 3.2, and the ΔE value in the green region was 2.7. In Comparative Example 5, only the first - stage pre - sintering was carried out during the staged low - temperature pre - sintering, the ΔE value in the blue region was 2.4, and the ΔE value in the green region was 4.5. In Comparative Example 6, the high - temperature sintering temperature was reduced to 800 °C, the ΔE value in the blue region was 3.8, and the ΔE value in the green region was 1.7. The above results show that the addition of lithium carbonate in the flux, the staged low - temperature pre - sintering process, and the appropriate high - temperature sintering temperature act together to significantly improve the color uniformity of the enamel coating. Lithium carbonate promotes the uniform distribution of metal oxides by providing ionic polarization; the staged low - temperature pre - sintering can effectively remove the organic carrier and create conditions for high - temperature sintering; high - temperature sintering enables the full diffusion and uniform distribution of metal oxides in the glass phase, jointly ensuring good color uniformity of the enamel products in different color regions.

[0096] Experimental Example 3

[0097] The Mohs hardness and color durability of the enamel products prepared in Examples 11 - 15 and Comparative Examples 7 - 9 were tested. The relevant results are summarized in Table 5.

[0098] The test method for Mohs hardness refers to Experimental Example 1.

[0099] The test method for color durability is the acid - immersion aging test method. Specifically: record the initial ΔE of the enamel product sample, spray it with an aqueous solution of hydrogen chloride with a mass concentration of 10%, and then place it in a dark and airtight environment. After being placed at a temperature of 25 °C and a humidity of 50% for 72 hours, test ΔE again. The ΔE increment before and after the test is used as the representation parameter of color durability. The larger the ΔE increment, the worse the color durability.

[0100] Table 5 Hardness and color durability of the enamel products prepared in Examples 11 - 15 and Comparative Examples 7 - 9

[0101]

[0102]

[0103] As shown in the hardness and color durability data in Table 5, the Mohs hardness of the enamel products prepared in Examples 11-15 is 6-7, and the color durability ΔE increment is 0.3-0.5. In Comparative Example 7, the magnetic field strength during the magnetic separation process is reduced to 0.05 Tesla, the Mohs hardness is 5-6, and the color durability ΔE increment is 1.3. In Comparative Example 8, the mass ratio of water and isopropyl alcohol in the dispersion medium is changed to 1:1, the Mohs hardness is 6-7, and the color durability ΔE increment is 0.8. In Comparative Example 9, the cooling rate of crystallization annealing is adjusted to 5 °C / min, the Mohs hardness is 4-5, and the color durability ΔE increment is 1.1. The above data show that the combined action of appropriate magnetic separation magnetic field strength, dispersion medium ratio, and crystallization annealing cooling rate can significantly improve the hardness and color durability of the enamel coating. Magnetic separation removes impurities and improves the purity of the enamel powder; the dispersion medium ensures the uniform dispersion of metal oxides; crystallization annealing promotes crystal growth and improves structural stability. The synergistic effect of the three together improves the hardness and color durability of the enamel layer of the enamel products.

[0104] Experimental Example 4

[0105] The boundary clarity and color uniformity of the enamel product patterns prepared in Examples 16-20 and Comparative Examples 10-12 were tested, and the relevant results are summarized in Table 6.

[0106] The test method for color uniformity refers to Experimental Example 1.

[0107] The test method for the boundary clarity of the pattern is as follows: Use an optical microscope to observe the color transition area of the color edge of the surface pattern of the enamel product and measure its width. The larger the width W (μm) of the transition area, the worse the boundary clarity.

[0108] Table 6 Color uniformity and boundary clarity of the enamel products prepared in Examples 16-20 and Comparative Examples 10-12

[0109]

[0110]

[0111] As shown in the color uniformity and boundary clarity data of Table 6, the color uniformity △E value of the enamel products prepared in Examples 16-20 is 0.8-1.1, and the pattern boundary clarity W value is 8-11μm. In Comparative Example 10, the water quenching cooling temperature is changed to 50°C, the color uniformity △E value is 1.7, and the pattern boundary clarity W value is 40μm. In Comparative Example 11, the amount of flux added is changed to 0.1% of the total mass of the glass melt, the color uniformity △E value is 2.9, and the pattern boundary clarity W value is 35μm. In Comparative Example 12, the temperature during the high-temperature melting process is reduced to 1100°C, the color uniformity △E value is 1.2, and the pattern boundary clarity W value is 72μm. The above data show that the temperature of water quenching cooling is crucial to improving the color uniformity and pattern boundary clarity of the enamel coating. The internal stress of the basic enamel powder is increased by high-temperature melting and water quenching cooling, the local agglomeration of the silicon-oxygen network is avoided in the subsequent high-temperature sintering process, and the bubbles inside the enamel glaze layer are eliminated by the decomposition effect of the flux, ensuring the precise control of the distribution range of the metal oxide powder, improving the boundary clarity of the pattern, and ensuring the high uniformity of the color distribution on the enamel products; the appropriate amount of flux added can effectively eliminate the bubbles inside the enamel glaze layer, ensure the precise control of the distribution range of the metal oxide powder, thereby improving the boundary clarity of the pattern and ensuring the high uniformity of the color distribution on the enamel products. Too little flux added will cause bubbles to remain, affecting the color uniformity and boundary clarity. High-temperature melting can fully mix the components, improve the uniformity of the melt, and thus improve the boundary clarity. Too low a temperature will cause uneven mixing of the components, affecting the boundary clarity.

[0112] In summary, the combined effect of water quenching cooling temperature, flux addition amount and high temperature melting temperature can significantly improve the color uniformity and pattern boundary clarity of the enamel coating. Water quenching cooling increases internal stress, flux eliminates bubbles, accurately controls the distribution of metal oxides, and high temperature melting ensures that the components are fully mixed, which together significantly improves the color uniformity and pattern boundary clarity of enamel products.

[0113] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A metal product enamel process capable of uniformly coloring, characterized in that: The enamel process is as follows: The glass former, flux, stabilizer and refining agent are mixed and melted at high temperature to obtain a glass melt; The glass melt is poured into water at 10-20° C. to break it into particles, thereby obtaining enamel fines; Grinding and magnetically separating the enamel fine material to obtain basic enamel powder; uniformly dispersing metal oxide powder in a dispersion medium to obtain a dye suspension; Dispersing and mixing the dyeing suspension and the basic enamel powder to obtain dyeing enamel powder; Pre-treating the surface of the metal product, and printing the dyed enamel powder onto the pre-treated surface by screen printing to obtain an enamel blank; The enamel blank is pre-fired at low temperature in stages to obtain rough enamel; The crude enamel is sintered at a high temperature and then subjected to crystallization annealing to obtain an enamel product.

2. The uniformly colored metal product enamel process according to claim 1, characterized in that: The glass former includes silicon dioxide and boric acid; the flux includes sodium carbonate, potassium carbonate and lithium carbonate; the added mass ratio of the glass former, the flux and the stabilizer is 5:2-3.2:1-1.5; the added mass ratio of silicon dioxide and the boric acid is 2.5:1-2.

3. The uniformly colored metal product enamel process according to claim 1, characterized in that: The stabilizer is alumina; the refining agent is potassium nitrate; the high-temperature melting process is: heating the mixed glass former, flux, stabilizer and refining agent to 1200-1270°C, stirring at a stirring speed of 100 rpm during the melting process, and maintaining for 60-120 minutes to obtain the glass melt.

4. The uniformly colored metal product enamel process according to claim 1, characterized in that: The grinding and magnetic separation process is as follows: grinding the enamel fine material to 200 meshes at a water-to-material ratio of 0.5-1, and then performing magnetic separation at a magnetic field strength of 0.1-0.5 Tesla to remove magnetic impurities to obtain the basic enamel powder.

5. The uniformly colored metal product enamel process according to claim 1, characterized in that: The metal oxide powder includes: zirconium oxide powder, chromium oxide powder, copper oxide powder, iron oxide powder, manganese oxide powder, ferroferric oxide powder and tin oxide powder; the pretreatment process is: degreasing, washing and acid immersing the surface of the metal product, and then sandblasting; the screen printing process is: covering the metal product with a screen with a preset pattern, applying the dyed enamel powder on the screen according to the color designed by the pattern, and transferring the dyed enamel powder to the surface of the metal product through the mesh to obtain an enamel blank.

6. The uniformly colored metal product enamel process according to claim 1, characterized in that: The process of staged low-temperature pre-firing is as follows: after the enamel body is dried, it is preheated at 75-90°C for 30 minutes, then heated to 200°C at a heating rate of 10°C / min, kept warm for 2 hours, then heated to 300°C at a heating rate of 10°C / min, kept warm for 1 hour, to obtain the rough enamel.

7. The uniformly colored metal product enamel process according to claim 1, characterized in that: The high temperature sintering process is: heating the crude enamel to 850-950°C at a heating rate of 15-20°C / min, keeping the temperature for 10 minutes, and then cooling it to 500°C at a cooling rate of 15°C / min.

8. The uniformly colored metal product enamel process according to claim 1, characterized in that: The process of the crystallization annealing is: the rough enamel that has been sintered at high temperature is kept at a treatment temperature of 500° C. for 3-5 hours, and then cooled to 25° C. at a cooling rate of 1° C. / min to obtain the enamel product.

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