In the present invention, the enameling temperature of the base glaze and the top glaze should differ by more than 80°C. Because the process of enamel enameling is the process of melting and releasing. If the enamel firing temperature of the base glaze and the top glaze is too low, it is easy to produce pinholes and bubbles when the top glaze is fired.
 1. Bottom glaze manufacturing and enameling process
 Weigh the chemical raw materials according to the formula listed in Figure 1, and pulverize and mix them thoroughly. When the heating temperature of the rotary furnace reaches 1200°C, the mixture is poured into the furnace, and the furnace body continues to be heated, rotated and stirred. The mixture is fully reacted and melted to form a melt. After wire drawing, knot testing, bending, etc., the molten material is poured into cold water and cooled to form a crushed glass-like crystal, which is the base glaze raw material.
 In addition, in order to expand the enamel firing range of the base glaze, to prevent burning during enamel firing. The present invention also designs the base glaze batch material. Its formula is SiO 2 40%, Al 2 O 3 5%, Na 2 O 14%, B 2 O 3 13%, CaF 2 8%, BaO 10%, NiO 1.5%, MnO 2 1.5%, Fe 2 O 3 0.7%, CaO 0.3%, P 2 O 5 3%, Pb O3%. In addition, a small amount of fine silica can be added.
 The manufacturing method of the base glaze glaze: 100 parts of the base glaze raw materials are used as the standard, then 10-15 parts of the base glaze batching material, 10 parts of clay, 5-10 parts of Fe 2 O 3 , 60 parts of water. Pour the above raw materials into a ball mill and grind. The particles of the muddy liquid formed after grinding need to be inspected by a 100-mesh fine sieve. It can be used as enamel to be evenly sprayed on the cold-rolled plate, and the thickness should be maintained at about 35-50 microns. After drying, the enamel layer is formed by sintering at 680°C to 720°C for 3 to 4 minutes in an enameling furnace.
 2. Surface glaze manufacturing and furnace lining process
 The surface glaze is divided into two categories: titanium surface glaze and antimony surface glaze. Titanium glaze is characterized by a better matt effect. But due to TiO 2 The color of the product is more difficult to adjust. The matt effect of antimony glaze is not as good as titanium glaze, but the color of the product is easier to adjust. In addition, with CeO 2 Replace TiO 2 Better toning effect, and CeO 2 The content should be kept between 8-12%.
 In the present invention, the matt effect of the top glaze depends on the composition and content of the abrasive. The traditional method in the enamel industry is grinding and adding silica to extinction. However, this method has a small enameling range and easily affects the fineness of the enamel paint film. In the present invention, fine mica or fluorite (biotite or blue mica is finally used), and a small amount of fine silica is used to achieve the delustering effect. In addition, 0.3-1% graphite is added to improve the fineness of the enamel film and the erasability of the blackboard. In addition, in order to better blend fresh and beautiful colors, the present invention adds CoO, CuO, Fe during the process of firing the antimony surface glaze. 2 O 3 , MnO 2 , Cr 2 O 3 When adding pigments, low-temperature pigments are used to make the enamel surface better colored. It uses low-temperature top glaze and high-temperature top glaze to match, with a small amount of mica, vermiculite, fluorite, and other grinding materials to achieve.
 The specific method is as follows:
 (1) Titanium surface glaze (cerium surface glaze) selects the raw materials according to the formula listed in Figure 1, and proceeds according to the production process of making the base glaze. But the temperature of firing the enamel is between 1200°C and 1250°C. Moreover, after the mixed raw materials are melted to form a melt, when the knot is drawn, the pitch of the knots is not large. That is, the enamel cannot be overfired.
Titanium surface glaze [(cerium surface glaze) namely No. 1 and No. 2 formula] manufacturing method: add the surface glaze according to 100 parts as the standard, then add 0.3-15 parts of mica powder (or add 20-50 parts of fluorite) and add 2 1 part of melanin, 1.5 part of green pigment, 0.5 part of blue pigment and 0.3 to 1 part of graphite, 6 parts of clay, 70 parts of water. Finally, these raw materials are poured into a ball mill to grind. The polished enamel liquid is tested through a 160-mesh fine sieve. Then spray it on the enamel layer after firing the bottom glaze, dry it and enter it into the enamel furnace and sinter it at 580℃~640℃ for 3~4 minutes to form the enamel layer and become the product.
 (2) Antimony surface glaze, select the raw materials according to the formula No. 5 listed in Figure 1, and proceed in accordance with the production process of making the base glaze. But the temperature of firing enamel is 1150℃~1200℃. Fire enamel should not be overheated. When the molten material is viscous, it is the raw material for surface glaze.
 In addition, select the raw materials according to the No. 3 formula listed in Figure 1. It is fired at a firing temperature of 1150°C to 1200°C. The molten material is wire-drawn, measured and out of the oven, which is the raw material of the surface glaze.
 The manufacturing method of antimony surface glaze: add 0.3-15 parts of mica, 6-7 parts of clay, 4-5 parts of pigment, 0.3-1 parts of graphite, 60 parts according to 100 parts of formula No. 3 or No. 5 ~70 parts of water. Pour these raw materials into a ball mill and grind together. After grinding, the porcelain shaft is inspected through a 160-mesh fine sieve. Then it is sprayed on the enamel layer of the sintered base glaze with a thickness of about 20-30 microns. After drying, it is sintered in an enameling furnace at 600°C-640°C for 3 to 4 minutes to form an enamel layer to become a product.
 (3) Antimony surface glaze matched with low temperature and high temperature. According to the No. 4 and No. 5 squares listed in Figure 1, the production process is carried out with the normal enamel glaze firing production process. The firing temperature of formula No. 4 is 1200°C, and the firing temperature of formula No. 5 is 1300°C to 1350°C.
 The preparation method of the enamel: take 100 parts as the standard of No. 4 formula, then add 30-60 parts of No. 5 enamel, add 6-7 parts of clay, add 0.3-10 parts of mica powder, add 4-5 parts of pigment, 0.3 to 1 part of graphite, 70 to 100 parts of water. After grinding, it becomes enamel.
 The preparation process of the glaze is as follows: a pulverize and mix the raw materials selected in the above combination; b heat and burn the mixture to form a melt, and then burn it at 1100°C to 1350°C for 30 to 60 minutes; c put the melt into cold water for cooling, Form a crushed glass-like glaze; then use a ball mill to grind into a fine powder; d Use the glaze containing the adhesive as the base glaze, add 6-10 parts of clay, 1 part of borax, and 50 parts of water to 100 parts of the glaze. Base glaze; e Use the glaze without adhesive as the top glaze, add 10 parts of clay, 25 parts of fine fluorite, 5 parts of pigment and 50 parts of water for 100 parts of the top glaze.
 The invention adopts a two-layer coating of a base glaze and a top glaze, and is completed by a two-spray and two-fire method. In order to ensure that the thermal deformation of the steel plate is within the allowable range, it is required to sinter at a temperature lower than 700°C. And it must have excellent adhesion and adhesion, and a coefficient of expansion compatible with cold-rolled sheets. Al in glaze 2 O 3 It is a component that can affect the mechanical properties of the resulting enamel layer. The glaze produced within the content range of 3 to 6% can be fired at a low temperature not exceeding 700°C and exhibits better mechanical properties. CaF 2 It is a good flux raw material, which can significantly reduce the viscosity of the melt in the enamel. Na in enamel 2 O, Li 2 O is the co-solvent in the enamel glaze. Enlarging the firing range can affect the firing temperature of the enamel, resulting in the gloss and durability of the enamel layer. BaO and PbO in the glaze are the components that affect the chemical durability, mechanical properties and thermal expansion coefficient of the enamel. PbO can significantly reduce the firing temperature of the enamel, and the combination of BaO and the adhesive plays a key role in the adhesive. B in the glaze 2 O 3 Can reduce the enamel firing temperature and the components that affect the gloss, SiO in the glaze 2 , TiO 2 It is a component that affects the chemical durability and mechanical properties of the generated enamel, and only in the present invention, the content of B 2 O 3 It can be fired at low temperature under the action of PbO and PbO. P in glaze 2 O 5 It can affect the enamel firing temperature and has a network structure to reduce the surface tension. CaF in glaze glaze 2 And TiO 2 Used together is the decisive factor for the matt effect, and CaF 2 The content is greater than TiO 2 Content to destroy TiO 2 The crystal form of the enamel has a matt effect. The joint use of these two compounds is contrary to the traditional enamel industry. At the same time, adding fine fluorite to the top glaze not only plays a matt effect, but also expands the buoyancy of the firing.
 The raw materials of the enamel frit of the present invention include: silica, feldspar, fluorite, borax, red lead, barium carbonate, lithium carbonate, saltpeter, sodium hydrogen phosphate, sodium silicofluoride, titanium oxide, magnesium oxide, cobalt oxide, nickel oxide Wait.
 First, prepare the chemical composition of the enamel glaze as shown in Figure 1: 1. Properly select the required amount from the raw materials listed above and fully crush and mix; 2. Heat and fire the resulting mixture and form a melt; 3 In the last stage of the aforementioned step 2, it is best to fire at 1100°C to 1250°C for 30 to 60 minutes; 4. Put the resulting melt into water, cool it down, and open it into a crushed glass-like glaze. Then, use the Swiss franc mill to develop it into a fine powder; 5 use the glaze containing the adhesive as the base glaze, add 10 parts of clay, 1 part of borax, and 50 parts of water to 100 parts of the glaze to form the base glaze. The glaze without adhesive is used as a top glaze, 100 parts of which are added with 10 parts of clay, 20-25 fine fluorite, 4 parts of dispersant sodium phosphate, 5 parts of pigment and 50 parts of water, are ground into a top glaze. The glaze of the present invention can be applied to ordinary steel plates. The steel plate is selected from 0.3 to 0.4 low-carbon cold-rolled plate. According to the enamel glaze ratio specified in Figure 2, the steel plate after the pickling treatment is coated with the top glaze, and then burned in the furnace at 650℃~720℃ for 3 minutes to form the bottom glaze enamel layer. After cooling, the top glaze is applied and the top glaze is applied in the furnace. The enamel layer is formed by firing at 600℃~700℃ for two minutes. The physical properties of the enamel produced are shown in Figure 2. The invention can not only make enamel blackboards and whiteboards, but can also be coated on flat plates, and can also be used on building decoration materials.