A cast iron enamel pot enamel primer and low temperature enamel preparation method

Abstract

The application discloses a cast iron enamel pot enamel bottom glaze and low-temperature enamel preparation method, which comprises the following steps: cast iron pot pretreatment, oil removal of the cast iron sample to be enameled by high-temperature carbonization, and removal of surface impurities by a shot blasting machine; preparation of glaze, including preparation of bottom glaze and preparation of surface glaze; low-temperature enamel, including bottom glaze enamel and surface glaze enamel, wherein the bottom glaze enamel comprises spraying the prepared bottom glaze on the cast iron sample to be enameled by a spray gun tool, drying, edge wiping treatment, and low-temperature sintering at 780-790 DEG C. The application can reduce the sintering temperature of the enamel glaze under the condition of ensuring the chemical stability of the enamel glaze, has the bonding strength between the bottom glaze and the cast iron pot by using the low-temperature enamel, solves the exhaust problem during sintering of the cast iron, saves energy resources, reduces the manufacturing cost, is beneficial to production, can not only maintain the original functional characteristics of the cast iron pot, but also prolongs the service life of the cast iron pot by using the enamel layer and improves the comfort of users.

Description

Technical Field

[0001] This invention relates to the field of production and manufacturing technology of cast iron enamel pots, and in particular to an enamel base glaze material and a method for preparing low-temperature enamel for cast iron enamel pots. Background Technology

[0002] With rapid economic development and a significant improvement in living standards, consumers are increasingly pursuing healthy living and delicious food. Cast iron enamel pots, as a traditional and safe cookware, have emerged as a popular choice in both domestic and international cookware markets. Made with cast iron and enamel, they are healthy and environmentally friendly, offering excellent cooking and usability, such as safety, heat retention, non-stick properties, and easy cleaning. However, due to the high carbon content of the base material, cast iron enamel pots have poor adhesion to the enamel, often resulting in enamel chipping and peeling. This not only affects the user experience but also requires additional enamel recoating during manufacturing, increasing manpower and resources and reducing production efficiency, thus significantly increasing the production cost of cast iron enamel pots.

[0003] Existing cast iron enamel pots are prone to porosity during the casting process. Porosity reduces the effective load-bearing area and causes stress concentration around the pores, decreasing the pot's impact and fatigue resistance. Furthermore, porosity reduces the casting's density, affecting its corrosion and heat resistance. Traditional enamel formulations, applying ordinary enamel techniques and enamels directly to cast iron enamel, hinder gas escape, resulting in numerous pores in the enamel layer and preventing the formation of a qualified enamel layer. Additionally, traditional enamel sintering temperatures reach highs of 840–850℃, making it difficult to reduce gas generation during sintering and wasting energy resources. Summary of the Invention

[0004] To address the issues of venting and energy waste associated with high-temperature enamel coatings in existing cast iron enamel pots, this invention provides an enamel base glaze and a low-temperature enamel preparation method for cast iron enamel pots. The improved enamel base glaze formula lowers the firing temperature of the enamel while ensuring its chemical stability. This low-temperature enamel method achieves good bonding between the enamel glaze and the cast iron pot with minimal deformation, thus saving energy and resources.

[0005] To achieve the above objectives, the present invention employs the following technical solution: an enamel base glaze for cast iron enamel pots, wherein the enamel glaze powder of the enamel base glaze comprises the following components by weight percentage:

[0006] SiO2 45-50%;

[0007] B2O3 10-15%;

[0008] Al2O3 10-15%;

[0009] CaF2 4-8%;

[0010] Na2B4O7·10H2O 2~5%;

[0011] BaMoO4 0.1–0.5%;

[0012] Na2O 3-10%;

[0013] KCl 3-10%;

[0014] Li2O 3-5%;

[0015] TiO2 3-5%;

[0016] CoO 0.1%–1%;

[0017] NiO 2-5%.

[0018] Preferably, the enamel base glaze includes the step of preparing enamel frit:

[0019] Weigh the raw materials according to the weight percentage of each component of the enamel glaze powder;

[0020] Mix the raw materials and pass them through a 60-80 mesh standard sieve;

[0021] The sieved raw material is placed in a crucible furnace and melted at a firing temperature of 1100-1200℃ for 1-2 hours to obtain enamel glaze.

[0022] The enamel glaze is quenched in water to form enamel flocs, which are then dried and set aside for later use.

[0023] Preferably, the enamel base glaze further includes a base glaze preparation step:

[0024] The dried enamel frit is ball-milled and vibrated, and then passed through a 30-60 mesh sieve to obtain base glaze powder. It is then poured into a beaker and the base glaze powder in the beaker is initially stirred evenly with a glass rod.

[0025] Divide the base glaze powder evenly into two ball mill jars, add the required amount of water, and mix them in a ball mill. The ratio of base glaze powder to water is 2:1 by weight.

[0026] Pour the mixed glaze into a 60-80 mesh sieve and vibrate it to obtain the base glaze.

[0027] On the other hand, the present invention provides the following technical solution: a method for preparing low-temperature enamel enamel for cast iron enamel pots, comprising the following steps:

[0028] For the pretreatment of cast iron pots, high-temperature carbonization is used to degrease the cast iron samples to be enamel-lined, and shot blasting is used to remove surface impurities.

[0029] The preparation of glazes includes the preparation of a base glaze and the preparation of a top glaze, wherein the base glaze is an enamel base glaze of a cast iron enamel pot as described above.

[0030] Low-temperature enamel includes base enamel and top enamel, among which:

[0031] The base enamel process involves spraying the prepared base enamel material onto the cast iron sample to be enamelted using a spray gun, drying, wiping the edges, and then sintering at a low temperature of 780–790°C.

[0032] The surface enamel process involves spraying the prepared surface enamel material onto the enamel cast iron sample with the completed base enamel using a spray gun, followed by drying, edge wiping, and low-temperature sintering at 760–770℃.

[0033] Preferably, the base enamel glaze further includes the following steps:

[0034] Pour the prepared base glaze into the cleaned spray gun, and place the cast iron sample to be enamelized on the spraying work stand. Apply glaze to both sides so that the enamel on the cast iron sample to be enamelized forms a non-glass transition layer.

[0035] The coated cast iron sample was placed in a drying oven to dry in order to remove moisture from the enamel after coating.

[0036] Use a knife to clean the edges of the cast iron sample to remove any residue;

[0037] The dried and edge-brushed cast iron samples are placed in a sintering furnace for sintering. The sintering settings include an initial sintering temperature of room temperature, a sintering heating time of 20-30 minutes, a sintering temperature of 780-790℃, a sintering time of 10-12 minutes, and a sintering end temperature of 780-790℃.

[0038] Preferably, the prepared glaze material comprises:

[0039] Weigh the following raw materials for the first glaze by weight: 100 parts transparent glaze, 4-6 parts clay, 3-5 parts pigment, 0.2-0.5 parts potassium chloride, and 45-50 parts water.

[0040] The transparent glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding.

[0041] The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the first glaze powder.

[0042] Add clay, pigment, and potassium chloride to the first glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill.

[0043] Pour the mixed first glaze material into a 60-80 mesh sieve and vibrate to obtain the first glaze material.

[0044] Preferably, the prepared glaze material comprises:

[0045] Weigh the following second glaze materials by weight: 100 parts matte glaze, 4-6 parts clay, 0.2-0.3 parts borax, 0.3-0.5 parts sodium nitrite, 4-6 parts melanin, and 45-50 parts water.

[0046] The matte glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding.

[0047] The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the second glaze powder.

[0048] Add clay, borax, sodium nitrite, and melanin to the second glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill.

[0049] Pour the mixed second glaze material into a 60-80 mesh sieve and vibrate to obtain the second glaze material.

[0050] Preferably, the surface enamel includes a first surface enamel and a second surface enamel:

[0051] The first enamel glaze includes spraying the first enamel material onto the enamel cast iron sample with the base enamel glaze using a spray gun, drying, wiping the edges, and sintering at a low temperature of 760-770℃.

[0052] The second enamel coating process involves spraying the second enamel material onto the enamel cast iron sample that has undergone the first enamel coating process using a spray gun, followed by drying, edge wiping, and low-temperature sintering at 760–770°C.

[0053] Preferably, the surface enamel includes the following steps:

[0054] Pour the first or second glaze into the cleaned spray gun, and place the enamel cast iron sample to be sprayed on the spraying work stand, and glaze both sides.

[0055] The coated enamel cast iron sample was placed in a drying oven to dry in order to remove the moisture from the enamel glaze.

[0056] Use a small knife to clean the edges of the enamel cast iron sample to remove any residue.

[0057] After drying and edge-wiping, the enamel cast iron sample is placed in a sintering furnace for sintering so that the surface glaze fuses at high temperature to form a smooth and flat vitreous porcelain layer. The sintering settings include an initial sintering temperature of room temperature, a sintering heating time of 20-30 minutes, a sintering temperature of 760-770℃, a sintering time of 10-15 minutes, and a sintering end temperature of 760-770℃.

[0058] Preferably, the base enamel is applied to both sides of the cast iron sample to be enamelized. The cast iron sample to be enamelized includes at least a pot body, a pot lid, and a handle. The thickness of the base enamel formed by the double-sided enamel application is 50-100 μm on the inner surface of the pot body and the inner surface of the pot lid, 70-150 μm on the outer surface of the pot body and the outer surface of the pot lid, 20-40 μm on the edge of the pot lid, and 20-200 μm on the inner side of the handle.

[0059] Preferably, the top glaze is applied to the enamel cast iron sample after the base glaze has been applied. The enamel cast iron sample includes at least a pot body, a pot lid, and a handle. The thickness of the top glaze is as follows: 150-300 μm on the inner surface of the pot body and the inner surface of the pot lid; 200-400 μm on the outer surface of the pot body and the outer surface of the pot lid; 50-100 μm on the edge of the pot lid; and 50-600 μm on the inner side of the handle.

[0060] Preferably, the cast iron sample to be enamelized is made of hot-rolled enamel-coated steel plate with a thickness of 1.5–3.0 mm; after low-temperature enamel enamel lining, a cast iron enamel-coated pot is obtained, wherein the enamel layer thickness on the inner surface of the pot body and the inner surface of the lid is 200–400 μm, the enamel layer thickness on the outer surface of the pot body and the outer surface of the lid is 300–500 μm, the enamel layer thickness on the edge of the lid is 100–150 μm, and the enamel layer thickness on the inner side of the handle is 100–1000 μm.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] This invention uses B2O3 and TiO2, which have similar chemical stability to SiO2 and Al2O3 but lower sintering temperatures, to replace part of SiO2 and Al2O3 in the enamel base glaze. This reduces the firing temperature of the enamel while ensuring its chemical stability. Furthermore, by using appropriate amounts of low-melting-point fluorite and barium molybdate, the high-temperature fluidity and adhesion of the enamel base glaze are increased, resulting in good bonding between the enamel glaze and the cast iron pot with minimal deformation.

[0063] This invention uses low-temperature enamel, which gives the base enamel a strong bond with the cast iron pot. It also solves the problem of venting during the sintering of cast iron. Low-temperature enamel can save energy and resources, reduce manufacturing costs, and facilitate production. It can not only maintain the original functional characteristics of the cast iron pot, but also extend its service life and improve user comfort by using the enamel layer. Attached Figure Description

[0064] To more clearly illustrate the technical solution, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0065] Figure 1 This is a schematic diagram of the low-temperature enamel preparation method in the embodiment. Detailed Implementation

[0066] In order to clearly and completely understand the technical solution, the present invention will be further described in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0068] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0069] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0070] One embodiment of the present invention provides an enamel base glaze for cast iron enamel pots, effectively reducing the firing temperature of enamel and ensuring the chemical stability of the enamel glaze. In traditional enamel glazes, SiO2 and Al2O3 are the main network components, offering advantages such as structural stability and improved chemical stability, but also high firing temperatures. This embodiment uses B2O3 and TiO2, which have similar chemical stability but lower sintering temperatures, to replace some of the SiO2 and Al2O3. Furthermore, regardless of whether it is a solvent-based or water-based coating, titanium dioxide plays not only a masking and decorative role, but more importantly, an important role in improving the physicochemical properties of the coating and enhancing its chemical stability. Specifically, the enamel glaze powder in the enamel base glaze of this embodiment, by weight percentage, includes the following components:

[0071] SiO2 45-50%;

[0072] B2O3 10-15%;

[0073] Al2O3 10-15%;

[0074] CaF2 4-8%;

[0075] Na2B4O7·10H2O 2~5%;

[0076] BaMoO4 0.1–0.5%;

[0077] Na2O 3-10%;

[0078] KCl 3-10%;

[0079] Li2O 3-5%;

[0080] TiO2 3-5%;

[0081] CoO 0.1%–1%;

[0082] NiO 2-5%.

[0083] In this embodiment, to increase the high-temperature fluidity of the enamel base glaze, a small amount of low-melting-point fluorite is added, namely 4-8% CaF2. Based on this embodiment, adding excessive fluoride will cause the sintered surface to contain burrs, making it susceptible to acid corrosion, while adding too little will result in poor fluidity at high temperatures and the formation of copper spots.

[0084] In this embodiment, barium molybdate is added as one of the adhesion agents, which can promote the impregnation of the glaze melt onto the metal surface, and its cost is relatively low. Therefore, in this embodiment, 0.1-0.5% BaMoO4 is added, which can effectively enhance the adhesion of the base glaze and prevent the formation of fish scale.

[0085] It should be noted that cast iron enamel pots use a wide variety of enamel glazes with corresponding sintering temperatures. Traditional cast iron enamel pots generally use three types of enamel base glaze and top glaze. If the sintering temperature is not properly controlled, the following problems will occur: If the sintering temperature of the enamel product is too high, the powder blank will heat up too quickly, resulting in defects such as external boiling and internal burning or external scorching and internal burning. It may also lead to incomplete physicochemical reactions of the enamel glaze, poor adhesion, cold cracking, and pores in the enamel layer, thus affecting the acid resistance, gloss, and other physicochemical properties of the enamel product. If the sintering temperature is too low, although the temperature difference between the inside and outside of the enamel product is reduced, the final molten viscosity of the enamel layer surface is relatively high, and the bubbles in the enamel layer are not easy to escape. The deposition rate of cobalt and nickel adhesives at the interface between the iron blank and the base glaze, as well as the dissolution, diffusion, and penetration reaction of FeO, are slow, resulting in defects such as poor adhesion, cracking, black lines, and mesh bubbles. At the same time, because the powder layer does not reach complete melting, the enamel surface is rough, and the gloss, resistance to rapid temperature changes, and chemical stability are relatively poor.

[0086] To avoid the aforementioned phenomena, this embodiment uses B2O3 and TiO2, which have similar chemical stability to SiO2 and Al2O3 but lower sintering temperatures, to replace part of the SiO2 and Al2O3 in the enamel glaze powder. This effectively lowers the sintering temperature, results in a low softening point, and is suitable for low-temperature enamel, saving energy. Using the enamel base glaze of this embodiment for low-temperature enamel can prevent the decomposition of iron carbide in cast iron into iron oxide and gases such as carbon monoxide and carbon dioxide at excessively high sintering temperatures, thus avoiding the formation of pores and bubbles in the enamel layer. Simultaneously, this embodiment increases fluidity by adding an appropriate amount of fluoride, resulting in a low viscosity (100.5–103.5 Pa·s) for the enamel base glaze. It should be noted that if the glaze viscosity is too high, it is difficult to flow, small bubbles are difficult to expel, and ripples are likely to appear on the glaze surface; if it is too low, it will cause glaze flow, uneven glaze thickness, or even glaze defects.

[0087] To better understand this, let's further explain why traditional enamel formulations, which directly apply ordinary enamel techniques and enamel powders to cast iron enamel, result in numerous pores in the enamel layer. Porosity is easily generated during the casting process of cast iron, thus affecting the performance of the casting. Because cast iron requires good casting performance and high strength, the carbon content in the cast iron blank is between 2.11% and 4.3%. During firing, the main reactions include: Fe3C + O2 → FeO + CO↑, Fe3C + O2 → FeO + CO2↑, etc., which generate a large amount of gases during high-temperature sintering, such as toxic gases like carbon monoxide, sulfur dioxide, and nitrogen dioxide. These gases not only endanger the personal safety of operators but also fail to escape in time before the molten metal forms a crust, thus forming pores. Porous cast iron pots will have reduced effective load-bearing area, and stress concentration will occur around the pores, reducing the impact resistance and fatigue resistance of the cast iron pot; at the same time, pores will also reduce the density of the casting, affecting its corrosion resistance and heat resistance. The enamel base glaze in this embodiment has a low softening point, making it suitable for low-temperature enamel. Within the softening point and sintering range, it facilitates gas discharge.

[0088] Obviously, the embodiments described above are only some embodiments of the present invention, and not all embodiments. To better understand the enamel base glaze of cast iron enamel pots, the preparation of the above-mentioned enamel base glaze is described below with reference to embodiments, but this is not intended to limit the technical solutions of the embodiments of the present invention. Specifically:

[0089] In an optional embodiment, the enamel base glaze includes the step of preparing enamel frit:

[0090] Weigh the raw materials according to the weight percentage of each component of the enamel glaze powder;

[0091] Mix the raw materials and pass them through a 60-80 mesh standard sieve;

[0092] The sieved raw material is placed in a crucible furnace and melted at a firing temperature of 1100-1200℃ for 1-2 hours to obtain enamel glaze.

[0093] The enamel glaze is quenched in water to form enamel flocs, which are then dried and set aside for later use.

[0094] The enamel frit is obtained through the above steps, and the enamel base glaze also includes a base glaze preparation step:

[0095] The dried enamel frit is ball-milled and vibrated, and then passed through a 30-60 mesh sieve to obtain base glaze powder. It is then poured into a beaker and the base glaze powder in the beaker is initially stirred evenly with a glass rod.

[0096] The base glaze powder is then divided equally into two ball mill jars, and the required amount of water is added. The mixture is then placed in a ball mill and mixed. The ratio of base glaze powder to water is 2:1 by weight, and the specific gravity of the glaze slurry is 1.68 to 1.74.

[0097] Pour the mixed glaze into a 60-80 mesh sieve and vibrate it to obtain the base glaze.

[0098] In some embodiments, since the enamel process requires controlling and adjusting the adsorption amount of the glaze slurry to 18-22g, if there is a deviation in the adhesion amount during the preparation of the glaze, such as if the adhesion amount is too small, it will affect the reaction between sodium pyrophosphate (Na2P2O7) and Cu. 2+ Fe 3+ Mn 2+ If the metal ions have strong complexing ability and colloidal properties, sodium pyrophosphate can be used to increase the amount of glaze slurry adhering without changing the specific gravity; if the amount of adhering is too large, water can be added to the slurry to dilute the glaze powder and reduce it.

[0099] Furthermore, the base glaze prepared in this embodiment has the following characteristics:

[0100] 1) Low viscosity (100.5~103.5 Pa·s). If the glaze viscosity is too high, it will not flow easily, small air bubbles will not be able to escape, and ripples will easily appear on the glaze surface; if it is too low, it will cause glaze flow, uneven glaze thickness, or even glaze defects.

[0101] 2) Lower softening point. When the sintering temperature is too high, the iron carbide in the cast iron easily decomposes into iron oxide and gases such as carbon monoxide and carbon dioxide, causing pores and bubbles to form in the ceramic layer. A lower softening point, within the softening point and sintering range, facilitates the expulsion of these gases.

[0102] 3) It has good air permeability during sintering. A certain amount of calcined quartz sand and other refractory materials are added to the base glaze to create pores or gaps between the particles, which overcomes the pores and bubbles generated in the ceramic layer. Before the surface of the cast iron sample melts, there are always certain gas channels in the powder layer, allowing the gas from the metal surface and the powder layer to escape in time.

[0103] 4) It has good wettability. Good wettability ensures a strong bond between the enamel and the metal. The melt has good fluidity, low intermolecular attraction and viscosity, all of which facilitate gas discharge.

[0104] 5) At the end of sintering, the enamel glaze has good sealing properties. After the powder layer has completely melted, the melt should effectively prevent the atmosphere from directly affecting the surface of the cast iron, avoiding further decomposition and volatilization of carbides in the cast iron. After the gas escapes, the good sealing properties will close the pores, thereby avoiding the formation of open pores.

[0105] Therefore, using the enamel base glaze material of this embodiment to perform base enamel enamel on cast iron enamel pots can not only effectively avoid the generation of open pores, but also improve the bonding force between the cast iron blank and the glaze powder, resulting in a reduction in overall deformation.

[0106] On the other hand, another embodiment of the present invention provides a low-temperature enamel preparation method for cast iron enamel pots, such as... Figure 1 As shown, it includes the following steps:

[0107] For the pretreatment of cast iron pots, high-temperature carbonization is used to degrease the cast iron samples to be enamel-lined, and shot blasting is used to remove surface impurities.

[0108] The preparation of glazes includes the preparation of a base glaze and the preparation of a top glaze. The base glaze is an enamel base glaze of a cast iron enamel pot as described in the foregoing embodiment. The preparation of the top glaze includes the preparation of a first top glaze and a second top glaze.

[0109] Low-temperature enamel includes base enamel and top enamel, among which:

[0110] The base enamel process involves spraying the prepared base enamel material onto the cast iron sample to be enamelted using a spray gun, drying, wiping the edges, and then sintering at a low temperature of 780–790°C.

[0111] The surface enamel enamel process involves spraying the prepared surface enamel material onto the enamel cast iron sample with the completed base enamel using a spray gun, followed by drying, edge cleaning, and sintering at a low temperature of 760–770°C. It should be noted that in some embodiments, the sintering temperature of the surface enamel enamel (760–770°C) is set slightly lower than the sintering temperature of the base enamel enamel (780–790°C) to avoid damage to the base enamel during secondary or multiple sintering processes.

[0112] The above pretreatment steps for cast iron pots remove impurities such as oxide scale and cementite from the surface of the cast iron pots, making the surface of the cast iron samples cleaner.

[0113] In an optional embodiment, the pretreatment of the cast iron pot utilizes high-temperature carbonization (500-550°C) to degrease the cast iron sample, which ensures that the surface of the cast iron sample remains clean after pretreatment. The sample is then shot-blasted twice using a shot blasting machine, with the required results being a cleanliness Sa≥2.5, a roughness Ra≥20μm, and a roughness Rz≥3μm.

[0114] The cast iron sample includes a pot body, a pot lid, a handle, and a low-temperature enamel layer applied internally or externally by spraying or impregnation. The cast iron material is selected based on the wall thickness of the product and the required mechanical strength; gray cast iron is commonly used, but ductile iron can also be used. In this embodiment, a hot-rolled enamel-lined steel plate with a thickness of 1.5–3.0 mm is preferred, and its chemical composition meets the requirements of the table below:

[0115]

[0116] In some embodiments, smooth pores of varying sizes, shapes, and colors (white, dark-colored, or covered with oxide scale) exist inside, on, or near the surface of the cast iron sample. In this embodiment, various additives such as coal powder (3-5%), hematite powder (1.5-2%), and ammonium dioxide (1.5-2.5%) can be added during the casting process of the cast iron sample or cast iron pot. This not only prevents sand adhesion to the casting but also inhibits the reaction of interfacial moisture and the formation of subcutaneous porosity. It reduces the amount of gas absorbed by the metal during smelting, decreases the amount of gas generated by the sand mold during casting, improves the casting structure, and increases the permeability of the sand mold and core, allowing gas inside the mold to escape smoothly. In addition, 2-3% asphalt or sawdust powder can also be added.

[0117] To better understand, the above-mentioned steps for preparing the surface glaze can be implemented in various ways. In one optional embodiment, the preparation of the surface glaze includes preparing a first surface glaze and preparing a second surface glaze, wherein:

[0118] The preparation of the first glaze material includes:

[0119] Weigh the following raw materials for the first glaze by weight: 100 parts transparent glaze, 4-6 parts clay, 3-5 parts pigment, 0.2-0.5 parts potassium chloride, and 45-50 parts water. The transparent glaze is a conventional colorless and colored clear transparent glaze.

[0120] The transparent glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding.

[0121] The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the first glaze powder.

[0122] Add clay, pigment, and potassium chloride to the first glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill.

[0123] Pour the mixed first glaze material into a 60-80 mesh sieve and vibrate to obtain the first glaze material.

[0124] The preparation of the second glaze includes:

[0125] Weigh the following second glaze raw materials by weight: 100 parts matte glaze, 4-6 parts clay, 0.2-0.3 parts borax, 0.3-0.5 parts sodium nitrite, 4-6 parts melanin, and 45-50 parts water. The matte glaze is a conventional matte glaze material.

[0126] The matte glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding.

[0127] The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the second glaze powder.

[0128] Add clay, borax, sodium nitrite, and melanin to the second glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill.

[0129] Pour the mixed second glaze material into a 60-80 mesh sieve and vibrate to obtain the second glaze material.

[0130] In this embodiment, to enhance the bonding strength between the enamel glaze and the cast iron pot, the enamel glaze formulation has a significant impact on the quality of the cast iron enamel pot, including the acid resistance, alkali resistance, gloss, impact resistance, and other physicochemical properties of the finished enamel product. When formulating the glaze powder, attention must be paid to whether the thickness of the base glaze layer facilitates gas escape, whether the sintering temperature of the base glaze is appropriate, and whether it can reduce gas generation during sintering. When formulating the top glaze, factors such as opacity, surface tension, and viscosity must be considered. Using the enamel base glaze provided in the aforementioned embodiment for enamel coating of a cast iron enamel pot, a non-glass transition layer can be enamelted onto the cast iron sample, giving the enamel layer and the cast iron sample a strong bond, while simultaneously solving the venting problem during cast iron sintering.

[0131] Further, the base enamel includes the following steps: pouring the prepared base enamel material into a cleaned spray gun, and placing the cast iron sample to be enamelted on a spraying work stand, enamelting both sides so that the enamel on the cast iron sample to be enamelted forms a non-glass transition layer.

[0132] The coated cast iron sample is placed in a drying oven to remove moisture from the enamel after coating. The drying temperature of the drying oven is set to 100-130℃ and the drying time is 20-30 minutes.

[0133] Use a knife to clean the edges of the cast iron sample to remove any residue;

[0134] The dried and edge-brushed cast iron samples are placed in a sintering furnace for sintering. The sintering settings include an initial sintering temperature of room temperature, a sintering heating time of 20-30 minutes, a sintering temperature of 780-790℃, a sintering time of 10-12 minutes, and a sintering end temperature of 780-790℃.

[0135] In an optional embodiment, the cast iron sample to be enamelized includes at least a pot body, a pot lid, and a handle. The thickness of the base glaze formed by glazing on both sides is 50-100 μm on the inner surface of the pot body and the inner surface of the pot lid, 70-150 μm on the outer surface of the pot body and the outer surface of the pot lid, 20-40 μm on the edge of the pot lid, and 20-200 μm on the inner side of the handle.

[0136] In this embodiment, the surface enamel includes a first surface enamel and a second surface enamel:

[0137] The first enamel glaze includes spraying the first enamel material onto the enamel cast iron sample with the base enamel glaze using a spray gun, drying, wiping the edges, and sintering at a low temperature of 760-770℃.

[0138] The second enamel coating process involves spraying the second enamel material onto the enamel cast iron sample that has undergone the first enamel coating process using a spray gun, followed by drying, edge wiping, and low-temperature sintering at 760–770°C.

[0139] It should be noted that the enamel application steps for the first and second surface enamels are similar and will not be repeated here. Specifically, the surface enamel application includes the following steps:

[0140] Pour the first or second glaze into the cleaned spray gun, and place the enamel cast iron sample to be sprayed on the spraying work stand, and glaze both sides.

[0141] The coated enamel cast iron sample was placed in a drying oven to dry in order to remove the moisture from the enamel glaze.

[0142] Use a small knife to clean the edges of the enamel cast iron sample to remove any residue.

[0143] After drying and edge-wiping, the enamel cast iron sample is placed in a sintering furnace for sintering so that the surface glaze fuses at high temperature to form a smooth and flat vitreous porcelain layer. The sintering settings include an initial sintering temperature of room temperature, a sintering heating time of 20-30 minutes, a sintering temperature of 760-770℃, a sintering time of 10-15 minutes, and a sintering end temperature of 760-770℃.

[0144] In an optional embodiment, the top glaze is applied to the enameled cast iron sample after the base glaze has been sprayed. The thickness of the top glaze is as follows: 150-300 μm on the inner surface of the pot and the inner surface of the lid; 200-400 μm on the outer surface of the pot and the outer surface of the lid; 50-100 μm on the edge of the lid; and 50-600 μm on the inner side of the handle.

[0145] In an optional embodiment, a cast iron enamel pot is obtained after low-temperature enamel coating, wherein the enamel layer thickness on the inner surface of the pot body and the inner surface of the lid is 200-400 μm, the enamel layer thickness on the outer surface of the pot body and the outer surface of the lid is 300-500 μm, the enamel layer thickness on the edge of the lid is 100-150 μm, and the enamel layer thickness on the inner side of the handle is 100-1000 μm.

[0146] It should be noted that, in some embodiments, the enamel base glaze is used not only for cast iron enamel pots but also for the surface of other cast iron products to prevent oxidation. Various enamel additives can also be added, and standards can be modified for the manufacture of various other tableware and kitchenware.

[0147] The above disclosures are merely one or more preferred embodiments of the present invention, intended to help understand the inventive concept of the technical solution, and are not intended to limit the present invention in any other way. Any other equivalent or conventional substitution schemes made by those skilled in the art based on the features defined by the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing low-temperature enamel enamel for cast iron enamel pots, characterized in that: Includes the following steps: For the pretreatment of cast iron pots, high-temperature carbonization at 500-550℃ is used to degrease the cast iron samples to be enamel-lined, and shot blasting is used to remove surface impurities. The preparation of glazes includes the preparation of a base glaze and a top glaze. The base glaze is the enamel base glaze used in cast iron enamel pots, and by weight percentage, it comprises the following components: SiO2 45-50%; B2O3 10-15%; Al2O3 10-15%; CaF2 4-8%; Na2B4O7·10H2O 2~5%; BaMoO4 0.1–0.5%; Na2O 3-10%; KCl 3-10%; Li2O 3-5%; TiO2 3-5%; CoO 0.1%–1%; NiO 2-5%; For the base enamel, the base enamel material is sprayed onto the surface of the pre-treated cast iron sample after the cast iron pot is prepared. The enamel is applied to both sides and dried at 100–130°C for 20–30 minutes. The edges are then wiped clean. The sample is then sintered in a sintering furnace at 780–790°C for 20–30 minutes, and sintered at this temperature for 10–12 minutes to obtain an enamel cast iron sample with a non-glass transition layer. This non-glass transition layer is formed by sintering the base enamel material at 780–790°C. This transition layer is used to suppress gas escape from the cast iron matrix during subsequent top enamel sintering. The base enamel material has a viscosity of 100.5–103.5 Pa·s at the sintering temperature of 780–790°C. A surface glaze is prepared, comprising a first surface glaze and a second surface glaze. The first surface glaze is made from the following raw materials in parts by weight: 100 parts transparent glaze, 4-6 parts clay, 3-5 parts pigment, 0.2-0.5 parts potassium chloride, and 45-50 parts water. The second surface glaze is made from the following raw materials in parts by weight: 100 parts matte glaze, 4-6 parts clay, 0.2-0.3 parts borax, 0.3-0.5 parts sodium nitrite, 4-6 parts melanin, and 45-50 parts water. For the top enamel coating, the first enamel material is sprayed onto the surface of the cast iron enameled sample obtained in the base enamel coating step, dried, and edge-wiping treatment is performed. The sample is then sintered at 760–770℃ for 10–15 minutes. The second enamel material is then sprayed onto its surface, dried, and edge-wiping treatment is performed. The sample is then sintered at 760–770℃ for 10–15 minutes to obtain the final cast iron enameled pot.

2. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that, The preparation of the base glaze includes the step of preparing enamel frit: Mix the raw materials and pass them through a 60-80 mesh standard sieve; The sieved raw material is placed in a crucible furnace and melted at a firing temperature of 1100-1200℃ for 1-2 hours to obtain enamel glaze. The enamel glaze is quenched in water to form enamel flocs, which are then dried and set aside for later use. The dried enamel frit is ball-milled and vibrated, and then passed through a 30-60 mesh sieve to obtain base glaze powder. It is then poured into a beaker and the base glaze powder in the beaker is initially stirred evenly with a glass rod. Divide the base glaze powder evenly into two ball mill jars, add the required amount of water, and mix them in a ball mill. The ratio of base glaze powder to water is 2:1 by weight. Pour the mixed glaze into a 60-80 mesh sieve and vibrate it to obtain the base glaze.

3. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that, The prepared glaze material includes: Weigh out the raw materials for the first glaze; The transparent glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding. The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the first glaze powder. Add clay, pigment, and potassium chloride to the first glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill. Pour the mixed first glaze material into a 60-80 mesh sieve and vibrate to obtain the first glaze material.

4. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that, The prepared glaze material includes: Weigh out the raw materials for the second glaze; The matte glaze was evenly divided into two ball mill jars and then placed in a ball mill for fine grinding. The refined powder is poured into a 60-80 mesh sieve, placed on a vibrating sieve machine, and then sieved to obtain the second glaze powder. Add clay, borax, sodium nitrite, and melanin to the second glaze powder according to the weight proportions, then divide it evenly into two ball mill jars, add water, and mix again in a ball mill. Pour the mixed second glaze material into a 60-80 mesh sieve and vibrate to obtain the second glaze material.

5. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that: The surface enamel coating includes the following steps: Pour the first or second glaze into the cleaned spray gun, and place the enamel cast iron sample to be sprayed on the spraying work stand, and glaze both sides. The coated enamel cast iron sample was placed in a drying oven to dry it in order to remove the moisture from the enamel after coating. Use a small knife to clean the edges of the enamel cast iron sample to remove any residue. After drying and edge-wiping, the enamel cast iron sample is placed in a sintering furnace for sintering so that the surface glaze fuses at high temperature to form a smooth and flat vitreous porcelain layer. The sintering parameters are set as follows: initial sintering temperature is room temperature, sintering heating time is 20-30 min, sintering temperature is 760-770℃, sintering time is 10-15 min, and sintering end temperature is 760-770℃.

6. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that: The base enamel is applied to both sides of the cast iron sample to be enamelized. The cast iron sample to be enamelized includes at least a pot body, a pot lid, and a handle. The base enamel formed by the double-sided enamel application includes a base enamel on the inner surface of the pot body, a base enamel on the inner surface of the pot lid, a base enamel on the outer surface of the pot body, a base enamel on the outer surface of the pot lid, a base enamel on the edge of the pot lid, and a base enamel on the inner side of the handle. The thickness of the base enamel on the inner surface of the pot body and the inner surface of the pot lid is 50-100 μm, the thickness of the base enamel on the outer surface of the pot body and the outer surface of the pot lid is 70-150 μm, the thickness of the base enamel on the edge of the pot lid is 20-40 μm, and the thickness of the base enamel on the inner side of the handle is 20-200 μm.

7. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that: The surface enamel coating is applied to the enameled cast iron sample after the base enamel coating has been completed. The enameled cast iron sample includes at least a pot body, a pot lid, and a handle. The surface enamel coating formed by the surface enamel coating includes an inner surface enamel coating of the pot body, an inner surface enamel coating of the pot lid, an outer surface enamel coating of the pot body, an outer surface enamel coating of the pot lid, an edge surface enamel coating of the pot lid, and an inner surface enamel coating of the handle. The thickness of the inner surface enamel coating of the pot body and the inner surface enamel coating of the pot lid is 150-300 μm, the thickness of the outer surface enamel coating of the pot body and the outer surface enamel coating of the pot lid is 200-400 μm, the thickness of the edge surface enamel coating of the pot lid is 50-100 μm, and the thickness of the inner surface enamel coating of the handle is 50-600 μm.

8. The method for preparing low-temperature enamel enamel for a cast iron enamel pot according to claim 1, characterized in that, The cast iron sample to be enamelized is made of hot-rolled enamel steel plate with a thickness of 1.5 to 3.0 mm. After low-temperature enamel enamel treatment, a cast iron enamel pot is obtained, wherein the enamel layer thickness on the inner surface of the pot body and the inner surface of the lid is 200 to 400 μm, the enamel layer thickness on the outer surface of the pot body and the outer surface of the lid is 300 to 500 μm, the enamel layer thickness on the edge of the lid is 100 to 150 μm, and the enamel layer thickness on the inner side of the handle is 100 to 1000 μm.

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