Black-matrix golden ceramic painting material based on hawksbill glaze color development, and preparation and firing methods thereof

Abstract

The invention belongs to the technical field of ceramic decorative materials, and provides a black-matrix golden ceramic painting material based on hawksbill glaze color development and a preparation and firing method thereof.The black-matrix golden ceramic painting material based on hawksbill glaze color development comprises a composite glaze component, and the composite glaze component is composed of a high-iron black glaze component and a low-iron light-colored glaze component; the high-iron black glaze comprises the following components in percentage by mass: 40-50% of feldspar, 10-20% of kaolin, 10-15% of limestone, 8-15% of iron oxide and 1-3% of manganese oxide. The low-iron light-colored glaze comprises the following components in percentage by mass: 50-60% of feldspar, 5-10% of straw ash, 10-15% of limestone and 1-3% of iron oxide. The method breaks through the randomness limitation of traditional hawksbill glaze stripes, replaces precious metal with mineral color development, realizes controllable and artistic expression of gold color patterns, has the characteristics of low cost, high temperature resistance and wear resistance, is suitable for art ceramics, domestic ceramics and building decoration tiles, and provides a new process path for ceramic decoration.

Description

Technical Field

[0001] This invention belongs to the field of ceramic decorative materials technology, and particularly relates to black-based gold-painted ceramic paint based on tortoiseshell glaze, its preparation and firing method. Background Technology

[0002] The existing tortoiseshell glaze decoration technique originates from the traditional Jizhou kiln technology. Its core process is "multi-layer glazing + high-temperature natural flow and fusion": First, a high-iron black glaze is applied to the surface of the ceramic body as a base glaze. Then, a low-iron yellow glaze is applied to the base glaze surface as a top glaze using a splashing method. The glazed body is then sent into the kiln for high-temperature firing. During the firing process, the base glaze and the top glaze flow naturally under high temperature, while simultaneously utilizing the oxidation state transformation of iron at high temperatures (…). The mutual transformation between the two and the local phase separation of the glaze ultimately form natural brownish-yellow spots on the ceramic surface. The coloring effect mainly depends on the physicochemical changes of the iron-based glaze at high temperature.

[0003] In the field of ceramic gold decoration, the mainstream techniques still use precious metals as the core material, that is, to create a golden decorative effect on the ceramic surface by applying gold leaf or brushing on gold liquid. The core principle of this technique is to use the stable chemical properties and metallic luster of gold to achieve high-end decoration of ceramics. However, because gold is a precious metal, its scarcity leads to high material costs. At the same time, the decorative layer formed by gold leaf or gold liquid has weak adhesion to the ceramic body and glaze, resulting in inherent structural defects.

[0004] The existing technology has the following problems: The formation of traditional tortoiseshell glaze patterns lacks controllability: the brownish-yellow spots of traditional tortoiseshell glaze rely entirely on the natural flow and fusion of low-iron yellow glaze on the surface of high-iron black glaze. The flow trajectory of the glaze is affected by various uncontrollable factors such as the temperature field distribution within the kiln, changes in glaze viscosity, and the angle at which the clay body is placed, resulting in highly accidental and random patterns. This randomness makes it impossible to replicate the patterns of the same batch or even the same product. It is impossible to achieve precise presentation of a pre-set pattern, and it is also difficult to meet the requirements for product consistency in industrial mass production, severely limiting its application in scenarios requiring specific pattern decoration. Traditional tortoiseshell glaze art has limited expressive power: limited by the "splashing glaze" technique, traditional tortoiseshell glaze can only form simple patterns in the form of blocks, spots, or irregular stripes. The patterns are monotonous and fixed, making it impossible to create refined artistic works. Whether it is complex patterns, regular text, or complete paintings, none of these can be achieved through traditional tortoiseshell glaze techniques. Its decorative effect remains at the level of "natural texture," lacking the space for proactive artistic expression and failing to meet the demands of modern ceramic decoration for diverse and personalized artistic effects. The precious metal gilding process has several drawbacks: First, the high price of precious metal materials such as gold leaf and gold glaze significantly increases the production cost of ceramic products using this process, limiting its widespread application in daily-use ceramics, architectural decorative tiles, and other large-scale application scenarios. Second, the bonding between the precious metal decorative layer and the ceramic body and glaze is mainly physical adhesion, resulting in poor structural stability. It is prone to falling off due to friction and collision during daily use. Furthermore, gold has limited high-temperature resistance and is prone to oxidation and discoloration in high-temperature environments, making it unsuitable for secondary firing or high-temperature use scenarios, thus greatly limiting its application scope. Therefore, it is necessary to address the above issues by using black-based gold-painted ceramic paints with tortoiseshell glaze as a base, along with their preparation and firing methods. Summary of the Invention

[0005] The purpose of this invention is to provide a black-based gold-painted ceramic coating based on tortoiseshell glaze, its preparation and firing method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a black-based gold-painted ceramic coating based on tortoiseshell glaze, comprising a composite glaze component, wherein the composite glaze component consists of a high-iron black glaze component and a low-iron light-colored glaze component; the high-iron black glaze component, by mass percentage, comprises 40-50% feldspar, 10-20% kaolin, 10-15% limestone, 8-15% iron oxide, and 1-3% manganese oxide; the low-iron light-colored glaze component, by mass percentage, comprises 50-60% feldspar, 5-10% rice straw ash, 10-15% limestone, and 1-3% iron oxide; The core composite formula system of the glaze was clearly defined. By precisely limiting the components and mass percentage range of high-iron black glaze and low-iron light-colored glaze, a two-component system of "high-iron base + low-iron color development" was constructed. Among them, the high proportion of iron oxide in the high-iron black glaze provides the material basis for the formation of the ceramic black base, and the addition of manganese oxide further assists in stabilizing the black tone. The straw ash, feldspar and limestone in the low-iron light-colored glaze work synergistically to ensure the melting characteristics of the glaze and lay the foundation for the subsequent color development of gold patterns through the low proportion of iron oxide. The synergistic combination of the two types of glazes achieves the prerequisite of "black base with gold color" at the composition level, while completely avoiding the use of precious metals, providing core support for the low-cost advantage.

[0007] A further technical solution is that the high-iron black glaze component and the low-iron light-colored glaze component are mixed to form a painting slurry, and the fineness of the painting slurry is ≥180 mesh. The fineness index of the painting paste is specified. The fineness requirement of ≥180 mesh ensures that the raw material particles of high iron black glaze and low iron light glaze are fully mixed and have uniform particle size. This avoids problems such as brush clogging and grainy lines caused by excessively large particles. At the same time, it creates good microscopic conditions for the uniform melting, phase separation and crystal precipitation of the glaze during the subsequent high-temperature firing process. It is a key structural parameter that enables the painting paste to adapt to painting operations and achieve uniform color development.

[0008] A further technical solution is that the viscosity of the drawing paste is 500-1000 mPa·s, which is suitable for brush drawing operations; The viscosity range of the drawing paste was clearly defined. The viscosity parameter of 500-1000 mPa·s was precisely optimized to ensure that the paste has sufficient fluidity to form smooth and continuous lines as the brush is dragged. At the same time, it avoids problems such as paste running and blurring of pattern boundaries due to too low viscosity, or excessive brush resistance and line breakage due to too high viscosity. It is perfectly adapted to the operation requirements of manual brush drawing and provides performance guarantee for the accurate presentation of patterns.

[0009] The preparation method of the black-based gold-painted ceramic paint based on tortoiseshell glaze coloring, applied to any of the aforementioned black-based gold-painted ceramic paints based on tortoiseshell glaze coloring, includes the following steps: S1. The raw materials of the high-iron black glaze component and the low-iron light-colored glaze component are ball-milled and mixed separately. S2. Pass the mixed raw materials through a 180-mesh sieve to obtain a uniform powder; S3. Add carboxymethyl cellulose solution to the uniform powder to prepare a slurry. A complete preparation process for the drawing ink, from raw materials to slurry, was established. The ball milling and mixing step ensured the uniform distribution of each component, avoiding uneven color development caused by local component differences. The 180-mesh sieve step strictly controlled the particle fineness, ensuring the drawing performance of the ink. The addition of carboxymethyl cellulose solution played a dual role in binding and thickening. The preset viscosity was achieved through precise slurry adjustment. The three-step process is progressive and works together to ensure the stability and consistency of the ink slurry, providing a reliable material basis for subsequent drawing operations.

[0010] In a further technical solution, in step S3, a suspending agent can be added to the drawing slurry. The suspending agent is a 20-40 wt% sucrose aqueous solution, and its addition amount is 3-6 wt% of the total amount of the drawing slurry. The performance of the ink paste has been optimized. By limiting the mass fraction (20-40wt%) and addition amount (3-6wt%) of the sucrose aqueous solution, the suspension stability problem of the ink paste during the painting process is specifically addressed. The sucrose aqueous solution can effectively reduce the settling velocity of raw material particles, ensuring the uniformity of the paste composition throughout the painting process. At the same time, its rheological properties can improve the interfacial interaction between the brush and the paste, enhance the smoothness of dragging, and avoid defects such as line accumulation and broken strokes, further optimizing the accuracy of the painting effect.

[0011] Further technical solutions also include the following steps: S4. Drawing steps: Use a brush to dip into the drawing paste and draw the preset pattern on the surface of the blank. The thickness of the drawing paste is 0.2±0.05mm. The application method and key control parameters of the painting materials were clearly defined. The brush painting method gives the pattern design a high degree of flexibility, breaking through the limitations of the traditional tortoiseshell glaze "splashing to form patterns". The painting thickness of 0.2±0.05mm was precisely calculated, which not only ensures that the amount of low iron light-colored glaze can meet the color concentration of the gold pattern, but also avoids problems such as glaze cracking and poor bonding with the glaze during the firing process due to excessive thickness. At the same time, it provides a reasonable basis for the thickness ratio of the glaze to the glaze in the later stage, which is the core operation link to achieve controllable pattern.

[0012] A further technical solution includes a glazing step after the drawing is completed: applying a glaze to the surface of the unglazed body and the drawn pattern, wherein the glaze is transparent or low-iron glaze and the thickness of the glaze is 0.6-0.8mm; The key processes for body treatment have been improved. The choice of transparent or low-iron glaze can not only avoid the interference of the glaze color itself on the color display effect of black background and gold color, but also provide physical protection for the painted pattern and prevent the pattern from being damaged during firing. The coating thickness of 0.6-0.8mm and the thickness of the painting layer form a reasonable ratio, which provides suitable space for the mutual wetting, melting and phase separation of glazes at high temperature, while enhancing the density and wear resistance of the ceramic surface and improving the overall performance of the product.

[0013] The firing method for black-based gold-painted ceramics based on tortoiseshell glaze, applied to any of the aforementioned black-based gold-painted ceramic paints based on tortoiseshell glaze and any of the aforementioned methods for preparing black-based gold-painted ceramic paints based on tortoiseshell glaze, includes the following stages: S1. Oxidize and heat to 1000℃ → switch to reducing atmosphere (C content 8-10%) and heat to 1250℃ → hold at 1250℃ for 5 minutes → cool rapidly with nitrogen to 800℃; S2. The oxidation heating to 1000℃ stage includes a heating process from room temperature to 980℃ (4 hours) and from 980 to 1000℃. The reducing atmosphere heating to 1250℃ stage includes a heating process from 1000 to 1150℃ and from 1150 to 1250℃ (1.5 hours each). A precise segmented firing process system was designed, with scientific optimization of the oxidation-reduction atmosphere transition points, temperature ranges, and firing times for each heating stage. A slow 4-hour heating process from room temperature to 980℃ ensures the complete removal of physical and chemical water from the body, allowing for pre-reaction of the glaze. Segmented heating from 980-1150℃ and 1150-1250℃ enables gradual melting and interpenetration of the glaze. The introduction of a reducing atmosphere provides the necessary conditions for the valence state transformation of iron. A 30-minute holding at 1250℃ ensures the full precipitation of crystals. Rapid nitrogen quenching quickly locks in the glaze color and crystal morphology. The entire process forms a complete reaction chain, providing technological assurance for color development and product performance.

[0014] A further technical solution involves controlling the atmosphere during the firing process to achieve the valence state conversion of iron, and to promote the combination of CaO and TiO2 in the glaze layer to precipitate CaTiO3 crystals, forming a layered color structure with a black base and gold patterns. This invention reveals the core color-developing mechanism: by controlling the atmosphere during the firing process, a stable valence state transformation of iron in the high-iron black glaze region is achieved, ensuring the uniform and stable color of the black base. Simultaneously, in the low-iron light-colored glaze region, atmosphere control promotes the full reaction of CaO and TiO2, precipitating CaTiO3 crystals with high refractive index. These crystals exhibit a stable golden luster, and the expansion difference at the glaze interface causes the golden area to float on the black glaze surface, forming a clear layered structure of "black base + gold color". This clarifies the formation path of the gold color effect from a principle perspective.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves precise control over gold-colored patterns, breaking through the randomness limitations of traditional tortoiseshell glaze. Through precise design of a composite glaze formula, high-iron black glaze and low-iron light-colored glaze are blended into a paste suitable for brush painting. Utilizing the active creative method of brush painting, the patterns are entirely determined by a pre-set design, completely eliminating the randomness of traditional tortoiseshell glaze's reliance on the natural flow of the glaze to form patterns. Simultaneously, through precise control of the painting thickness (0.2±0.05mm), glaze thickness (0.6-0.8mm), and segmented firing process, it ensures that the same design can be highly replicated on different products. This satisfies the needs of refined artistic creation while also enabling industrial mass production, solving the core problems of uncontrollable and unreplicable patterns in traditional tortoiseshell glaze. This invention significantly enhances artistic expression and expands the creative space of ceramic decoration: The paint slurry of this invention has been optimized in terms of viscosity (500-1000 mPa·s) and suspension stability, possessing excellent adaptability to brush painting. It can accurately draw fine lines, complex patterns, regular text, and complete paintings, completely changing the limitation of traditional tortoiseshell glaze, which can only form simple blocky and speckled patterns. Creators can freely express themselves according to design needs, deeply integrating art forms such as calligraphy and painting with ceramic decoration, upgrading the decorative effect of ceramic products from "natural texture" to "active artistic expression," greatly expanding the artistic creative space of ceramic decoration and meeting the diverse and personalized needs of modern ceramic decoration. This invention significantly reduces production costs while possessing excellent wear resistance and high-temperature resistance. It uses mineral iron oxide as the core coloring component, achieving a golden effect by controlling the valence state transformation of iron and the precipitation of CaTiO3 crystals. This completely replaces precious metal materials such as gold foil and gold solution used in traditional gold painting processes, reducing product costs by 90% compared to precious metal gold painting processes. This significantly enhances the product's market competitiveness and facilitates its widespread application in large-scale scenarios such as daily-use ceramics and architectural decorative tiles. Furthermore, after being fired in stages at 1250℃ using an oxidation-reduction process, the painting layer forms a tightly bonded integral structure with the base glaze and top glaze. The stable presence of CaTiO3 crystals gives the gold pattern extremely strong wear resistance; friction tests show no peeling after >6000 revolutions, and it can withstand high-temperature environments of 1250℃. This effectively solves the defects of traditional precious metal gold painting processes, such as high cost, poor wear resistance, and poor high-temperature resistance, thus improving the product's service life and applicability.

[0016] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the complete preparation process of the black-based gold-painted ceramic coating of the present invention; Figure 2 This is a schematic diagram of the segmented firing process of the black-based gold-colored ceramic of the present invention. Figure 3 The microstructure of the tortoiseshell glaze surface of this invention was modulated into a slurry using SEM to create a slurry image. Figure 4 The microstructure of the tortoiseshell glaze layer in the vertical section of the present invention was modulated into a SEM image of the slurry. Figure 5 The microstructure of the glaze layer during the high-temperature firing (1250℃) stage of this invention was modulated into a slurry image using SEM. Figure 6The image shows the final microstructure of the tortoiseshell glaze after natural cooling, as visualized by SEM. Detailed Implementation

[0018] The present invention will be further described below with reference to embodiments.

[0019] The following embodiments are used to illustrate the present invention, but should not be used to limit the scope of protection of the present invention. The conditions in the embodiments can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention are all within the scope of protection claimed by the present invention.

[0020] like Figure 1-6 As shown, this embodiment of the invention provides a black-based gold-painted ceramic enameling material based on tortoiseshell glaze, its preparation, and a firing method, wherein: The black-based gold-painted ceramic paint based on tortoiseshell glaze includes a composite glaze component, which consists of a high-iron black glaze component and a low-iron light-colored glaze component. The high-iron black glaze component, by mass percentage, contains 40-50% feldspar, 10-20% kaolin, 10-15% limestone, 8-15% iron oxide, and 1-3% manganese oxide. The low-iron light-colored glaze component, by mass percentage, contains 50-60% feldspar, 5-10% rice straw ash, 10-15% limestone, and 1-3% iron oxide. The high-iron black glaze component and the low-iron light-colored glaze component are mixed to form a paint slurry with a fineness ≥180 mesh and a viscosity of 500-1000 mPa·s, suitable for brush painting.

[0021] The preparation method of black-based gold-painted ceramic paint based on tortoiseshell glaze includes the following steps: S1. The raw materials of the high-iron black glaze component and the low-iron light-colored glaze component are ball-milled and mixed separately. S2. Pass the mixed raw materials through a 180-mesh sieve to obtain a uniform powder; S3. Add carboxymethyl cellulose solution to the uniform powder to prepare a slurry; A suspending agent, which is a 20-40 wt% sucrose aqueous solution, can be added to the slurry, and the amount added is 3-6 wt% of the total slurry volume. S4. Drawing steps: Use a brush to dip into the drawing paste and draw the preset pattern on the surface of the blank. The thickness of the drawing paste is 0.2±0.05mm. After the drawing is completed, the process also includes a glazing step: applying a glaze to the surface of the unglazed body and the drawn pattern. The glaze is transparent or low-iron glaze, and the thickness of the glaze is 0.6-0.8 mm.

[0022] The firing method for black-based gold-decorated ceramics based on tortoiseshell glaze, used for bisques after firing, includes the following stages: S1. Oxidize and heat to 1000℃ → switch to reducing atmosphere (C content 8-10%) and heat to 1250℃ → hold at 1250℃ for 5 minutes → cool rapidly with nitrogen to 800℃; S2. The oxidation heating to 1000℃ stage includes a heating process from room temperature to 980℃ (4 hours) and from 980 to 1000℃. The reducing atmosphere heating to 1250℃ stage includes a heating process from 1000 to 1150℃ and from 1150 to 1250℃ (1.5 hours each). During the firing process, the valence state of iron is changed by controlling the atmosphere, which promotes the combination of CaO and TiO2 in the glaze to precipitate CaTiO3 crystals, forming a layered color structure with a black base and gold patterns.

[0023] In this embodiment, the paint formulation is prepared by weight percentage: the high-iron black glaze consists of 45% feldspar, 15% kaolin, 12% limestone, 10% iron oxide, and 2% manganese oxide; the low-iron light-colored glaze consists of 55% feldspar, 8% rice straw ash, 12% limestone, and 2% iron oxide. During paint preparation, the two types of glaze raw materials are first ball-milled and mixed, then passed through a 180-mesh sieve. A carboxymethyl cellulose solution is then added to adjust the viscosity to 700 mPa·s, forming a paint slurry. A brush is used to apply the paint slurry to the surface of the unglazed body to create floral patterns, controlling the paint thickness to 0.2 mm. After painting, a 0.7 mm thick transparent glaze is applied over the surface. The firing process strictly follows the steps of oxidative heating to 1000℃ (room temperature → 980℃ for 4 hours, 980-1000℃ for 0.5 hours) → switching to a reducing atmosphere (9% C content) and heating to 1250℃ (1000-1150℃ for 1.5 hours, 1150-1250℃ for 1.5 hours) → holding at 1250℃ for 5 minutes → rapid cooling with nitrogen to 800℃ → natural cooling. The final ceramic product, after testing, exhibits a uniform black base, clear gold floral patterns, and a uniform and densely distributed CaTiO3 crystal precipitation structure (SEM) in the gold flowers. It shows no flaking after 6500 revolutions of friction, withstands a high temperature of 1250℃, and has a cost 90% lower than precious metal gold decoration, making it suitable for artistic ceramic decoration. Example 2

[0024] The difference between this embodiment and Embodiment 1 is that a sucrose aqueous solution was added as a suspending agent during the preparation of the paint, and the ratio of some raw materials of high-iron black glaze and low-iron light-colored glaze was adjusted.

[0025] In this embodiment, the high-iron black glaze consists of 40% feldspar, 20% kaolin, 10% limestone, 15% iron oxide, and 1% manganese oxide; the low-iron light-colored glaze consists of 50% feldspar, 10% rice straw ash, 15% limestone, and 1% iron oxide. During the preparation of the glaze, the two types of raw materials are ball-milled and mixed, then passed through an 180-mesh sieve. A carboxymethyl cellulose solution is added to adjust the slurry to a viscosity of 500 mPa·s. Then, a 20 wt% sucrose aqueous solution (density 1.08 g / cm³ at 25°C) is added at 3 wt% of the total slurry volume and stirred until homogeneous. Text and patterns are then drawn on the surface of the unglazed body using a brush, with the glaze thickness controlled at 0.15 mm. After drawing, a 0.6 mm thick low-iron glaze is applied. The firing process is the same as in Example 1.

[0026] In this embodiment, due to the addition of sucrose aqueous solution as a suspending agent, the suspension stability of the slurry is significantly improved. After 24 hours of standing, there is no obvious particle settling, the brush strokes are smooth, and there is no broken stroke or accumulation. The edges of the strokes of the text and patterns are neat and clear. The black base of the finished product has a rich color, and the gold text and patterns are clearly layered with the black base. The wear resistance test shows that it can withstand 6200 revolutions without peeling off. The color is stable. The sucrose aqueous solution is completely decomposed during the firing process, leaving no residue that affects the gloss of the glaze. It is suitable for text decoration scenes on daily-use porcelain. Example 3

[0027] The difference between this embodiment and Embodiment 2 is that the ratio of raw materials for the pigment, the amount of suspending agent added, and the content of reducing atmosphere C during the firing process were adjusted.

[0028] In this embodiment, the high-iron black glaze consists of 50% feldspar, 10% kaolin, 15% limestone, 8% iron oxide, and 3% manganese oxide; the low-iron light-colored glaze consists of 60% feldspar, 5% rice straw ash, 10% limestone, and 3% iron oxide. During the preparation of the painting material, the raw materials were ball-milled and mixed, then passed through an 180-mesh sieve. A carboxymethyl cellulose solution was added to adjust the viscosity to 1000 mPa·s. Then, a 40 wt% sucrose aqueous solution (density 1.18 g / cm³ at 25°C) was added at 6 wt% of the total slurry volume. A landscape painting was then applied to the surface of the unglazed body using a brush, with a painting thickness of 0.25 mm. After painting, a 0.8 mm thick transparent glaze was applied over the painting. During firing, the carbon content of the reducing atmosphere was controlled at 10%, and the remaining firing parameters were the same as in Example 1.

[0029] In this embodiment, the paint slurry has a higher viscosity, making it suitable for drawing detailed landscape textures. The brush adaptability is further optimized, enabling it to accurately present the layering of rocks and trees. After firing, the glaze phases separate fully, and the gold pattern boundary blurring effect is natural, highly matching the artistic conception of the landscape painting. Sufficient CaTiO3 crystal precipitation results in a rich golden luster. The finished product shows no discoloration or cracking after a high-temperature test at 1250℃, and no peeling after a friction test of 7000 revolutions. It has excellent acid and alkali resistance and is suitable for high-end art ceramics and architectural decorative tiles that require high artistic expression and durability.

[0030] Working principle and usage process of this invention: Based on the color development mechanism of tortoiseshell glaze, controllable color development of gold decoration on a black background is achieved through composite paint formula design, precise preparation process, and segmented firing control. The specific process is as follows: Painting material preparation stage: First, select high-iron black glaze raw materials (feldspar 40-50%, kaolin 10-20%, limestone 10-15%, iron oxide 8-15%, manganese oxide 1-3%) and low-iron light-colored glaze raw materials (feldspar 50-60%, straw ash 5-10%, limestone 10-15%, iron oxide 1-3%) according to the preset mass percentage. Ball mill and mix the two types of raw materials separately to ensure that each component is evenly distributed. Then, pass the mixed raw materials through a 180-mesh sieve to obtain powder with uniform particles. Add carboxymethyl cellulose solution to the powder and adjust the viscosity to 500-1000 mPa·s. If further optimization of the painting effect is required, add 20-40 wt% sucrose aqueous solution as a suspending agent according to 3-6 wt% of the total slurry. After stirring evenly, a painting material slurry suitable for brush painting is formed. During the subsequent firing process, the sucrose aqueous solution will gradually decompose in the range of 200-600℃ and completely burn into CO2 and water above 800℃, leaving only a very small amount of inorganic ash (less than 0.05wt% of the total amount of paint), which has no adverse effect on the final glaze color. Body preparation stage: Using a brush, dip it into the prepared painting paste and draw on the surface of the unglazed body according to the preset design pattern. Strictly control the painting thickness to 0.2±0.05mm to ensure the pattern is clear and the thickness is uniform. After the painting is completed, apply a transparent or low-iron glaze evenly to the surface of the unglazed body and the painted pattern. The glaze thickness is controlled to 0.6-0.8mm. The glaze can protect the painted pattern from being damaged during the firing process and can also work synergistically with the painting layer and the base glaze to provide a suitable environment for subsequent high-temperature color development. Firing and color development stage: The treated bisque is sent into the kiln and processed according to the pre-set segmented firing process. Oxidation heating stage: Starting from room temperature, the temperature is slowly increased to 980℃ over 4 hours, maintaining an oxidizing atmosphere throughout. The core purpose of this stage is to fully remove physical and chemical water from the body and glaze, while promoting the initial decomposition of organic components in the paint (such as carboxymethyl cellulose and sucrose), thus preventing the body from cracking due to rapid evaporation of moisture or violent decomposition of organic matter in the subsequent high-temperature stage. Then, the oxidation heating continues to 1000℃ to prepare for the atmosphere change. Reduction heating stage: When the temperature reaches 1000℃, the kiln atmosphere is switched to a reducing atmosphere (CO content 8-10%), and the temperature continues to rise to 1150℃ (lasting 1.5 hours), and then to 1250℃ (lasting 1.5 hours). During this stage, the glaze gradually melts, and the high-iron black glaze and the low-iron light-colored glaze undergo microscopic liquid-liquid phase separation due to differences in composition (SiO2 / Al2O3 ratio, iron oxide content, etc.), forming micro-area aggregations of iron-rich phase (corresponding to the black base area) and iron-poor phase (corresponding to the gold pattern area); at the same time, the reducing atmosphere promotes the valence state transformation of iron elements, laying the foundation for the stable color of the black base; Heat preservation stage: After the temperature reaches 1250℃, maintain this temperature for 5 minutes. During this process, the reducing atmosphere continues to act, and CaO and TiO2 in the glaze layer react fully to precipitate CaTiO3 crystals with high refractive index. These crystals exhibit a stable golden luster. At the same time, the expansion difference at the glaze layer interface causes the golden pattern area to float on the black glaze surface, forming a clear "black base with gold color" layered structure. Iron oxides stabilize the color, ensuring that the black base is uniform. Cooling stage: After the heat preservation is completed, nitrogen gas is introduced into the kiln for rapid cooling, which quickly reduces the temperature to 800℃, locking in the morphology and glaze color of CaTiO3 crystals and preventing phase transformation or glaze color shift during the cooling process; then the nitrogen gas is stopped, and the temperature inside the kiln is allowed to cool naturally to room temperature, reducing the internal stress between the glaze layer and the body, preventing the porcelain from cracking, and finally forming a black-based gold-colored ceramic product with a stable black base and gold patterns.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A black-based ceramic painting material with gold decoration based on tortoiseshell glaze, characterized in that, The product includes a composite glaze component, which consists of a high-iron black glaze component and a low-iron light-colored glaze component. The high-iron black glaze component, by mass percentage, contains 40-50% feldspar, 10-20% kaolin, 10-15% limestone, 8-15% iron oxide, and 1-3% manganese oxide. The low-iron light-colored glaze component, by mass percentage, contains 50-60% feldspar, 5-10% rice straw ash, 10-15% limestone, and 1-3% iron oxide.

2. The black-based gold-painted ceramic enameling material based on tortoiseshell glaze coloring according to claim 1, characterized in that, The high-iron black glaze component and the low-iron light-colored glaze component are mixed to form a painting slurry, and the fineness of the painting slurry is ≥180 mesh.

3. The black-based gold-painted ceramic enameling material based on tortoiseshell glaze coloring according to claim 2, characterized in that, The viscosity of the paint slurry is 500-1000 mPa·s, which is suitable for brush painting operations.

4. A method for preparing a black-based gold-painted ceramic enameling material based on tortoiseshell glaze, applicable to the black-based gold-painted ceramic enameling material based on tortoiseshell glaze as described in any one of claims 1-3, characterized in that... Includes the following steps: S1. The raw materials of the high-iron black glaze component and the low-iron light-colored glaze component are ball-milled and mixed separately. S2. Pass the mixed raw materials through a 180-mesh sieve to obtain a uniform powder; S3. Add carboxymethyl cellulose solution to the uniform powder to prepare a slurry.

5. The method for preparing black-based gold-painted ceramic pigment based on tortoiseshell glaze according to claim 4, characterized in that, In step S3, a suspending agent can be added to the slurry. The suspending agent is a sucrose aqueous solution with a mass fraction of 20-40 wt%, and the amount added is 3-6 wt% of the total slurry volume.

6. The method for preparing black-based gold-painted ceramic pigment based on tortoiseshell glaze according to claim 4, characterized in that, It also includes the following steps: S4. Drawing steps: Use a brush to dip into the drawing paste and draw a preset pattern on the surface of the blank. The thickness of the drawing paste is 0.2±0.05mm.

7. The method for preparing black-based gold-painted ceramic pigment based on tortoiseshell glaze according to claim 6, characterized in that, After the drawing is completed, the process also includes a glazing step: applying a glaze to the surface of the unglazed body and the drawn pattern. The glaze is transparent or low-iron glaze, and the thickness of the glaze is 0.6-0.8 mm.

8. A firing method for black-based gold-painted ceramics based on tortoiseshell glaze, applied to the preparation methods of black-based gold-painted ceramic paints based on tortoiseshell glaze as described in any one of claims 1-3 and black-based gold-painted ceramic paints based on tortoiseshell glaze as described in any one of claims 4-7, characterized in that... For the unglazed blank after firing, the following stages are included: S1. Oxidize and heat to 1000℃ → switch to reducing atmosphere (C content 8-10%) and heat to 1250℃ → hold at 1250℃ for 5 minutes → cool rapidly with nitrogen to 800℃; S2. The oxidation heating to 1000℃ stage includes a heating process from room temperature to 980℃ (4 hours) and from 980 to 1000℃. The reducing atmosphere heating to 1250℃ stage includes a heating process from 1000 to 1150℃ and from 1150 to 1250℃ (1.5 hours each).

9. The firing method for black-based gold-decorated ceramics based on tortoiseshell glaze according to claim 8, characterized in that, During the firing process, the valence state of iron is changed by controlling the atmosphere, which promotes the combination of CaO and TiO2 in the glaze to precipitate CaTiO3 crystals, forming a layered color structure with a black base and gold patterns.

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