Method for preparing lightweight wood-fired ceramic product with obvious fire marks

Abstract

The present invention discloses a method for preparing a light-weight wood-fired ceramic product with obvious fire marks, comprising the following steps: (1) removing impurities, crushing, screening and cleaning the original soil, and then adding water to seal and age to obtain mud; (2) adding plant ash and sawdust coated with metal oxides to the mud, stirring evenly and dehydrating to obtain mud material; the metal oxides include zinc oxide and lanthanum oxide; (3) molding the mud material to obtain a green body; (4) wood-fired the green body to obtain the light-weight wood-fired ceramic product with obvious fire marks. The present invention can reduce the weight of wood-fired ceramics by optimizing the mud formula and firing process, and can also form relatively obvious and uniform fire mark textures and ash glaze on the finished ceramics, thereby ensuring the quality of the final product.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic preparation, in particular to a method for preparing a lightweight wood-fired ceramic product with obvious fire marks. Background Art

[0002] Wood-fired ceramics are ceramic products fired with firewood as fuel. Wood-fired ceramics were once the most common method of firing ceramics in human history. After the modern technological revolution, this "backward" firing method that should have been eliminated was rediscovered from an artistic perspective. There are two types of wood-fired crafts: traditional wood-fired and modern wood-fired. Traditional wood-fired is a relatively pure wood-fired process. In order to avoid direct contact between the body and the flame and ash during the firing process, people place the body in a kiln for firing. Modern wood-fired ceramics pursue the effect of natural ash falling. The body is directly placed in the kiln, and wood is used as fuel. The combustion produces ash. Under high temperature, the ash falling on the body reacts with the metal in the soil to form a natural ash glaze.

[0003] Traditional wood-fired ceramic clay is usually heavy, which limits its use in certain scenarios. In addition, the production process of traditional wood-fired ceramics is complicated and time-consuming, and during the firing process, the formation and distribution of fire marks are often difficult to control, resulting in inconsistent effects and affecting its quality. Summary of the invention

[0004] The present invention aims to overcome the above-mentioned problems existing in wood-fired ceramics in the prior art and provides a method for preparing lightweight wood-fired ceramic products with obvious fire marks. By optimizing the clay formula and firing process, the weight of the wood-fired ceramics can be reduced. At the same time, relatively obvious and uniform fire mark texture and ash glaze can be formed on the finished ceramics, thereby ensuring the quality of the final product.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0007] (1) removing impurities, crushing, screening and washing the original soil, and then adding water to seal and age it to obtain mud; the components of the original soil include, by mass percentage, 0.2-0.3% Na2O, 0.1-0.3% MgO, 34-35% Al2O3, 58-60% SiO2, 1-2% K2O, 0.1-0.3% CaO, 0.3-0.6% TiO2, 2-3% Fe2O3, and the remainder is loss on ignition;

[0008] (2) adding wood ash and sawdust coated with metal oxides into the mud, stirring evenly and then dehydrating to obtain mud; the metal oxides include zinc oxide and lanthanum oxide;

[0009] (3) forming the clay into a green body;

[0010] (4) The green body is fired by wood-fired firing to obtain the lightweight wood-fired ceramic product with obvious fire marks.

[0011] The present invention adds sawdust to the mud material, and the sawdust can be burned out during the high-temperature firing process, leaving gaps in the ceramic body to obtain a porous ceramic material, thereby greatly reducing the density of the ceramic material, and can produce lightweight wood-fired ceramic products, expanding the application scenarios of wood-fired ceramic products. However, firstly, lightweight sawdust is easily floated on the surface of the mud when directly added to the mud, and it is difficult to be evenly dispersed in the mud material, affecting the uniformity of the ceramic product; secondly, the present invention has found that the addition of sawdust is not conducive to the formation of fire marks on the surface of wood-fired ceramics, which may be due to the porous structure formed by the burning of sawdust, which is not conducive to the transfer of heat. Therefore, the present invention uses metal oxides to coat the sawdust, which can increase the specific gravity of the sawdust on the one hand, prevent it from floating in the mud, improve its wettability and dispersibility in the mud, thereby improving the uniformity of the ceramic product, which is conducive to improving its quality and producing uniform fire marks; on the other hand, the coating of metal oxides is conducive to improving the uniformity and density of the ceramic material, and is conducive to producing obvious fire marks after wood burning.

[0012] At the same time, the present invention also adds plant ash to the mud material, which is beneficial to cooperate with the ash falling when burning wood to form a more obvious ash glaze. In addition, the present invention uses zinc oxide and lanthanum oxide as metal oxides to coat the sawdust, which is beneficial to produce obvious fire marks and is also more conducive to reacting with wood ash to form a more obvious ash glaze.

[0013] Preferably, the wood-fired firing method in step (4) is: first heating to 75-85°C within 1.5-2.5 hours, then heating to 1200-1300°C within 30-40 hours, and then keeping warm at 1100-1200°C for 15-20 hours; opening the flue cover, heating to 1250-1310°C within 10-15 hours, and finally keeping warm at 1290-1300°C for 45-60 minutes, and naturally cooling for 20-24 hours before exiting the kiln.

[0014] During the wood-firing process, the firing process has a significant impact on the generation of fire marks. During wood-firing, the smoke and ash generated by the burning firewood will diffuse in the kiln and generate a reducing atmosphere. The reducing atmosphere will affect the oxides on the surface of the ceramic products, thereby forming fire marks during the firing process. During the firing of the present invention, the moisture in the green body is first removed at a relatively low temperature to avoid cracking of the green body during the high-position firing process; then the temperature is raised to perform the oxidation stage, and after a period of heat preservation, the flue cover is opened to allow oxygen to enter the flue through the cover, thereby achieving secondary combustion, eliminating the original smoke, and performing weak reduction at the same time. The ceramic products finally obtained can produce obvious and relatively uniform fire marks.

[0015] Preferably, the preparation method of the metal oxide-coated sawdust described in step (2) is: dissolving soluble zinc salt and lanthanum salt in deionized water to obtain a metal salt solution; adding urea, stirring evenly, adding sawdust to the solution, stirring and dispersing evenly, adding ammonia water dropwise to the system, adjusting the pH of the system to 6-7, separating, washing and drying the product after hydrothermal reaction to obtain the metal oxide-coated sawdust.

[0016] Preferably, among the zinc salt and lanthanum salt added, Zn 2+ and La 3+ The molar ratio of Zn is 3 to 5:1; in the metal salt solution, 2 + The concentration of urea added in the metal salt solution is 0.2-0.3 mol / L; the concentration of urea added in the metal salt solution is 0.1-0.3 mol / L; the concentration of sawdust added in the metal salt solution is 30-50 g / L.

[0017] Preferably, the hydrothermal reaction temperature is 120-150° C., and the time is 3-12 h.

[0018] Preferably, the particle size of the wood chips is 60-100 meshes.

[0019] Preferably, in the mud obtained in step (2), the mass ratio of the original soil, the plant ash and the sawdust coated with metal oxide is 70-80:8-10:20-30. The addition ratio of the plant ash and the metal oxide needs to be controlled within an appropriate range to obtain wood-fired ceramic products with more obvious fire marks and ash glaze and better quality.

[0020] Preferably, the moisture content of the mud obtained in step (2) is 15 to 30 wt%.

[0021] Preferably, the original soil is screened through a 60-80 mesh sieve in step (1).

[0022] Preferably, the aging time in step (1) is 3 to 6 months.

[0023] Therefore, the present invention has the following beneficial effects:

[0024] (1) Adding sawdust to the clay can reduce the density of the ceramic material and produce lightweight wood-fired ceramic products, which expands the application scenarios of wood-fired ceramic products;

[0025] (2) Adding wood ash to the clay helps it to work with the ash from burning wood, forming a more obvious ash glaze;

[0026] (3) Coating sawdust with zinc oxide and lanthanum oxide is beneficial for producing obvious and uniform fire marks on ceramic products, and is also more conducive to reacting with wood ash to form a more obvious ash glaze. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific implementation methods.

[0028] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0029] Overall embodiment:

[0030] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0031] (1) removing impurities, crushing, screening and washing the original soil, and then adding water to seal and age it to obtain mud; the components of the original soil include, by mass percentage, 0.2-0.3% Na2O, 0.1-0.3% MgO, 34-35% Al2O3, 58-60% SiO2, 1-2% K2O, 0.1-0.3% CaO, 0.3-0.6% TiO2, 2-3% Fe2O3, and the remainder is loss on ignition;

[0032] (2) adding wood ash and sawdust coated with metal oxides into the mud, stirring evenly and then dehydrating to obtain mud; the metal oxides include zinc oxide and lanthanum oxide;

[0033] (3) forming the clay into a green body;

[0034] (4) The green body is fired by wood-fired firing to obtain the lightweight wood-fired ceramic product with obvious fire marks.

[0035] As a preferred solution, in step (1), the original soil is screened through a 60-80 mesh sieve and the aging time is 3-6 months.

[0036] As a preferred solution, the method for preparing the metal oxide-coated wood chips in step (2) is: dissolving soluble zinc salt and lanthanum salt in deionized water to obtain a metal salt solution, Zn 2+ and La 3+ The molar ratio of Zn is 3 to 5:1. 2+ The concentration of urea is 0.2-0.3 mol / L; urea is added to make its concentration in the metal salt solution 0.1-0.3 mol / L; after stirring evenly, wood chips with a particle size of 60-100 mesh are added to the solution, and the concentration of the wood chips in the metal salt solution is 30-50 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, the pH value of the system is adjusted to 6-7, and after hydrothermal reaction at 120-150° C. for 3-12 hours, the product is separated, washed, and dried to obtain the wood chips coated with the metal oxide.

[0037] As a preferred solution, in the mud obtained in step (2), the mass ratio of original soil, wood ash and sawdust coated with metal oxides is 70-80:8-10:20-30; and the moisture content of the mud obtained is 15-30wt%.

[0038] As a preferred solution, the wood-fired firing method in step (4) is as follows: first, the temperature is raised to 75-85°C within 1.5-2.5 hours, then the temperature is raised to 1200-1300°C within 30-40 hours, and then the temperature is kept at 1100-1200°C for 15-20 hours; the flue cover is opened, the temperature is raised to 1250-1310°C within 10-15 hours, and finally the temperature is kept at 1290-1300°C for 45-60 minutes, and the temperature is naturally reduced for 20-24 hours before being discharged from the kiln.

[0039] Embodiment 1:

[0040] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0041] (1) Remove impurities such as stones and branches from the original soil (soil from Guangxi), crush the original soil with a crusher and then pass it through a 60-mesh sieve; wash the sieved original soil with water to remove floating soil and other soluble impurities; then add water and seal it for aging for 4 months to obtain mud; using the method in GB / T 4734-1996, the components in the original soil are measured by mass percentage: 0.26% Na2O, 0.20% MgO, 34.95% Al2O3, 59.02% SiO2, 1.44% K2O, 0.20% CaO, 0.49% TiO2, 2.45% Fe2O3, and the remainder is the ignition loss;

[0042] (2) adding wood ash (particle size 60 mesh) and sawdust coated with metal oxides into the mud, stirring evenly and dehydrating to obtain a mud material with a moisture content of 20 wt %; in the obtained mud material, the mass ratio of the original soil, wood ash and sawdust coated with metal oxides is 75:9:25; the preparation method of the sawdust coated with metal oxides is as follows: dissolving zinc nitrate and lanthanum nitrate in deionized water to obtain a metal salt solution, wherein Zn in the metal salt solution is 1:1; 2+ and La 3+ The molar ratio of Zn is 4:1. 2+ The concentration of the metal oxide is 0.25 mol / L; 0.2 mol / L urea is added to the solution, and after stirring, pine sawdust with a particle size of 80 mesh is added to the solution, and the concentration of the added pine sawdust in the metal salt solution is 40 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH of the system is adjusted to 6.8. After hydrothermal reaction at 130° C. for 6 hours, the product is separated, washed, and dried to obtain the metal oxide-coated sawdust;

[0043] (3) forming the clay into 10 identical blanks;

[0044] (4) The green body is fired simultaneously with pine firewood to obtain the lightweight wood-fired ceramic product with obvious fire marks; the firing method is: firstly heating to 80°C within 2 hours, then heating to 1250°C within 35 hours, and then keeping at 1150°C for 17 hours; opening the flue cover, heating to 1290°C within 12 hours, and finally keeping at 1300°C for 60 minutes, and then naturally cooling for 20 hours before taking out of the kiln.

[0045] Embodiment 2:

[0046] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0047] (1) Adding plant ash (particle size 60 mesh) and sawdust coated with metal oxide to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 30 wt %; in the obtained slurry, the mass ratio of the original soil, plant ash and sawdust coated with metal oxide is 70:8:20; the preparation method of the sawdust coated with metal oxide is as follows: dissolving zinc nitrate and lanthanum nitrate in deionized water to obtain a metal salt solution, wherein Zn in the metal salt solution is 0.1%; 2+ and La 3+ The molar ratio of Zn is 4:1. 2+ The concentration of the metal oxide is 0.25 mol / L; 0.2 mol / L urea is added to the solution, and after stirring, pine sawdust with a particle size of 80 mesh is added to the solution, and the concentration of the added pine sawdust in the metal salt solution is 40 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH of the system is adjusted to 6.8. After hydrothermal reaction at 130° C. for 6 hours, the product is separated, washed, and dried to obtain the metal oxide-coated sawdust;

[0048] (2) forming the clay into 10 identical blanks;

[0049] (3) The green body is fired simultaneously with pine firewood to obtain the lightweight wood-fired ceramic product with obvious fire marks; the firing method is: firstly, the temperature is raised to 80°C within 2 hours, then the temperature is raised to 1210°C within 30 hours, and then the temperature is kept at 1100°C for 20 hours; the flue cover is opened, the temperature is raised to 1250°C within 12 hours, and finally the temperature is kept at 1300°C for 60 minutes, and the temperature is naturally reduced for 24 hours before the green body is taken out of the kiln.

[0050] Embodiment 3:

[0051] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0052] (1) Adding plant ash (particle size 60 mesh) and sawdust coated with metal oxide to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 15 wt %; in the obtained slurry, the mass ratio of the original soil, plant ash and sawdust coated with metal oxide is 80:10:30; the preparation method of the sawdust coated with metal oxide is as follows: dissolving zinc nitrate and lanthanum nitrate in deionized water to obtain a metal salt solution, wherein Zn in the metal salt solution is 1:10:30; 2+ and La 3+ The molar ratio of Zn is 4:1. 2+ The concentration of the metal oxide is 0.25 mol / L; 0.2 mol / L urea is added to the solution, and after stirring, pine sawdust with a particle size of 80 mesh is added to the solution, and the concentration of the added pine sawdust in the metal salt solution is 40 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH of the system is adjusted to 6.8. After hydrothermal reaction at 130° C. for 6 hours, the product is separated, washed, and dried to obtain the metal oxide-coated sawdust;

[0053] (2) forming the clay into 10 identical blanks;

[0054] (3) The green body is fired simultaneously with pine firewood to obtain the lightweight wood-fired ceramic product with obvious fire marks; the firing method is: firstly, the temperature is raised to 75°C within 1.5 hours, then the temperature is raised to 1300°C within 36 hours, and then the temperature is kept at 1200°C for 15 hours; the flue cover is opened, the temperature is raised to 1290°C within 15 hours, and finally the temperature is kept at 1300°C for 50 minutes, and the product is discharged from the kiln after natural cooling for 24 hours.

[0055] Embodiment 4:

[0056] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0057] (1) Adding plant ash (particle size 60 mesh) and sawdust coated with metal oxide to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 20 wt %; in the obtained slurry, the mass ratio of the original soil, plant ash and sawdust coated with metal oxide is 75:9:25; the preparation method of the sawdust coated with metal oxide is as follows: dissolving zinc nitrate and lanthanum nitrate in deionized water to obtain a metal salt solution, wherein Zn in the metal salt solution is 0.1%; 2+ and La 3+ The molar ratio of Zn is 3:1. 2+The concentration of the metal oxide is 0.2 mol / L; 0.3 mol / L urea is added to the solution, and after stirring, pine sawdust with a particle size of 80 mesh is added to the solution, and the concentration of the added pine sawdust in the metal salt solution is 30 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH of the system is adjusted to 6.5. After hydrothermal reaction at 120° C. for 12 hours, the product is separated, washed, and dried to obtain the metal oxide-coated sawdust;

[0058] (2) forming the clay into 10 identical blanks;

[0059] (3) The green body is fired simultaneously with pine firewood to obtain the lightweight wood-fired ceramic product with obvious fire marks; the firing method is: firstly, the temperature is raised to 85°C within 2.5 hours, then the temperature is raised to 1300°C within 40 hours, and then the temperature is kept at 1200°C for 15 hours; the flue cover is opened, the temperature is raised to 1290°C within 15 hours, and finally the temperature is kept at 1310°C for 45 minutes, and the temperature is naturally reduced for 24 hours before the kiln is discharged.

[0060] Embodiment 5:

[0061] A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, comprising the following steps:

[0062] (1) Adding plant ash (particle size 60 mesh) and sawdust coated with metal oxide to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 20 wt %; in the obtained slurry, the mass ratio of the original soil, plant ash and sawdust coated with metal oxide is 75:9:25; the preparation method of the sawdust coated with metal oxide is as follows: dissolving zinc nitrate and lanthanum nitrate in deionized water to obtain a metal salt solution, wherein Zn in the metal salt solution is 0.1%; 2+ and La 3+ The molar ratio of Zn is 5:1. 2+ The concentration of the metal oxide is 0.3 mol / L; 0.1 mol / L urea is added to the solution, and after stirring, pine sawdust with a particle size of 80 mesh is added to the solution, and the concentration of the added pine sawdust in the metal salt solution is 50 g / L; after stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH of the system is adjusted to 7.0. After hydrothermal reaction at 150° C. for 5 hours, the product is separated, washed, and dried to obtain the metal oxide-coated sawdust;

[0063] (2) forming the clay into 10 identical blanks;

[0064] (3) The green body is fired simultaneously with pine firewood to obtain the lightweight wood-fired ceramic product with obvious fire marks; the firing method is: firstly heating to 80°C within 2 hours, then heating to 1250°C within 35 hours, and then keeping at 1150°C for 17 hours; opening the flue cover, heating to 1290°C within 12 hours, and finally keeping at 1300°C for 60 minutes, and then naturally cooling for 20 hours before taking out of the kiln.

[0065] Comparative Example 1 (without adding sawdust):

[0066] A method for preparing a wood-fired ceramic product comprises the following steps:

[0067] (1) Adding plant ash (particle size 60 mesh) to the mud obtained in Example 1, stirring evenly and dehydrating to obtain a mud material with a moisture content of 20wt%; in the obtained mud material, the mass ratio of original soil to plant ash is 75:9;

[0068] (2) forming the clay into 10 identical blanks;

[0069] (3) Using pine wood to simultaneously fire the green body to obtain the wood-fired ceramic product; the firing method is: first raising the temperature to 80°C within 2 hours, then raising the temperature to 1250°C within 35 hours, and then keeping it at 1150°C for 17 hours; opening the flue cover, raising the temperature to 1290°C within 12 hours, and finally keeping it at 1300°C for 60 minutes, and naturally cooling it for 20 hours before taking it out of the kiln.

[0070] Comparative Example 2 (without coating the wood chips):

[0071] A method for preparing a wood-fired ceramic product comprises the following steps:

[0072] (1) Adding plant ash (particle size 60 mesh) and pine sawdust (particle size 80 mesh) to the mud obtained in Example 1, stirring evenly and dehydrating to obtain a mud material with a moisture content of 20wt%; in the obtained mud material, the mass ratio of original soil, plant ash and sawdust is 75:9:25; (2) Molding the mud material to obtain 10 identical blanks;

[0073] (3) Using pine wood to simultaneously fire the green body to obtain the wood-fired ceramic product; the firing method is: first raising the temperature to 80°C within 2 hours, then raising the temperature to 1250°C within 35 hours, and then keeping it at 1150°C for 17 hours; opening the flue cover, raising the temperature to 1290°C within 12 hours, and finally keeping it at 1300°C for 60 minutes, and naturally cooling it for 20 hours before taking it out of the kiln.

[0074] Comparative Example 3 (coated with zinc oxide only):

[0075] A method for preparing a wood-fired ceramic product comprises the following steps:

[0076] (1) Adding plant ash (particle size 60 mesh) and zinc oxide-coated sawdust to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 20 wt %; in the obtained slurry, the mass ratio of the original soil, plant ash and zinc oxide-coated sawdust is 75:9:25; the preparation method of zinc oxide-coated sawdust is as follows: dissolving zinc nitrate in deionized water to obtain Zn 2+ A metal salt solution with a concentration of 0.25 mol / L; adding 0.2 mol / L urea to the solution, stirring evenly, adding pine sawdust with a particle size of 80 mesh to the solution, wherein the concentration of the added pine sawdust in the metal salt solution is 40 g / L; stirring and dispersing evenly, adding ammonia water dropwise to the system, adjusting the pH of the system to 6.8, and performing a hydrothermal reaction at 130° C. for 6 hours, separating, washing, and drying the product to obtain the zinc oxide-coated sawdust;

[0077] (2) forming the clay into 10 identical blanks;

[0078] (3) Using pine wood to simultaneously fire the green body to obtain the wood-fired ceramic product; the firing method is: first raising the temperature to 80°C within 2 hours, then raising the temperature to 1250°C within 35 hours, and then keeping it at 1150°C for 17 hours; opening the flue cover, raising the temperature to 1290°C within 12 hours, and finally keeping it at 1300°C for 60 minutes, and naturally cooling it for 20 hours before taking it out of the kiln.

[0079] Comparative Example 4 (only coated with lanthanum oxide):

[0080] A method for preparing a wood-fired ceramic product comprises the following steps:

[0081] (1) Adding plant ash (particle size 60 mesh) and sawdust coated with lanthanum oxide to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 20 wt%; in the obtained slurry, the mass ratio of the original soil, plant ash and sawdust coated with lanthanum oxide is 75:9:25; the preparation method of the sawdust coated with lanthanum oxide is as follows: dissolving lanthanum nitrate in deionized water to obtain La 3+ A metal salt solution with a concentration of 0.25 mol / L; adding 0.2 mol / L urea to the solution, stirring evenly, adding pine sawdust with a particle size of 80 mesh to the solution, wherein the concentration of the added pine sawdust in the metal salt solution is 40 g / L; stirring and dispersing evenly, adding ammonia water dropwise to the system, adjusting the pH of the system to 6.8, and performing a hydrothermal reaction at 130° C. for 6 hours, separating, washing, and drying the product to obtain the lanthanum oxide-coated sawdust;

[0082] (2) forming the clay into 10 identical blanks;

[0083] (3) Using pine wood to simultaneously fire the green body to obtain the wood-fired ceramic product; the firing method is: first raising the temperature to 80°C within 2 hours, then raising the temperature to 1250°C within 35 hours, and then keeping it at 1150°C for 17 hours; opening the flue cover, raising the temperature to 1290°C within 12 hours, and finally keeping it at 1300°C for 60 minutes, and naturally cooling it for 20 hours before taking it out of the kiln.

[0084] Comparative Example 5 (without adding plant ash):

[0085] A method for preparing a wood-fired ceramic product comprises the following steps:

[0086] (1) Adding metal oxide coated sawdust to the slurry obtained in Example 1, stirring evenly and dehydrating to obtain a slurry with a moisture content of 20 wt%; in the obtained slurry, the mass ratio of the original soil to the metal oxide coated sawdust is 75:25; the preparation method of the metal oxide coated sawdust is the same as that in Example 1;

[0087] (2) forming the clay into 10 identical blanks;

[0088] (3) Using pine wood to simultaneously fire the green body to obtain the wood-fired ceramic product; the firing method is: first raising the temperature to 80°C within 2 hours, then raising the temperature to 1250°C within 35 hours, and then keeping it at 1150°C for 17 hours; opening the flue cover, raising the temperature to 1290°C within 12 hours, and finally keeping it at 1300°C for 60 minutes, and naturally cooling it for 20 hours before taking it out of the kiln.

[0089] The volume density of the ceramic products prepared in the above-mentioned embodiment and comparative example 1 was tested (taking the average value of 10 test results), and the formation of fire marks and ash glaze was observed. The results are shown in Table 1.

[0090] Table 1: Performance test results of wood-fired ceramic products.

[0091]

[0092] As can be seen from Table 1, the wood-fired ceramic products prepared by the method of the present invention in Examples 1 to 5 have a lower bulk density. Ten green bodies fired in the same kiln can all produce relatively obvious fire marks and ash glaze, and have good quality stability. In Comparative Example 1, no sawdust is added to the mud, and the density of the ceramic product is significantly improved compared with that in the embodiment, which limits its application; and the ash glaze formed is also shallow. In Comparative Example 2, the sawdust is not coated with metal oxides, and the sawdust is not easy to disperse evenly in the mud. The uniformity of the green body is not good, which is not conducive to the formation of fire marks, and the quality of the ceramic product is difficult to control. In Comparative Example 3, only zinc oxide is used to coat the sawdust, and the addition of lanthanum oxide is missing. The ceramic product is not easy to produce obvious ash glaze, which also has a certain effect on the formation of fire marks. In Comparative Example 4, only lanthanum oxide was used to coat the sawdust, and zinc oxide was not added, which had a significant effect on the formation of the fire mark, indicating that the type of metal oxide will affect the formation of the fire mark and the ash glaze. This may be because different metal oxides will affect the sintering temperature of the ceramic, and different metals react differently with the ash, which affects the formation of the ash glaze of the fire mark. In Comparative Example 5, no plant ash was added to the clay, and the formation of the ash glaze was more difficult.

[0093] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a lightweight wood-fired ceramic product with obvious fire marks, characterized in that: The steps include: (1) removing impurities, crushing, screening and washing the original soil, and then adding water to seal and age it to obtain mud; the components of the original soil include, by mass percentage, 0.2-0.3% Na2O, 0.1-0.3% MgO, 34-35% Al2O3, 58-60% SiO2, 1-2% K2O, 0.1-0.3% CaO, 0.3-0.6% TiO2, 2-3% Fe2O3, and the remainder is loss on ignition; (2) adding wood ash and sawdust coated with metal oxides into the mud, stirring evenly and then dehydrating to obtain mud; the metal oxides include zinc oxide and lanthanum oxide; (3) forming the clay into a green body; (4) The green body is fired by wood-fired firing to obtain the lightweight wood-fired ceramic product with obvious fire marks.

2. The preparation method according to claim 1, characterized in that The wood-fired firing method in step (4) is as follows: firstly, the temperature is raised to 75-85°C within 1.5-2.5 hours, then the temperature is raised to 1200-1300°C within 30-40 hours, and then the temperature is kept at 1100-1200°C for 15-20 hours; the flue cover is opened, the temperature is raised to 1250-1310°C within 10-15 hours, and finally the temperature is kept at 1290-1300°C for 45-60 minutes, and the temperature is naturally lowered for 20-24 hours before being discharged from the kiln.

3. The preparation method according to claim 1, characterized in that: The method for preparing the metal oxide-coated wood chips described in step (2) is as follows: dissolving a soluble zinc salt and a lanthanum salt in deionized water to obtain a metal salt solution; Urea is added, and after stirring evenly, sawdust is added to the solution. After stirring and dispersing evenly, ammonia water is added dropwise to the system, and the pH value of the system is adjusted to 6-7. After the hydrothermal reaction, the product is separated, washed, and dried to obtain the sawdust coated with the metal oxide.

4. The preparation method according to claim 3, characterized in that Among the zinc and lanthanum salts added, Zn 2+ and La 3+ The molar ratio of Zn is 3~5:1; in the metal salt solution, 2+ The concentration of urea in the metal salt solution is 0.2~0.3 mol / L; the concentration of sawdust in the metal salt solution is 0.1~0.3 mol / L; the concentration of sawdust in the metal salt solution is 30~50g / L.

5. The preparation method according to claim 3 or 4, characterized in that: The hydrothermal reaction temperature is 120~150℃ and the time is 3~12h.

6. The preparation method according to claim 3, characterized in that: The particle size of the wood chips is 60-100 meshes.

7. The preparation method according to claim 1, characterized in that: In the mud material obtained in step (2), the mass ratio of the original soil, the wood ash and the sawdust coated with the metal oxide is 70-80:8-10:20-30.

8. The preparation method according to claim 1 or 7, characterized in that: The moisture content of the mud obtained in step (2) is 15-30wt%.

9. The preparation method according to claim 1, characterized in that: In step (1), the original soil is screened through a 60-80 mesh sieve.

10. The preparation method according to claim 1, characterized in that: The aging time in step (1) is 3 to 6 months.

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