A method for removing impurities from ceramics and a ceramic product

Abstract

The present invention provides a method for removing impurities from ceramics and a ceramic product. The green ceramic body is subjected to a first-stage heat treatment and a cooling treatment to obtain the green ceramic body after the first-stage treatment; the green ceramic body after the first-stage treatment is successively impregnated and dried with a chromium nitrate solution to obtain a completely dried impregnated ceramic body; the completely dried impregnated ceramic body is subjected to a second-stage heat treatment and a cooling treatment to obtain the green ceramic body after the second-stage treatment; the green ceramic body after the second-stage treatment is subjected to a sintering treatment to obtain a ceramic product. The process is simple, can efficiently remove glue, effectively reduce the generation and deposition of harmful substances during the sintering process, and reduce the bending rejection rate of the ceramic product.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic impurity removal, and specifically relates to a ceramic impurity removal method and a ceramic product. Background Art

[0002] In the degumming process of ceramics, traditional methods usually adopt a slow and low-temperature method for treatment. Although this method can achieve the purpose of degumming to a certain extent, its efficiency is low and the time consumption is long, seriously affecting the overall production capacity of the production line. In addition, slow and low-temperature degumming may also have an adverse impact on the microstructure of ceramic materials, thereby affecting the final performance of ceramics. Therefore, exploring a degumming method that is efficient and has little damage to ceramic materials has become an urgent need in the current industry.

[0003] In addition, sintering is a core step in the preparation process of ceramic materials, and its success or failure directly affects a series of key performance indicators such as the density, strength, and hardness of ceramic products. However, when sintering ZTA (zirconia toughened alumina) ceramics impregnated with chromium nitrate, technicians face a series of complex and severe challenges.

[0004] First of all, chromium nitrate will decompose during high-temperature sintering to produce a large amount of chromium smoke and nitrogen oxides. These harmful substances not only have strong corrosiveness, can seriously damage the heating elements in the sintering furnace, shorten their service life, but also may escape into the production environment, causing environmental pollution and threatening the health and safety of operators.

[0005] Secondly, the chromium smoke gas-phase substances are easy to accumulate in the sintering furnace at high temperature and deposit on the surface of ceramics. This will not only damage the surface quality of ceramic products, but also may cause sintering defects such as deformation and cracking, resulting in an increase in the rejection rate of products due to bending and other quality problems, seriously affecting production efficiency and cost control.

[0006] The disclosure of the above background art content is only used to assist in understanding the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application, nor will it necessarily give technical guidance; without clear evidence indicating that the above content was publicly available before the filing date of this patent application, the above background art should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention proposes a ceramic impurity removal method and a ceramic product, with a simple process, which can not only degum efficiently, but also effectively reduce the generation and deposition of harmful substances during sintering, and reduce the rejection rate of ceramic products due to bending.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] The present invention provides a method for removing impurities from ceramics, comprising the following steps:

[0010] S1 Perform heat treatment in the first stage and cooling treatment on the green ceramic body: Place the green ceramic body in a porous ceramic jig, gradually heat it from room temperature to 650 - 700 °C for heat preservation heat treatment, cool the heat-treated green ceramic body to room temperature and then take it out to obtain the green ceramic body after the first-stage treatment;

[0011] S2 Immerse and dry the green ceramic body after the first-stage treatment with a chromium nitrate solution in sequence to obtain a completely dried impregnated ceramic body;

[0012] S3 Perform heat treatment in the second stage and cooling treatment on the completely dried impregnated ceramic body: Place the completely dried impregnated ceramic body in a porous ceramic jig, heat it from room temperature to 500 - 700 °C for heat preservation heat treatment, and cool the heat-treated ceramic body to obtain the ceramic body after the second-stage treatment;

[0013] S4 Perform sintering treatment on the ceramic body after the second-stage treatment: Gradually heat the ceramic body after the second-stage treatment to 1500 - 1600 °C and then perform heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product.

[0014] The present invention provides a method for removing impurities from ceramics and a ceramic product. The process is simple, which can not only efficiently remove glue, but also effectively reduce the generation and deposition of harmful substances during the sintering process, and reduce the rejection rate of the ceramic product due to bending.

[0015] As a preferred technical solution, in step S1, placing the green ceramic body in a porous ceramic jig and gradually heating it from room temperature to 650 - 700 °C for heat preservation heat treatment specifically comprises the following steps:

[0016] S101 Place the green ceramic body in a porous ceramic jig, heat it from room temperature to 200 - 300 °C, with a heating rate of 5 - 10 °C / min and a heat preservation time of 30 - 60 min;

[0017] S102 Then heat it from 200 °C - 300 °C to 350 - 450 °C, with a heating rate of 1 - 5 °C / min and a heat preservation time of 60 - 90 min;

[0018] S103 Finally, heat it from 350 - 450 °C to 650 - 700 °C, with a heating rate of 0.5 - 1 °C / min and a heat preservation time of 90 - 120 min.

[0019] As a preferred technical solution, in step S2, immersing and drying the green ceramic body after the first-stage treatment with a chromium nitrate solution in sequence specifically comprises the following steps:

[0020] S201 Prepare a chromium nitrate solution with a concentration of 1 - 1.5 g / ml;

[0021] S202 Immerse the ceramic green body after the first-stage treatment in the chromium nitrate solution to obtain the immersed ceramic green body;

[0022] S203 Take out the immersed ceramic green body and dry it to obtain a completely dried impregnated ceramic green body.

[0023] As a preferred technical solution, the drying in step S203 specifically includes the following steps:

[0024] Perform drying by keeping warm in an oven at 38 - 42 °C for 3 - 4 h.

[0025] As a preferred technical solution, in step S3, place the completely dried impregnated ceramic green body in a porous ceramic fixture, and heat it from room temperature to 500 - 700 °C for heat preservation and heat treatment, which specifically includes the following steps:

[0026] S301 Place the completely dried impregnated ceramic green body in a porous ceramic fixture, heat it from room temperature to 500 - 700 °C, with a heat preservation time of 90 - 120 min and a heating rate of 1 - 5 °C, to obtain the ceramic green body after heat preservation and heat treatment.

[0027] As a preferred technical solution, in step S3, cool the ceramic green body after heat preservation and heat treatment to obtain the ceramic green body after the second-stage treatment, which specifically includes the following steps:

[0028] S302 Cool the ceramic green body after heat preservation and heat treatment from 500 - 700 °C to 25 - 100 °C to obtain the ceramic green body after the second-stage treatment.

[0029] As a preferred technical solution, the cooling rate from 500 - 700 °C to 25 - 100 °C in step S302 is 5 - 10 °C.

[0030] As a preferred technical solution, in step S4, heat the ceramic green body after the second-stage treatment in stages to 1500 - 1600 °C and then perform heat preservation and sintering treatment, which specifically includes the following steps:

[0031] S401 Heat the ceramic green body after the second-stage treatment from 25 °C - 100 °C to 1300 - 1400 °C for sintering treatment, with a heat preservation time of 30 - 60 min and a heating rate of 6 - 15 °C / min;

[0032] S402 Then heat it from 1300 - 1400 °C to 1500 - 1600 °C for sintering treatment, with a heat preservation time of 120 - 150 min and a heating rate of 2 - 8 °C / min.

[0033] As a preferred technical solution, all process steps of the ceramic impurity removal method are carried out in an air atmosphere.

[0034] The present invention also provides a ceramic product prepared according to the ceramic impurity removal method described in any one of the above.

[0035] The ceramic impurity removal method and ceramic product provided by the present invention have the following beneficial effects:

[0036] 1) Its process is simple. It can not only efficiently degum, but also effectively reduce the generation and deposition of harmful substances during the sintering process, reducing the bending rejection rate of ceramic products.

[0037] 2) After the second-stage heat treatment and cooling treatment are carried out on the completely dried impregnated ceramic green body, the second-stage heat treatment of the completely dried impregnated ceramic green body is carried out at 500-700 °C for heat preservation heat treatment. After the heat preservation is completed, the temperature starts to drop for cooling treatment; this can ensure that the excess chromium in the product escapes in the form of gas phase. After escaping, it can be absorbed by the porous ceramic fixture in the solution, and timely temperature reduction is also beneficial to the gas phase deposition in the porous ceramic fixture above the product; reducing the deposition of chromium smoke gas-phase substances on the outside of the ceramic product, causing sintering defects in the ceramic product and resulting in deformation problems, reducing the bending rejection rate of ceramic products.

[0038] 3) During the manufacturing process of ceramics, the organic binder in the green body needs to be effectively removed to ensure the density and strength of the sintered ceramics; this method realizes efficient degumming through the following steps:

[0039] The first-stage heat treatment: Place the ceramic green body in a porous ceramic fixture and heat it up in stages to 650-700 °C for heat preservation heat treatment; the main purpose of this stage is to make the organic binder in the ceramic green body start to soften and decompose and partially volatilize; the use of the porous ceramic fixture helps the uniform transfer of heat and the escape of organic matter, thereby improving the degumming efficiency.

[0040] A staged degreasing process is adopted, and the temperature is gradually increased from room temperature to 650-700 °C for heat preservation heat treatment; this staged heating method helps to gradually remove the adhesive in the ceramic green body while reducing the thermal stress damage to the ceramic material caused by rapid heating.

[0041] Specifically, in S101, the temperature is raised to 200-300 °C and held for a period of time, which can initially remove some adhesives and volatile substances. The heating rate in this stage is relatively fast (5-10 °C / min), but it is still within the controllable range to avoid excessive thermal shock to the ceramic material.

[0042] In stage S102, the temperature is further increased to 350 - 450 °C and held for a longer time (60 - 90 min); the heating rate in this stage slows down (1 - 5 °C / min) to remove more adhesives and residues in a gentler manner; the extension of the holding time also helps to ensure the complete removal of the adhesives;

[0043] Finally, in stage S103, the temperature is raised to 650 - 700 °C and held for 90 - 120 min; this is the high-temperature stage in the debinding process, which helps to completely remove the remaining adhesives and ensure the stability of the microstructure of the ceramic material; the heating rate in this stage is the slowest (0.5 - 1 °C / min) to minimize the impact of thermal stress on the ceramic material.

[0044] Impregnation and drying with chromium nitrate solution: After the first-stage heat treatment, the pore structure inside the green ceramic body becomes more open, which is conducive to the penetration of the chromium nitrate solution; chromium nitrate not only acts as a strengthening agent but also reacts with the ceramic material at high temperatures to form stable compounds; at the same time, the drying process further removes the moisture and residual organic binders in the green ceramic body, laying the foundation for the subsequent sintering treatment;

[0045] Second-stage heat treatment: Heat preservation treatment is carried out at a temperature of 500 - 700 °C. The main purpose of this stage is to make chromium nitrate react fully with the ceramic material to form stable compounds, thereby reducing the generation of chromium smoke and nitrogen oxides during sintering; at the same time, the heat treatment in this stage also helps to further remove the residual organic matter in the green ceramic body and reduce the pollution during sintering;

[0046] Stepwise heating: The green ceramic body after the second-stage treatment is heated to 1500 - 1600 °C in steps for heat preservation sintering treatment; stepwise heating helps to control the temperature gradient during the sintering process and reduce the damage of thermal stress to the ceramic material;

[0047] During the first-stage treatment and the second-stage treatment, the product needs to be placed in a porous ceramic fixture to absorb the harmful gas phases generated during the heat treatment, so that no substances are deposited on the surface of the product during the cooling process, reducing the bending rejection rate of the ceramic product;

[0048] After sintering is completed, the furnace is cooled to room temperature; this step helps to avoid cracks and deformations in the ceramic product caused by rapid cooling. Brief Description of the Drawings

[0049] Figure 1 TG-DTA spectrum (Example 1) of a ceramic impurity removal method provided by the present invention; Detailed Description of the Embodiment

[0050] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] The present invention provides a method for removing impurities from ceramics, comprising the following steps:

[0052] S1 Perform heat treatment and cooling treatment on the green ceramic body in the first stage: Place the green ceramic body in a porous ceramic jig, heat it in stages from room temperature to 650 - 700 °C for heat preservation heat treatment, cool the heat-treated green ceramic body to room temperature and then take it out to obtain the green ceramic body after the first-stage treatment;

[0053] S2 Immerse and dry the green ceramic body after the first-stage treatment successively with a chromium nitrate solution to obtain a completely dried impregnated ceramic body;

[0054] S3 Perform heat treatment and cooling treatment on the completely dried impregnated ceramic body in the second stage: Place the completely dried impregnated ceramic body in a porous ceramic jig, heat it from room temperature to 500 - 700 °C for heat preservation heat treatment, and cool the heat-treated ceramic body to obtain the ceramic body after the second-stage treatment;

[0055] S4 Perform sintering treatment on the ceramic body after the second-stage treatment: Heat the ceramic body after the second-stage treatment in stages to 1500 - 1600 °C and then perform heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product.

[0056] The present invention provides a method for removing impurities from ceramics and a ceramic product, with a simple process, which can not only efficiently degum, but also effectively reduce the generation and deposition of harmful substances during the sintering process, and reduce the bending rejection rate of the ceramic product.

[0057] Preferably, in step S1, placing the green ceramic body in a porous ceramic jig and heating it in stages from room temperature to 650 - 700 °C for heat preservation heat treatment specifically includes the following steps:

[0058] S101 Place the green ceramic body in a porous ceramic jig, heat it from room temperature to 200 - 300 °C, with a heating rate of 5 - 10 °C / min and a heat preservation time of 30 - 60 min;

[0059] S102 Then heat it from 200 - 300 °C to 350 - 450 °C, with a heating rate of 1 - 5 °C / min and a heat preservation time of 60 - 90 min;

[0060] S103 Finally, heat it from 350 - 450 °C to 650 - 700 °C, with a heating rate of 0.5 - 1 °C / min and a heat preservation time of 90 - 120 min.

[0061] Preferably, in step S2, immersing and drying the green ceramic body after the first-stage treatment successively with a chromium nitrate solution specifically includes the following steps:

[0062] S201 Prepare a chromium nitrate solution with a concentration of 1 - 1.5 g / ml;

[0063] S202 Immerse the ceramic green body after the first - stage treatment in the chromium nitrate solution to obtain the immersed ceramic green body;

[0064] S203 Take out the immersed ceramic green body and dry it to obtain a completely dried impregnated ceramic green body.

[0065] Preferably, the drying in step S203 specifically includes the following steps:

[0066] Perform drying by keeping warm in an oven at 38 - 42 °C for 3 - 4 h.

[0067] Preferably, in step S3, place the completely dried impregnated ceramic green body in a porous ceramic fixture, and heat it from room temperature to 500 - 700 °C for heat - preservation heat treatment, which specifically includes the following steps:

[0068] S301 Place the completely dried impregnated ceramic green body in a porous ceramic fixture, heat it from room temperature to 500 - 700 °C, keep it warm for 90 - 120 min, and the heating rate is 1 - 5 °C to obtain the ceramic green body after heat - preservation heat treatment.

[0069] Preferably, in step S3, cool the ceramic green body after heat - preservation heat treatment to obtain the ceramic green body after the second - stage treatment, which specifically includes the following steps:

[0070] S302 Cool the ceramic green body after heat - preservation heat treatment from 500 - 700 °C to 25 - 100 °C to obtain the ceramic green body after the second - stage treatment.

[0071] Preferably, the cooling rate from 500 - 700 °C to 25 - 100 °C in step S302 is 5 - 10 °C.

[0072] Preferably, in step S4, heat the ceramic green body after the second - stage treatment in stages to 1500 - 1600 °C and then perform heat - preservation sintering treatment, which specifically includes the following steps:

[0073] S401 Heat the ceramic green body after the second - stage treatment from 25 °C - 100 °C to 1300 - 1400 °C for sintering treatment, keep it warm for 30 - 60 min, and the heating rate is 6 - 15 °C / min;

[0074] S402 Then heat it from 1300 - 1400 °C to 1500 - 1600 °C for sintering treatment, keep it warm for 120 - 150 min, and the heating rate is 2 - 8 °C / min.

[0075] Preferably, all the technological steps of the ceramic impurity - removal method are carried out in an air atmosphere.

[0076] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method described in any one of the above.

[0077] Example 1

[0078] The present invention provides a ceramic impurity removal method, comprising the following steps:

[0079] S1 Under an air atmosphere, perform a first-stage heat treatment and a cooling treatment on the green ceramic body: Place the green ceramic body in a porous ceramic jig, and gradually heat it from room temperature to 650 °C for heat preservation heat treatment. After cooling the heat-treated green ceramic body to room temperature, take it out to obtain the green ceramic body after the first-stage treatment; specifically, it includes the following steps:

[0080] S101 Place the green ceramic body in a porous ceramic jig, heat it from room temperature to 200 °C, with a heating rate of 5 °C / min and a heat preservation time of 60 min;

[0081] S102 Then heat it from 200 °C to 350 °C, with a heating rate of 1 °C / min and a heat preservation time of 90 min;

[0082] S103 Finally, heat it from 350 °C to 650 °C, with a heating rate of 0.5 °C / min and a heat preservation time of 120 min;

[0083] S104 Cool the heat-treated green ceramic body to room temperature and then take it out to obtain the green ceramic body after the first-stage treatment;

[0084] S2 Use a chromium nitrate solution to impregnate and dry the green ceramic body after the first-stage treatment in sequence to obtain a completely dried impregnated ceramic body, specifically including the following steps:

[0085] S201 Prepare a chromium nitrate solution with a concentration of 1 g / ml;

[0086] S202 Immerse the green ceramic body after the first-stage treatment in the chromium nitrate solution to obtain an immersed ceramic body;

[0087] S203 Take out the immersed ceramic body and keep it in an oven at 38 °C for 4 h to obtain a completely dried impregnated ceramic body;

[0088] S3 Under an air atmosphere, perform a second-stage heat treatment and a cooling treatment on the completely dried impregnated ceramic body: Place the completely dried impregnated ceramic body in a porous ceramic jig, heat it from room temperature to 500 °C for heat preservation heat treatment, and cool the heat-treated ceramic body to 25 °C to obtain the ceramic body after the second-stage treatment, specifically including the following steps:

[0089] S301 Place the completely dried impregnated ceramic green body in a porous ceramic fixture, heat it from room temperature to 500 °C, keep it at this temperature for 100 min, and the heating rate is 3 °C;

[0090] S302 Then cool it from 500 °C to 25 °C, and the cooling rate is 5 °C, obtaining the ceramic green body after the second-stage treatment;

[0091] S4 Under an air atmosphere, sinter the ceramic green body after the second-stage treatment: heat the ceramic green body after the second-stage treatment in stages to 1500 °C and then carry out heat preservation sintering treatment, and then cool it to room temperature with the furnace, obtaining a ceramic product, which specifically includes the following steps:

[0092] S401 Heat the ceramic green body after the second-stage treatment from 25 °C to 1350 °C for sintering treatment, keep it at this temperature for 60 min, and the heating rate is 10 °C / min;

[0093] S402 Then heat it from 1350 °C to 1570 °C for sintering treatment, keep it at this temperature for 150 min, and the heating rate is 5 °C / min;

[0094] S403 Cool it to room temperature with the furnace to obtain a ceramic product.

[0095] The present invention also provides a ceramic product prepared according to the above-mentioned ceramic impurity removal method.

[0096] Example 2

[0097] The present invention provides a ceramic impurity removal method, including the following steps:

[0098] S1 Carry out the first-stage heat treatment and cooling treatment on the ceramic green body: place the ceramic green body in a porous ceramic fixture, heat it from room temperature in stages to 675 °C for heat preservation heat treatment, cool the ceramic green body after the heat preservation heat treatment to room temperature and then take it out, obtaining the ceramic green body after the first-stage treatment, which specifically includes the following steps:

[0099] S101 Place the ceramic green body in a porous ceramic fixture, heat it from room temperature to 250 °C, the heating rate is 8 °C / min, and the heat preservation time is 45 min;

[0100] S102 Then heat it from 250 °C to 400 °C, the heating rate is 3 °C / min, and the heat preservation time is 75 min;

[0101] S103 Finally heat it from 400 °C to 675 °C, the heating rate is 0.8 °C / min, and the heat preservation time is 105 min;

[0102] S104 Cool the ceramic green body after the heat preservation heat treatment to room temperature and then take it out, obtaining the ceramic green body after the first-stage treatment;

[0103] S2 impregnates and dries the green ceramic body after the first-stage treatment with a chromium nitrate solution in sequence to obtain a completely dried impregnated ceramic body, which specifically includes the following steps:

[0104] S201 Prepare a chromium nitrate solution with a concentration of 1.3 g / ml;

[0105] S202 Immerse the green ceramic body after the first-stage treatment in the chromium nitrate solution to obtain an immersed ceramic body;

[0106] S203 Take out the immersed ceramic body and keep it warm in an oven at 40 °C for 3.5 h to obtain a completely dried impregnated ceramic body;

[0107] S3 conducts a second-stage heat treatment and a cooling treatment on the completely dried impregnated ceramic body: Place the completely dried impregnated ceramic body in a porous ceramic fixture, heat it from room temperature to 600 °C for heat preservation treatment, and cool the ceramic body after the heat preservation treatment to 60 °C to obtain the ceramic body after the second-stage treatment, which specifically includes the following steps:

[0108] S301 Place the completely dried impregnated ceramic body in a porous ceramic fixture, heat it from room temperature to 600 °C, with a heat preservation time of 105 min and a heating rate of 3 °C;

[0109] S302 Then cool it from 600 °C to 60 °C, with a cooling rate of 8 °C, to obtain the ceramic body after the second-stage treatment;

[0110] S4 conducts a sintering treatment on the ceramic body after the second-stage treatment: Heat the ceramic body after the second-stage treatment in stages to 1550 °C and then conduct a heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product; specifically includes the following steps:

[0111] S401 Heat the ceramic body after the second-stage treatment from 62 °C to 1350 °C for sintering treatment, with a heat preservation time of 45 min and a heating rate of 11 °C / min;

[0112] S402 Then heat it from 1350 °C to 1550 °C for sintering treatment, with a heat preservation time of 135 min and a heating rate of 5 °C / min;

[0113] S403 Cool it to room temperature with the furnace to obtain a ceramic product.

[0114] The present invention also provides a ceramic product prepared according to the above-mentioned ceramic impurity removal method.

[0115] Example 3

[0116] The present invention provides a ceramic impurity removal method, including the following steps:

[0117] S1 performs the first-stage heat treatment and cooling treatment on the green ceramic body: Place the green ceramic body in a porous ceramic fixture, heat it from room temperature to 700 °C in stages for heat preservation treatment, cool the heat-treated green ceramic body to room temperature and then take it out to obtain the green ceramic body after the first-stage treatment; specifically, it includes the following steps:

[0118] S101 Place the green ceramic body in a porous ceramic fixture, heat it from room temperature to 300 °C at a heating rate of 10 °C / min, and keep it at a constant temperature for 60 min;

[0119] S102 Then heat it from 300 °C to 450 °C at a heating rate of 5 °C / min, and keep it at a constant temperature for 90 min;

[0120] S103 Finally, heat it from 450 °C to 700 °C at a heating rate of 1 °C / min, and keep it at a constant temperature for 90 min;

[0121] S104 Cool the heat-treated green ceramic body to room temperature and then take it out to obtain the green ceramic body after the first-stage treatment;

[0122] S2 uses a chromium nitrate solution to impregnate and dry the green ceramic body after the first-stage treatment in sequence to obtain a completely dried impregnated ceramic body, specifically including the following steps:

[0123] S201 Prepare a chromium nitrate solution with a concentration of 1.5 g / ml;

[0124] S202 Immerse the green ceramic body after the first-stage treatment in the chromium nitrate solution to obtain an immersed ceramic body;

[0125] S203 Take out the immersed ceramic body and keep it in an oven at 42 °C for 3 h to obtain a completely dried impregnated ceramic body;

[0126] S3 performs the second-stage heat treatment and cooling treatment on the completely dried impregnated ceramic body: Place the completely dried impregnated ceramic body in a porous ceramic fixture, heat it from room temperature to 700 °C for heat preservation treatment, and cool the heat-treated ceramic body to 100 °C to obtain the ceramic body after the second-stage treatment, specifically including the following steps:

[0127] S301 Place the completely dried impregnated ceramic body in a porous ceramic fixture, heat it from room temperature to 700 °C, keep it at a constant temperature for 90 min, and the heating rate is 5 °C;

[0128] S302 Then cool it from 700 °C to 100 °C at a cooling rate of 10 °C to obtain the ceramic body after the second-stage treatment;

[0129] S4 Sinter the green ceramic body after the second-stage treatment: Gradually heat the green ceramic body after the second-stage treatment to 1600 °C in stages, then perform heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product; specifically, it includes the following steps:

[0130] S401 Heat the green ceramic body after the second-stage treatment from 100 °C to 1400 °C for sintering treatment, with a heat preservation time of 30 min and a heating rate of 15 °C / min;

[0131] S402 Then heat from 1400 °C to 1600 °C for sintering treatment, with a heat preservation time of 120 min and a heating rate of 8 °C / min;

[0132] S403 Cool to room temperature with the furnace to obtain a ceramic product.

[0133] The present invention also provides a ceramic product prepared according to the above-mentioned ceramic impurity removal method.

[0134] Comparative Example 1

[0135] Comparative Example 1 provides a ceramic impurity removal method, including the following steps:

[0136] S1 Under an air atmosphere, perform the first-stage heat treatment and cooling treatment on the green ceramic body: Place the green ceramic body in a porous ceramic jig, gradually heat it from room temperature to 650 °C for heat preservation heat treatment, and after cooling the heat-preserved heat-treated green ceramic body to room temperature, take it out to obtain the green ceramic body after the first-stage treatment; specifically, it includes the following steps:

[0137] S101 Place the green ceramic body in a porous ceramic jig, heat it from room temperature to 200 °C, with a heating rate of 5 °C / min and a heat preservation time of 60 min;

[0138] S102 Then heat from 200 °C to 350 °C, with a heating rate of 1 °C / min and a heat preservation time of 90 min;

[0139] S103 Finally, heat from 350 °C to 650 °C, with a heating rate of 0.5 °C / min and a heat preservation time of 120 min;

[0140] S104 After cooling the heat-preserved heat-treated green ceramic body to room temperature, take it out to obtain the green ceramic body after the first-stage treatment;

[0141] S2 Use a chromium nitrate solution to impregnate and dry the green ceramic body after the first-stage treatment in sequence to obtain a completely dried impregnated ceramic body, specifically including the following steps:

[0142] S201 Prepare a chromium nitrate solution with a concentration of 1 g / ml;

[0143] S202 Immerse the ceramic green body after the first-stage treatment in a chromium nitrate solution to obtain the immersed ceramic green body;

[0144] S203 Take out the immersed ceramic green body and keep it warm in an oven at 38 °C for 4 h to obtain a completely dried impregnated ceramic green body;

[0145] S3 Under an air atmosphere, perform sintering treatment on the completely dried impregnated ceramic green body: Gradually heat the ceramic green body after the second-stage treatment to 1570 °C in stages and then perform heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product, which specifically includes the following steps:

[0146] S301 Gradually heat the ceramic green body after the second-stage treatment from 25 °C to 1350 °C for sintering treatment, with a heat preservation time of 60 min and a heating rate of 10 °C / min;

[0147] S302 Then gradually heat it from 1350 °C to 1570 °C for sintering treatment, with a heat preservation time of 150 min and a heating rate of 5 °C / min;

[0148] S303 Cool it to room temperature with the furnace to obtain a ceramic product.

[0149] The present invention also provides a ceramic product prepared according to the above-mentioned ceramic impurity removal method.

[0150] Comparative Example 2

[0151] Comparative Example 2 provides a ceramic impurity removal method, including the following steps:

[0152] S1 Under an air atmosphere, perform the first-stage heat treatment and cooling treatment on the ceramic green body: Place the ceramic green body in a porous ceramic fixture, gradually heat it from room temperature to 650 °C for heat preservation heat treatment, and take out the ceramic green body after the heat preservation heat treatment after cooling it to room temperature to obtain the ceramic green body after the first-stage treatment; specifically includes the following steps:

[0153] S101 Place the ceramic green body in a porous ceramic fixture, heat it from room temperature to 200 °C, with a heating rate of 5 °C / min and a heat preservation time of 60 min;

[0154] S102 Then heat it from 200 °C to 350 °C, with a heating rate of 1 °C / min and a heat preservation time of 90 min;

[0155] S103 Finally, heat it from 350 °C to 650 °C, with a heating rate of 0.5 °C / min and a heat preservation time of 120 min;

[0156] S104 Take out the ceramic green body after the heat preservation heat treatment after cooling it to room temperature to obtain the ceramic green body after the first-stage treatment;

[0157] S2 impregnates and dries the green ceramic body after the first-stage treatment with a chromium nitrate solution in sequence to obtain a completely dried impregnated green ceramic body, which specifically includes the following steps:

[0158] S201 Prepare a chromium nitrate solution with a concentration of 1 g / ml;

[0159] S202 Immerse the green ceramic body after the first-stage treatment in the chromium nitrate solution to obtain an immersed green ceramic body;

[0160] S203 Take out the immersed green ceramic body and keep it warm in an oven at 38 °C for 4 h to obtain a completely dried impregnated green ceramic body;

[0161] S3 Under an air atmosphere, perform a second-stage heat treatment on the completely dried impregnated green ceramic body: Place the completely dried impregnated green ceramic body in a porous ceramic fixture, heat it from room temperature to 500 °C for heat preservation treatment to obtain the green ceramic body after the second-stage treatment, which specifically includes the following steps:

[0162] S301 Place the completely dried impregnated green ceramic body in a porous ceramic fixture, heat it from room temperature to 500 °C, with a heat preservation time of 100 min and a heating rate of 3 °C to obtain the green ceramic body after the second-stage treatment;

[0163] S4 Under an air atmosphere, perform a sintering treatment on the green ceramic body after the second-stage treatment: Heat the green ceramic body after the second-stage treatment to 1570 °C in stages and then perform heat preservation sintering treatment, and then cool it to room temperature with the furnace to obtain a ceramic product, which specifically includes the following steps:

[0164] S401 Heat the green ceramic body after the second-stage treatment from 500 °C to 1350 °C for sintering treatment, with a heat preservation time of 60 min and a heating rate of 10 °C / min;

[0165] S402 Then heat it from 1350 °C to 1570 °C for sintering treatment, with a heat preservation time of 150 min and a heating rate of 5 °C / min;

[0166] S403 Cool it to room temperature with the furnace to obtain a ceramic product.

[0167] The present invention also provides a ceramic product prepared according to the above-mentioned ceramic impurity removal method.

[0168] Experimental means for experimental data testing

[0169] The testing means for the bending rejection rate of the ceramic products (cylindrical) prepared in Examples 1-3 and Comparative Examples 1-2 are as follows:

[0170] 1. Testing of the degree of bending:

[0171] (1) Place a piece of the product flat on the projectable panel;

[0172] (2) The computer reads the information on the projection and converts it into image information;

[0173] (3) At this time, a projection image of the cylindrical specimen appears on the computer, which is a rectangular image;

[0174] (4) The computer software will automatically fit one of the edges of the long side of the rectangle into a straight line, and this straight line is denoted as the "0" position;

[0175] (5) Automatically calculate the distance between the actual edge and the fitted edge on this side,

[0176] The maximum distance of the part exceeding the fitted line from the fitted line is denoted as D 1 = a,

[0177] The maximum distance of the part not exceeding the fitted line from the fitted line is denoted as D 2 = -b;

[0178] (6) Finally, the value of the curvature of this piece of product = |D 1 | + |D 2 | = |a| + |-b|, with the unit of μm;

[0179] (7) Measure continuously 3 times, and take the maximum value of the curvatures of the 3 measurements as the final curvature of this piece of product;

[0180] 2. Calculation of the rejection rate due to curvature (rounded to two decimal places):

[0181] Measure the curvatures of 50 to 100 pieces of products under each set of experimental conditions, and count the proportion of products with curvatures exceeding 70 μm. For example, among 75 pieces of products, 13 pieces have curvatures exceeding 70 μm, then for this set of experimental conditions, the rejection rate due to curvature is 17.33%;

[0182] The experimental data of the rejection rates due to curvature of the ceramic products prepared in Examples 1 - 3 and Comparative Examples 1 - 2 are shown in Table 1 below, with 75 pieces tested in each group.

[0183] Table 1 Experimental data of the rejection rates due to curvature of the ceramic products prepared in Examples 1 - 3 and Comparative Examples 1 - 2

[0184] Name Scrap rate due to bending (%) Example 1 4.00 Example 2 6.67 Example 3 17.33 Comparative Example 1 48.00 Comparative Example 2 69.33

[0185] From the experimental data of the bending rejection rate of the ceramic products prepared in Examples 1-3 and Comparative Examples 1-2 shown in Table 1, we can observe that in Examples 1-3, after the second-stage heat treatment and cooling treatment were carried out on the completely dried impregnated ceramic green bodies, the second-stage heat treatment of the completely dried impregnated ceramic green bodies was carried out at 500-700 °C for heat preservation treatment. After the heat preservation ended, the temperature began to drop for cooling treatment; this can ensure that the excess chromium in the product escapes in the form of gas phase, and after escaping, it can be absorbed by the porous ceramic fixture, and timely cooling is also beneficial to the gas phase deposition in the porous ceramic fixture above the product; reducing the deposition of chromium smoke gas-phase substances on the outside of the ceramic product, causing sintering defects in the ceramic product and resulting in deformation problems, and reducing the bending rejection rate of the ceramic product to 4.00%-17.33%;

[0186] In Comparative Example 1, the second-stage heat treatment and cooling treatment were not carried out on the completely dried impregnated ceramic green body compared with Example 1, resulting in the bending rejection rate of the ceramic product in Comparative Example 1 rising to 48%. This is because the chromium nitrate in the impregnated ceramic green body after soaking decomposed completely, and the chromium smoke gas-phase substances generated at high sintering temperature were deposited on the ceramic surface;

[0187] In Comparative Example 2, compared with Example 1, although the second-stage heat treatment was carried out on the completely dried impregnated ceramic green body, but no cooling treatment was carried out after the second-stage heat treatment of the completely dried impregnated ceramic green body, resulting in the bending rejection rate of the ceramic product in Comparative Example 1 rising to 69.33%. This is because the chromium smoke was not absorbed by the porous ceramic fixture and was deposited on the outside of the ceramic product, causing sintering defects in the ceramic product and resulting in a relatively high bending rejection rate of the ceramic product.

[0188] As Figure 1 shown, Example 1 provides a TG-DTA spectrum of a ceramic impurity removal method. During the second-stage heat treatment of the completely dried impregnated ceramic green body, there is an oxidative decomposition of chromium nitrate, and chromium nitrate will decompose into chromium smoke and nitrogen oxides; Figure 1 In it, at about 436.9 °C, the decomposition of the substances in chromium nitrate is completed and the weight loss reaches the maximum; Figure 1 In it, 93.6 °C is the water evaporation point of the product. At about 152.6 °C, chromium smoke and nitrogen oxides begin to be generated, and finally at about 436.9 °C, the substances in chromium nitrate are completely decomposed.

[0189] It can be understood that the present invention is described by means of some embodiments. Those skilled in the art will know that, without departing from the spirit and scope of the present invention, various changes or equivalent substitutions can be made to these features and embodiments. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein. All changes or equivalent substitutions that fall within the scope of the claims of this application are included. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein. All embodiments that fall within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A ceramic impurity removal method, characterized in that: The following steps are involved: S1 performs a first-stage heat treatment and a cooling treatment on the ceramic green body: the ceramic green body is placed in a porous ceramic fixture, and the temperature is raised in stages from room temperature to 650-700° C. for heat preservation treatment, and the ceramic green body after the heat preservation treatment is cooled to room temperature and then taken out to obtain the ceramic green body after the first-stage treatment; S2: using chromium nitrate solution to sequentially impregnate and dry the ceramic green body after the first stage treatment to obtain a completely dried impregnated ceramic green body; S3: performing a second-stage heat treatment and cooling treatment on the completely dried impregnated ceramic green body: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating the temperature from room temperature to 500-700°C for heat preservation treatment, the heat preservation time is 90-120 minutes, the heating rate is 1-5°C, cooling the ceramic green body after the heat preservation treatment, cooling the ceramic green body after the heat preservation treatment from 500-700°C to 25-100°C, the cooling rate is 5-10°C, and obtaining the ceramic green body after the second-stage treatment; S4 sintering the ceramic green body after the second stage treatment: heating the ceramic green body after the second stage treatment to 1500-1600° C. in stages, sintering at a heat preservation temperature, and then cooling down to room temperature with the furnace to obtain a ceramic product.

2. The ceramic impurity removal method according to claim 1, characterized in that: In step S1, the ceramic green body is placed in a porous ceramic fixture and the temperature is raised in stages from room temperature to 650-700° C. for heat treatment, which specifically includes the following steps: S101 placing the ceramic green body in a porous ceramic fixture, heating from room temperature to 200-300°C, with a heating rate of 5-10°C / min, and a holding time of 30-60min; S102 is then heated from 200°C to 300°C to 350°C to 450°C, with a heating rate of 1 to 5°C / min and a holding time of 60 to 90 min; S103 is finally heated from 350-450°C to 650-700°C, with a heating rate of 0.5-1°C / min and a holding time of 90-120min.

3. The ceramic impurity removal method according to claim 1, characterized in that: In step S2, the ceramic green body treated in the first stage is sequentially impregnated and dried with a chromium nitrate solution, which specifically includes the following steps: S201 prepares a chromium nitrate solution with a concentration of 1 to 1.5 g / ml; S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body; S203 takes out the soaked ceramic green body and dries it to obtain a completely dried soaked ceramic green body.

4. The ceramic impurity removal method according to claim 3, characterized in that: The drying in step S203 specifically includes the following steps: Keep in an oven at 38-42°C for 3-4 hours for drying.

5. The ceramic impurity removal method according to claim 1, characterized in that: In step S4, the ceramic green body after the second stage treatment is heated to 1500-1600° C. in stages and then subjected to heat preservation sintering treatment, which specifically includes the following steps: S401: heating the ceramic green body after the second stage treatment from 25°C to 100°C to 1300-1400°C for sintering, with a holding time of 30-60min and a heating rate of 6-15°C / min; S402 is then heated from 1300-1400°C to 1500-1600°C for sintering, with a holding time of 120-150 minutes and a heating rate of 2-8°C / min.

6. The ceramic impurity removal method according to any one of claims 1 to 5, characterized in that: The entire process steps of the ceramic impurity removal method are carried out under air atmosphere.

7. A ceramic product, characterized in that: The ceramic impurity removal method is prepared according to any one of claims 1 to 6.

Images