Ceramic impurity removal method and ceramic product

Abstract

The invention provides a ceramic impurity removal method and a ceramic product, a ceramic green body is subjected to first-stage heat treatment and cooling treatment, and the ceramic green body subjected to first-stage treatment is obtained; sequentially impregnating and drying the ceramic green body treated in the first stage by adopting a chromic nitrate solution to obtain a completely dried impregnated ceramic green body; performing second-stage heat treatment and cooling treatment on the completely dried impregnated ceramic green body to obtain a ceramic green body subjected to second-stage treatment; performing sintering treatment on the ceramic green body subjected to the second-stage treatment to obtain a ceramic product; the process is simple, efficient degumming can be achieved, generation and deposition of harmful substances in the sintering process can be effectively reduced, and the rejection rate of ceramic products due to bending is reduced.

Description

Technical Field

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

[0002] In the degumming process of ceramics, the traditional method usually adopts a slow and low-temperature method for processing. Although this method can achieve the purpose of degumming to a certain extent, it is inefficient and time-consuming, which seriously affects the overall production capacity of the production line. In addition, slow and low-temperature degumming may also have an adverse effect on the microstructure of the ceramic material, thereby affecting the final performance of the ceramic. Therefore, exploring an efficient degumming method that causes 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 is directly related to a series of key performance indicators such as density, strength, hardness, etc. 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] Firstly, chromium nitrate will decompose during the high-temperature sintering process to produce a large amount of chromium fume and nitrogen oxides. These harmful substances are not only highly corrosive, which can seriously damage the heating elements in the sintering furnace and shorten their service life, but may also escape into the production environment, causing environmental pollution and threatening the health and safety of operators.

[0005] Secondly, the gas phase substances of chromium fume tend to accumulate in the sintering furnace at high temperatures and deposit on the ceramic surface, which not only damages the surface quality of the ceramic products, but may also cause sintering defects such as deformation and cracking, resulting in an increase in the scrap rate of products due to quality problems such as bending, seriously affecting production efficiency and cost control.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present 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, which has a simple process, can not only efficiently debond, but also effectively reduce the generation and deposition of harmful substances during the sintering process, and reduce the scrap 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 ceramic impurity removal method, comprising the following steps:

[0010] 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;

[0011] 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;

[0012] 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, cooling the ceramic green body after the heat preservation treatment, and obtaining a ceramic green body after the second-stage treatment;

[0013] 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.

[0014] The invention provides a ceramic impurity removal method and a ceramic product, which has a simple process, can effectively remove the glue, and can effectively reduce the generation and deposition of harmful substances in the sintering process, thereby reducing the scrap rate of ceramic products due to bending.

[0015] As a preferred technical solution, 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 preservation treatment, which specifically includes the following steps:

[0016] 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;

[0017] 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;

[0018] 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.

[0019] As a preferred technical solution, in step S2, the ceramic green body after the first stage treatment is sequentially impregnated and dried with a chromium nitrate solution, which specifically includes the following steps:

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

[0021] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0022] S203 takes out the soaked ceramic green body and dries it to obtain a completely dried soaked ceramic green body.

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

[0024] Keep in an oven at 38-42°C for 3-4 hours for drying.

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

[0026] S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 500-700°C, keeping it warm for 90-120 minutes, and heating it up at a rate of 1-5°C, to obtain a ceramic green body after heat treatment.

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

[0028] S302 cools the ceramic green body after the heat preservation 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, 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:

[0031] 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;

[0032] 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.

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

[0034] The present invention also provides a ceramic product, which is prepared according to any one of the ceramic impurity removal methods described above.

[0035] The present invention provides a ceramic impurity removal method and a ceramic product, which have the following beneficial effects:

[0036] 1) The process is simple, which can not only efficiently debond, but also effectively reduce the generation and deposition of harmful substances during the sintering process, and reduce the scrap rate of ceramic products due to bending;

[0037] 2) After the dried impregnated ceramic green body is subjected to the second stage heat treatment and cooling treatment, the dried impregnated ceramic green body is subjected to the second stage heat treatment and heat preservation heat treatment at 500-700°C. After the heat preservation is completed, the temperature is lowered for cooling treatment; this ensures that the excess chromium in the product escapes in the gas phase, which can be absorbed by the porous ceramic fixture in the scheme after escaping, and timely cooling is also conducive to gas phase deposition in the porous ceramic fixture above the product; reducing the deposition of chromium fume gas phase substances on the outside of the ceramic product, causing sintering defects in the ceramic product, resulting in deformation problems, and reducing the scrap rate of the ceramic product due to bending;

[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 ceramics after sintering; this method achieves efficient debonding through the following steps:

[0039] The first stage of heat treatment: the ceramic green body is placed in a porous ceramic fixture and the temperature is raised to 650-700℃ in stages for heat preservation. The main purpose of this stage is to soften and decompose the organic binder in the ceramic green body and partially volatilize it. The use of porous ceramic fixtures helps to evenly transfer heat and escape organic matter, thereby improving debonding efficiency.

[0040] A staged degreasing process is adopted, starting from room temperature and gradually heating up to 650-700℃ for heat preservation 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 the rapid heating;

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

[0042] In the S102 stage, the temperature is further increased to 350-450°C and kept at this temperature for a longer time (60-90 min). The heating rate is slowed down in this stage (1-5°C / min), and more adhesive and residue are removed in a gentler way. The extension of the holding time also helps to ensure the full removal of the adhesive.

[0043] Finally, in the S103 stage, the temperature rises to 650-700°C and is kept for 90-120 minutes; this is the high-temperature stage in the degreasing process, which helps to completely remove the remaining adhesive 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] Chromium nitrate solution impregnation and drying: After the first stage of heat treatment, the ceramic green body has a more open internal pore structure, which is conducive to the penetration of chromium nitrate solution; chromium nitrate not only acts as a reinforcing agent, but also reacts with ceramic materials at high temperatures to form stable compounds; at the same time, the drying process further removes moisture and residual organic binders in the ceramic green body, laying the foundation for subsequent sintering treatment;

[0045] The second stage of heat treatment: heat preservation heat treatment is carried out at a temperature of 500-700℃. The main purpose of this stage is to make chromium nitrate fully react with ceramic materials 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 residual organic matter in the ceramic green body and reduce pollution during sintering.

[0046] Heating in stages: The ceramic green body after the second stage treatment is heated in stages to 1500-1600℃ for heat preservation sintering. Heating in stages 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 and second stage treatments, the product needs to be placed in a porous ceramic fixture to absorb harmful gases generated during the heat treatment process, so that no substances are deposited on the product surface during the cooling process, reducing the scrap rate of ceramic products due to bending;

[0048] After sintering, the furnace is cooled to room temperature; this step helps to avoid cracks and deformation of ceramic products caused by rapid cooling. BRIEF DESCRIPTION OF THE DRAWINGS

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

[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 ceramic impurity removal method, comprising the following steps:

[0052] 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;

[0053] 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;

[0054] 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, cooling the ceramic green body after the heat preservation treatment, and obtaining a ceramic green body after the second-stage treatment;

[0055] 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.

[0056] The invention provides a ceramic impurity removal method and a ceramic product, which has a simple process, can effectively remove the glue, and can effectively reduce the generation and deposition of harmful substances in the sintering process, thereby reducing the scrap rate of ceramic products due to bending.

[0057] Preferably, 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:

[0058] 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;

[0059] S102 is then heated from 200-300°C to 350-450°C, with a heating rate of 1-5°C / min and a holding time of 60-90min;

[0060] 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.

[0061] Preferably, in step S2, the ceramic green body after the first stage treatment is sequentially impregnated and dried with a chromium nitrate solution, which specifically comprises the following steps:

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

[0063] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0064] S203 takes out the soaked ceramic green body and dries it to obtain a completely dried soaked ceramic green body.

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

[0066] Keep in an oven at 38-42°C for 3-4 hours for drying.

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

[0068] S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 500-700°C, keeping it warm for 90-120 minutes, and heating it up at a rate of 1-5°C, to obtain a ceramic green body after heat treatment.

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

[0070] S302 cools the ceramic green body after the heat preservation 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, 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:

[0073] 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;

[0074] 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.

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

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

[0077] Example 1

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

[0079] S1, in an air atmosphere, subjecting the ceramic green body to a first-stage heat treatment and a cooling treatment: placing the ceramic green body in a porous ceramic fixture, heating the ceramic green body in stages from room temperature to 650°C for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain a ceramic green body after the first-stage treatment; specifically comprising the following steps:

[0080] S101: placing the ceramic green body in a porous ceramic fixture, heating it from room temperature to 200°C, with a heating rate of 5°C / min and a holding time of 60min;

[0081] S102 was then heated from 200°C to 350°C at a heating rate of 1°C / min and the holding time was 90 min;

[0082] S103 was finally heated from 350°C to 650°C at a heating rate of 0.5°C / min and a holding time of 120 min;

[0083] S104: cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first stage treatment;

[0084] S2 uses 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, which specifically includes the following steps:

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

[0086] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0087] S203 taking out the soaked ceramic green body and keeping it in an oven at 38° C. for 4 hours to obtain a completely dried soaked ceramic green body;

[0088] S3, in an air atmosphere, 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° C. for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to 25° C., and obtaining the ceramic green body after the second stage treatment, specifically comprising the following steps:

[0089] S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 500°C, keeping it for 100 minutes, and heating rate of 3°C;

[0090] S302 is then cooled from 500°C to 25°C at a cooling rate of 5°C to obtain a ceramic green body after the second stage of treatment;

[0091] S4, in an air atmosphere, sintering the ceramic green body after the second stage treatment: heating the ceramic green body after the second stage treatment to 1500° C. in stages, sintering at a temperature of 1500° C., and then cooling the green body to room temperature with the furnace to obtain a ceramic product, specifically comprising the following steps:

[0092] S401: the ceramic green body after the second stage treatment is heated from 25°C to 1350°C for sintering, the holding time is 60min, and the heating rate is 10°C / min;

[0093] S402 is then sintered by heating from 1350°C to 1570°C, with a holding time of 150 min and a heating rate of 5°C / min;

[0094] S403 The furnace is cooled to room temperature to obtain a ceramic product.

[0095] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method as described above.

[0096] Example 2

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

[0098] S1 performs a first-stage heat treatment and a cooling treatment on the ceramic green body: placing the ceramic green body in a porous ceramic fixture, heating the ceramic green body from room temperature to 675°C in stages for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first-stage treatment, specifically comprising the following steps:

[0099] S101: placing the ceramic green body in a porous ceramic fixture, heating it from room temperature to 250°C, with a heating rate of 8°C / min and a holding time of 45min;

[0100] S102 was then heated from 250°C to 400°C at a heating rate of 3°C / min and the holding time was 75min;

[0101] S103 was finally heated from 400°C to 675°C at a heating rate of 0.8°C / min and a holding time of 105min;

[0102] S104: cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first stage treatment;

[0103] S2 uses 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, which specifically includes the following steps:

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

[0105] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0106] S203 taking out the soaked ceramic green body and keeping it in an oven at 40° C. for 3.5 hours to obtain a completely dried soaked ceramic green body;

[0107] S3 performs 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 600° C. for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to 60° C., and obtaining the ceramic green body after the second-stage treatment, specifically comprising the following steps:

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

[0109] S302 is then cooled from 600°C to 60°C at a cooling rate of 8°C to obtain a ceramic green body after the second stage of treatment;

[0110] S4 sintering the ceramic green body after the second stage treatment: heating the ceramic green body after the second stage treatment to 1550°C in stages, sintering at a heat preservation temperature, and then cooling it to room temperature with the furnace to obtain a ceramic product; specifically comprising the following steps:

[0111] S401: the ceramic green body after the second stage treatment is heated from 62°C to 1350°C for sintering, the holding time is 45min, and the heating rate is 11°C / min;

[0112] S402 is then heated from 1350°C to 1550°C for sintering, with a holding time of 135 min and a heating rate of 5°C / min;

[0113] S403 The furnace is cooled to room temperature to obtain a ceramic product.

[0114] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method as described above.

[0115] Example 3

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

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

[0118] S101: placing the ceramic green body in a porous ceramic fixture, heating it from room temperature to 300°C, with a heating rate of 10°C / min and a holding time of 60min;

[0119] S102 was then heated from 300°C to 450°C at a heating rate of 5°C / min and the holding time was 90 min;

[0120] S103 was finally heated from 450°C to 700°C at a heating rate of 1°C / min and a holding time of 90 min;

[0121] S104: cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first stage treatment;

[0122] S2 uses 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, which specifically includes the following steps:

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

[0124] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0125] S203 taking out the soaked ceramic green body and keeping it in an oven at 42° C. for 3 hours to obtain a completely dried soaked ceramic green body;

[0126] S3 performs 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 700° C. for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to 100° C., and obtaining the ceramic green body after the second-stage treatment, specifically comprising the following steps:

[0127] S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 700°C, keeping it at this temperature for 90 minutes, and heating rate of 5°C;

[0128] S302 is then cooled from 700°C to 100°C at a cooling rate of 10°C to obtain a ceramic green body after the second stage of treatment;

[0129] S4 sintering the ceramic green body after the second stage treatment: heating the ceramic green body after the second stage treatment to 1600° C. in stages, sintering at a heat preservation temperature, and then cooling to room temperature with the furnace to obtain a ceramic product; specifically comprising the following steps:

[0130] S401: the ceramic green body after the second stage treatment is heated from 100°C to 1400°C for sintering, the holding time is 30min, and the heating rate is 15°C / min;

[0131] S402 is then heated from 1400°C to 1600°C for sintering, with a holding time of 120 min and a heating rate of 8°C / min;

[0132] S403 The furnace is cooled to room temperature to obtain a ceramic product.

[0133] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method as described above.

[0134] Comparative Example 1

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

[0136] S1, in an air atmosphere, subjecting the ceramic green body to a first-stage heat treatment and a cooling treatment: placing the ceramic green body in a porous ceramic fixture, heating the ceramic green body in stages from room temperature to 650°C for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain a ceramic green body after the first-stage treatment; specifically comprising the following steps:

[0137] S101: placing the ceramic green body in a porous ceramic fixture, heating it from room temperature to 200°C, with a heating rate of 5°C / min and a holding time of 60min;

[0138] S102 was then heated from 200°C to 350°C at a heating rate of 1°C / min and the holding time was 90 min;

[0139] S103 was finally heated from 350°C to 650°C at a heating rate of 0.5°C / min and a holding time of 120 min;

[0140] S104: cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first stage treatment;

[0141] S2 uses 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, which specifically includes the following steps:

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

[0143] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0144] S203 taking out the soaked ceramic green body and keeping it in an oven at 38° C. for 4 hours to obtain a completely dried soaked ceramic green body;

[0145] S3, in an air atmosphere, sintering the completely dried impregnated ceramic green body: heating the ceramic green body after the second stage treatment to 1570°C in stages, sintering at a temperature of 1570°C, and then cooling it to room temperature with the furnace to obtain a ceramic product, specifically comprising the following steps:

[0146] S301: the ceramic green body after the second stage treatment is heated from 25°C to 1350°C for sintering, the holding time is 60min, and the heating rate is 10°C / min;

[0147] S302 is then heated from 1350°C to 1570°C for sintering, with a holding time of 150 min and a heating rate of 5°C / min;

[0148] S303 The furnace is cooled to room temperature to obtain a ceramic product.

[0149] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method as described above.

[0150] Comparative Example 2

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

[0152] S1, in an air atmosphere, subjecting the ceramic green body to a first-stage heat treatment and a cooling treatment: placing the ceramic green body in a porous ceramic fixture, heating the ceramic green body in stages from room temperature to 650°C for heat preservation treatment, cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain a ceramic green body after the first-stage treatment; specifically comprising the following steps:

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

[0154] S102 was then heated from 200°C to 350°C at a heating rate of 1°C / min and the holding time was 90 min;

[0155] S103 was finally heated from 350°C to 650°C at a heating rate of 0.5°C / min and a holding time of 120 min;

[0156] S104: cooling the ceramic green body after the heat preservation treatment to room temperature and then taking it out to obtain the ceramic green body after the first stage treatment;

[0157] S2 uses 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, which specifically includes the following steps:

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

[0159] S202: soaking the ceramic green body after the first stage treatment in a chromium nitrate solution to obtain a soaked ceramic green body;

[0160] S203 taking out the soaked ceramic green body and keeping it in an oven at 38° C. for 4 hours to obtain a completely dried soaked ceramic green body;

[0161] S3, in an air atmosphere, performing a second stage heat 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° C. for heat preservation, and obtaining a ceramic green body after the second stage treatment, specifically comprising the following steps:

[0162] S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 500°C, keeping it for 100 minutes, and heating rate of 3°C, to obtain the ceramic green body after the second stage treatment;

[0163] S4, in an air atmosphere, sintering the ceramic green body after the second stage treatment: heating the ceramic green body after the second stage treatment to 1570°C in stages, sintering at a temperature of 1570°C, and then cooling it to room temperature with the furnace to obtain a ceramic product, specifically comprising the following steps:

[0164] S401: the ceramic green body after the second stage treatment is heated from 500°C to 1350°C for sintering, the holding time is 60min, and the heating rate is 10°C / min;

[0165] S402 is then sintered by heating from 1350°C to 1570°C, with a holding time of 150 min and a heating rate of 5°C / min;

[0166] S403 The furnace is cooled to room temperature to obtain a ceramic product.

[0167] The present invention also provides a ceramic product, which is prepared according to the ceramic impurity removal method as described above.

[0168] Experimental means of experimental data testing

[0169] The testing method for the scrap rate of the ceramic products (cylindrical) prepared in Examples 1-3 and Comparative Examples 1-2 due to bending is as follows:

[0170] 1. Curvature test:

[0171] (1) Place a product flat on a projection panel;

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

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

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

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

[0176] The maximum distance between the part exceeding the fitting line and the fitting line is recorded as D1=a.

[0177] The maximum distance between the part that does not exceed the fitting line and the fitting line is recorded as D2 = -b;

[0178] (6) The final curvature value of the sheet product = |D1| + |D2| = |a| + |-b|, in μm;

[0179] (7) Measure three times in a row and take the maximum value of the three curvatures as the final curvature of the product;

[0180] 2. Calculation of scrap rate due to bending (round to two decimal places):

[0181] For each experimental condition, the curvature of 50 to 100 products is measured, and the proportion of products with a curvature exceeding 70μm is counted. For example, if the curvature of 13 products out of 75 products exceeds 70μm, the scrap rate due to curvature in this experimental condition is 17.33%;

[0182] Experimental data on the scrap rate due to bending 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 scrap rate of ceramic products prepared in Examples 1-3 and Comparative Examples 1-2 due to bending

[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 scrap rate of 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 dried impregnated ceramic green body is subjected to the second stage heat treatment and cooling treatment, the dried impregnated ceramic green body is subjected to the second stage heat treatment at 500-700°C for heat preservation, and after the heat preservation is completed, the temperature is lowered for cooling treatment; in this way, the excess chromium in the product can be ensured to escape in the gas phase, which can be absorbed by the porous ceramic fixture after escaping, and timely cooling is also conducive to gas phase deposition in the porous ceramic fixture above the product; the deposition of chromium fume gas phase substances on the outside of the ceramic product is reduced, so that the ceramic product has sintering defects, resulting in deformation problems, and the scrap rate of the ceramic product due to bending is reduced to 4.00%-17.33%;

[0186] Compared with Example 1, Comparative Example 1 did not perform the second stage heat treatment and cooling treatment on the completely dried impregnated ceramic green body, resulting in the ceramic product of Comparative Example 1 The scrap rate due to bending increased to 48%. This is because the chromium nitrate in the ceramic green body after immersion is completely decomposed, and the chromium fume gas phase substances generated at the high temperature of sintering are deposited on the ceramic surface;

[0187] Compared with Example 1, although the second-stage heat treatment is performed on the completely dried impregnated ceramic green body in Comparative Example 2, no cooling treatment is performed after the second-stage heat treatment of the completely dried impregnated ceramic green body, resulting in the ceramic product of Comparative Example 1 having a scrap rate due to bending increased to 69.33%. This is because the chromium fume is not absorbed by the porous ceramic jig and is deposited on the outside of the ceramic product, causing sintering defects in the ceramic product, resulting in a high scrap rate of the ceramic product due to bending.

[0188] like Figure 1 As 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 oxidative decomposition of chromium nitrate, and the chromium nitrate decomposes into chromium fumes and nitrogen oxides; Figure 1 At about 436.9℃, the substances in chromium nitrate are completely decomposed and the weight loss reaches the maximum; Figure 1 Among them, 93.6℃ is the evaporation point of water in the product. At about 152.6℃, chromium smoke and nitrogen oxides begin to be produced. Finally, at about 436.9℃, the substances in chromium nitrate are completely decomposed.

[0189] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may 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, and all various changes or equivalent substitutions falling within the scope of the claims of the present application are included. In addition, under the teachings of the present invention, these features and embodiments may 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, and all embodiments falling within the scope of the claims of the present application are within 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, cooling the ceramic green body after the heat preservation treatment, and obtaining a 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 S3, the completely dried impregnated ceramic green body is placed in a porous ceramic fixture and heated from room temperature to 500-700° C. for heat treatment, which specifically includes the following steps: S301: placing the completely dried impregnated ceramic green body in a porous ceramic fixture, heating it from room temperature to 500-700°C, keeping it warm for 90-120 minutes, and heating it up at a rate of 1-5°C, to obtain a ceramic green body after heat treatment.

6. The ceramic impurity removal method according to claim 1, characterized in that: In step S3, the ceramic green body after the heat preservation treatment is cooled to obtain the ceramic green body after the second stage treatment, which specifically includes the following steps: S302 cools the ceramic green body after the heat preservation treatment from 500-700° C. to 25-100° C. to obtain the ceramic green body after the second stage treatment.

7. The method for removing impurities from ceramics according to claim 6, characterized in that: In step S302, the cooling rate from 500-700°C to 25-100°C is 5-10°C.

8. The method for removing impurities from ceramics 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.

9. The ceramic impurity removal method according to any one of claims 1 to 8, characterized in that: The entire process steps of the ceramic impurity removal method are carried out under air atmosphere.

10. A ceramic product, characterized in that: The ceramic impurity removal method is prepared according to any one of claims 1 to 9.

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