CN112939617B - Method for screening functional ceramic sintering aid - Google Patents

Abstract

The invention provides a method for screening a functional ceramic sintering aid. The method comprises the steps of covering a sintering aid to be screened on the surface of a functional ceramic blank, then carrying out co-calcination at a preset sintering temperature, and finally judging whether the sintering aid to be screened can be used as the sintering aid of the functional ceramic according to the apparent characteristics of the co-calcined functional ceramic blank and the sintering aid to be screened. The method can quickly and efficiently screen out the low-temperature sintering aid suitable for a specific functional ceramic system; in addition, the method greatly shortens the trial and error period, so that the method can obviously reduce the production cost of enterprises.

Description

A method for screening functional ceramic sintering aids

technical field

The invention relates to the field of sintering preparation of special functional ceramics, and mainly relates to a method for screening functional ceramic sintering aids.

Background technique

With the development of science and technology, especially the rapid development of new energy, high-tech and modern manufacturing, the requirements for related materials are becoming more and more stringent, and materials scientists urgently need to develop various new high-performance materials. However, while further improving and improving the specific properties of materials, the corresponding cost investment is often increased. In the field of advanced special ceramics, relevant personnel have carried out long-term explorations and attempts to obtain the most cost-effective ceramic materials, and have made great progress. But for ceramic materials, its performance and cost input are often a pair of contradictions. How to reduce the production cost as much as possible on the premise of ensuring the performance of the ceramic material is also the most concerned by the relevant practitioners.

The main preparation process of special functional ceramics includes three links: blank preparation, molding and sintering. After the molding process is completed, the high-temperature sintering process can control the grain growth of the ceramic material matrix, which has a crucial impact on the performance of the ceramic material. So far, ceramic sintering technology has also been a field of continuous breakthroughs by materials workers. Among them, the realization of low-temperature sintering of ceramics is the key to reducing the energy consumption and cost of producing ceramic materials, which can quickly promote the industrial production and large-scale application of special functional ceramic products.

For ceramic materials, there are generally two ways to reduce the densification and sintering temperature: one is to achieve the purpose of reducing the sintering temperature by obtaining ultra-fine, non-agglomerated and uniformly dispersed good sintering active raw material powder; the other is to add an appropriate amount of In order to achieve the purpose of promoting the densification of ceramic materials and low-temperature sintering. The first method will further increase the production input cost because of the increased requirements for raw material particle size and sintering activity. As for the way to reduce the densification and sintering temperature of the ceramic matrix by adding sintering aids, ceramic material researchers have already reached a consensus.

However, in this field, researchers usually adopt the method of introducing low melting point oxides or glass phase sintering aids to reduce the densification sintering temperature of the ceramic matrix. However, the selection criteria of sintering aids in the current research are mainly based on whether the melting point of the sintering aid is lower than that of the ceramic matrix, and even the same sintering aid still has obvious differences in the wetting of different ceramic matrices. Blindly copying and copying between different ceramic systems.

Therefore, there is an urgent need in the art for a universal and efficient screening method for sintering aids.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for rapid and efficient screening of sintering aids suitable for functional ceramic materials. To achieve this purpose, the present invention provides a method for screening functional ceramic sintering aids. The details are as follows:

The present invention provides a method for screening functional ceramic sintering aids, the specific steps of which include:

Step 1, according to the number of types of sintering aids to be screened, determine the number of functional ceramic embryos, and obtain at least one functional ceramic embryo;

Step 2, place the functional ceramic embryo on a setter plate covered with zirconia powder, and cover the surface of each functional ceramic embryo with the sintering aid to be screened to obtain at least one calcined body;

Step 3, determining the sintering temperature according to the melting point of the functional ceramic green body, and sintering the pre-calcined body at the sintering temperature and cooling with the furnace;

Step 4: Determine whether the sintering aid to be screened can be used as a sintering aid for the functional ceramic green body according to the apparent characteristics of each of the pre-calcined bodies after sintering is cooled with the furnace.

Preferably, in the step 2, the mass ratio of the sintering aid to be screened and the functional ceramic green body is 1:4-6.

Preferably, in the step 3, the sintering temperature is at least 100°C lower than the melting point of the functional ceramic green body;

During sintering, the heating rate is 3°C/min, and the temperature is kept for 5-15h.

Preferably, in the step 4, the apparent characteristics include: the degree of melting of the pre-calcined body and/or the degree of spreading of the sintering aid to be screened on the surface of the functional ceramic green body.

Preferably, the step 4 includes:

Screening out the pre-calcined body with the largest melting degree, and determining the sintering aid to be screened corresponding to the pre-calcined body as the sintering aid for the functional ceramic green body; and/or

The sintering aid to be screened with the largest spreading degree on the surface of the functional ceramic body is screened, and the sintering aid to be screened is determined as the sintering aid of the functional ceramic body.

Preferably, in the step 1, the functional ceramic embryo is obtained after pre-calcination, grinding, granulation and debinding.

Preferably, the preparation steps of the functional ceramic embryo body are:

Step 0-1, weighing the raw material powder required for preparing the functional ceramic embryo body according to the stoichiometric ratio;

Step 0-2, mixing the weighed raw material powder evenly, adding zirconia grinding balls and absolute ethanol to the mixed powder for ball milling, drying, and pre-sintering to obtain a pre-sintered block;

Step 0-3, using the same ball milling and drying operations as described in Step 0-2, the pre-sintered block is subjected to secondary ball milling and crushing, and sieved with an 80-mesh screen;

Step 0-4, adding polyvinyl butyral/ethanol solution to the sieved powder, granulating, and pressing into a ceramic embryo, and degumming and insulating the ceramic embryo to obtain the The functional ceramic embryo.

Preferably, in the step 0-1, the purity of the raw material powder is greater than or equal to 99%.

Preferably, in the step 0-2, the mass ratio of the mixed powder to the zirconia grinding ball is 1:1.2～1:1.5, and the mass of the mixed powder to the ethanol is 1:1:1. 1;

The ball milling is mixed for 4-12 hours, the drying temperature is 80-120°C, and the pre-sintering temperature is 600-1100°C.

Preferably, in the steps 0-4, the mass percentage of polyvinyl butyral in the polyvinyl butyral/ethanol solution is 4%, and the pressure selected for the pressing is 40-100 MPa;

The diameter of the ceramic embryo body is 8-15mm, and the thickness is 1-1.5mm;

The degumming temperature is 600-700 DEG C, and the holding time is 5-10h.

The invention provides a method for screening functional ceramic sintering aids. In the method, the sintering aid to be screened is covered on the surface of the functional ceramic body, and then co-calcined at a preset sintering temperature, and finally, according to the apparent characteristics of the functional ceramic body and the sintering aid to be screened after co-calcination, It can be judged whether the sintering aid to be screened can be used as the sintering aid for the functional ceramic green body. The method can quickly and efficiently screen out low-temperature sintering aids suitable for a specific functional ceramic system; moreover, the method greatly shortens the trial-and-error cycle, so the method can significantly reduce the production cost of enterprises.

Description of drawings

1 shows a flow chart of a method for screening functional ceramic sintering aids in an embodiment of the present invention;

Fig. 2 shows the state comparison diagram before and after sintering when each sintering aid and the green body are co-sintered in Example 1 of the present invention;

FIG. 3 shows the XRD pattern of the 2.5wt% CuO-doped Na ₃ Zr ₂ Si ₂ PO ₁₂ ceramic prepared in Example 1 of the present invention;

Fig. 4 shows the state comparison diagram before and after sintering when each sintering aid and the green body are co-sintered in Example 2 of the present invention;

FIG. 5 shows the room temperature XRD pattern of the 2.5wt% CuO-doped LiZr ₂ (PO ₄ ) ₃ ceramic prepared in Example 2 of the present invention.

Detailed ways

The following examples are provided for a better understanding of the present invention, and are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by combining with the features of other prior art shall fall within the protection scope of the present invention.

If the specific experimental steps or conditions are not indicated in the examples, it can be carried out according to the operations or conditions of the conventional experimental steps described in the prior art in the field. The reagents and other instruments used without the manufacturer's indication are all conventional reagent products that can be purchased in the market.

In the prior art, the screening scheme of sintering aids is usually based on whether the melting point of the sintering aid is lower than the melting point of the ceramic matrix. Therefore, if the screening is only based on the melting point of the sintering aid, there is a problem that the screening period of the sintering aid is too long. In order to solve this problem, the technical idea proposed in the embodiment of the present invention is as follows: the sintering aid to be screened is covered on the surface of the ceramic body, co-sintered at a specific temperature, and then screened based on the apparent characteristics after sintering . The apparent characteristics include: whether the sintering aid to be screened reacts with the ceramic matrix to form a solid solution (that is, whether it is partially or completely melted after sintering), and whether the sintering aid to be screened generates a liquid phase and wets the ceramic matrix (that is, whether Whether it is melted and spread on the surface of the functional ceramic body after sintering). In this way, the experimenter can screen out effective sintering aids through this co-sintering operation in advance in actual operation, so as to shorten the trial and error cycle and reduce the production cost of the enterprise.

Based on the above-mentioned technical concept proposed by the inventor, the method for screening functional ceramic sintering aids provided by the present invention, the specific implementation contents are as follows:

First, an embodiment of the present invention provides a method for screening functional ceramic sintering aids, as shown in FIG. 1 , which specifically includes the following steps:

Step 1 (S1): According to the number of types of sintering aids to be screened, determine the number of functional ceramic embryos, and obtain at least one functional ceramic embryo.

In specific implementation, first determine the number of types of sintering aids to be screened, and then determine the number of functional ceramic embryos according to the types of sintering aids to be screened, to obtain at least one functional ceramic embryo. For example, for a certain functional ceramic material, there are 9 kinds of sintering aids to be screened, and 9 embryo bodies of the functional ceramic body are also set.

In this implementation step, the diameter of each functional ceramic body may be 8-15 mm, and the thickness may be 1-1.5 mm. In actual operation, the actual size of the embryo body may be determined according to actual needs, which is not limited in this embodiment.

In this implementation step, the functional ceramic embryo is obtained after pre-calcination, grinding, granulation and degumming. The preparation steps of the functional ceramic embryo body can be as follows:

Step 0-1, weighing the raw material powder required for preparing the functional ceramic embryo body according to the stoichiometric ratio.

In the specific implementation, high-purity raw material powder is selected, and the raw material powder required for preparing various functional ceramic materials is weighed according to the stoichiometric ratio.

In this implementation step, in order to ensure the accuracy of the melting point of the functional ceramic body, the purity of the raw material powder should be greater than or equal to 99%.

In step 0-2, the weighed raw material powders are uniformly mixed, and zirconia grinding balls and absolute ethanol are added to the mixed powders for ball milling, drying and pre-sintering to obtain pre-sintered blocks.

In this implementation step, the mass ratio of the mixed powder to the zirconia grinding balls is 1:1.2 to 1:1.5, and the mass of the mixed powder to ethanol is 1:1; the balls are milled for 4 to 12 hours, and then dried. The temperature of sintering is 80~120℃, and the temperature of pre-sintering is 600~1100℃.

In step 0-3, the same operations as the ball milling and drying described in step 0-2 are used, and the pre-sintered block is subjected to secondary ball milling and crushing, and sieved with an 80-mesh screen.

Steps 0-4, adding polyvinyl butyral/ethanol solution to the sieved powder, granulating, and pressing into a ceramic embryo, degumming and insulating the ceramic embryo to obtain a functional ceramic embryo body.

In specific implementation, the operations of step 0-3 and step 0-4 may be as follows: the pre-sintered block obtained in step 0-2 is subjected to secondary ball milling and crushing, and the specific process is as described in step 0-2. Dry in an oven at 80-120°C, sieve with an 80-mesh sieve, add a 4% mass percent polyvinyl butyral (PVB) ethanol solution to the sieved powder, granulate, and put Pressed into a ceramic embryo body (diameter ~ 10mm, thickness 1 ~ 1.5mm) under the pressure of 40 ~ 100MPa, degumming at 600 ~ 700 ℃, and heat preservation for 5 ~ 10h.

Step 2 (S2), placing the functional ceramic body on a setter plate covered with zirconia powder, and covering the surface of each functional ceramic body with the sintering aid to be screened to obtain At least one pre-calcined body.

In the specific implementation, the functional ceramic body is placed on a setter plate covered with zirconia powder, and the sintering aid to be screened is covered on the surface of each functional ceramic body to obtain at least one pre-calcined body. Wherein, a sintering aid to be screened is spread on the surface of each functional ceramic body to obtain a pre-sintered forging body.

In this implementation step, the mass ratio of the sintering aid to be screened and the functional ceramic green body is 1:4-6.

In this implementation step, the function of the zirconia powder is to prevent the ceramic sheet from adhering to the setter after sintering.

In step 3 (S3), the sintering temperature is determined according to the melting point of the functional ceramic green body, and the pre-calcined body is sintered at the sintering temperature and cooled with the furnace.

During specific implementation, the sintering temperature is determined according to the melting point of the functional ceramic green body. Among them, in order to screen out a sintering aid more suitable for the functional ceramic, in this implementation step, the sintering temperature is set to be at least 100°C lower than the melting point of the functional ceramic green body. Then, the pre-calcined body is sintered at the set sintering temperature and cooled with the furnace.

In this implementation step, during sintering, the heating rate is 3°C/min, and the temperature is kept for 5-15 hours.

In step 4 (S4), it is determined whether the sintering aid to be screened can be used as a sintering aid for the functional ceramic green body according to the apparent characteristics of each of the pre-calcined bodies after sintering and cooling in the furnace.

In this implementation step, the apparent characteristics include: the degree of melting of the pre-calcined body and/or the degree of spreading of the sintering aid to be screened on the surface of the functional ceramic green body.

When the sintering aid acts on the ceramic matrix, there are two main mechanisms of action: one is to react with the ceramic matrix to form a solid solution, which promotes the material transfer of the matrix during the sintering process; the other is to react at a relatively low temperature. The liquid phase is formed under the lower temperature, which wets the grain boundary and accelerates the densification and sintering process of the matrix at low temperature. Therefore, the specific implementation process of this implementation step can be as follows:

First of all, make a preliminary judgment with the naked eye. If the pre-calcined body with the highest melting degree can be directly screened by the naked eye, the sintering aid to be screened corresponding to the pre-calcined body is determined as the sintering aid for the functional ceramic embryo; The sintering aid to be screened with the largest spreading degree on the surface of the functional ceramic body is directly screened, and the sintering aid to be screened is determined as the sintering aid of the functional ceramic body. Then, when the degree of melting or spreading is similar and the naked eye cannot give an accurate judgment, scanning electron microscope (SEM) and optical microscope can be used to observe the spreading and wetting of the sintering aid on the surface of the target ceramic body. The phase analysis of the target ceramic block was carried out by X-ray diffractometer (XRD).

Compared with the prior art method, the screening method provided by the embodiment of the present invention has the beneficial effects as follows: 1. It can quickly screen effective sintering aids suitable for a specific functional ceramic system and shorten the experimental period; 2. Determine the sintering temperature The temperature is at least 100°C lower than the melting point of the functional ceramic embryo. Therefore, the selected sintering aids can promote the densification and sintering of functional ceramics at a lower temperature, reduce energy consumption, shorten the firing cycle, and reduce the loss of kiln and kiln furniture. , thereby reducing production costs.

In order for those skilled in the art to better understand the present invention, the following describes the method for screening functional ceramic sintering aids provided by the embodiments of the present invention through a plurality of specific embodiments.

Example 1

Screening of sintering aids suitable for NASICON type Na ₃ Zr ₂ Si ₂ PO ₁₂ sodium ion ceramic electrolyte, the specific steps are as follows:

(1) First, accurately weigh the sodium source compound, zirconium source compound, silicon source compound and phosphorus source compound with a purity of more than 99% according to the molar ratio of Na, Zr, Si and P elements of 3.1:2:2:1.

In this implementation step, the sodium oxalate is selected as the sodium source compound, and during specific implementation, sodium carbonate, sodium nitrate, sodium isopropoxide, sodium oxide or sodium hydroxide can also be selected; the zirconium source compound is selected from zirconia, and in In the specific implementation, zirconium oxynitrate, zirconium oxychloride, zirconium acetylacetonate, zirconium acetate or zirconium hydroxide can also be selected; the silicon source compound is selected from silicon dioxide, and in the specific implementation, tetramethyl orthosilicate can also be selected. ester or ethyl orthosilicate; the phosphorus source compound is ammonium dihydrogen phosphate, and in specific implementation, diammonium hydrogen phosphate or phosphoric acid can also be selected.

(2) Then mix the weighed powder evenly, add anhydrous ethanol to the raw material powder according to the mass of the powder and ethanol at 1:1, mix by ball milling for 4 hours, and place the material in an oven at 80 °C after discharging. Dry in medium, transfer to an alumina crucible, and pre-sinter at 1000 °C.

(3) The pre-sintered block obtained above is subjected to secondary ball milling and crushing. The specific process is as described in (2). After discharging, it is dried in an oven at 80°C, sieved with an 80-mesh sieve, and added after sieving. A polyvinyl butyral (PVB) ethanol solution with a mass percentage of 4% was granulated, and a ceramic green sheet was prepared under a pressure of 40 MPa, which was degummed at 650° C. and kept for 5 hours.

(4) First, determine the 11 sintering aids to be screened, namely: ZnF ₂ , AlF ₃ , FeF ₃ , MgF ₂ , CuF ₂ , MnO ₂ , ZnO, CuO, Ga ₂ O ₃ , Na ₄ B ₄ O ₇ , NaF; then take 12 degummed ceramic embryos from the ceramic green sheets prepared in step (3), and place them on the setter plate covered with zirconia powder, and then weigh the above 11 kinds of sintering aid powders to be screened, weighing about 0.05g, and laying these sintering aids to be screened on the surface of each ceramic green sheet, among which one ceramic green sheet is a blank group. , without any sintering aids to be screened.

(5) Sintering is carried out at 1150°C, the heating rate is 3°C/min, and the temperature is kept for 10h.

(6) Cool with the furnace.

(7) Using a preliminary judgment with the naked eye, FIG. 2 shows a comparison diagram of the states before and after sintering when each sintering aid and the green body are co-sintered in Example 1 of the present invention. It can be seen from Fig. 2 that MnO ₂ , CuF ₂ and CuO sintering aids can significantly wet the ceramic matrix, thus, MnO ₂ , CuF ₂ and CuO can be used as the sintering agent of NASICON type Na ₃ Zr ₂ Si ₂ PO ₁₂ sodium ion ceramic electrolyte Auxiliary. Scanning electron microscope (SEM) and optical microscope were used to observe the spreading and wetting of the sintering aid on the surface of the target ceramic sheet, and it was concluded that the wetting effect of CuO was the best. The best sintering aid for Na ₃ Zr ₂ Si ₂ PO ₁₂ sodium ion ceramic electrolyte.

In addition, it can also be seen from Figure 2 that the wetting effect of NaF is poor, and the ceramic matrix even exhibits swelling. Therefore, NaF is generally not used as a sintering aid for NASICON type Na ₃ Zr ₂ Si ₂ PO ₁₂ sodium ion ceramic electrolytes .

Then, using CuO as the sintering aid of Na ₃ Zr ₂ Si ₂ PO ₁₂ solid ceramic electrolyte, the Na ₃ Zr ₂ Si ₂ PO ₁₂ solid ceramic electrolyte raw material proportion of 2.5wt% CuO powder was doped into Na ₃ Zr ₂ Si ₂ PO ₁₂ solid-state ceramic electrolyte was used as the raw material, and co-sintered at 1100° C. for 10 h to obtain 2.5wt% CuO-doped Na ₃ Zr ₂ Si ₂ PO ₁₂ solid-state ceramic electrolyte. Then, phase analysis of 2.5wt% CuO-doped Na ₃ Zr ₂ Si ₂ PO ₁₂ solid ceramic electrolyte was carried out by powder X-ray diffractometer (XRD). FIG. 3 is a room temperature XRD pattern of the 2.5wt% CuO-doped Na ₃ Zr ₂ Si ₂ PO ₁₂ solid ceramic electrolyte in Example 1. FIG. It can be seen from Fig. 3 that the main crystal phase of the obtained 2.5wt% CuO-doped Na ₃ Zr ₂ Si ₂ PO ₁₂ ceramic electrolyte is a monoclinic phase.

In this embodiment, the two ball millings are carried out in a planetary ball mill, and the rotational speed of the ball milling is 300-400 r/min, and zirconia balls and anhydrous ethanol are added as grinding media during the ball milling. The mass ratio of the material to be ground to the zirconia balls is 1:1.2～1:1.5.

Example 2

To screen a sintering aid suitable for NASICON type LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte, the specific steps are as follows:

(1) First, the lithium source compound, the zirconium source compound, and the phosphorus source compound with a purity of more than 99% are accurately weighed according to the molar ratio of Li, Zr, and P elements of 1.1:2:3.

In this implementation step, the sodium oxalate is selected as the sodium source compound, and during specific implementation, sodium carbonate, sodium nitrate, sodium isopropoxide, sodium oxide or sodium hydroxide can also be selected; the zirconium source compound is selected from zirconia, and in In specific implementation, zirconium oxynitrate, zirconium oxychloride, zirconium acetylacetonate, zirconium acetate or zirconium hydroxide can also be selected; the phosphorus source compound is ammonium dihydrogen phosphate, and in specific implementation, diammonium hydrogen phosphate can also be selected or phosphoric acid.

(2) Then mix the weighed powder evenly, add anhydrous ethanol to the raw material powder according to the mass of the powder and ethanol at 1:1, mix by ball milling for 4 hours, and place the material in an oven at 80 °C after discharging. Dry in medium, transfer to an alumina crucible, and pre-fire at 1100 °C.

(3) The pre-sintered block obtained above is subjected to secondary ball milling and crushing. The specific process is as described in (2). After discharging, it is dried in an oven at 80°C, sieved with an 80-mesh sieve, and added after sieving. A polyvinyl butyral (PVB) ethanol solution with a mass percentage of 4% was granulated, and a ceramic embryo body was prepared under a pressure of 40 MPa, which was degummed at 650° C. and kept for 5 hours.

(4) First, determine the 11 sintering aids to be screened, namely: ZnF ₂ , AlF ₃ , FeF ₃ , MgF ₂ , CuF ₂ , MnO ₂ , ZnO, CuO, Ga ₂ O ₃ , Na ₄ B ₄ O ₇ , NaF; then take 12 degummed ceramic embryos from the ceramic green sheets prepared in step (3), and place them on the setter plate covered with zirconia powder, and then weigh the above 11 kinds of sintering aid powders to be screened, weighing about 0.05g, and laying these sintering aids to be screened on the surface of each ceramic green sheet, among which one ceramic green sheet is a blank group. , without any sintering aids to be screened.

(5) Sintering is carried out at 1000° C., the heating rate is 3° C./min, and the temperature is kept for 12 hours.

(6) Cool with the furnace.

(7) Using the preliminary judgment with the naked eye, FIG. 4 shows the state comparison diagram before and after sintering when each sintering aid and the green body are co-sintered in Example 2 of the present invention. It can be seen from Figure 4 that CuF ₂ and CuO can significantly wet the ceramic matrix, thus, CuF ₂ and CuO can be used as sintering aids for NASICON type LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte. Scanning electron microscope (SEM) and optical microscope were used to observe the spreading and wetting of the sintering agent on the surface of the target ceramic sheet, and it was concluded that CuO had the best wetting effect. In practical applications, CuO can be used as NASICON type LiZr ₂ (PO ₄ ) ₃ is the best sintering aid for lithium ion ceramic electrolytes.

Then, using CuO as a sintering aid for LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte, LiZr 2 (PO 4 ) 3 LiZr 2 (PO 4 ) 3 LiZr 2 (PO 4 ) 3 LiZr ₂ (PO ₄ ) ₃ Lithium ion ceramic electrolyte raw material specific gravity of 2.5wt% CuO powder is doped into LiZr ₂ (PO 4 ) 3 lithium ion ceramic electrolyte. ₄ ) ₃ lithium ion solid state ceramic electrolyte raw materials, and co-sintering at 1100° C. for 10 h to obtain 2.5wt% CuO doped LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte. Then, phase analysis was performed on the target ceramic bulk body (ie, 2.5wt% CuO-doped LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte) by powder X-ray diffractometer (XRD). FIG. 5 is the room temperature XRD pattern of the 2.5wt% CuO-doped LiZr ₂ (PO ₄ ) ₃ solid-state ceramic electrolyte in Example 2. FIG. It can be seen from FIG. 5 that the main crystal phase of the obtained ceramic sample (ie, the 2.5wt% CuO-doped LiZr ₂ (PO ₄ ) ₃ lithium ion ceramic electrolyte) is a rhombohedral phase.

In this embodiment, the two ball millings are carried out in a planetary ball mill, and the rotational speed of the ball milling is 300-400 r/min, and zirconia balls and anhydrous ethanol are added as grinding media during the ball milling. The mass ratio of the material to be ground to the zirconia balls is 1:1.2～1:1.5.

Example 3

Perovskite potassium sodium niobate (Li _0.058 (K _0.49 Na _0.51 ) _0.942 NbO ₃ ) lead-free piezoelectric ceramic sintering aid screening method, the specific steps are as follows:

(1) First, the lithium source compound, the sodium source compound and the niobium source chemical compound with a purity greater than 99% are accurately weighed according to the stoichiometric ratio.

In this implementation step, the lithium source compound is selected from lithium carbonate, and during specific implementation, lithium oxalate, lithium nitrate, lithium isopropoxide, lithium oxide or lithium hydroxide can also be selected; the sodium source compound is selected from sodium carbonate, and in In specific implementation, sodium oxalate, sodium nitrate, sodium isopropoxide, sodium oxide or sodium hydroxide can also be selected; the niobium source chemical can be selected from niobium pentoxide, and can also be selected from niobium oxalate, niobium hydroxide or niobium acetate.

(2) Then mix the weighed powder evenly, add anhydrous ethanol to the powder in the form of 1:1 mass of powder and ethanol, mix by ball milling for 4 hours, and put it in an oven at 80°C after discharging. Dry, transfer to an alumina crucible, and pre-fire at 750°C.

(3) The pre-sintered block obtained above is subjected to secondary ball milling and crushing, and the specific process is as described in (2), drying in an oven at 80 ° C after discharging, sieving with an 80-mesh sieve, and adding after sieving. A polyvinyl butyral (PVB) ethanol solution with a mass percentage of 4% was granulated, and a ceramic embryo body was prepared under a pressure of 40 MPa, which was degummed at 650° C. and kept for 5 hours.

(4) First, determine the 11 sintering aids to be screened, namely: ZnF ₂ , AlF ₃ , FeF ₃ , MgF ₂ , CuF ₂ , MnO ₂ , ZnO, CuO, Ga ₂ O ₃ , Na ₄ B ₄ O ₇ , NaF; then take 12 degummed ceramic embryos from the ceramic green sheets prepared in step (3), and place them on the setter plate covered with zirconia powder, and then weigh the above The glass phase powders of 11 sintering aids to be screened are weighed in an amount of about 0.05 g, and these sintering aids to be screened are spread on the surface of each ceramic green sheet respectively, among which there is one ceramic green sheet For the blank group, no sintering aids to be screened were applied.

(5) Sintering is carried out at 1000°C, the heating rate is 3°C/min, and the temperature is kept for 5h.

(6) Cool with the furnace.

(7) The specific operations of this implementation step are the same as those in Example 1, which are: first, the apparent characteristics of the pre-sintered body before and after sintering are preliminarily judged with the naked eye, and a better sintering aid is selected; Optical microscope was used to observe the spreading and wetting of the optimal sintering aid on the surface of the target ceramic body, and the optimal sintering aid was selected. Phase analysis.

In this implementation step, the two ball millings are carried out in a planetary ball mill, and the rotational speed of the ball milling is 300-400 r/min, and zirconia balls and anhydrous ethanol are added as grinding media in the ball milling process. The mass ratio of the material to be ground to the zirconia balls is 1:1.2～1:1.5.

Example 4

Barium titanate (BaTiO ₃ ) lead-free piezoelectric ceramic sintering aid screening method, the specific steps are as follows:

(1) First, accurately weigh the barium source compound and the titanium source compound with a purity greater than 99% according to the stoichiometric ratio.

In this implementation step, barium carbonate is selected as the barium source compound, and barium oxide or barium hydroxide can also be selected during specific implementation; titanium dioxide is selected as the titanium source compound, and tetrabutyl titanate can also be selected during specific implementation. .

(2) Then mix the weighed powder evenly, add anhydrous ethanol to the powder in the form of 1:1 mass of powder and ethanol, mix by ball milling for 4 hours, and put it in an oven at 80°C after discharging. Dried, transferred to an alumina crucible, and pre-fired at 950°C.

(3) The pre-sintered block obtained above is subjected to secondary ball milling and crushing, and the specific process is as described in (2), drying in an oven at 80 ° C after discharging, sieving with an 80-mesh sieve, and adding after sieving. A polyvinyl butyral (PVB) ethanol solution with a mass percentage of 4% was granulated, and a ceramic embryo body was prepared under a pressure of 40 MPa, which was degummed at 650° C. and kept for 5 hours.

(4) First, determine the 11 sintering aids to be screened, namely: ZnF ₂ , AlF ₃ , FeF ₃ , MgF ₂ , CuF ₂ , MnO ₂ , ZnO, CuO, Ga ₂ O ₃ , Na ₄ B ₄ O ₇ , NaF; then take 12 degummed ceramic embryos from the ceramic green sheets prepared in step (3), and place them on the setter plate covered with zirconia powder, and then weigh the above 11 kinds of sintering aid powders to be screened, weighing about 0.05g, and laying these sintering aids to be screened on the surface of each ceramic green sheet, among which one ceramic green sheet is a blank group. , without any sintering aids to be screened.

(5) Sintering is carried out at 1000°C, the heating rate is 3°C/min, and the temperature is kept for 5h.

(6) Cool with the furnace.

(7) The specific operations of this implementation step are the same as those in Example 1, which are: first, the apparent characteristics of the pre-sintered body before and after sintering are preliminarily judged with the naked eye, and a better sintering aid is selected; Optical microscope was used to observe the apparent characteristics of the spread and wetting of the optimal sintering aid on the surface of the target ceramic body, and the optimal sintering aid was selected; finally, the target ceramic block corresponding to the optimal sintering aid was analyzed by powder X-ray diffractometer. phase analysis of the body.

In this implementation step, the two ball millings are carried out in a planetary ball mill, and the rotational speed of the ball milling is 300-400 r/min, and zirconia balls and anhydrous ethanol are added as grinding media in the ball milling process. The mass ratio of the material to be ground to the zirconia balls is 1:1.2～1:1.5.

It should be noted that the steps and methods in the various embodiments of the present application are not limited to the corresponding embodiments, and the operation details and precautions of the various embodiments are corresponding to each other. The value range of each substance and the value range of each parameter are only the preferred solutions of the present invention, and the present invention does not limit the value range, and any value range applicable to the present invention is feasible.

The method embodiments are described as a series of action combinations for the sake of simple description, but those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, some steps Other sequences or concurrently may be used. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

A method for screening functional ceramic sintering aids provided by the present invention has been described in detail above. The principles and implementations of the present invention are described with specific examples in this paper. The method of the invention and its core idea; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. In summary, the content of this description should not be understood to limit the present invention.

Claims (9)

1. A method of screening for a functional ceramic sintering aid, the method comprising the steps of:

step 1, determining the blank number of a functional ceramic blank according to the number of types of sintering aids to be screened to obtain at least one functional ceramic blank;

step 2, placing the functional ceramic blank on a sintering bearing plate paved with zirconia powder, and covering the sintering aid to be screened on the surface of each functional ceramic blank to obtain at least one pre-calcined body;

step 3, determining a sintering temperature according to the melting point of the functional ceramic blank, sintering the precalcined body at the sintering temperature, and cooling the precalcined body along with a furnace; wherein the sintering temperature is at least 100 ℃ lower than the melting point of the functional ceramic blank;

step 4, determining whether the sintering aid to be screened can be used as the sintering aid of the functional ceramic blank body according to the apparent characteristics of each pre-calcined body after the sintering is cooled along with the furnace;

wherein the apparent features include: the melting degree of the pre-calcined body and/or the spreading degree of the sintering aid to be screened on the surface of the functional ceramic blank.

2. The method according to claim 1, wherein in the step 2, the mass ratio of the sintering aid to be screened to the functional ceramic green body is 1.

3. The method according to claim 1, wherein in the step 3, the temperature is raised at a rate of 3 ℃/min and maintained for 5 to 15 hours during sintering.

4. The method of claim 1, wherein the step 4 comprises:

screening out a pre-calcined body with the maximum melting degree, and determining a sintering aid to be screened corresponding to the pre-calcined body as the sintering aid of the functional ceramic blank; and/or

And screening out the sintering aid to be screened with the maximum spreading degree on the surface of the functional ceramic blank, and determining the sintering aid to be screened as the sintering aid of the functional ceramic blank.

5. The method according to claim 1, wherein in the step 1, the functional ceramic green body is a ceramic green body obtained by pre-calcining, grinding, granulating and degumming.

6. The method according to claim 5, wherein the functional ceramic green body is prepared by:

step 0-1, weighing raw material powder required for preparing the functional ceramic blank according to a stoichiometric ratio;

0-2, uniformly mixing the weighed raw material powder, adding zirconia grinding balls and absolute ethyl alcohol into the mixed powder, and performing ball milling, drying and presintering to obtain a presintering agglomeration block;

step 0-3, performing secondary ball milling crushing on the pre-sintered lumps by adopting the same ball milling and drying operation as the operation in the step 0-2, and sieving by using a 80-mesh sieve;

and step 0-4, adding a polyvinyl butyral/ethanol solution into the sieved powder, granulating, pressing into a ceramic blank, and carrying out glue discharging and heat preservation on the ceramic blank to obtain the functional ceramic blank.

7. The method according to claim 6, wherein the purity of the raw material powder in the step 0-1 is 99% or more.

8. The method according to claim 6, wherein in the step 0-2, the mass ratio of the mixed powder to the zirconia grinding balls is 1.2-1.5, and the mass ratio of the mixed powder to the ethanol is 1;

the ball milling is carried out for mixing for 4-12 h, the drying temperature is 80-120 ℃, and the pre-sintering temperature is 600-1100 ℃.

9. The method as claimed in claim 6, wherein in the steps 0 to 4, the polyvinyl butyral/ethanol solution has a polyvinyl butyral weight percentage of 4%, and the pressing is performed at a pressure of 40 to 100MPa;

the diameter of the ceramic blank is 8-15 mm, and the thickness of the ceramic blank is 1-1.5 mm;

the temperature of the binder removal is 600-700 ℃, and the heat preservation time is 5-10 h.

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