阅读说明：本技术 一种陶瓷流延浆料及其制备方法 (Ceramic tape-casting slurry and preparation method thereof ) 是由 葛荘 贺贤汉 王斌 孙泉 欧阳鹏 张进 于 2021-08-18 设计创作，主要内容包括：本发明提供了一种陶瓷流延浆料及其制备方法,按重量百分比计,包含30％-55％陶瓷粉体、0.5％-2％分散剂、3％-10％粘结剂、3％-10％塑化剂,余量为醇类和酯类混合溶剂。其中,醇类和酯类混合溶剂中,醇类溶剂和酯类溶剂的质量比为1:1,醇类溶剂为乙醇与丙三醇的混合溶液,乙醇与丙三醇质量比为9～9.5：1～0.5；酯类溶剂为乙酸乙酯与乙酸丙酯的混合溶液,乙酸乙酯与乙酸丙酯质量比为9.5-9.8:0.5-0.2。本发明采用的醇类和酯类混合溶剂安全性高、材料易得,且体系稳定,乙醇、丙三醇、乙酸乙酯、乙酸丙酯均为有机溶剂,具备有机溶剂体系稳定、挥发速度快的性能,对于分散剂、粘结剂、塑化剂等有机物料的溶解性强,有助于提升分散剂、粘结剂、塑化剂的选择范围,并提升体系稳定性。(The invention provides a ceramic tape casting slurry and a preparation method thereof, which comprises 30-55% of ceramic powder, 0.5-2% of dispersant, 3-10% of binder, 3-10% of plasticizer and the balance of alcohol and ester mixed solvent in percentage by weight. In the alcohol and ester mixed solvent, the mass ratio of the alcohol solvent to the ester solvent is 1:1, the alcohol solvent is a mixed solution of ethanol and glycerol, and the mass ratio of the ethanol to the glycerol is 9-9.5: 1 to 0.5; the ester solvent is a mixed solution of ethyl acetate and propyl acetate, and the mass ratio of the ethyl acetate to the propyl acetate is 9.5-9.8: 0.5-0.2. The alcohol and ester mixed solvent adopted by the invention has high safety, easily obtained materials and stable system, and the ethanol, the glycerol, the ethyl acetate and the propyl acetate are all organic solvents, so that the alcohol and ester mixed solvent has the advantages of stable organic solvent system and high volatilization speed, has strong solubility on organic materials such as a dispersing agent, a binding agent, a plasticizing agent and the like, and is beneficial to improving the selection range of the dispersing agent, the binding agent and the plasticizing agent and improving the stability of the system.)

1. A ceramic tape-casting slurry comprising, in weight percent:

30 to 55 percent of ceramic powder, 0.5 to 2 percent of dispersant, 3 to 10 percent of binder, 3 to 10 percent of plasticizer and the balance of mixed solvent of alcohol and ester,

wherein in the mixed solvent of the alcohols and the esters, the mass ratio of the alcohol solvent to the ester solvent is 1:1,

the alcohol solvent is a mixed solution of ethanol and glycerol, and the mass ratio of the ethanol to the glycerol is (9-9.5): 1 to 0.5; the ester solvent is a mixed solution of ethyl acetate and propyl acetate, and the mass ratio of the ethyl acetate to the propyl acetate is 9.5-9.8: 0.5-0.2.

2. Ceramic casting slurry according to claim 1, characterized in that:

wherein, the pottery is made ofThe specific surface area of the ceramic powder is 5-15m²The material is characterized by comprising powder and a sintering aid, wherein the mass ratio of the powder to the sintering aid is (8-9.5): 0.5 to 2.

3. Ceramic casting slurry according to claim 2, characterized in that:

wherein the powder is one or more of silicon nitride powder, alumina powder, aluminum nitride powder and silicon carbide powder;

the sintering aid is a mixture of two or three of yttrium oxide, ytterbium oxide, magnesium silicide nitride, magnesium oxide, yttrium fluoride, ytterbium fluoride and magnesium silicide.

4. Ceramic casting slurry according to claim 2, characterized in that:

the sintering aid is magnesium stearate and ytterbium oxide, and the molar ratio of the magnesium stearate to the ytterbium oxide to the powder is 5:5: 90.

5. Ceramic casting slurry according to claim 1, characterized in that:

wherein the dispersant is one or more of triethyl phosphate, triolein and castor oil;

the binder is one or two of polyvinyl butyral and polymethyl methacrylate;

the plasticizer is dibutyl phthalate and polyethylene glycol in a mass ratio of 1:1 is prepared by mixing the components in a ratio of 1,

the mass ratio of the plasticizer to the binder is 0.5-1: 1.

6. ceramic casting slurry according to claim 5, characterized in that:

wherein, the molecular weight of the polyvinyl butyral is 30000-80000, and the molecular weight of the polymethyl methacrylate is 50000-150000.

7. Ceramic casting slurry according to claim 1, characterized in that:

wherein, the slurry is also added with defoamer n-butyl alcohol or polypropylene glycol 1200 for chemical defoaming,

the slurry also contains carbomer which accounts for 0.01-0.1% of the total mass of the slurry.

8. A method of producing a ceramic casting slurry according to any one of claims 1 to 7, characterized by comprising the steps of:

s1) dispersant pre-dissolution

Weighing a dispersing agent according to the mass fraction of 0.5-2%, dissolving the dispersing agent in a mixed solvent of alcohol and ester, and then placing the mixture in a ball mill for ball milling for 1-2 hours at the ball milling temperature of 15-35 ℃;

s2) primary ball milling

Adding 30-55% of ceramic powder by mass into the solution obtained in the step S1, and performing ball milling for 12-24h at the ball milling temperature of 15-35 ℃;

s3) secondary ball milling

Adding 3-10% of binder and 3-10% of plasticizer by mass into the solution obtained in the step S2, wherein the mass ratio of the plasticizer to the binder is 0.5: 1;

s4) vacuum defoaming

Pumping the ball-milled slurry into a defoaming machine through a screen of 80-320 meshes, wherein the vacuum degree is more than-0.09 MPa, the vacuum stirring defoaming time is 0.5-2 h, standing for aging for 2-12h after defoaming, sampling for testing viscosity after aging, and carrying out tape casting.

Technical Field

The invention belongs to the technical field of preparation of ceramic insulation lining plates, and particularly relates to ceramic tape-casting slurry and a preparation method thereof.

Background

Ceramics have characteristics such as high thermal conductivity, high electrical insulation, high mechanical strength, and low expansion, and have high bondability with copper foil, and are generally used as a backing plate in semiconductors.

Tape casting is a common preparation process for ceramic liners, and the process comprises mixing ceramic powder with a dispersant, a binder and a plasticizer in a solvent to form uniform and stable suspended slurry. The slurry flows from a hopper of a casting machine to a base band, and is formed through the relative movement of a base band scraper to form a blank film, and the blank film is dried to evaporate the solvent to obtain a ceramic blank to be treated.

Currently, the most common ceramic slurry tape casting solvents are water and organic solvents. The water is used as a solvent, and the method has the advantages of safe use, environmental protection and low cost, but the water has large surface tension, is difficult to effectively wet ceramic powder, is slow in volatilization, long in drying time, difficult in degassing of slurry of a water-based system, and seriously affects the blank quality due to bubbles, and the water-based system has few types of selectable binders and plasticizers and is limited in use.

Therefore, in actual industrial mass production, the organic solvent is mostly adopted when preparing the high-performance ceramic casting blank body due to the stable organic solvent system and the high volatilization speed. However, organic solvents have serious environmental protection problems, and take butanone, toluene and xylene which are commonly used as examples, which all have great threats to the environment and the health of users.

Therefore, the development of an environment-friendly organic solvent for ceramic tape casting and a corresponding ceramic slurry tape casting system which can ensure the quality of a ceramic body and reduce the harm to the environment is very important for the healthy development of the ceramic industry.

Disclosure of Invention

The invention is carried out based on the research, provides a novel ceramic tape-casting slurry system aiming at the defects of great harm of organic solvent environment and human body in the current ceramic tape-casting slurry, and improves the environmental friendliness of the ceramic tape-casting slurry system.

Based on the angles of safety, easy material obtaining and low cost, the invention provides the following ceramic tape-casting slurry: according to weight percentage, the ceramic powder comprises 30-55 percent of ceramic powder, 0.5-2 percent of dispersant, 3-10 percent of binder, 3-10 percent of plasticizer and the balance of alcohol and ester mixed solvent.

Wherein, in the mixed solvent of alcohols and esters, the mass ratio of the alcohol solvent to the ester solvent is 1: 1; the alcohol solvent is a mixed solution of ethanol and glycerol, and the mass ratio of the ethanol to the glycerol is (9-9.5): 1-0.5, wherein the ester solvent is a mixed solution of ethyl acetate and propyl acetate, and the mass ratio of the ethyl acetate to the propyl acetate is 9.5-9.8: 0.5-0.2.

Preferably, in the ceramic casting slurry provided by the invention, the specific surface area of the ceramic powder is 5-15m²The material is characterized by comprising powder and a sintering aid, wherein the mass ratio of the powder to the sintering aid is 8-9.5: 0.5 to 2.

Further, the powder is one or more of silicon nitride powder, alumina powder, aluminum nitride powder and silicon carbide powder; the sintering aid is two or three of yttrium oxide, ytterbium oxide, magnesium silicide nitride, magnesium oxide, yttrium fluoride, ytterbium fluoride and magnesium silicide.

In addition, the sintering aid can also be magnesium stearate and ytterbium oxide, and the molar ratio of the magnesium stearate to the ytterbium oxide to the powder is 5:5: 90. The use of magnesium stearate allows the magnesium source to be more uniformly dispersed in the slurry.

Preferably, in the ceramic tape-casting slurry provided by the invention, the dispersant is one or more of triethyl phosphate, triolein and castor oil; the binder is one or two of polyvinyl butyral and polymethyl methacrylate; the plasticizer is dibutyl phthalate and polyethylene glycol in a mass ratio of 1:1, and mixing the components in a ratio of 1.

Preferably, in the ceramic casting slurry provided by the invention, the mass ratio of the plasticizer to the binder is 0.5: 1.

Preferably, in the ceramic casting slurry provided by the invention, the molecular weight of the polyvinyl butyral is 30000-80000, and the molecular weight of the polymethyl methacrylate is 50000-150000.

Preferably, in the ceramic casting slurry provided by the invention, a defoaming agent n-butyl alcohol or polypropylene glycol 1200 is also added into the slurry for chemical defoaming; the slurry also contains carbomer which accounts for 0.01-0.1% of the total mass of the slurry.

In a second aspect of the present invention, there is provided a method for producing the above-described ceramic casting slurry, characterized by comprising the steps of:

s1) dispersant pre-dissolution

Weighing a dispersing agent according to the mass fraction of 0.5-2%, dissolving the dispersing agent in a mixed solvent of alcohol and ester, and then placing the mixture in a ball mill for ball milling for 1-2 hours at the ball milling temperature of 15-35 ℃;

s2) primary ball milling

Adding 30-55% of ceramic powder by mass into the solution obtained in the step S1, and performing ball milling for 12-24h at the ball milling temperature of 15-35 ℃;

s3) secondary ball milling

Adding 3-10% of binder and 3-10% of plasticizer by mass into the solution obtained in the step S2, wherein the mass ratio of the plasticizer to the binder is 0.5: 1;

s4) vacuum defoaming

Pumping the ball-milled slurry into a defoaming machine through a screen of 80-320 meshes, wherein the vacuum degree is more than-0.09 MPa, the vacuum stirring defoaming time is 0.5-2 h, standing for aging for 2-12h after defoaming, sampling for testing viscosity after aging, and carrying out tape casting.

After the ceramic tape-casting slurry is used for tape-casting molding, drying, stripping the base band and preparing a blank, the appearance of the ceramic tape-casting slurry is the same as that of a ceramic blank prepared by the prior art, and the surface is smooth without defects such as bubbles which affect the quality of the blank.

The invention has the following beneficial effects:

the invention selects an alcohol solvent and an ester solvent mixed solvent with the mass ratio of 1:1 as a slurry system solvent, the alcohol solvent is a mixed solution of ethanol and glycerol with the mass ratio of 9-9.5: 1-0.5, and the ester solvent is a mixed solution of ethyl acetate and propyl acetate with the mass ratio of 9.5-9.8:0.5-0.2, and has the following advantages:

(1) the safety is high: compared with solvents such as butanone, toluene, xylene and isopropanol used in the existing ceramic tape-casting slurry system, ethanol, glycerol, ethyl acetate and propyl acetate are all nontoxic and harmless reagents, so that the use safety is high, and the environment friendliness is strong;

(2) the material is easy to obtain, and the cost is low: the ethanol, the glycerol, the ethyl acetate and the propyl acetate are all common industrial solvents, the production process is mature, the yield is high, and the use cost is low;

(3) the system is stable, ethanol, glycerol, ethyl acetate and propyl acetate are all organic solvents, the organic solvent system has the advantages of being stable and high in volatilization speed, the organic materials such as a dispersing agent, a binding agent and a plasticizing agent are high in solubility, the selection range of the dispersing agent, the binding agent and the plasticizing agent is favorably widened, and the system stability is improved.

Drawings

FIG. 1 is a flow chart of the preparation of a ceramic casting slurry according to the present invention;

FIG. 2 is a picture of a ceramic body prepared using the ceramic casting slurry of the present invention;

FIG. 3 is a microphotograph of a silicon nitride ceramic body of the present invention at 2000 times magnification.

Detailed Description

The following embodiments are implemented on the premise of the technical scheme of the present invention, and give detailed implementation modes and specific operation procedures, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

The ceramic casting slurry of the embodiment comprises, by weight, 30% of ceramic powder, 0.5% of a dispersant, 5% of a binder, 5% of a plasticizer, 0.01% of carbomer, 0.01% of defoamer n-butanol, and the balance of an alcohol and ester mixed solvent with a mass fraction of about 59.5%.

The specific surface area of the ceramic powder is 5-15m²The silicon nitride powder per gram is composed of powder and sintering aid, and the mass ratio of the powder to the sintering aid is 8: 2. The sintering aid is magnesium stearate and ytterbium oxide, the molar ratio of the magnesium stearate to the ytterbium oxide to the powder is preferably 5:5:90, and the magnesium source can be uniformly dispersed in the slurry by adopting the magnesium stearate.

The dispersant is one or more of triethyl phosphate, triolein and castor oil; the binder is one or two of polyvinyl butyral and polymethyl methacrylate; the plasticizer is dibutyl phthalate and polyethylene glycol in a mass ratio of 1:1, wherein the molecular weight of the polyvinyl butyral is 30000-80000, and the molecular weight of the polymethyl methacrylate is 50000-150000.

In the mixed solvent of alcohols and esters, the mass ratio of the alcohol solvent to the ester solvent is 1: 1; the alcohol solvent is a mixed solution of ethanol and glycerol, and the mass ratio of the ethanol to the glycerol is (9): 1, the ester solvent is a mixed solution of ethyl acetate and propyl acetate, and the mass ratio of the ethyl acetate to the propyl acetate is 9.5: 0.5.

The preparation method of the slurry comprises the following steps:

s1) dispersant pre-dissolution

Weighing the dispersing agent according to the mass fraction, dissolving the dispersing agent in a mixed solvent of alcohol and ester, and then placing the mixture in a ball mill for ball milling for 1-2h at the ball milling temperature of 15-35 ℃;

s2) primary ball milling

Adding 30% ceramic powder into the solution obtained in the step S1, and performing ball milling for 12-24h at the ball milling temperature of 15-35 ℃;

s3) secondary ball milling

Adding 3% by mass of a binder and 3% by mass of a plasticizer into the solution obtained in the step S2;

s4) vacuum defoaming

Pumping the ball-milled slurry into a defoaming machine through a screen of 80-320 meshes, wherein the vacuum degree is more than-0.09 MPa, the vacuum stirring defoaming time is 0.5-2 h, standing for aging for 2-12h after defoaming, sampling for testing viscosity after aging, and performing tape casting;

s5) casting, drying, stripping base band, and making blank

And (3) pumping the slurry subjected to vacuum defoaming and ageing to a head of a casting machine, molding by a scraper, heating and drying by hot air and a bottom plate, and stripping the PET base band to obtain a blank, wherein the surface of the blank has no defects such as cracks, peeling, depressions and the like, so that the qualified casting blank is prepared.

Example 2

The ceramic casting slurry of the embodiment comprises, by weight, 55% of ceramic powder, 2% of a dispersant, 10% of a binder, 5% of a plasticizer, 0.1% of carbomer, 0.01% of an antifoaming agent n-butanol, and the balance of an alcohol and ester mixed solvent with a mass fraction of about 28%.

The specific surface area of the ceramic powder is 5-15m²The silicon nitride powder per gram is composed of powder and sintering aid, and the mass ratio of the powder to the sintering aid is 9.5: 0.5. The sintering aid is selected from two or three of yttrium oxide, ytterbium oxide, magnesium silicide nitride, magnesium oxide, yttrium fluoride, ytterbium fluoride and magnesium silicide.

The dispersant is one or more of triethyl phosphate, triolein and castor oil; the binder is one or two of polyvinyl butyral and polymethyl methacrylate; the plasticizer is dibutyl phthalate and polyethylene glycol in a mass ratio of 1:1, wherein the molecular weight of the polyvinyl butyral is 30000-80000, and the molecular weight of the polymethyl methacrylate is 50000-150000.

In the mixed solvent of alcohols and esters, the mass ratio of the alcohol solvent to the ester solvent is 1: 1; the alcohol solvent is a mixed solution of ethanol and glycerol, and the mass ratio of the ethanol to the glycerol is (9.5): 0.5, the ester solvent is a mixed solution of ethyl acetate and propyl acetate, and the mass ratio of the ethyl acetate to the propyl acetate is 9.8: 0.2.

The preparation method of the slurry is the same as that of the first embodiment.

The appearance diagram of the silicon nitride ceramic body prepared by the two embodiments is shown in fig. 2, the appearance of the silicon nitride ceramic body is the same as that of the ceramic body prepared by the prior art, and the silicon nitride ceramic body has smooth surface and no defects such as bubbles which influence the quality of the body.

And (3) performance test aspects: the thickness is tested by a micrometer, the density is tested by an Archimedes drainage method, the tensile strength test refers to the vulcanized rubber tensile strength measurement standard (GB/T528-2009) similar to that of a green body, the flexibility of the green body refers to the condition that the green body is curled and then whether cracks exist or not is observed as shown in figure 2, and the microstructure of the green body is observed by a scanning electron microscope.

The results of the green body performance test are summarized in table 1: the thickness of the green body is uniform, and the thickness range of five sampling points is smaller than 10 percent of the average value, which is considered as uniform thickness of the green body; the average green body density reaches 2.082g/cm³At 3.2g/cm³For a silicon nitride ceramic theoretical densimeter, the density of the invention reaches 65 percent of the ceramic theoretical density, more than 50 percent is regarded as qualified, and the prepared blank has larger density; the tensile strength is more than 5MPa, and the tensile strength is excellent; the blank has no crack after being curled and has better flexibility (figure 2). The microstructure test of the green body is shown in figure 3, the green body has no large pores, and the sintering aid is uniformly dispersed (the white part is the aid).

According to the test results, the green body prepared by the method has excellent performance, and the corresponding slurry formula is reasonable and feasible.

Table 1 summary of green body performance tests

In the embodiment of the invention, the silicon nitride powder with the highest preparation difficulty is used as the ceramic powder, and the blank forming performance of the ceramic tape-casting slurry after the new mixed solvent is adopted is researched. The surface properties of the alumina powder, the aluminum nitride powder, the silicon carbide powder and the silicon nitride powder are close to each other, and the three can be suitable for an organic solvent formula, and the invention is a further improvement of the organic solvent formula; the solvent and the formula can support the silicon nitride powder to be formed into a blank, and the alumina powder, the aluminum nitride powder and the silicon carbide powder can be formed into the blank by adjusting the drying temperature, the hot air circulation amount (fan frequency), the casting belt speed, the scraper gap, the slurry pumping pressure, the setting of a drying section and an exhaust section and the like of a casting machine in the field. From the above results, it is found that a ceramic casting slurry obtained by using a mixed solvent of an alcohol and an ester as a solvent and selecting other components based on the solvent can completely realize the silicon nitride powder preform and is excellent in performance.

While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited thereto, and that various changes and modifications may be made without departing from the spirit of the invention, and the scope of the appended claims is to be accorded the full scope of the invention.