阅读说明：本技术 一种高致密性熔融石英陶瓷的生产方法 (Production method of high-compactness fused quartz ceramic ) 是由 乔刚 于 2020-04-29 设计创作，主要内容包括：一种高致密性熔融石英陶瓷的生产方法,包括如下步骤：(1)料浆的制备；(2)凝胶固化：对所述料浆进行超声振动,分别加入引发剂、催化剂,所述料浆凝胶固化；(3)干燥；(4)微波烧结,得到所述高致密性熔融石英陶瓷。本发明所述的高致密性熔融石英陶瓷的生产方法,优化了工艺,解决了现有技术中注凝成型工艺导致熔融石英陶瓷制品低密度性的技术问题,使得制造的熔融石英陶瓷具有高致密性,并且具有高抗弯曲强度、体积密度的优点,应用前景广泛。(A method for producing high-compactness fused quartz ceramic comprises the following steps: (1) preparing slurry; (2) and (3) gel curing: carrying out ultrasonic vibration on the slurry, respectively adding an initiator and a catalyst, and solidifying the slurry gel; (3) drying; (4) and (4) performing microwave sintering to obtain the high-compactness fused quartz ceramic. The production method of the high-compactness fused quartz ceramic optimizes the process, solves the technical problem of low density of the fused quartz ceramic product caused by the injection molding process in the prior art, ensures that the manufactured fused quartz ceramic has high compactness, has the advantages of high bending strength and volume density, and has wide application prospect.)

1. A method for producing high-compactness fused quartz ceramic is characterized by comprising the following steps:

(1) preparing slurry: ball-milling the fused quartz powder by a ball mill; dissolving an organic monomer N-hydroxymethyl acrylamide and a cross-linking agent in deionized water, and uniformly stirring to prepare a precursor solution; weighing fused quartz powder for later use after ball milling, and adding the fused quartz powder into the precursor

Adding a dispersing agent into the solution, adjusting the pH to 4-5, and mechanically stirring at the rotating speed of 30-50 r/min to prepare slurry;

(2) and (3) gel curing: carrying out ultrasonic vibration on the slurry, respectively adding an initiator and a catalyst, and solidifying the slurry gel;

(3) and (3) drying: putting the gel-solidified slurry into a drying oven, drying and heating to 70-80 ℃, and drying and molding at constant temperature to obtain a fused quartz ceramic green body;

(4) microwave sintering: setting the microwave early-stage heating rate to be 5-10 ℃/min, the output power to be 1500W, heating to 600 ℃, and keeping the temperature for 30 min; and (3) raising the temperature to 1100-1150 ℃ at the later-stage heating rate of 25-30 ℃/min and the output power of 2000W, and preserving the temperature for 2h to obtain the high-compactness fused quartz ceramic.

2. The method for producing high-density fused quartz ceramic according to claim 1, wherein the ball milling in the step (1) comprises the following specific steps: the rotating speed of the ball mill is 250r/min, the ball milling mode adopts positive and negative rotation ball milling, the ball milling time is 6h, and the fused quartz powder after ball milling passes through a 500-mesh sieve.

3. The method for producing a high-density fused quartz ceramic according to claim 1, wherein the crosslinking agent in the step (1) is N, N-methylenebisacrylamide, and the dispersing agent is ammonium citrate.

4. The method for producing a high-density fused quartz ceramic according to claim 3, wherein the organic monomer N-methylolacrylamide is added in an amount of 9wt%, the N, N-methylenebisacrylamide is added in an amount of 1 wt%, and the ammonium citrate is added in an amount of 2 wt%.

5. The method for producing a high-densification fused silica ceramic according to claim 2, wherein the ultrasonic vibration time in the step (1) is 30 min.

6. The method for producing a high-density fused quartz ceramic according to claim 5, wherein the initiator is ammonium persulfate and the catalyst is ammonium citrate.

7. The method for producing a high-density fused quartz ceramic according to claim 6, wherein the ammonium persulfate is added in an amount of 0.2 wt% and the ammonium citrate is added in an amount of 0.2 wt%.

8. The method for producing a high-density fused silica ceramic according to claim 1, wherein in the step (4), the green fused silica ceramic is placed therein using a graphite crucible with a SiC chip as auxiliary heating.

Technical Field

The invention belongs to the technical field of fused quartz ceramic production, and particularly relates to a production method of high-compactness fused quartz ceramic.

Background

Fused quartz ceramics are products which are manufactured by taking fused quartz or quartz glass as main raw materials through crushing, molding, sintering and other manufacturing process equipment. First in the 20 th century in the 60 s, the development in the united states was successful and put into industrial production. The quartz ceramic is an upgraded product of quartz glass, so that the quartz ceramic not only has the advantages of the quartz glass, but also has other excellent properties which the quartz glass does not have. Therefore, once developed, the fused quartz ceramic is widely applied to various fields of the national civilization, such as aerospace science and technology, electronic industry, smelting industry and the like.

Because the fused quartz ceramic is generally used under very harsh conditions, the requirement on the performance of the fused quartz ceramic is high, the process production difficulty is high, the companies which can carry out large-scale production at present have a flexible number, and the famous companies adopt the slip casting process. As a novel forming process, the gel casting is one of the most suitable processes for large-size production of fused quartz ceramics at present, and the development of the process is also hindered due to the low density of prepared samples, and the process is not widely used in the ceramic field.

How to prepare the fused quartz ceramic with high compactness and put into production on a large scale becomes a key step of the development of the fused quartz ceramic. Therefore, it is necessary to develop a method for producing high-density fused silica ceramics, which can greatly improve the production efficiency of fused silica ceramics and reduce the development cost of new products, and can improve the quality of fused silica ceramics.

The Chinese patent application No. CN201610726924.9 discloses a preparation method of a waterproof fused quartz ceramic product, and the prepared waterproof microcrystalline glass coating has the excellent performances of small thermal expansion coefficient, excellent thermal shock resistance, high temperature resistance, high strength and the like, can obviously prolong the service life of the fused quartz ceramic product in severe working condition environments, and does not improve the compactness of the fused quartz ceramic product.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the defects, the invention aims to provide a method for producing high-compactness fused quartz ceramic, optimizes the process, solves the technical problem of low density of the fused quartz ceramic product caused by a condensation molding process in the prior art, ensures that the produced fused quartz ceramic has high compactness, has the advantages of high bending strength and volume density, and has wide application prospect.

The purpose of the invention is realized by the following technical scheme:

a method for producing high-compactness fused quartz ceramic is characterized by comprising the following steps:

(1) preparing slurry: ball-milling the fused quartz powder by a ball mill; dissolving an organic monomer N-hydroxymethyl acrylamide and a cross-linking agent in deionized water, and uniformly stirring to prepare a precursor solution; weighing fused quartz powder for later use after ball milling, and adding the fused quartz powder into the precursor

Adding a dispersing agent into the solution, adjusting the pH to 4-5, and mechanically stirring at the rotating speed of 30-50 r/min to prepare slurry;

(2) and (3) gel curing: carrying out ultrasonic vibration on the slurry, respectively adding an initiator and a catalyst, and solidifying the slurry gel;

(3) and (3) drying: putting the gel-solidified slurry into a drying oven, drying and heating to 70-80 ℃, and drying and molding at constant temperature to obtain a fused quartz ceramic green body;

(4) microwave sintering: setting the microwave early-stage heating rate to be 5-10 ℃/min, the output power to be 1500W, heating to 600 ℃, and keeping the temperature for 30 min; and (3) raising the temperature to 1100-1150 ℃ at the later-stage heating rate of 25-30 ℃/min and the output power of 2000W, and preserving the temperature for 2h to obtain the high-compactness fused quartz ceramic.

The production method of the high-compactness fused quartz ceramic solves the technical problem of low density of the fused quartz ceramic product caused by a condensation forming process in the prior art, prepares slurry with solid phase content of about 60 percent and low viscosity by adopting a low-toxicity gel system, reduces the porosity of a green body by an ultrasonic vibration method, and adds an initiator and a catalyst to promote the gel polymerization process of an organic monomer so as to solidify and densify the slurry gel to obtain the fused quartz ceramic green body.

In order to improve the compactness of the fused quartz ceramic and inhibit crystallization to a certain extent, a microwave sintering method is adopted for sintering, the temperature rise rate in the early stage is 5-10 ℃/min, otherwise, the fused quartz ceramic green body is easy to crack, because the ceramic powder is solidified through a three-dimensional network structure formed by a monomer/a cross-linking agent, the temperature rise rate is too high, and the ceramic powder is not completely diffused and bonded. Once the organic monomer/cross-linker is removed quickly, the fused silica powder does not have a scaffold, resulting in cracking, and if the temperature rise rate is too slow, the process time is increased, increasing the production cost. Certain organic matters exist in the fused quartz ceramic green body, the organic matters begin to be lost in the sintering process, the degreasing is basically finished when the temperature reaches about 500 ℃, but in order to prevent the organic matters from remaining, the early-stage temperature rise is set to be most appropriate when the temperature is raised to 600 ℃, and the heat preservation is carried out for 30min, so that the compactness is enhanced.

After degreasing, quick sintering is carried out, the heating rate is 25-30 ℃/min, the bending strength of a product burned out is increased along with the acceleration of the heating rate, microwaves are integrally heated, the problem of temperature gradient can be hardly caused in the heating process, and the phenomenon of thermal runaway can not be caused by the quick heating in the later stage. When the temperature reaches 1000 ℃, the bending strength is rapidly increased, which shows that the fused quartz ceramic particles start to participate in sintering at the temperature higher than 1000 ℃, and the bending strength is gradually increased along with the continuous increase of the temperature, but the strength is weakened and the cristobalite transformation starts after the temperature is increased to 1200 ℃, so that the temperature is increased to 1100-1150 ℃, the effect is best, the temperature is kept for 2 hours, the migration of mass points is completed, the quartz particles are also bonded and solidified, the heat preservation time is prolonged, the production time is increased, the production cost is increased, and the cristobalite transformation can be caused.

Further, in the method for producing the fused quartz ceramic with high compactness, the ball milling in the step (1) specifically comprises the following steps: the rotating speed of the ball mill is 250r/min, the ball milling mode adopts positive and negative rotation ball milling, the ball milling time is 6h, and the fused quartz powder after ball milling passes through a 500-mesh sieve.

Further, in the above method for producing high-density fused quartz ceramic, the crosslinking agent in step (1) is N, N-methylenebisacrylamide, and the dispersing agent is ammonium citrate.

Further, in the method for producing the fused quartz ceramic with high compactness, the addition amount of the organic monomer N-methylolacrylamide is 9wt%, the addition amount of the N, N-methylene bisacrylamide is 1 wt%, and the addition amount of the ammonium citrate is 2 wt%.

The adding amounts of the organic monomers of N-methylol acrylamide, N-methylene bisacrylamide and ammonium citrate are respectively 9wt%, 1 wt% and 2 wt% relative to the fused quartz powder.

Further, in the above method for producing high-density fused silica ceramic, the ultrasonic vibration time in the step (1) is 30 min.

Further, in the production method of the fused quartz ceramic with high compactness, the initiator is ammonium persulfate, and the catalyst is ammonium citrate.

Further, in the production method of the high-compactness fused quartz ceramic, the adding amount of the ammonium persulfate is 0.2 wt%, and the adding amount of the ammonium citrate is 0.2 wt%.

The adding amount of ammonium persulfate and ammonium citrate is 0.2 wt% and 0.2 wt% relative to fused quartz powder.

Further, in the above method for producing high-density fused silica ceramic, in the step (4), a graphite crucible and a SiC piece are used as auxiliary heating, and the fused silica ceramic green body is placed therein.

Compared with the prior art, the invention has the following beneficial effects:

the production method of the high-compactness fused quartz ceramic adopts a low-toxicity gel system to prepare high-solid-phase low-viscosity slurry, combines an ultrasonic vibration method and an auxiliary agent to enable a green body to be compacted, and then adopts a microwave sintering method for sintering, so that the controllability is high, the performance of the fused quartz ceramic product is obviously improved, the sintering efficiency is improved, the process is optimized, the technical problem of low density of the fused quartz ceramic product caused by a condensation molding process in the prior art is solved, and the manufactured fused quartz ceramic has high compactness, has the advantages of high bending strength and volume density, and has wide application prospect.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to specific experimental data, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The following examples 1, 2, 3, 4, and 5 provide a method for producing a fused silica ceramic having high compactness,