阅读说明：本技术 一种刚玉莫来石质铂金坩埚保护衬套及其制备方法 (Corundum-mullite platinum crucible protection bushing and preparation method thereof ) 是由 唐冰杰 薛新建 仵小曦 郭荒 于 2020-05-25 设计创作，主要内容包括：本发明一种刚玉莫来石质铂金坩埚保护衬套及其制备方法,保护衬套包括骨料、基质和添加剂；骨料包括莫来石40～50份、钛铝酸钙空心球10～30份,基质包括刚玉细粉10～30份、α-活性氧化铝微粉5～10份、铝酸盐水泥1～5份；添加剂包括减水剂,减水剂占骨料和基质总质量的0.1％～0.7％。在制备保护衬套时,包括步骤1,将钛铝酸钙空心球、骨料和添加剂混合均匀,再与莫来石混合均匀,向混合物中加入水后搅拌,直到呈花瓣状,得到浇注料；步骤3,在振动下添加至模具中,使表面平整、无气泡上浮且无密水现象；步骤4,自然养护后脱模,干燥后烧成,制得的保护衬套具有耐高温、热震稳定性好、使用寿命长的特点。(The invention relates to a corundum mullite platinum crucible protection bushing and a preparation method thereof, wherein the protection bushing comprises aggregate, a matrix and an additive; the aggregate comprises 40-50 parts of mullite and 10-30 parts of calcium titanoaluminate hollow spheres, and the matrix comprises 10-30 parts of corundum fine powder, 5-10 parts of alpha-activated alumina micro powder and 1-5 parts of aluminate cement; the additive comprises a water reducing agent, and the water reducing agent accounts for 0.1-0.7% of the total mass of the aggregate and the matrix. When the protective lining is prepared, the method comprises the following steps of 1, uniformly mixing the calcium titanium aluminate hollow spheres, the aggregate and the additive, uniformly mixing the mixture with mullite, adding water into the mixture, and stirring until the mixture is petal-shaped to obtain a castable; step 3, adding the mixture into a mold under vibration to enable the surface to be flat without bubbles floating upward and without dense water; and 4, demolding after natural curing, drying and sintering, wherein the prepared protective lining has the characteristics of high temperature resistance, good thermal shock stability and long service life.)

1. A corundum-mullite platinum crucible protection bushing is characterized by comprising aggregate, a matrix and an additive;

the aggregate comprises 40-50 parts of mullite and 10-30 parts of calcium titanoaluminate hollow spheres by weight, and the matrix comprises 10-30 parts of corundum fine powder, 5-10 parts of alpha-activated alumina micro powder and 1-5 parts of aluminate cement;

the additive comprises a water reducing agent, and the water reducing agent accounts for 0.1-0.7% of the total mass of the aggregate and the matrix.

2. The corundum-mullite platinum crucible protective sleeve as claimed in claim 1, wherein said matrix further comprises not more than 5 parts of silica micropowder.

3. The corundum-mullite platinum crucible protective bushing as claimed in claim 1, wherein said aluminate cement is Secar71 cement.

4. The corundum-mullite platinum crucible protective bushing as claimed in claim 1, wherein the water reducing agent is a polycarboxylic acid composite water reducing agent, sodium hexametaphosphate or a mixture of the polycarboxylic acid composite water reducing agent and sodium hexametaphosphate.

5. A method for preparing a corundum mullite platinum crucible protection bushing, which is characterized in that the corundum mullite platinum crucible protection bushing based on any one of claims 1-4 comprises the following steps,

step 1, uniformly mixing a calcium titanium aluminate hollow sphere, aggregate and an additive to obtain an initial castable;

step 2, uniformly mixing the initial castable and mullite to obtain a mixture, adding water into the mixture, and stirring until the obtained mixed system is petal-shaped to obtain a final castable;

step 3, adding the final casting material into a mold corresponding to the platinum crucible protective bushing under the vibration condition, so that the surface of the final casting material is flat, no bubbles float upwards and no dense water phenomenon exists, and a sample to be maintained is obtained;

step 4, naturally curing the sample to be cured for 20-30 h, and then demolding to obtain a preliminarily formed corundum-mullite platinum crucible protective bushing;

and 5, drying and sintering the protective bushing obtained in the step 4 to obtain the corundum mullite platinum crucible protective bushing.

6. The method for preparing a corundum-mullite platinum crucible protective bushing as claimed in claim 5, wherein in step 2, water accounts for 3% -5% of the total mass of the initial castable and mullite.

7. The method for preparing a corundum-mullite platinum crucible protective bushing as claimed in claim 5, wherein in step 3, when the final castable is added into the mold, a layer of oil is brushed on the inner wall of the mold.

8. The method for preparing a corundum-mullite platinum crucible protective bushing according to claim 5, wherein in the step 5, the protective bushing obtained in the step 4 is dried at 90-110 ℃ for 12-36 h.

9. The method for preparing the corundum-mullite platinum crucible protective bushing according to claim 5, wherein in the step 5, the protective bushing obtained in the step 4 is dried and then is fired at 1400-1650 ℃ for 1-6 h.

10. The corundum mullite platinum crucible protective bushing obtained by the preparation method of the corundum mullite platinum crucible protective bushing as claimed in any one of claims 5 to 9.

Technical Field

The invention belongs to the technical field of refractory materials, and particularly relates to a corundum mullite platinum crucible protective bushing and a preparation method thereof.

Background

The crucible used in the development experiment of the silicate glass frit prescription at present mainly comprises a common ceramic crucible, a corundum crucible, a graphite crucible, a platinum crucible and the like, wherein the ceramic crucible is low in price but can only be used under the condition of medium and low temperature, generally is less than about 1450 ℃, and can crack after being used for a long time; the corundum crucible can be melted at high temperature, and the bearing temperature is improved by about 200 ℃ compared with that of a ceramic crucible. For glass melting work, a ceramic crucible or a corundum crucible is very easy to be co-melted with glass, a sample is not easy to take out, and the service life of the crucible is generally only once; although the graphite crucible does not react with glass basically, most of glass melting is an oxidizing atmosphere, the graphite crucible needs to be introduced with a protective atmosphere, and carbon components in the crucible can be melted into the glass after long-time melting, so that the transparency of the glass is affected; the first three kinds of crucibles can be selected as small-scale experimental research, and have large consumption and relatively low price. Compared with the first three types of crucibles, the platinum crucible has the characteristics of high melting point (1773.5 ℃), smooth surface, uniform wall thickness, easy control of temperature field, long service life and the like, so that the platinum crucible is widely used by enterprises or universities.

Although the platinum crucible is expensive, the thermal conductivity is high (71.4W/mK) and the temperature is reduced quickly, so that the viscosity of molten glass at high temperature is high, the discharging difficulty is increased, the platinum is soft and easy to deform, and the operation is not easy to operate when the platinum is used, but necessary conditions are provided for continuously melting the glass. Therefore, it is necessary to prepare a protective lining of the platinum crucible, which has the function of heat preservation and protects the platinum crucible.

The protective lining of the current platinum crucible is mainly made of mullite refractory material, and the existing mullite lining has the problems of poor thermal shock resistance, easy cracking and easy peeling, and finally short service life.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a corundum mullite platinum crucible protection bushing and a preparation method thereof, and the prepared protection bushing has the characteristics of high temperature resistance, good thermal shock stability and long service life.

The invention is realized by the following technical scheme:

a corundum mullite platinum crucible protection bushing comprises aggregate, a substrate and an additive;

the aggregate comprises 40-50 parts of mullite and 10-30 parts of calcium titanoaluminate hollow spheres by weight, and the matrix comprises 10-30 parts of corundum fine powder, 5-10 parts of alpha-activated alumina micro powder and 1-5 parts of aluminate cement;

the additive comprises a water reducing agent, and the water reducing agent accounts for 0.1-0.7% of the total mass of the aggregate and the matrix.

Preferably, the matrix further comprises not more than 5 parts of silica micropowder.

Preferably, the aluminate cement is Secar71 cement.

Preferably, the water reducing agent is a polycarboxylic acid compound water reducing agent, sodium hexametaphosphate or a mixture of the polycarboxylic acid compound water reducing agent and sodium hexametaphosphate.

A preparation method of a corundum mullite platinum crucible protection bushing is based on any one of the corundum mullite platinum crucible protection bushing and comprises the following steps,

step 1, uniformly mixing a calcium titanium aluminate hollow sphere, aggregate and an additive to obtain an initial castable;

step 2, uniformly mixing the initial castable and mullite to obtain a mixture, adding water into the mixture, and stirring until the obtained mixed system is petal-shaped to obtain a final castable;

step 3, adding the final casting material into a mold corresponding to the platinum crucible protective bushing under the vibration condition, so that the surface of the final casting material is flat, no bubbles float upwards and no dense water phenomenon exists, and a sample to be maintained is obtained;

step 4, naturally curing the sample to be cured for 20-30 h, and then demolding to obtain a preliminarily formed corundum-mullite platinum crucible protective bushing;

and 5, drying and sintering the protective bushing obtained in the step 4 to obtain the corundum mullite platinum crucible protective bushing.

Furthermore, in the step 2, water accounts for 3-5% of the total mass of the initial castable and mullite.

And 3, when the final casting material is added into the mold in the step 3, firstly brushing a layer of oil on the inner wall of the mold.

And further, in the step 5, drying the protective lining obtained in the step 4 at the temperature of 90-110 ℃ for 12-36 h.

And further, in the step 5, the protective lining obtained in the step 4 is dried and then is sintered for 1-6 hours at 1400-1650 ℃.

The corundum mullite platinum crucible protective bushing is obtained by the preparation method of the corundum mullite platinum crucible protective bushing.

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

the corundum-mullite quality protection lining sleeve provided by the invention can provide a certain content of Al by designing the specific content of mullite to be 40-50% by mass₂O₃The introduced calcium titanium aluminate hollow sphere is an excellent refractory heat-insulating material, 10-30% by mass of the calcium titanium aluminate hollow sphere can reduce the heat conductivity of a protective lining and enhance the heat-insulating effect, the corundum fine powder is used as a matched substrate raw material and is also a main raw material, 10-30% by mass of corundum fine powder and 5-10% by mass of α -activated alumina micro powder can be filled in a gap between aggregate and the calcium titanium aluminate hollow sphere and are beneficial to improving the volume density of the castable after high-temperature calcination and solid-phase reaction, 1-5% by mass of aluminate cement is used as a bonding agent to combine the raw material components and accelerate the solidification of the castable, a water reducing agent accounts for 0.1-0.7% of the total mass of the main materials, the interface energy of the raw material component particles can be reduced, the coagulation of mullite ions can be destroyed, the fluidity of the castable is improved, the sample is easy to form during pouring, and the water consumption required by the castable can be reduced, so that the corundum fine powder and the corundum formed by the corundum have the characteristics of high-temperature resistance, high-temperature strength, the final high alumina ceramic crucible protective lining, high alumina linear strength and high platinum linear shrinkage rate, and high apparent porosity and high linear shrinkage rate of the mullite crucible, and high temperatureHas the advantages of good thermal shock stability and long service life.

Furthermore, the silicon powder with the weight not more than 5 parts can improve the volume density, and simultaneously has the function of a water reducing agent, so that the water consumption is reduced, and the fluidity of the mixture is improved.

The preparation method of the corundum-mullite protective bushing comprises the steps of uniformly mixing 40-50 parts of mullite, 10-30 parts of calcium titanium aluminate hollow spheres, 10-30 parts of corundum fine powder, 10-30 parts of alpha-active alumina micro powder, 1-5 parts of aluminate cement and a water reducing agent accounting for 0.1% -0.7% of the total mass of the raw materials, adding water to obtain a petal-shaped castable, and obtaining the corundum-mullite platinum crucible protective bushing after vibration molding, natural curing, drying and firing.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention relates to a corundum mullite platinum crucible protective bushing and a preparation method thereof, wherein the corundum mullite platinum crucible protective bushing comprises the following raw materials in percentage by mass: the water reducing agent is prepared by using 40-50% of mullite (with the grain diameter of 0-5 mm), 10-30% of calcium titanium aluminate hollow spheres (with the grain diameter of 0-1 mm), 10-30% of corundum fine powder (with the grain diameter of 0-1 mm), 5-10% of alpha-activated alumina micro powder, 0-5% of silicon micro powder and 1-5% of aluminate cement as raw materials, and the added raw materials are 0.1-0.7% of the total mass of the main materials.

Wherein the aluminate cement is Secar71 cement.

The water reducing agent is one or a mixture of a polycarboxylic acid composite water reducing agent and sodium hexametaphosphate.

The preparation method of the corundum mullite platinum crucible protective lining comprises the following steps of uniformly mixing the raw materials, adding 3-5% of water by mass, uniformly stirring, casting, vibrating and forming to obtain the corundum mullite platinum crucible protective lining,

step 1, premixing the substrate,

accurately weighing the titanium-calcium aluminate hollow spheres, the fine corundum powder, the alpha-activated alumina micro powder, the silicon micro powder, the aluminate cement and the water reducing agent according to the proportion, then pouring the weighed materials into a three-dimensional mixer (without limitation on model) for mixing for 25-35 min without the requirement of sequence, and uniformly mixing for later use;

step 2, forming a casting material,

pouring mullite particles and the matrix premixed uniformly in the step 1 into a stirring pot, uniformly mixing by using a paste mixer (with unlimited model), then mixing a small amount of the materials for many times according to conditions, so that the materials are easily mixed uniformly, adding water with the mass fraction of 3% -5% of the raw materials while stirring, continuously mixing the materials until the raw materials are uniformly attached to the wall of the stirring pot, and forming the shape of a petal, wherein a low-speed gear of equipment is generally selected, the stirring speed is 135-145 rpm, the stirring time is 3-18 min, and the shape is continuously changed due to the longer time, and the stirring is stopped at the moment, so that the mixture not only has certain fluidity, but also is not easy to generate the water-tight phenomenon in the vibration forming process;

step 3, vibration molding is carried out,

placing a forming die coated with oil inside on a cement mortar vibrating table (model is not limited) for fixing, gradually adding the casting material in the step 2 into a die corresponding to the platinum crucible protective lining while vibrating, continuously vibrating after the die is filled until the surface of the casting material is flat, no air bubbles float upwards and no water sealing phenomenon exists, and then floating water in the casting material; the mould is coated with oil to facilitate demoulding, and a layer of oil is brushed, so that the oil quantity does not influence the experiment, and common oil can be used;

step 4, the natural curing is carried out,

naturally curing the protective lining sample formed by vibration in the step 3 with a mold for 20-30 h, then demolding, cleaning the mold, and oiling and curing;

and step 5, drying the mixture,

putting the protective lining sample obtained in the step 4 into a vacuum drying oven, and drying for 12-36 hours at 90-110 ℃;

and step 6, sintering the mixture,

and (4) placing the dried sample in the step (5) into a muffle furnace to be sintered at 1400-1650 ℃, heating to a target temperature, and then keeping the temperature for 1-6 h, wherein the heating rate can be set to be 2-10 ℃/min.