阅读说明：本技术 一种窑炉内衬复合砖 (Composite brick for kiln lining ) 是由 朱喜仲 张汉义 朱晓兵 李旭 孙建 周立 李秋南 姜晓灵 周波 王立公 黄涛 于 2021-07-27 设计创作，主要内容包括：本发明提出了一种窑炉内衬复合砖,包括氮化硅结合碳化硅陶瓷层和与之相结合的塞隆结合氧化铝空心球层,所述氮化硅结合碳化硅陶瓷层靠近窑炉工作面,与炉内气体直接接触。本发明复合砖采用双层结构,其中氮化硅结合碳化硅层具有耐侵蚀、耐磨等作用,塞隆结合氧化铝空心球层具有隔热保温的作用,将两者结合起来不仅解决了窑炉内层砖受窑炉气体的侵蚀和反复高温老化而出现剥落和掉渣的情况,同时也满足了外层砖的良好保温隔热效果。(The invention provides a kiln lining composite brick, which comprises a silicon nitride and silicon carbide combined ceramic layer and a sialon combined alumina hollow sphere layer combined with the silicon nitride and silicon carbide combined ceramic layer, wherein the silicon nitride and silicon carbide combined ceramic layer is close to the working surface of a kiln and is in direct contact with gas in the kiln. The composite brick adopts a double-layer structure, wherein the silicon nitride and silicon carbide layers have the effects of corrosion resistance, wear resistance and the like, and the sialon and aluminum oxide hollow sphere layer have the effects of heat insulation and preservation, so that the problem that the inner layer brick of the kiln is corroded by kiln gas and repeatedly aged at high temperature to peel off and drop slag is solved, and the good heat insulation effect of the outer layer brick is also met.)

1. The composite brick for the lining of the kiln is characterized in that: the silicon nitride and silicon carbide ceramic hollow sphere comprises a silicon nitride and silicon carbide ceramic layer and a sialon and aluminum oxide hollow sphere layer which are combined with the silicon nitride and silicon carbide ceramic layer, wherein the silicon nitride and silicon carbide ceramic layer is close to a furnace core and is in direct contact with gas in a furnace.

2. The composite brick for the lining of a kiln as claimed in claim 1, wherein: the thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer is 1 (3-50).

3. The composite brick for the lining of a kiln as claimed in claim 1, wherein: the silicon nitride and silicon carbide ceramic layer is prepared from 60-80 parts by weight of silicon carbide sand, 1-4 parts by weight of silicon micropowder, 10-18 parts by weight of metal silicon powder and 2-7 parts by weight of a binding agent.

4. The composite brick for the lining of a kiln as claimed in claim 3, wherein: the granularity of the silicon carbide sand is less than or equal to 5 mm.

5. The composite brick for the lining of a kiln as claimed in claim 1, wherein: the sialon-alumina hollow sphere layer comprises, by weight, 65-85 parts of alumina hollow spheres, 2-8 parts of aluminum powder, 9-16 parts of metal silicon powder, 2-6 parts of alumina powder, 1-4 parts of rare earth oxide, 1-3 parts of silicon micropowder and 3-6 parts of a binding agent.

6. The composite brick for the lining of a kiln as claimed in claim 5, wherein: the granularity of the alumina hollow sphere is 5-1 mm.

7. The composite brick for the lining of a kiln as claimed in claim 5, wherein: the rare earth oxide is one or a combination of more of neodymium oxide, yttrium oxide, lanthanum oxide, gadolinium oxide and ytterbium oxide.

8. The composite brick for the lining of a kiln as claimed in any one of claims 3 and 5, wherein: the binding agent is one or more of polyvinyl alcohol, lignosulfonate, carboxymethyl cellulose, silica sol and dextrin.

9. The composite brick for the lining of a kiln as claimed in any one of claims 1 to 7, wherein: the preparation method comprises the following steps:

s1, mixing 15-20 parts of silicon carbide sand with the granularity of 0.5-0mm, 20-30 parts of 1.43-0.5mm and 25-30 parts of 5-1.43mm with 1-4 parts of silicon powder, 10-18 parts of metal silicon powder and 2-7 parts of a bonding agent to obtain a mixture of a silicon nitride-silicon carbide ceramic layer;

s2, respectively taking 10-20 parts of alumina hollow spheres with the particle sizes of 5-3mm, 25-30 parts of 3-2mm and 30-35 parts of 2-1mm, 2-8 parts of aluminum powder, 9-16 parts of metal silicon powder, 2-6 parts of alumina powder, 1-4 parts of rare earth oxide, 1-3 parts of silicon micropowder and 3-6 parts of a binding agent, and mixing to obtain a mixture of the sialon-alumina hollow sphere layer;

s3, sequentially placing the mixture of the silicon nitride and silicon carbide ceramic layers and the mixture of the sialon and aluminum oxide hollow ball layers into a mold, obtaining a composite brick blank by adopting a vibration compaction molding or casting molding method, placing the composite brick blank into a kiln, drying at the temperature of 100 plus materials and 160 ℃, placing into a nitriding furnace, introducing nitrogen, firing at the pressure of 0.01-0.05MPa of nitrogen and at the temperature of 1050 plus materials and 1450 ℃, and obtaining the composite brick for heat preservation of the kiln.

10. The composite brick for the lining of a kiln as claimed in claim 9, wherein: the method for vibration compaction forming comprises the following steps: slowly adding the raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a mould, and vibrating and compacting under the condition of 0.15-0.5MPa to obtain a blank; carrying out rough surface treatment on the surface of the blank, slowly adding the raw material mixture of the sialon and the alumina hollow sphere layer into a mould for vibration compaction again, and demoulding after compaction to obtain the composite brick blank for furnace heat preservation;

the casting molding method comprises the following steps: under the condition that the vibration frequency is 15-65Hz, the raw material mixture of the silicon nitride and the silicon carbide ceramic layer is gradually added into a gypsum mould, then the raw material mixture of the sialon and the alumina hollow sphere layer is gradually added into the gypsum mould, after the addition, the vibration molding is carried out for 5-10min, after the vibration is finished, the standing is carried out for 20-30min, and the gypsum mould is removed, thus obtaining the composite brick blank for furnace heat preservation.

Technical Field

The invention relates to the technical field of composite bricks, in particular to a composite brick for a kiln lining.

Background

Many thermal equipment in production require refractory bricks, such as the linings of industrial kilns, which have excellent thermal stability and are also subject to high temperatures and chemical attack and wear of the materials therein. The sialon combined alumina hollow ball is a light refractory material with high temperature resistance and excellent energy saving performance, is very stable when used in various atmospheres, has obvious effects on reducing the weight of a furnace body, modifying a structure, saving materials and saving energy, and is a common refractory heat-insulating material. However, the sialon-alumina hollow ball brick has low high-temperature strength, and can be corroded by kiln gas and repeatedly aged at high temperature to cause the conditions of peeling and slag falling when being used in a kiln, so that the service life of the heat-insulating material of the kiln is influenced. Therefore, it is important to develop a heat-insulating brick with good heat-insulating performance, difficult slag falling and long service life.

Disclosure of Invention

In view of the above, the invention provides a composite brick for kiln heat preservation, which is not easy to slag fall, has good heat preservation and heat insulation performance and long service life.

The technical scheme of the invention is realized as follows: the invention provides a kiln lining composite brick, which comprises a silicon nitride and silicon carbide combined ceramic layer and a sialon combined alumina hollow sphere layer combined with the silicon nitride and silicon carbide combined ceramic layer, wherein the silicon nitride and silicon carbide combined ceramic layer is close to a furnace core and is directly contacted with gas in a furnace.

Based on the technical scheme, the thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer is preferably 1 (3-50).

On the basis of the technical scheme, preferably, the silicon nitride and silicon carbide ceramic layer is prepared from 60-80 parts of silicon carbide sand, 1-4 parts of silicon micropowder, 10-18 parts of metal silicon powder and 2-7 parts of a binding agent by weight.

On the basis of the technical scheme, the granularity of the carborundum sand is preferably less than or equal to 5 mm.

On the basis of the technical scheme, preferably, the sialon-alumina hollow sphere layer is prepared from 65-85 parts by weight of alumina hollow spheres, 2-8 parts by weight of aluminum powder, 9-16 parts by weight of metal silicon powder, 2-6 parts by weight of alumina powder, 1-4 parts by weight of rare earth oxide, 1-3 parts by weight of silicon powder and 3-6 parts by weight of a binder.

On the basis of the technical scheme, the granularity of the alumina hollow sphere is preferably 5-1 mm.

On the basis of the above technical solution, preferably, the rare earth oxide is one or a combination of more of neodymium oxide, yttrium oxide, lanthanum oxide, gadolinium oxide, and ytterbium oxide.

On the basis of the technical scheme, preferably, the binding agent is one or a combination of more of polyvinyl alcohol, lignosulfonate, carboxymethyl cellulose, silica sol and dextrin.

The invention also provides a preparation method of the kiln lining composite brick, which comprises the following steps:

s1, mixing 15-20 parts of silicon carbide sand with the granularity of 0.5-0mm, 20-30 parts of 1.43-0.5mm and 25-30 parts of 5-1.43mm with 1-4 parts of silicon powder, 10-18 parts of metal silicon powder and 2-7 parts of a bonding agent to obtain a mixture of a silicon nitride-silicon carbide ceramic layer;

s2, respectively taking 10-20 parts of alumina hollow spheres with the particle sizes of 5-3mm, 25-30 parts of 3-2mm and 30-35 parts of 2-1mm, 2-8 parts of aluminum powder, 9-16 parts of metal silicon powder, 2-6 parts of alumina powder, 1-4 parts of rare earth oxide, 1-3 parts of silicon micropowder and 3-6 parts of a binding agent, and mixing to obtain a mixture of the sialon-alumina hollow sphere layer;

s3, sequentially placing the mixture of the silicon nitride and silicon carbide ceramic layers and the mixture of the sialon and aluminum oxide hollow ball layers into a mold, obtaining a composite brick blank by adopting a vibration compaction molding or casting molding method, placing the composite brick blank into a kiln, drying at the temperature of 100 plus materials and 160 ℃, placing into a nitriding furnace, introducing nitrogen, firing at the pressure of 0.01-0.05MPa of nitrogen and at the temperature of 1050 plus materials and 1450 ℃, and obtaining the composite brick for heat preservation of the kiln.

On the basis of the above technical solution, preferably, the method for forming by vibrocompaction comprises: slowly adding the raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a mould, and vibrating and compacting under the condition of 0.15-0.5MPa to obtain a blank; and (3) performing rough surface treatment on the surface of the blank, slowly adding the raw material mixture of the sialon and the alumina hollow sphere layer into a mould, vibrating and compacting again, and demoulding after compacting to obtain the composite brick blank for furnace heat preservation.

On the basis of the above technical solution, preferably, the casting method comprises: under the condition that the vibration frequency is 15-65Hz, the raw material mixture of the silicon nitride and the silicon carbide ceramic layer is gradually added into a gypsum mould, then the raw material mixture of the sialon and the alumina hollow sphere layer is gradually added into the gypsum mould, after the addition, the vibration molding is carried out for 5-10min, after the vibration is finished, the standing is carried out for 20-30min, and the gypsum mould is removed, thus obtaining the composite brick blank for furnace heat preservation.

On the basis of the technical scheme, preferably, the composite brick blank is compacted at intervals according to the silicon nitride-bonded silicon carbide ceramic layer and the sialon-bonded alumina hollow sphere layer, and finally the composite brick blank for furnace heat preservation is obtained after the last layer of compaction and demoulding.

Compared with the prior art, the kiln lining composite brick has the following beneficial effects:

1. the sialon-bonded alumina hollow ball is a light refractory material with high temperature resistance and excellent energy saving performance, and the silicon nitride-bonded silicon carbide material has good high temperature resistance, so that the sialon-bonded alumina hollow ball and the silicon nitride-bonded silicon carbide material are combined, thereby not only solving the problem that inner layer bricks of a kiln are corroded by kiln gas and are repeatedly aged at high temperature to peel off and drop slag, but also meeting the good heat insulation effect of outer layer bricks.

2. According to the invention, the rare earth oxide is introduced, so that the nitridation reaction of the silicon powder is improved, the strength and the high-temperature gas corrosion resistance of the heat-insulating composite brick are improved, and the service life of the heat-insulating composite brick is prolonged.

3. The composite brick of the invention has low volume density, light weight and reduced kiln load; the strength is high, the acid and alkali resistance is good, the corrosion of high-temperature gas in the furnace can be resisted, the acid and alkali corrosion stripping phenomenon of the insulating brick is avoided, and the service life of the kiln is prolonged; the heat conductivity is low, and good heat preservation and insulation effects are achieved.

4. The invention adopts two methods of vibration compaction molding and casting molding to manufacture the blank, the vibration compaction has the advantages of high strength and quick molding, and the casting molding can be carried out according to molds with different shapes and can be applied to different scenes.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example one

A composite brick for the lining of kiln is composed of a silicon nitride-silicon carbide ceramic layer close to the core of kiln and in direct contact with the gas in kiln, and a sialon-alumina hollow ball layer combined with said silicon nitride-silicon carbide ceramic layer. The thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer was 1: 3.

The silicon nitride and silicon carbide combined ceramic layer comprises the following raw materials in parts by weight: 15 parts of carborundum sand with the grain diameter of 0.5-0mm, 20 parts of 1.43-0.5mm and 25 parts of 5-1.43mm, 1 part of silicon powder, 10 parts of metal silicon powder and 2 parts of polyvinyl alcohol.

The sialon combined alumina hollow sphere layer comprises the following raw materials in parts by weight: 10 parts of alumina hollow spheres with the particle sizes of 5-3mm, 25 parts of 3-2mm and 30 parts of 2-1mm, 2 parts of aluminum powder, 9 parts of metal silicon powder, 2 parts of alumina powder, 1 part of neodymium oxide, 1-3 parts of silicon micropowder and 3 parts of lignosulfonate.

The preparation method of the composite brick for kiln heat preservation comprises the following steps:

s1, taking 15 parts of silicon carbide sand with the grain diameter of 0.5-0mm, 20 parts of 1.43-0.5mm and 25 parts of 5-1.43mm, 1 part of silicon powder, 10 parts of metal silicon powder and 2 parts of polyvinyl alcohol, and mixing to obtain a raw material mixture of the silicon nitride and silicon carbide ceramic layer;

s2, taking 5-3mm 10 parts, 3-2mm 25 parts and 2-1mm 30 parts of alumina hollow spheres, 2 parts of aluminum powder, 9 parts of metal silicon powder, 2 parts of alumina powder, 1 part of neodymium oxide, 1-3 parts of silicon micropowder and 3 parts of lignosulfonate, and mixing to obtain a raw material mixture of the sialon combined alumina hollow sphere layer;

s3, mixing the raw materials of the silicon nitride and silicon carbide ceramic layers, slowly adding the mixture into a mould, and vibrating and compacting under the condition of 0.15MPa to obtain a blank; carrying out rough surface treatment on the surface of the blank, slowly adding the raw material mixture of the sialon and the alumina hollow sphere layer into a mould for vibration compaction again, and demoulding after compaction to obtain the composite brick blank for furnace heat preservation;

s4, placing the composite brick blank into a kiln, drying at 100 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.01MPa, firing at 1050 ℃.,/min by stage heating at 5 ℃/min, preserving heat for 10h at 1050-.

Example two

A composite brick for the lining of kiln is composed of a silicon nitride-silicon carbide ceramic layer close to the core of kiln and in direct contact with the gas in kiln, and a sialon-alumina hollow ball layer combined with said silicon nitride-silicon carbide ceramic layer. The thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer was 1: 50.

The silicon nitride and silicon carbide combined ceramic layer comprises the following raw materials in parts by weight: 20 parts of silicon carbide sand with the granularity of 0.5-0mm, 30 parts of 1.43-0.5mm and 30 parts of 5-1.43mm, 15 parts of silicon powder, 19 parts of metal silicon powder, 3 parts of lignosulfonate and 4 parts of carboxymethyl cellulose.

The sialon combined alumina hollow sphere layer comprises the following raw materials in parts by weight: 20 parts of alumina hollow spheres with the particle sizes of 5-3mm, 30 parts of 3-2mm and 35 parts of 2-1mm, 8 parts of aluminum powder, 16 parts of metal silicon powder, 6 parts of alumina powder, 2 parts of yttrium oxide, 2 parts of lanthanum oxide, 3 parts of silicon micropowder, 3 parts of polyvinyl alcohol and 3 parts of carboxymethyl cellulose.

The preparation method of the composite brick for kiln heat preservation comprises the following steps:

s1, taking 20 parts of silicon carbide sand with the granularity of 0.5-0mm, 30 parts of 1.43-0.5mm and 30 parts of 5-1.43mm, 15 parts of silicon powder, 19 parts of metal silicon powder, 3 parts of lignosulfonate and 4 parts of carboxymethyl cellulose, and mixing to obtain a raw material mixture of the silicon nitride and silicon carbide ceramic layer;

s2, taking 5-3mm 20 parts, 3-2mm 30 parts and 2-1mm 35 parts of alumina hollow spheres, 8 parts of aluminum powder, 16 parts of metal silicon powder, 6 parts of alumina powder, 2 parts of yttrium oxide, 2 parts of lanthanum oxide, 3 parts of silicon micropowder, 3 parts of polyvinyl alcohol and 3 parts of carboxymethyl cellulose, and mixing to obtain a raw material mixture of the sialon combined alumina hollow sphere layer;

s3, slowly adding the raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a mould, and vibrating and compacting under the condition of 0.5MPa to obtain a blank; carrying out rough surface treatment on the surface of the blank, slowly adding the raw material mixture of the sialon and the alumina hollow sphere layer into a mould for vibration compaction again, and demoulding after compaction to obtain the composite brick blank for furnace heat preservation;

s4, placing the composite brick blank into a kiln, drying at 160 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.05MPa, firing at 1050 ℃.,/min by stage heating at 10 ℃/min, preserving heat for 20h at 1050-.

EXAMPLE III

A composite brick for the lining of kiln is composed of a silicon nitride-silicon carbide ceramic layer close to the core of kiln and in direct contact with the gas in kiln, and a sialon-alumina hollow ball layer combined with said silicon nitride-silicon carbide ceramic layer. The thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer was 1: 40.

The silicon nitride and silicon carbide combined ceramic layer comprises the following raw materials in parts by weight: 17 parts of silicon carbide sand with the granularity of 0.5-0mm, 25 parts of 1.43-0.5mm and 27 parts of 5-1.43mm, 2 parts of silicon powder, 14 parts of metal silicon powder, 1 part of carboxymethyl cellulose, 1 part of silica sol and 2 parts of dextrin.

The sialon combined alumina hollow sphere layer comprises the following raw materials in parts by weight: 15 parts of alumina hollow spheres with the particle sizes of 5-3mm, 27 parts of 3-2mm and 33 parts of 2-1mm, 6 parts of aluminum powder, 14 parts of metal silicon powder, 5 parts of alumina powder, 1 part of yttrium oxide, 1 part of lanthanum oxide, 1 part of gadolinium oxide, 2 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate and 2 parts of carboxymethyl cellulose.

The preparation method of the composite brick for kiln heat preservation comprises the following steps:

s1, taking 17 parts of silicon carbide sand with the granularity of 0.5-0mm, 25 parts of 1.43-0.5mm and 27 parts of 5-1.43mm, 2 parts of silicon powder, 14 parts of metal silicon powder, 1 part of carboxymethyl cellulose, 1 part of silica sol and 2 parts of dextrin, and mixing to obtain a raw material mixture of the silicon nitride and silicon carbide ceramic layer;

s2, taking 15 parts of alumina hollow spheres with the particle sizes of 5-3mm, 27 parts of 3-2mm and 33 parts of 2-1mm, 6 parts of aluminum powder, 14 parts of metal silicon powder, 5 parts of alumina powder, 1 part of yttrium oxide, 1 part of lanthanum oxide, 1 part of gadolinium oxide, 2 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate and 2 parts of carboxymethyl cellulose, and mixing to obtain a raw material mixture of the sialon combined alumina hollow sphere layer;

s3, slowly adding the raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a mould, and vibrating and compacting under the condition of 0.2MPa to obtain a blank; carrying out rough surface treatment on the surface of the green body, slowly adding the raw material mixture of the sialon and the alumina hollow sphere layer into a mould for vibration compaction again, and demoulding after compaction to obtain the composite brick green body for heat preservation of the kiln;

s4, placing the composite brick blank into a kiln, drying at 130 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.02MPa, firing at 1100-.

Example four

A composite brick for the lining of kiln is composed of a silicon nitride-silicon carbide ceramic layer close to the core of kiln and in direct contact with the gas in kiln, and a sialon-alumina hollow ball layer combined with said silicon nitride-silicon carbide ceramic layer. The thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer was 1: 20.

The silicon nitride and silicon carbide combined ceramic layer comprises the following raw materials in parts by weight: 16 parts of carborundum sand with the granularity of 0.5-0mm, 22 parts of 1.43-0.5mm and 26 parts of 5-1.43mm, 2 parts of silicon powder, 12 parts of metal silicon powder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose and 1 part of silica sol.

The sialon combined alumina hollow sphere layer comprises the following raw materials in parts by weight: the composite material comprises, by weight, 5-3mm 12 parts, 3-2mm 28 parts and 2-1mm 31 parts of alumina hollow spheres, 4 parts of aluminum powder, 12 parts of metal silicon powder, 3 parts of alumina powder, 0.5 part of yttrium oxide, 0.5 part of lanthanum oxide, 0.5 part of gadolinium oxide, 1 part of ytterbium oxide, 1.5 parts of silica micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose, 1 part of silica sol and 1 part of dextrin.

The preparation method of the composite brick for kiln heat preservation comprises the following steps:

s1, taking 16 parts of silicon carbide sand with the granularity of 0.5-0mm, 22 parts of 1.43-0.5mm and 26 parts of silicon carbide sand with the granularity of 5-1.43mm, 2 parts of silicon powder, 12 parts of metal silicon powder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose and 1 part of silica sol, and mixing to obtain a raw material mixture of a silicon nitride and silicon carbide ceramic layer;

s2, taking 5-3mm 12 parts, 3-2mm 28 parts and 2-1mm 31 parts of alumina hollow spheres, 4 parts of aluminum powder, 12 parts of metal silicon powder, 3 parts of alumina powder, 0.5 part of yttrium oxide, 0.5 part of lanthanum oxide, 0.5 part of gadolinium oxide, 1 part of ytterbium oxide, 1.5 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose, 1 part of silica sol and 1 part of dextrin, and mixing to obtain a raw material mixture of the sialon combined alumina hollow sphere layer;

s3, dividing the raw material mixture of the silicon nitride-bonded silicon carbide ceramic layer and the raw material mixture of the sialon-bonded alumina hollow sphere layer into 5 equal parts respectively; slowly adding a part of raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a mould, and vibrating and compacting under the condition of 0.4MPa to obtain a first layer of blank body; carrying out rough surface treatment on the surface of the first layer of blank, slowly adding a part of raw material mixture of the sialon combined alumina hollow sphere layer into a mould, and vibrating and compacting again to obtain a second layer of blank; performing rough surface treatment on the surface of the second layer of blank, slowly adding a layer of raw material mixture of a silicon nitride and silicon carbide ceramic layer, and vibrating and compacting to obtain a third layer of blank; slowly adding a part of the raw material mixture of the sialon combined alumina hollow sphere layer into a mould, and vibrating and compacting again to obtain a fourth layer of green body; repeating the steps until all the raw materials are added;

compacting the composite brick body at intervals according to a silicon nitride-combined silicon carbide ceramic layer and a sialon-combined alumina hollow sphere layer, and demoulding after the final layer is compacted to obtain the composite brick body for furnace heat preservation;

s4, placing the composite brick blank into a kiln, drying at 140 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.03MPa, firing at 1200-plus-1400 ℃ by stage heating at the speed of 7 ℃/min, preserving heat for 12h at 1200-plus-1250 ℃, preserving heat for 25h at 1250-plus-1300 ℃, preserving heat for 11h at 1300-plus-1350 ℃ and preserving heat for 18h at 1350-plus-1400 ℃ to obtain the composite brick for kiln heat preservation.

EXAMPLE five

A composite brick for the lining of kiln is composed of a silicon nitride-silicon carbide ceramic layer close to the core of kiln and in direct contact with the gas in kiln, and a sialon-alumina hollow ball layer combined with said silicon nitride-silicon carbide ceramic layer. The thickness ratio of the silicon nitride-bonded silicon carbide ceramic layer to the sialon-bonded alumina hollow sphere layer was 1: 45.

The silicon nitride and silicon carbide combined ceramic layer comprises the following raw materials in parts by weight: 19 parts of silicon carbide sand with the granularity of 0.5-0mm, 28 parts of 1.43-0.5mm and 29 parts of 5-1.43mm, 3 parts of silicon powder, 13 parts of metal silicon powder, 2 parts of lignosulfonate, 1 part of carboxymethyl cellulose and 1 part of silica sol.

The sialon combined alumina hollow sphere layer comprises the following raw materials in parts by weight: 18 parts of alumina hollow spheres with the particle sizes of 5-3mm, 3-2mm and 29 parts of 2-1mm and 34 parts of aluminum powder, 5 parts of aluminum powder, 13 parts of metal silicon powder, 4 parts of aluminum oxide powder, 0.5 part of yttrium oxide, 0.5 part of lanthanum oxide, 0.5 part of gadolinium oxide, 0.5 part of ytterbium oxide, 1.5 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose, 1 part of silica sol and 1 part of dextrin.

The preparation method of the composite brick for kiln heat preservation comprises the following steps:

s1, taking 19 parts of silicon carbide sand with the granularity of 0.5-0mm, 28 parts of 1.43-0.5mm and 29 parts of silicon carbide sand with the granularity of 5-1.43mm, 3 parts of silicon powder, 13 parts of metal silicon powder, 2 parts of lignosulfonate, 1 part of carboxymethyl cellulose and 1 part of silica sol, and mixing to obtain a raw material mixture of the silicon nitride and silicon carbide ceramic layer;

s2, taking and mixing 18 parts of alumina hollow spheres with the particle sizes of 5-3mm, 3-2mm and 29 parts of alumina hollow spheres with the particle sizes of 2-1mm and 34 parts of alumina powder, 5 parts of aluminum powder, 13 parts of metal silicon powder, 4 parts of alumina powder, 0.5 part of yttrium oxide, 0.5 part of lanthanum oxide, 0.5 part of gadolinium oxide, 0.5 part of ytterbium oxide, 1.5 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate, 1 part of carboxymethyl cellulose, 1 part of silica sol and 1 part of dextrin to obtain a raw material mixture of the sialon combined alumina hollow sphere layer;

s3, dividing the raw material mixture of the silicon nitride-bonded silicon carbide ceramic layer and the raw material mixture of the sialon-bonded alumina hollow sphere layer into 5 equal parts respectively; under the condition that the vibration frequency is 20Hz, firstly, slowly adding one part of raw material mixture of the silicon nitride and the silicon carbide ceramic layer into a gypsum mould, firstly, gradually adding 1 part of raw material mixture of the silicon nitride and the silicon carbide ceramic layer into the gypsum mould, then, gradually adding 1 part of raw material mixture of the sialon and the alumina hollow sphere layer into the gypsum mould, repeating the steps until all the raw materials are added to obtain a composite brick blank body with the silicon nitride and the silicon carbide ceramic layer and the sialon and the alumina hollow sphere layer arranged at intervals, carrying out vibration molding for 10min after the addition is finished, standing for 30min after the vibration is finished, and removing the gypsum mould to obtain the composite brick blank body for furnace heat preservation.

S4, placing the composite brick blank into a kiln, drying at 140 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.04MPa, firing at 1200-plus-1400 ℃ by stage heating at the speed of 7 ℃/min, preserving heat for 12h at 1200-plus-1250 ℃, preserving heat for 25h at 1250-plus-1300 ℃, preserving heat for 11h at 1300-plus-1350 ℃ and preserving heat for 18h at 1350-plus-1400 ℃ to obtain the composite brick for kiln heat preservation.

Comparative example 1

Comparative example one is a single layer structure of example one, i.e., a silicon nitride bonded silicon carbide ceramic layer structure, fired in the same manner as the preparation of example one.

The composite brick for the lining of the kiln comprises, by weight, 0.5-0mm 15 parts, 1.43-0.5mm 20 parts, 5-1.43mm 25 parts of carborundum sand, 1 part of silicon micropowder, 10 parts of metal silicon powder and 2 parts of polyvinyl alcohol.

The firing method comprises the following steps of (1) firing the silicon nitride and silicon carbide ceramic layer according to the weight part:

s1, uniformly mixing the raw materials, slowly adding the raw materials into a mold, vibrating and compacting under the condition of 0.3MPa, and demolding to obtain a kiln insulating brick blank;

s2, placing the blank into a kiln, drying at 100 ℃, placing into a nitriding furnace, introducing nitrogen with the pressure of 0.05MPa, firing at 1050-.

Comparative example No. two

Comparative example two is a single layer structure of example two, i.e., a sialon bonded alumina hollow sphere layer, fired in the same manner as example two.

The composite brick for the kiln lining comprises, by weight, 20 parts of alumina hollow spheres with the particle sizes of 5-3mm, 30 parts of 3-2mm and 35 parts of 2-1mm, 8 parts of aluminum powder, 16 parts of metal silicon powder, 6 parts of alumina powder, 2 parts of yttrium oxide, 2 parts of lanthanum oxide, 3 parts of silicon micropowder, 3 parts of polyvinyl alcohol and 3 parts of carboxymethyl cellulose.

The firing method comprises the following steps:

s1, uniformly mixing the raw materials, slowly adding the raw materials into a mold, vibrating and compacting, and demolding to obtain a kiln insulating brick blank;

s2, placing the blank into a kiln, drying at 160 ℃, placing into a nitriding furnace, introducing nitrogen with the pressure of 0.03MPa, firing at 1050-.

Comparative example No. three

Comparative example three is the non-layered structure of example three, i.e., the raw materials of the silicon nitride bonded silicon carbide ceramic layer and the sialon bonded alumina hollow sphere layer were mixed and fired in the same manner as the preparation method of example three.

A kiln lining composite brick comprises 17 parts by weight of carborundum sand with the granularity of 0.5-0mm, 25 parts by weight of 1.43-0.5mm and 27 parts by weight of 5-1.43mm, 2 parts by weight of silicon micropowder and 14 parts by weight of silicon metal powder; 15 parts of alumina hollow spheres with the particle sizes of 5-3mm, 27 parts of 3-2mm and 33 parts of 2-1mm, 6 parts of aluminum powder, 14 parts of metal silicon powder, 5 parts of alumina powder, 1 part of yttrium oxide, 1 part of lanthanum oxide, 1 part of gadolinium oxide, 2 parts of silicon micropowder, 1 part of polyvinyl alcohol, 1 part of lignosulfonate and 2 parts of carboxymethyl cellulose.

The preparation method of the kiln insulating brick comprises the following steps:

s1, uniformly mixing the raw materials, slowly adding the raw materials into a mold, vibrating and compacting, and demolding to obtain a kiln insulating brick blank;

s2, placing the composite brick blank into a kiln, drying at 130 ℃, placing into a nitriding furnace, introducing nitrogen, wherein the nitrogen pressure is 0.04MPa, firing at 1100-.

The physicochemical properties of the insulating bricks of the examples and the comparative examples were tested, and the results were as follows:

TABLE 1 physicochemical properties of the thermal insulation composite brick of the present invention

As can be seen from Table 1: the single-layer structure has poor performances of heat conductivity, compressive strength and acid and alkali corrosion resistance, and is not as excellent as the composite brick of the invention. Compared with the comparative example, the composite brick of the invention has low volume density, light weight and reduced kiln load; the acid and alkali resistance is good; the heat conductivity is low, and good heat preservation and insulation effects are achieved. Along with the increase of the thickness of the sialon combined alumina hollow sphere, the heat insulation effect and the load are gradually enhanced. The fifth embodiment has the best effect, and shows that on the basis of increasing the thickness of the sialon-bonded alumina hollow sphere layer, the composite brick blank prepared by alternately compacting the silicon nitride-bonded silicon carbide ceramic layer and the sialon-bonded alumina hollow sphere layer has better strength and corrosion resistance.

TABLE 2 use effect of the composite brick of the present invention

Table 2 shows that: the high-temperature rupture strength of the insulating brick at 1400 ℃ is higher than that of the comparative example; the kiln built by the composite insulating bricks runs intermittently at 1450 ℃, the using times can reach more than 350, and the kiln body does not have obvious phenomena of falling off and slag falling. The effect of the fifth example is optimal, which shows that the composite brick body prepared by alternately compacting the silicon nitride-bonded silicon carbide ceramic layer and the sialon-bonded alumina hollow sphere layer shows higher high-temperature breaking strength and use times, and shows that the insulating brick of the invention shows better anti-stripping performance and use effect in the use process.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.