Synthetic mullite introduction

Mullite (Mullite) is compound in atmospheric Al2O3-SiO2 two series in the only stable, chemical formula 3Al2O3 – 2SiO2, the theory of composition of Al2O3 71.8%, SiO2 28.2%. Mullite is a mineral name, because of the moire Island Natural Minerals first discovered on the west coast of Scotland (Mull) and the name. Natural mullite mineral is very small, Lin County of China’s Wuan County in Hebei province and Henan province has been found, but so far the world has yet no industrial value of the deposit. Mullite artificial synthetic stone commonly used sintering method or electric melting method. Synthesis of mullite in 1926 and the first with electric melting method, in 1928 the successful development of sintering method. Currently the world’s electric melting mullite consumed 10000~20000 tons, 500000~600000 tons of sintered mullite. Synthesis of mullite is a high-quality refractory raw material; it has the expansion uniformity, thermal shock stability, excellent high load softening point, high temperature creep value characteristics of small, high hardness, resistance to chemical corrosion and good.

Structure of refractory brick can also cause brick burst

Structure of refractory bricks will burst and its product itself also has the very big relations. Refractory brick thermal spalling, refers to the subject of the refractory brick thermal shock, in refractory brick surface and internal temperature difference, because of differences in thepresence of internal expansion, leading to refractory brick masonry produce stress, when the stress accumulation caused to a certain extent is the heat burst. So, cause the refractory brick thermal spalling reason which to have:

1, silica brick mineral phases such as quartz, tridymite, cristobalite, due to the temperature change and also accompanied by quartz crystal type conversion, volume change, so the heating or cooling brick masonry structure, the need to pay particular attention to the problem of thermal explosion.

2, magnesia brick and magnesia chrome brick, because its thermal expansion coefficient is larger, the thermal decrepitating temperature mutation is also easy to produce refractory brick.

3, insulating refractory brick, because of its low thermal conductivity, the temperature gradient in brick, and because of its relatively low strength, so it is also easy to produce hot crack problems.

As the introduction, is it right? Ofrefractory bricks have a further understanding of it; the content above is only for your reference, the specific reasons but also according to the specific circumstances to determine. More detailed content of http://www.yilongrefractory.com

Features of refractory fibers

1. High temperature.

The highest use temperature up to 1250~2500 DEG C. The most commonly used asbestos only 500~550 DEG C, slag wool is 580~830 DEG C, and aluminum silicate fiber above 1000 degrees.

2. Heat capacity is low.

Refractory fiber under high temperature heat conduction ability is very low, such as 1000 DEG C, conductivity of aluminium silicate fiber is only 20% light clay brick, clay brick 38%.

3. Small volume density.

Usually 0.1~0.2g/cm fand, general clay brick for 1/20~1/10, 1/10~1/5 light clay brick. Therefore, application of refractory fiber industrial furnace instead of refractory bricks, which can make the furnace body weight, furnace wall thickness. If the heating furnace using fiber lining reduces 80%, furnace wall thickness of 50%.

4. Good chemical stability.

In addition to alkali, fluoride, sulphate, erosion is almost unaffected by chemicals.

5. Good thermal shock resistances.

Both fiber materials and products of refractory brick, has the incomparable good thermalshock resistance.

6 low thermal capacity.

1/72 heat capacity of the fiber material only refractory brick, light clay brick 1/42.Refractory fiber lining for storage, loss is small, fuel saving, fast temperature rise, the intermittent operation furnace affection is obvious.

7. Soft, easy processing.

Can be made into a variety of products and personnel shape parts, construction is convenient, the labor intensity is low, the effect is good.

Details of knowledge should pay attention to the selection of refractory materials

Selection of refractory materials needs to pay attention to the details of knowledge. High temperature industrial development cannot do without refractory material function, especially in the iron and steel, nonferrous metals, glass, ceramics, cement, petrochemical, machinery,boilers, light industry, electric power, military and other fields, is the basic material of an operation and technology industrial production, with each field of industry continue to increase, the demand quantity of refractory products is also gradually increasing, which requires every manufacturer increase the output, while at the same time ensuring the production quality of the product is the most critical, it is also the fundamental in all areas of normal operation. How to choose the appropriate refractory should be for the majority of the use of units? This is we have been very concerned about the problem; here we take a look at it.

1 according to the structure, working characteristics and motion conditions of the furnace and the analysis of material damage reasons, in order to choose the appropriate refractory. Accurate understanding and grasp the temperature changes of all parts of the material, carefully observe the material to prevent by all kinds of destructive effects, such as: high temperature molten metal erosion.

2 familiar with the material chemical composition and physical, work performance, so as to give full play to the characteristics of material.

3 so that all parts of the furnace material reasonable match, in order to avoid the mutual damage at the same time between material, but also take measures to ensure that the service life of the whole.

4 basic principles in satisfying the conditions above, to solve the resource and cost as much as possible. Can choose prices and transport costs low material, at the same time, vigorously develop the recycling, reduce the cost of.

The four question above is each big unit using refractory selection needs to be considered, which can ensure the quality of products and reduce the cost, is a very good selection principle.

Classification and application of mullite insulating bricks

Classification of  mullite insulating brick:

Mullite insulating brick is different according to the density is divided into light and heavy mullite brick, according to the use of different temperature are divided into: 1350 mullite bricks, 1450 mullite bricks, 1550 mullite bricks etc..

Performance and application of mullite insulating brick:

Refractory degree is high, can reach more than 1790 DEG C. Refractoriness under load was 1600 ~ 1700 DEG C. Compressive strength of 70 ~ 260MPa. Good thermal shock resistance. Sintered mullite brick and fused mullite brick two. Sintered mullite brick with high alumina bauxite clinker as the main raw material, adding a small amount of clay or raw bauxite as binder, after molding, sintering and made. Electric cast mullite brick with high alumina, A12O3 and refractory clay as raw material, adding charcoal or coke fines as a reducing agent, after forming by reduction of electric melting method to manufacture. Crystal fused mullite than sintered mullite, thermal shock resistance than sintered products. Uniformity of content in the high temperature properties of alumina and mullite mainly depends on their distribution and glass. Mainly used for blast furnace hot blast stove top, bottom, and glass furnace regenerator, ceramic sintering furnace, petroleum cracking system dead lining.

What is fire resistant plastic

Fire resistant plastic is composed of 70% ~ 80% granular and powdery materials, plus 10% ~ 25% plasticity clay binder and refractory material amount of plasticizer prepared.

Plastics can be made into flake, lump. Some bond can be added in the construction. Whenusing the mixture compaction or ramming, when baked to form dense lining and structures. In the pre hardening plasticity is good; with certain strength after hardening. Have good sintering performance and volume stability of certain and other high temperature properties at high temperature. A stiff mud paste, and keep in a long period, high plasticity clay plasticity contain more points, water is ramming material much. Mainly used for various heating furnace is not in direct contact with the molten material, material for clay and high alumina, there are silica based, magnesia and chrome, zircon and silicon carbide etc..

Mainly used for lining of the body in the iron and steel industry for various kinds of heating furnaces and soaking furnace, annealing furnace, sintering furnace and furnace top etc..

Visual inspection and processing of pre laying refractory material

Boiler refractory brick masonry for planning is not the same for different, some refractory brick standard and scale error can not be satisfied with the penetration of building qualityrequirements, especially for hook range, azimuth and swollen joints of pipeline and the demand of pre laying refractory brick selection, processing or modification. According to the construction unit and product properties of refractory brick and insulating materials, all need the rainproof, moisture-proof, masonry construction is in the boiler plant engineering all completed before beginning construction, time is very tight, so the construction preparation work is very important

Some of the furnace body layout on boiler lying disorderly and the quality demand strict site, use of shaped refractory brick masonry part, a part of elected for pre laying, the pre laying intention:

1 see refractory brick shape is the quality demand is not to the satisfaction of the refractory brick masonry, according to the supply of a variety of refractory bricks and viewing and processing are not the same error mutual deployment status of application.

2 see planning drawings and refractory brick use is not a fault.

3 the operation personnel know characteristic and quality requirement of furnace body layout, understand the methods of operation, construction and what information the application state.

4 see refractory brick masonry function and quality status of mud

5 pairs of new materials, new technology and new method of operation to experiment

Pre laying flat places usually consolidation in the room. Refractory brick and method of operation of the use of the pre laying all should be the same as the formal construction conditions, in order to truthfully reflect the existence of doubt. The pre laying results should be recorded, about the existence of doubt to have solutions.