First, we know aerogel is the lightest solid in the world. Second, it shows many special performances in fields like thermology, optics, electricity and mechanics, and is called ‘magical material that will change the world’. Under the premise that we know aerogel is a material, what’s it like and what are its features? Gel is also known as frozen gel. Colloidal particles or polymers in soliquid or solution are interconnected under certain conditions and form a space net structure, in which liquid (it could be air in dry gel, so dry gel is called aerogel) functioning as dispersion medium is full. Such a special dispersion system is called gel.
1>No air convection so no heat travel.
2>Rich Nano pores inside separate heat notably.
3>Thermal conduction moves along pore walls but the infinite paths in aerogel make thermal conduction much slower.
Vacuum ladle is a transfer device as well as a container of molten aluminium. It’s a difficult problem to keep molten aluminium in high temperature while transferring it. So two special functions are required for vacuum ladles: high temperature resistance and good insulation performance. A common refractory material in market is refractory bricks, and asbestos plate is used as thermal insulation material.
The masonry of refractory bricks is One of the vacuum ladle manufacturing process. So what is refractory brick, and what is work for , how to carry out the process, and what is the detail we need to pay attention to , There is some information I need to explain to you below :
Definition of firebrick:
Vacuum lined lining needs refractories filling, of which the most important layer is the refractory brick masonry pavement.As we can tell that , refractory bricks are made of refractory clay or other refractory materials fired from refractory materials. There are many refractory materials, and our vacuum ladle refractory is high alumina bricks.
High alumina refractory brick's main performance indicators
High alumina brick raw material by molding and calcined. High stable thermal performance, refractoriness above 1770 ℃. Good slag resistance. Can be used for masonry steel furnace, glass furnace, cement rotary kiln lining. In the vacuum ladle applications are also very extensive. So what are its specific performance indicators?
Alumina brick refractory is higher than clay brick and half-brick refractory high, up to 1750-1790 ℃, is a senior refractory material.
B.The load softens the temperature
Because the high alumina product is in high content of Al2O3, less impurities, the formation of friable vitreous less, so the load softening temperature higher than the clay brick, but because of the formation of mullite mesh structure, so the load softening temperature is still no high silica brick.
High alumina brick contains Al2O3 more close to the neutral refractory material, can resist acid and alkaline slag erosion, due to which contains SiO2, so the ability of anti-alkaline residue weaker than the acid-resistant slag capacity.
Other usage of high alumina bricks
In addition to masonry in vacuum lifts, it can also be used for masonry blast furnaces, hot blast stoves, electric furnace roofs, blast furnaces, reverberatory furnaces and rotary kiln linings. In addition, high alumina bricks are also widely used as hearth regenerative lattice bricks, plugs used in casting systems, nozzle bricks and the like.
Firebrick paving paving process
For a certain understanding of high alumina refractory bricks, we have to understand how to pave the way in the vacuum ladle.
The first is the vacuum cladding of a thermal insulation blanket pavement, the inner wall welded with steel nails, so that the insulation felt firmly carried in the inner wall of the vacuum lift package, and then start masonry brick.
In the bottom of the vacuum lift the first layer of half-piece tile, that is 1/2 standard bricks, Note: is tiled. Then stand a layer of standard high alumina refractory bricks, pay attention: is standing shop. When the molten aluminum pumping into the bag the moment the high temperature and the erosion force is easy to erosion refractory bricks, so pay attention to the degree of density. Then the vacuum pumping the inner wall of the shop, where the required high-alumina brick is shaped, that is curved refractory brick. Refractory bricks in this area need to be noted that the use of inspection seal filling material need to grasp the inner wall, making it solid and reliable. The rest can not fill the place with castables to fill. The above are the cognitive description of refractory bricks and pavement process. Jiu Da only for the production of more high quality vacuum lift service, focusing on intellectual-made 22-year electrolytic aluminum equipment.
There are two kinds of materials in the packing process of vacuum ladle inner lining. One is refractory brick pavement, one is castable pavement. We have already introduced the main process of refractory bricks before, and then we specifically talk about pure castable lining insulation.
The concept of castable
Castables, also known as refractory castables, is a refractory material by adding a certain amount of binder made of granular and powdery materials, with high liquidity, casting pouring amorphous refractory material.
Compared with other monolithic refractories, binder and moisture content is higher, the better liquidity, so castable has a wide application range, the materials and binders are to be selected according to the using conditions. It can be directly cast into the lining to use, and also can be used in prefabricated blocks by pouring or vibrating.
The casting material used for vacuum ladle is high aluminum casting material. High alumina refractory slurry is divided into two types of 8 models according to the content and bond strength of Al2O3. Common high alumina refractory mud: LN - 55A, LN - 65A, LN-75A. The phosphate combined high alumina refractory mud: LN - 55B, LN - 65B, LN - 75B, LN - 85B, GN - 85B. High aluminum refractory mortar body material is high aluminum clinker, bonding agent is soft clay or chemical bond. The content of Al2O3 is determined by the masonry composition and requirements of the masonry site.
It can be widely used in all kinds of industrial kilns of high alumina brick masonry. Such as for masonry roof, heat storage room, combustion chamber of hot air furnace; in the bottom of blast furnace, hearth, hearth and waist, etc.; to repair the furnace roof and furnace wall of industrial kiln. Advantages as below: good plasticity and convenient construction; Strong bond strength and corrosion resistance; high degree of fire resistance; good anti-slag penetration; excellent hot peeling property.
Spraying process of casting material
For vacuum ladle lining insulation, spraying casting is the cheapest kind of operation. In addition, there are some areas in the vacuum ladle that can't be paved with firebricks, so you must use castables. The aluminum outlet of the vacuum ladle and the inner cover of the vacuum ladles are sprayed with castings.
The spraying process of castable is relatively simple, according to different materials, product description, water cement ratio, and the ratio of technical requirements for spraying, and then use vibrating rod to tap operation, until lined with coagulation, 7 days into the testing session, then completes the quality testing before leaving the factory.