Mullite casting is made of high-quality porous mullite aggregate, adding fine powder and additives to stir refractory castings. The critical particle size of mullite aggregate is 12mm; The long-term use temperature is 1350 ℃. The construction of mullite high-strength wear-resistant refractory castable is rigorous. The refractory castable shall be mixed with clean water. The formwork poured with water shall have sufficient rigidity and strength. The mold size shall be accurate. Deformation shall be prevented during construction. The formwork joints shall be tight.
In the construction requirements of mullite refractory castable, anti sticking measures shall be taken for the formwork, and the surface of thermal insulation masonry contacting the castable shall be waterproof. The castable shall be mixed with a strong mixer. The mixing time and liquid volume shall be in accordance with the construction instructions. The mixer, hopper and weighing container shall be cleaned when changing the number of trays. The mixing of fused castings shall be completed within 30min or according to the construction instructions. Newly formed casting materials shall not be used. The integral expansion joint of cast refractory shall be set according to the design requirements.
No external force or vibration shall be applied during curing. Open the mold. No formwork shall be loaded, and the strength of the casting material shall be such that the surface and corners of the folded mould are not damaged or deformed and can be removed. After the casting material reaches 70% of the design strength, the bearing formwork shall be removed. The hot and hard castings shall be baked to the specified temperature before folding. The pouring lining surface shall be free of peeling, cracks, cavities, etc. Slight network cracks are allowed. Prefabricated refractory castings shall not be stacked in the open air. Rain proof and moisture-proof measures shall be taken when stacking in the open air.
The mullite castable has high temperature and can be directly exposed to the working lining, realizing high temperature energy saving, light unit weight and 40~60% reduction in structure weight Low thermal conductivity, porous mullite aggregate, low thermal conductivity, good thermal insulation performance, fast drying, shorten drying time, significant economic benefits.
A kind of binder made of mullite castable can maintain the excellent performance of mullite. The binder is the best binder, which can form mullite at a certain temperature. Considering the use of castable in various occasions, mullite should be formed at a low temperature as much as possible. Obviously, silica gel is a suitable adhesive. Considering the low price, silica gel is used for self matching colloidal suspension, in which Al2O3: SiO2 should be close to or equal to the proportion of mullite.
Aluminum has good hydration and natural hardening properties. The surface activity is very high, so its role in refractory castable is to react with SiO2 powder to form mullite at a lower temperature, so the addition amount of Al2O3+SiO2 is an ideal binder. The results show that the two binders can form mullite and have good cold strength.
Post time: Oct-24-2022