Properties of Plastic castable
01 "0" expansion design
The plastic castable adopts the "0" expansion design principle, which makes the internal stress of the material "pull" or "press" each other very small at high temperatures, and the furnace lining body is in a stable state, with good overall integrity of the furnace lining. During the construction of pouring materials, PVC expansion joint plates must be buried, and the overall integrity of the furnace lining or bottom is poor. The variation of "expansion joint width temperature" on a length of 1500mm shows that the expansion joint width of the casting material is 0 at 800 ℃. After the temperature exceeds 800 ℃, compressive stress will be generated inside the refractory material of the casting material, which is not conducive to the overall stability of the refractory material. At 1300 ℃, the expansion joint width force of plastic is close to the normal operating temperature of metallurgical heating furnaces. Therefore, using plastic can ensure that the overall internal stress of the refractory material is minimized during normal use of the heating furnace.
02 Good thermal shock resistance
Plastic can withstand drastic changes in furnace temperature, resist flame impact, and can be frequently shut down and heated without worrying about lining peeling. Its heat shock resistance is 3 to 6 times that of general refractory castables. Therefore, heating furnaces with fully plastic lining allow for rapid heating and cooling in daily use, while casting materials may cause problems such as peeling.
03 Rapid drying oven
Plastic is suitable for construction throughout the year and does not require maintenance. It can be heated immediately after construction. The heating rate of the oven is 50 ℃/h, and it usually takes 24 hours to reach the required furnace temperature for production operations, greatly shortening the oven drying time and reducing oven drying costs. However, the casting material needs to wait for solidification, curing, and a long drying process after construction, and is not suitable for winter construction. Antifreezing must be taken into account.
04 Good chemical resistance
Plastic does not contain cement, but uses neutral materials as binders with strong acid and alkali resistance, so there are no special requirements for fuel
05 Reasonable construction technology
During the construction of plastic, the construction technology of preloading and formwork construction is adopted, especially in the construction of the furnace top. The construction technology of preloading and formwork construction can ensure that the deformation of the steel structure of the furnace top is basically synchronized with the deformation of the furnace lining, and ensure that the anchor bricks are evenly stressed, avoiding the possibility of fracture and collapse during use. However, the casting material is constructed using formwork, which will cause secondary deformation after the removal of the furnace wall and roof formwork, resulting in uneven stress on the anchor bricks and easy accidents such as collapse during use.
06 Good construction performance
Plastic has good construction performance, and the formwork can be removed immediately after construction, especially in the construction of complex furnace roofs. Good construction performance is a necessary condition for obtaining a long-life furnace roof.
07Good stability of construction quality
Compared with castables, plastics have the advantage of good quality stability. Plastic can be directly opened and used during construction, and its ratio has been strictly controlled in the production process. In the repeated labor of pounding, human factors have little impact on the construction quality, and the quality of the lining can be easily guaranteed. However, the pouring material needs to be controlled on-site for additives, dry mixing, wet mixing, vibration and other processes, and each link will have an impact on the quality of the pouring material lining. Plastic construction procedure: Open the box and use it directly → pull the mold → compact it → remove the mold → grind it → directly bake it. Pouring material casting procedure: Pouring material ↘ Water → Proportional control of dosage → Formwork support → Control of mixing time → Pouring → Vibration → Curing → Demoulding → Oven additive ↗
08 has good economic efficiency in use
The service life of plastic is generally higher than that of castable, and can reach more than 10 years. (2) Compared with the injection material, the density of the drying material is about 10% lower, the furnace top is lighter, and the steel structure is safer. (3) Plastic has low thermal conductivity, good insulation performance, and saves energy.
Compared with castables, thermoplastic materials have a longer construction period, but they have outstanding characteristics such as good resistance to peeling, ability to withstand drastic changes in furnace temperature, and long service life, making them the most suitable for use on the top of the furnace. Plastic is a type of amorphous refractory material, which is made of refractory aggregate, fine clay powder, water, and chemical binders mixed in a certain proportion to form a clay like or clay like refractory material with certain viscosity and plasticity. It is constructed by pounding, vibrating, and other methods. Plastic classification: High alumina plastic: Suitable for furnace tops, walls, burner bricks, etc. with long-term working temperatures above 1400 ℃. Clay plastic: suitable for furnace tops, walls, burner bricks, etc. with long-term working temperatures below 1400 ℃. Plastic repair material: suitable for repairing various parts of the heating furnace lining. At present, plastic is mainly used as lining and roof materials for various furnaces in the steel industry. This article compares and analyzes the differences and advantages between plasticizers and castables, and systematically compares the application of plasticizers and castables in heating furnaces.
