Product introduction of steel fiber castable and solution to expansion problem

Product introduction of steel fiber castable and solution to expansion problem

Steel fiber reinforced refractory castable is a steel fiber reinforced refractory castable (about 2035 mm in length and about 0.13~0.2 cm in cross-sectional area) composed of refractory materials, binders and additives, that is, steel fiber reinforced refractory Castable.

Compared with the casting material without heat-resistant steel fiber, the casting material has the following characteristics

(1) It can inhibit the shrinkage of the casting material under curing, baking and high temperature

(2) Improve the toughness, mechanical impact and mechanical strength of the casting material

(3) Improve the thermal shock resistance of the casting material

(4) The microcracks generated in the casting material expand or expand under the action of thermal stress and mechanical stress

The external size, cross-sectional shape and addition amount of heat-resistant steel fibers used to strengthen the castable will affect the reinforcement effect. The fiber type is linear, corrugated, sawtooth, staple type, etc., and the cross-sectional shape is circular, square, diamond, sawtooth, etc. At present, straight fibers with a crescent-shaped cross-section (produced by the melting and pumping method) are generally used. The fibers of this shape can increase the contact area between the steel fiber and the castable matrix, increase the friction force, and do not affect the mixing and stirring performance. It is easy to disperse evenly in the matrix. At present, there are many heat-resistant steel fiber materials and varieties used to strengthen refractory castables, but there are only 5 widely used brands. Generally below 1000 ℃, the castable lining of single-sided heating is reinforced with stainless steel fibers of MF304 and MF430 brands, and above 1000 ℃ with heat-resistant stainless steel fibers of ME446, ME310 and ME330 brands. The main function of the steel fiber reinforced castable is to improve the strain performance under stress, thereby improving the toughness, mechanical strength and thermal shock resistance of the castable lining. The amount of steel fiber added is different, and the reinforcing effect is also different.

What problems should be paid attention to in steel fiber reinforced castable lining?

Compared with ordinary castable refractories, steel fiber reinforced castables have many advantages, but some problems must be paid attention to in order to achieve the ideal use effect. So, what problems should be paid attention to in steel fiber reinforced castable lining? Reading these can help you find out.

The use effect of steel fiber reinforced castable lining is also closely related to its production process, so the following points should be paid attention to in the production process:

(1) The appropriate brand of high-temperature alloy steel fiber and its addition amount must be selected according to the conditions of use (generally, adding too much between 1% and 3% will have a negative effect;

(2) When mixing and stirring, it is better to add water to the dry castable and stir evenly, and then add steel fiber to stir evenly, which not only makes the castable itself easy to mix evenly, but also does not bend and deform due to the long stirring time and repeated stirring of the blades ;

(3) In vibration molding, a bonded vibrator is generally used, and the vibrator is applied from the outside of the model to make the steel fibers evenly distributed. It is not possible to insert vibrating rods for construction, otherwise the uniform distribution of the steel fibers will be damaged. When making prefabricated parts, a plane vibration table can also be used for construction.

Steel fiber reinforced castables are mainly used to construct industrial kiln linings that only contact high temperature gas or solid materials, such as electric furnace roofs, ladle covers, heating furnace roofs, soaking furnace roofs and furnace walls, heat treatment furnace roofs, high temperature cyclone separator roofs , Cement rotary kiln cooling cylinder roof, vertical baking furnace roof, etc. Steel fiber reinforced castable linings can also be used for containers, launders and parts that are discontinuously contacted with high temperature melts, such as electric furnace tapping grooves, integral spray guns for spray metallurgy, argon blowing guns, and molten iron desulfurization mixers. In the case of discontinuous (intermittent) use, the temperature fluctuates greatly, and the thermal stress and mechanical stress are large. Reinforcement with steel fiber can improve the thermal vibration resistance and mechanical vibration resistance.

How to identify the quality of steel fiber castables?

Adding a certain proportion of steel fibers to ordinary refractory castables can improve the fire resistance and fire resistance of castables, improve the spalling resistance of steel fiber castables, identify the excellent quality of steel fiber castables, and mainly test the quality of steel fibers. The quality of the fibers determines the durability of the high-temperature inner walls and chimney walls of various kilns. Therefore, when purchasing steel fiber castables in bulk, the content ratio and toughness strength of steel fibers can be properly checked and tested to ensure that qualified steel fiber castables are purchased.

How to solve the expansion problem of steel fiber castable?

In the application process of steel fiber castables, refractory castables often have a certain degree of expansion coefficient, which affects the quality of the castables. How to solve the expansion problem of steel fiber castables? Steel fiber castables are granular and powder materials made of refractory materials, consisting of a certain amount of binder and moisture. Real Gold Refractory explains how to solve the expansion problem of steel fiber castables:

1. Aluminum dihydrogen phosphate can be added to the steel fiber castable, and the addition amount of aluminum dihydrogen phosphate should be controlled at 13%~15%. However, since the liquid aluminum dihydrogen phosphate reacts with the metallic iron in the refractory to generate hydrogen at room temperature, the cast lining will expand and form a porous body.

Because cement contains a certain amount of metallic iron. Therefore, be sure to add an anti-swell inhibitor, or add liquid potassium dihydrogen phosphate in two batches when the castable is mixed. It is introduced in detail that 6%~7% potassium dihydrogen phosphate is used to add 6%~7% potassium dihydrogen phosphate in the castable for the first time, and it is semi-humidified for 24 hours. Before adding potassium dihydrogen phosphate for the second time, first add 2~3% coagulant, stir evenly, then add the remaining 6~7% potassium dihydrogen phosphate solution, stir evenly and pour. Usually prevents swelling.