The reinforcement effect of alumina fiber reinforced refractory castable is inferior to steel fiber refractory castable at medium and low temperature, and is better than steel fiber refractory castable at medium and high temperature.
In refractory castables and refractory plastics and other materials, adding a certain amount and suitable length of refractory fiber materials can increase the strength and improve the performance of the matrix.
The production methods of refractory fiber materials are divided into two types: melting method and colloid method. The former is amorphous fiber, mainly ordinary and high-purity aluminum silicate fiber, high-aluminum fiber and chromium-containing aluminum silicate fiber, etc. The long-term use temperature is 1000~1300℃; the latter is crystalline fiber, mainly alumina For fiber and zirconia fiber, the long-term use temperature is 1400~1500℃. In unshaped refractory materials, as fiber reinforced materials, amorphous fibers can be used at medium and low temperatures, and crystalline fibers should be used at high temperatures to achieve good results.
The high temperature flexural strength of ultra-low cement refractory castables at 1400°C is about 2MPa, when heat-resistant steel fiber is added, it is about 5MPa, and when alumina fiber is added, it is about 6MPa. This shows that adding fibers has a reinforcing effect, and inorganic fibers are better than steel fibers.
The petrographic analysis of alumina fiber-reinforced refractory castables proves that the addition of crystalline alumina fiber is beneficial to the formation and development of secondary mullite due to its crystal nucleus. Without inorganic fiber, the amount of mullite formed at high temperature is small, and it is in the shape of fine needles, and the crystal is better; after adding fiber, the amount of mullite formed at high temperature is large and develops into small columnar crystals with complete crystals and cross It grows and the organization is dense and firm, so the high temperature strength is higher, that is, the enhancement effect is obvious.
It should be pointed out that the main crystal phase of crystalline fiber is α-Al2O3, and the maximum use temperature is about 1600°C. Even so, long-term use at high temperatures will gradually deteriorate the crystalline fiber, which is manifested as fracture damage or even powdering, but the process is slow, so it has less impact on the crystalline fiber-reinforced refractory castable and can be used for a long time. Used on thermal kilns. When amorphous fiber is used as a reinforcing material, it is easier to crystallize and pulverize at high temperatures, so the long-term use temperature of amorphous fiber-reinforced refractory castable is about 1400°C.
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selection of machinery
selection of machinery :
PUDA will choose the suitable machine based on material's bulk density, air content, water content, bag's type, packing speed.
