Application of Alumina Hollow Spheres

Subsidiary Classification： Product knowledge

Release time：2024-02-20

Alumina hollow ball and its products are a kind of light refractory material with high temperature resistance, energy saving and consumption reduction.

　　Product classification:

Alumina hollow ball has two kinds of mixed grade ball and grading ball

Mixed ball size: 0.2-5mm

Grading ball size: 0.2-0.5mm,0.5-1mm

　　1-2mm，2-3mm，3-5mm

　　Product Features:

Alumina hollow ball to do ordinary castable use, according to your needs of the ambient temperature, a reasonable choice.

The characteristics and properties of alumina hollow spheres: alumina hollow spheres light closed-cell high temperature, with good thermal insulation performance, aluminum chloride hollow spheres as the main body, can be made into various shapes of products, the highest use temperature 1800C, products high mechanical strength, several times for the general light products, and the volume density is only 1/2 of corundum products.

　Application of Alumina Hollow Spheres

Alumina hollow ball and its products are a kind of light refractory material with high temperature resistance, energy saving and consumption reduction.

2. Alumina hollow ball is the ideal heat insulation filling material for high temperature kiln, heat insulation and energy saving refractory material. Can be used to do high temperature, ultra-high temperature insulation filler, high temperature refractory concrete lightweight aggregate, high temperature lightweight refractory castable, alumina hollow ball lightweight brick, etc.

The formation process of hollow spheres is completed in 10-30 seconds by blowing the alumina melt under high pressure air. The balling process is actually a rapid cooling and shrinking process. Alumina has a point of 2050C, and the temperature suitable for blowing balls should be higher than the melting point of 200-300C, that is, it needs to be heated to 2200-2300C. If the temperature of the melt is low and the viscosity is high, it is easy to blow into thick squash or honeycomb hollow spheres.

　　Production process

Blown alumina hollow ball is divided into 3 stages:

1. In the melting stage, increase the temperature and reduce the viscosity of the melt.

2. Ball blowing stage:

3. Cooling and curing stage.

The formation of alumina hollow spheres is a process of rapid cooling volume shrinkage of alumina high temperature melt after injection. This process is the alumina melt in the high pressure air blowing action, is blown into numerous small droplets. These droplets are in the air, falling in a parabolic path. In this movement process, under the action of surface tension and centrifugal force, the small droplets first form a small ball. When the small ball is quenched, the surface is instantly solidified, while the inside of the ball is still in a liquid state. Under the action of centrifugal force, at the same time, the shrinking liquid produces a large volume shrinkage, so that the melt quickly and evenly condense on the shell of the hollow ball, so as to complete the hollow ball of the whole process.

The internal shrinkage of the hollow sphere is due to the volume expansion of the alumina during the heating process. Although alumina has only 1.6 to 1.8 percent of the linear expansion when heated to 1800C, when the oxide is heated to the melting point temperature, when the substance changes from the solid phase to the liquid phase, it will produce a volume expansion of 20 to 40 percent. This volume expansion is related to the chemical bonds of the molecules. When the chemical bond in the molecule such as ionic bond component is larger, the volume difference between the volume of the melt and the volume of the body is larger, on the contrary, the larger the covalent bond component, the smaller the volume difference. When alumina changes from solid phase to liquid phase, the volume of alumina expands by about 23.5%. Therefore, thermal expansion and contraction is the fundamental reason for the formation of alumina hollow spheres. When the alumina hollow ball is blown, the temperature fluctuation of the alumina melt is 2200 ~ 2300C. Alumina in a high temperature liquid state has a greater thermal expansion rate. The linear expansion coefficient of high temperature liquid is generally 3 times that of solid state. The inside of the high temperature liquid contains a certain gas partial pressure, which accelerates the expansion of the high temperature liquid and is an important factor to promote the formation of alumina hollow spheres.

Keyword： Application of Alumina Hollow Spheres

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