A corundum tube manufacturer shares knowledge about corundum crucibles

Alumina crucibles, also known as corundum crucibles. Generally, those with an alumina content exceeding 95% are called corundum crucibles. Corundum tube The manufacturer indicates that they are generally available in arc and cylindrical shapes, characterized by high temperature resistance, acid and alkali resistance, rapid cooling and heating resistance, and chemical corrosion resistance.

　　Working principle of corundum crucible:

　　1. 99.70% corundum 1800 1650-1700 Corundum crucibles exhibit excellent high-temperature insulation and mechanical strength in oxidizing and reducing atmospheres.

　　2. 99.35% corundum 1750℃ 1600℃--1650℃ Corundum crucibles in oxidizing and reducing atmospheres.

　　3. 85.00% high-alumina crucibles of 1350 and 1290 exhibit excellent high-temperature insulation and mechanical strength in oxidizing and reducing atmospheres. High thermal conductivity and low thermal expansion coefficient. No reaction with air, water vapor, hydrogen, carbon monoxide, etc. Can be used for extended periods under conditions of minimal temperature fluctuation in the temperature field.

      Corundum tube The manufacturer states, Corundum crucibles come in various models and specifications, are not limited by production scale, batch size, or the type of smelting material, allowing for arbitrary selection and strong applicability, ensuring the purity of the smelting material.

　　1. After use, place it in a dry place to prevent rainwater from entering; before use, slowly bake it to 500.

　　2. Add materials according to capacity, avoid overfilling, and prevent metal thermal expansion from cracking the crucible.

　　3. When removing molten metal, use a spoon to scoop it out, and try to use calipers as little as possible. If calipers or other tools are used, they must conform to the shape of the crucible to avoid localized stress and shorten the service life.

　　4. Service life is related to usage. Strong oxidizing flames should be avoided from directly spraying onto the crucible, as this will oxidize the material and shorten its lifespan.

　　 Corundum tube The manufacturer indicates that crucible production materials can be divided into three categories: first, crystalline natural graphite; second, malleable refractory clay; and third, calcined hard kaolin skeleton clinker. Since 2008, high-temperature synthetic materials such as silicon carbide, aluminum oxide silicon carbide, and ferrosilicon have been selected as skeleton clinker. This clinker has a significant effect on improving the quality of crucible products, increasing crucible density, and enhancing mechanical strength.

Corundum crucible forming methods:

1. Dry pressing method

　　 Corundum tube The manufacturer states that because the stroke pressure of the hydraulic press is uniform, the height of the press varies depending on the powder filling. Particles larger than 60 microns and between 60 and 200 mesh can move freely and lose the pressure forming effect. The corundum tube manufacturer explains that the technique of dry pressing silicon carbide furnace tubes using iron oxide ceramics is limited to products with pure shapes and inner wall thicknesses exceeding one millimeter, with an aspect ratio not exceeding four to one.

2. Slurry casting method

　　During hollow slurry casting, when the slurry absorbed by the mold wall reaches the required thickness, the excess slurry needs to be poured out. To increase the elongation of the green body, an excessive amount of deep and shallow slurry should be used. Generally, water is used as a fluxing agent medium, then mullite crucible glue and binder are added, the current waste gas is fully ground, and then the waste gas is poured into the gypsum mold.