Silica dry vibrating material is a mixture made of quartz (SiO2) as the main raw material and a small amount of sintering agent. Prepare its quartz raw materials such as quartz sand and fused quartz. It can be selected or used in combination according to requirements. However, generally, silica is crushed and crushed to obtain quartz sand as the raw material for vibrating materials.
The crystal transformation of SiO2 in natural silica will produce volume expansion effect during the heating process. The volume expansion effect makes silica especially suitable as raw material for dry vibrating materials. However, attention must be paid to the particle gradation of the quartz sand, and a reasonable particle gradation is a key factor to prevent offset during construction and increase the volume density of the constructed lining. Generally, the maximum particle size is 3~5mm. Appropriately reducing the amount of coarse particles and increasing the amount of medium particles can reduce segregation and increase the volume density of the well-constructed lining, thereby improving erosion resistance and permeability resistance.
Compounds used as siliceous sintering agents include boric acid, alkali metal borates, alkali metal silicates, and alkali metal phosphates. These compounds have the effect of promoting sintering at medium and low temperatures. However, boric acid (H3BO3) or boric anhydride (B2O3) is often used. Silicon is mainly used for the lining of coreless induction furnaces for melting and heat preservation of iron, steel and non-ferrous metals (copper).
Corundum dry vibrating material is made of corundum as the main raw material and sintering aid. The corundum raw materials that can be used are: fused corundum, sintered alumina, tabular corundum (tabular alumina). However, fused corundum is generally used, and fused corundum is divided into white fused corundum, brown fused corundum, dense fused corundum and high-alumina corundum (also known as sub-white corundum), which can be selected according to the conditions of use. The particle size range of corundum is 0~6mm, and the particle gradation is also according to the closest packing ratio.
Corundum is mainly used as the lining of melting channel induction furnace and coreless induction furnace.
The lining of the coreless induction furnace melting pool is mainly made of in-situ reaction to form spinel bond, or corundum dry vibrating material with pre-synthesized spinel. This lining is suitable for smelting pure iron, low alloy steel, high Alloy steel, Cr and Cr/Ni alloy steel. The characteristic of corundum with magnesia (MgO) is that during high temperature use, periclase will react with alumina to form spinel in situ, resulting in volume expansion, and this volume expansion effect can inhibit (compensate) the sintering shrinkage of the lining , so as to prevent obvious cracking of the lining.
There are two main types of alkaline dry vibrating materials for intermediate frequency induction furnaces: (1) magnesium dry vibrating materials; (2) magnesium aluminum dry vibrating materials. The raw material of magnesia used in magnesia dry material is fused magnesia, the content of MgO is 96%~98%, CaO/SiO2≥2.0, the bigger the periclase grains in fused magnesia, the better, and the bulk density is not less than 3.54g/cm2. The spinel used in the magnesium-aluminum dry material is fused spinel, and the bulk density is required to be not less than 3.48g/cm.
