Refractory materials should meet those requirements

Refractory materials are used in a variety of high-temperature equipment, which is subject to physical and chemical erosion and mechanical damage at high temperature conditions, so the performance of the refractories should meet the following requirements:

1, high degree of refractoriness. The heating temperatures of modern metallurgical furnaces and other industrial furnaces are generally between 1000 and 1800°C. Refractory materials should have non-melting properties under high temperature.

2, high-temperature structural strength should be large. The refractory material should not only have a high melting temperature, but also should not be subject to softening deformation and collapse under the load of the furnace masonry or other mechanical vibration.

3, thermal stability is better. In metallurgical furnaces and other industrial furnaces, due to sudden changes in temperature during the operation, the temperatures of various parts of the refractory material are not uniform, and stress is generated inside the masonry to cause fission and flaking of the material. Therefore, the refractory material should have the ability to resist such damage.

4, strong slag resistance. Refractory materials are often subjected to chemical attack by high temperature slag, metal, and furnace dust during use. Therefore, the refractory must have the ability to resist erosion.

5, high temperature volume stability. In the long-term high temperature use of refractory materials, volume shrinkage or expansion occurs inside the brick body, causing damage to the refractory material masonry. Therefore, it is required that the refractory material be stable at a high temperature.

6, the regular size, tolerances should be small. Refractory masonry bricks are filled with fire-resistant mud, but their density and strength are worse than that of refractory materials. They are easily detached during the drying and making process. Therefore, brick joints are weak links in masonry, and they are easy to leak and erode. Therefore, the smaller the bricks should be, the better, only the exact dimensions can meet this requirement. Therefore, the refractory materials can not have large distortions, lack of edges, missing corners, cavities and cracks, etc., and the dimensional tolerances should meet the requirements. Claim.

In fact, not all refractory materials should have all the above-mentioned properties, and the refractory materials should be reasonably selected according to specific conditions.

Refractory material adhesion

For amorphous refractory binders, adhesion is one of their important technical indicators.

Thermal furnaces and equipment require a combination of refractory brick masonry structures of many specific shapes. This requires materials that have a certain bonding ability at both normal and elevated temperatures. Usually we use refractory mud to achieve our purpose. Silica, clay, high-aluminum, and magnesia fire-resistant muds, at room temperature, are bonded to each other through intermolecular forces. During high temperature use, ceramic bonding is generally achieved due to sintering. In order to achieve ceramic bonding at lower temperatures, sintering aids are often added to the slurry to allow it to pre-sinter.

Recently, more and more composite adhesives have been used. These include the dextrins, silica sols, water glass, brines, fire-resistant cements, lacquer, various resins, etc. at room temperature, as well as chemical or other forms of bonding that can be promoted or achieved at moderate or elevated temperatures. To improve the strength of the index material. In addition to the above-mentioned refractories, most of them have such functions as phosphoric acid, various phosphates, polyphosphates, metaphosphates, sulfates, and various ultrafine powders.

In addition, organic binders are one of the most commonly used refractory binders. They include tars, resins, modified asphalts, and the like. These binders have good bonding strength at room temperature, and can form a carbon bonding network after high temperature.

Since the composite binder has complementarity to various properties, the organic binder is beneficial to the high-temperature use performance of the refractory material due to its residual carbon, so the research work on them is rapidly expanding and deepening.