Knowledge of amorphous refractories

Amorphous refractories are loose refractories made of aggregate, fine powder and binder mixture, and appropriate admixtures can be added if necessary. It has no fixed shape, is loose, paste or paste, so it is also called loose refractory. In addition, amorphous refractories can be made into prefabricated blocks for use or made into jointless integral structures, so they are also called integral refractories. The amorphous refractory has the characteristics of simple production process, short production cycle, energy saving, good integrity in use, strong adaptability and easy mechanized construction. The basic composition of amorphous refractories is aggregate and fine powder refractories, which can be composed of various materials according to the requirements of use. In order to combine these refractory materials as a whole, add the appropriate variety and number of binders, and add a small amount of admixtures according to the specific requirements of amorphous refractories to improve the plasticity, fluidity, coagulability and so on.

The chemical and mineral composition of amorphous refractories mainly depends on the aggregate and fine powder used, and is also closely related to the variety and quantity of the binder. At the same time, its performance depends to a large extent on its operating performance, construction methods and technology. There are many kinds of amorphous refractory materials, which can be classified according to the type of material, construction method, combination method, etc. According to the refractory material used, it can be divided into corundum, high aluminum, clay, silicon, aluminum spinel, magnesium, silicon carbide, carbonaceous and other amorphous refractories.

According to the combination form can be divided into:

① Hydration combination (also known as hydraulic combination), at room temperature through hydration condensation and hardening.

(2) Ceramic bonding, at high temperatures, the amorphous and crystalline forms formed by sintering are connected together.

(3) Chemical combination, at room temperature or high temperature, through a chemical reaction (not hydration reaction) produced by hardening, divided into inorganic and organic combination of two categories.

(4) Adhesive bonding, composite bonding produced by the adsorption, diffusion and electrostatic action of the binder.

(5) Condensation combination, through the mutual attraction between particles (colloidal particles) close contact, with the help of van der Waals forces and combined. If several bonds are used together, they are named according to the nature of the bond that plays a major role in the hardening process.

According to the construction method can be divided into:

① Refractory ramming materials, amorphous refractory materials constructed by ramming (mechanical or manual) method.

② Refractory plastic, with high plasticity, in soft billet, block or sheet state delivery, heating hardening after construction of amorphous refractory.

③ Refractory castables, mainly delivered in powder, poured after mixing with water or other liquids, can also be prepared into prefabricated parts for delivery

④ Refractory pressed material, when used, add water or liquid binder to blend into paste or paste, and use extrusion method to construct amorphous refractory material.

(5) Refractory spray paint, amorphous refractory material constructed by mechanical spraying.

⑥ Masonry joint material, which can be constructed with a trowel or similar tool, and can also be used for caulking or dipping. This material can be divided into three categories, hydraulic refractory mud (fine refractory aggregate, refractory powder and cement binder mixture), hot refractory mud (fine refractory aggregate, refractory powder and hot hardening agent such as phosphoric acid or phosphate mixture), air refractory mud (fine refractory aggregate, refractory powder and air hardening agent such as sodium silicate mixture).

(7) Refractory paste, a mixture consisting of refractory aggregate, powder and binder, applied by manual or mechanical brushing or coating method.

⑧ Dry vibration material, without adding water or liquid binder, amorphous refractory constructed by vibration method. Amorphous refractory · With its short production process, energy saving and other characteristics, more than ten years of rapid development, in many occasions to replace the shaped refractory products. In China, amorphous refractories account for about 30% of the total production of refractory materials, and is still in a growing state, amorphous refractories are widely used in metallurgical industry, machinery industry, energy, chemical industry and building materials industry of various kilns and thermal structures