Properties, Configuration and Use of Refractory Plastics

Refractory plastic is an unshaped refractory material that is in the form of a hard mud paste and maintains high plasticity for a long time. It is composed of granular and powdery materials and binders such as plastic clay, and then adds a small amount of water.

The main components of refractory plastic are granular and powdery materials, accounting for 70% to 85% of the total. It can be made of refractory raw materials of various materials. Clay clinker and high-aluminum clinker are generally used. Lightweight granular materials are usually used to prepare lightweight plastics.

Plastic Properties

01 Plastic working properties

Plastics should have high plasticity and still have a certain degree of plasticity after long-term storage.

The plasticity of refractory materials is related to the properties of the amount of clay and the amount of water. It mainly depends on the amount of water. The water amount is generally 5% to 10%.

In order to control the amount of clay in plastics and reduce water consumption, plasticizers can be added. There are many materials that can be used as plasticizers, such as pulp waste liquid, naphthenic acid, lignosulfonate, lignophosphate, lignochromate and other inorganic and organic colloidal protective agents.

02 Hardening and strength of plastic

Plastics without chemical binders are called ordinary plastics. This kind of plastic has very low strength before sintering, but as the temperature increases, moisture escapes and the strength increases. After high-temperature sintering, the cold strength increases.

The strength of plastics added with sodium silicate increases rapidly as the temperature increases. However, during the drying process, this binding agent may migrate to the surface of the structure or product, preventing the smooth removal of moisture and causing stress and deformation of the skin. In addition, plastic scraps after construction should not be reused. Plastics containing this kind of binder should be used for the construction of large kilns with long construction periods and for furnace tops.

Aluminum phosphate is the most widely used thermosetting binder in plastics. It can obtain high strength after drying and baking.

03 Thermal shock resistance of plastics

Compared with sintered refractory products and other unshaped refractory materials of the same material, plastic refractory materials have better thermal shock resistance.

The Production and Use of Refractory Plastics

The preparation process of plastics is:batching -- mixing, degassing and extruding into strips - -cutting or re-extruded into blocks or other required shapes -- sealed storage - -supply for use. Some also use other densification methods, such as vibration, compaction, etc. to make blocks.

Refractory plastics do not require special techniques during construction. When used to make furnace lining, take the plastic out of the sealed container, spread it between hanging bricks or hooks, and tamp it down in layers (each layer is 50~70mm thick) with a mallet or air hammer. Surface processing can be performed before hardening. If it is used to make an integral furnace cover, it can be constructed on the bottom form first and then hoisted after drying.

Plastics are mainly used in various heating furnaces, soaking furnaces, annealing furnaces, carburizing furnaces, hot blast furnaces, sintering furnaces, etc. It can also be used for the furnace covers of small electric arc furnaces, burners of high-temperature furnaces and other similar parts.