1. Plasticity of refractory materials
Plasticity refers to the ability of refractory materials, binders, and diluents to be adjusted to a specified consistency and kneaded to form, when subjected to external force, the shape changes but does not crack. Generally speaking, all refractory materials mixed with binders have a certain degree of plasticity. Refractory plastics, ramming materials, bonded clays or materials mixed with certain bonding agents have obvious plastic properties, but the plasticity of semi-dry molded products pressed by machinery is extremely poor.
2, the adhesion of refractory materials
Refractory brick masonry requires materials that have a certain degree of adhesion at room temperature and high temperature, so refractory mortar is usually used. Silica, clay, high-aluminum, and magnesia refractory slurries can achieve adhesion between refractory products through intermolecular forces at room temperature. In a high temperature environment, due to the sintering effect, ceramic bonding can be achieved. In order to achieve ceramic bonding at a lower temperature, some sintering promotion can be added to the mud.
3. The resilience of refractory materials
The resilience of refractory materials is for spray paint. During spraying construction, it often occurs that refractory spray coatings are wasted due to the rebound and scattering of aggregate particles, and the particle gradation of the sprayed layer is unreasonable, and the bulk density decreases, which affects the service life of the inner lining.
4. Consistency and flooding of refractory materials
(1) Consistency is used to express the flowability of refractory materials. The concept of consistency is widely used in the construction of refractory slurries, castables, plasticity and some wet spray coatings. Use the specified metal cone to sink into the flowable material. The sinking depth value is the consistency of the material, with 0.1mm as the unit of measurement.
The adjustment of consistency is mainly realized by adjusting the particle gradation of the material and the ratio of binder and diluent. Adding an appropriate amount of water reducing agent can also adjust the consistency index.
(2) Flooding refers to the phenomenon that a layer of grout appears on the surface of the material due to vibration and ramming during the construction of refractory concrete. It is mainly caused by the continuous sinking of aggregate particles.
When the construction of multi-layer refractory castables with larger volume or thickness is carried out, the first layer of material should be vibrated, the flooding layer should be cut and the second layer of material should be added. Due to the lighter surface of the flooding layer, it is easy to cause thickness delamination.
5. Hardening time of refractory materials
"Hardening" refers to the mechanical strength of the structure formed by the physical and chemical changes between the refractory material and the binder under certain external environmental conditions.
A variety of unshaped refractory materials, under the action of cement, do not need to undergo high temperature sintering, as long as it meets its specific requirements, it can achieve chemical or physical combination to achieve the hardening of refractory materials and have high strength. For example, various types of refractory cement, when mixed with refractory aggregate, powder and water, after a period of curing and continuous hardening, the strength is continuously improved. High-temperature fired refractories, or hot-gunned refractories, in the process of temperature drop, the original liquid phase is vitrified or the crystal activity is reduced to realize the hardening process.