Different properties of refractory castables

The amorphous characteristics of refractory castables make them widely used in industrial kilns, and their performance differences are mainly determined by factors such as aggregate type, binder type, porosity, and construction method. The following is a classification and comparative analysis of different properties of refractory castables:

1、 Classified by binder type

Hydrated composite castable

Portland cement bonding: used at temperatures of 700-1200 ℃, with high strength but low fire resistance at room temperature, suitable for non corrosive parts such as thermal equipment foundations.

Aluminate cement bonding: fast hardening and high strength, with a fire resistance of 1400-1800 ℃ and good thermal shock resistance, used in high-temperature sections of metallurgical furnaces and heating furnaces.

Chemical bonding castables

Phosphate binding: Hardened by heating, resistant to temperatures above 1800 ℃, excellent thermal shock resistance, suitable for high-temperature impact areas.

Water glass bonding: air hardening, acid resistant and wear-resistant, but with low fire resistance (≤ 1400 ℃), used for lining chemical equipment.

Low cement/non cement castables

Low cement series (CaO<2.5%): high-density, low porosity, compressive strength up to 80-150MPa, used in harsh environments such as blast furnace iron trenches.

ρ - Al ₂ O3 bonding: CaO free, with superior high-temperature performance compared to cement bonding, suitable for ultra-high temperature scenarios (such as steel ladle lining).

2、 Classified by aggregate material

High alumina castable

Features: Al ₂ O ∝ content>60%, compressive strength 50-75MPa (110 ℃), load softening temperature>1500 ℃, but poor alkali resistance.

Application: High temperature areas such as heating furnaces and steel ladles.

Jadeite based casting material

Features: Al ₂ O ∝>90%, compressive strength 80-150MPa (1500 ℃), good wear resistance, but high cost.

Lightweight castables

Features: porosity>45%, thermal conductivity 0.2-0.4 W/(m · K), used for lining insulation layer, but with low strength (1.3-8.1 MPa).

Alkaline castables (magnesium/spinel)

Characteristics: Strong alkali resistance, but high coefficient of thermal expansion, requiring the solution of thermal shock resistance.

3、 Classified by construction and performance characteristics

Dense castable

Volume density>2.2 g/cm ³, high strength, wear-resistant, used for working layers (such as furnace bottom and flue).

Self flowing casting material

Good fluidity, no need for vibration, suitable for filling complex shapes, but water addition needs to be controlled (5% -8%).

Steel fiber reinforced castable

By incorporating 2% -8% heat-resistant steel fibers, the mechanical impact resistance is improved by 2-5 times, making it suitable for wear-resistant parts of heating furnaces.

4、 Suggestions for selecting application scenarios

High temperature slag resistant area: preferably using corundum or phosphate bonded castables.

Insulation requirement: Lightweight castables (such as alumina hollow spheres).

Quick repair: Steel fiber reinforced castables or self flowing products.

The selection of refractory castables should take into account factors such as temperature, erosion environment, and mechanical stress, and optimize the ratio and construction process based on specific working conditions.