The compressive strength of refractories is the ultimate load that refractories can bear per unit area without being damaged at a certain temperature.
Compressive Strength of Refractories Introduction
The compressive strength of refractories is divided into normal temperature compressive strength and high temperature compressive strength.
The normal temperature compressive strength can indicate the sintering condition of the material and the properties related to its microstructure. In addition, the normal temperature compressive strength can indirectly evaluate other properties, such as wear resistance, impact resistance, etc.
Factors Affecting the Compressive Strength of Refractories
The normal temperature compressive strength of refractory is related to the material itself. However, the production process has a great impact on it. The high normal temperature compressive strength indicates that the green pressing quality of the material and the sintering condition of the brick are good.
The compressive strength at room temperature is related to its bulk density and apparent porosity. The higher the bulk density, the lower the porosity, and the higher the normal temperature compressive strength. Therefore, the production process that can improve the density of materials is also beneficial to improve the compressive strength at room temperature. Such as using well sintered and compact raw materials, reasonable particle grading, high-pressure molding, high-temperature sintering and appropriately extending the holding time.
Determination of Compressive Strength of Refractories
The value of high temperature compressive strength can reflect the change of the state of materials under high temperature bonding, especially for unshaped refractories. Due to the addition of a certain amount of binder, the temperature rises and the bonding state changes. So it is more necessary to measure its high-temperature compressive strength.
1. Room Temperature Compressive Strength
Room temperature compressive strength refers to the ultimate pressure per unit area at room temperature, that is, the ultimate stress when the specimen is damaged by pressure load at room temperature. Its strength depends on the amount and type of binder and mixture used. The purity of raw materials, mixing ratio, mixing liquid volume, construction method and maintenance system will also affect it. Compressive strength test is to apply compressive stress to the specimen on a special pressure device until the specimen is destroyed at the specified loading rate. The compression surface is 40x40mm.
2. Compressive Strength after Drying and Burning
Dry compressive strength refers to the pressure on a unit area after drying. This index is not only the basis of kiln design, but also a reference standard for evaluating material properties.
The compressive strength after sintering refers to the ultimate pressure borne by the sample per unit area after heating to the specified temperature, and the compressive strength when it is naturally cooled to room temperature with the furnace. This index can directly analyze the mineral composition and structural changes of castables, and predict some properties of castables.
3. High Temperature Compressive Strength
High temperature compressive strength refers to the ultimate stress when the specimen is damaged under the specified high temperature pressure load. It can judge the wear resistance, slag resistance and spalling resistance of refractory castables, as well as the selection of materials and their application parts.
When the heating temperature is lower than 800 ℃, the refractory castable sample is in the elastic deformation stage, and the high-temperature compressive strength is generally similar to or slightly lower than that after combustion. When it is higher than 800 ℃, the sample is in the deformation stage, and the high-temperature compressive strength gradually decreases with the increase of heating temperature. At 1400 ℃, the high-temperature compressive strength is 1 ≤ 10 MPa.