Performance indicators for refractory materials are critical for assessing their suitability for specific applications and ensuring their longevity and effectiveness. The specific importance of these performance metrics varies by application and industry. Therefore, when selecting and evaluating the performance of refractory materials, we must consider the unique requirements of their use.
Performance at High Temperatures of Refractory Materials
Refractoriness
The ability of refractory materials to resist high temperatures without melting when there is no load is called refractory degree. It is a basic scale to measure the ability of refractory materials to withstand high temperatures. The refractoriness of carbon refractory bricks can reach over 2000℃. The amount of high-melting point periclase in magnesia refractory bricks reaches more than 87%, and its refractoriness can exceed 2000℃.
Refractoriness Under Load
The corresponding temperature at which refractory materials deform to varying degrees under high temperature and constant load is called the load softening temperature. It reflects the degree of strain of a refractory material subjected to a constant load at a certain temperature. It is an important quality index that characterizes the high-temperature structural hardness of refractory materials.
Thermal Shock Resistance
The ability of refractory materials to resist rapid changes in temperature without being damaged is called thermal shock resistance. This is an important sign to judge the quality of materials, and it is also one of the bases for design, material selection and operation. Thermal shock stability is measured by the number of times it can be repeatedly heated and cooled without damage.
Volume Stability at High Temperatures
The ability of refractory materials to maintain stable shape and volume at high temperatures is called high temperature volume stability. High-temperature volume stability is directly related to cracking damage of masonry in the furnace. Generally speaking, alkaline refractory bricks have better high-temperature volume stability.
Chemical Stability at High Temperatures
The ability of refractory materials to resist the chemical effects of various corrosive substances, such as solid materials, furnace gas, slag, etc. under high temperature conditions is called high temperature chemical stability, also known as slag resistance. Chemical attack is one of the main factors leading to high-temperature damage to refractory materials. Corundum bricks are widely used in various industrial fields due to their excellent fire resistance and chemical stability.
Macro Organizational Structure of Refractory Materials
Apparent Porosity
The pores of refractory materials are distributed in coarse particles, binders and between coarse particles and binders. Its presence improves the thermal insulation performance of refractory materials and reduces the corrosion resistance of refractory materials.
Bulk Density
Bulk density refers to the mass per unit volume including all pores, expressed in g/cm³ or kg/m³. It is one of the performance indicators indicating the density of refractory products.
Mechanical Properties of Refractory Materials
Compressive Strength
The compressive strength of refractory products mainly depends on the strength of the raw material particles themselves, the firmness of the mutual bonding of the particles, the number and existence of pores, and the binding ability of the added binder. Products in the lightweight refractory brick series are often much worse in strength than high alumina bricks and refractory clay bricks. Therefore, some processes are generally required to improve its compressive strength.
Breaking Strength
Breaking strength refers to the ultimate bending stress that can be sustained per unit area, expressed in MPa. It represents the ability of a refractory material to resist bending moments or fractures under various circumstances.
Thermal Properties of Refractory Materials
Thermal Conductivity
Thermal conductivity is the rate of heat flow through unit area under unit temperature gradient. It is divided into normal temperature thermal conductivity and high temperature thermal conductivity. It is the main parameter for calculating the lining thickness or heat dissipation loss of industrial furnaces and thermal equipment and is also an important basis for material selection.
Specific Heat Capacity
The heat required to increase the temperature of the unit mass of refractory material by 1°C under normal pressure is called specific heat capacity, and the unit is kJ/(kg*K). It is an important physical quantity for evaluating the thermal properties of refractory materials and one of the important parameters for calculating and designing the thermal process and thermal system of thermal equipment.
Thermal Expansion Coefficient
The ability of a material to increase in length and volume as temperature increases is called thermal expansion. Thermal expansion is the basis for determining the expansion joints in masonry and formulating the thermal system.
Linear Change Rate of Reburning
The Linear change of reburning is an indicator of the volume stability of the refractory material. It refers to the residual expansion or contraction that occurs when refractory products are cooled to room temperature after being kept at a specified temperature for a certain period of time. The allowable refire volume change of various refractory materials generally does not exceed 0.5%~1.0%.
Zhengzhou Kerui (Group) Refractory Co., Ltd. is a company that has been producing refractory materials for many years. We have rich production experience and practical foundation. Kerui has always stood at the forefront of industry development, focuses on technological innovation, and continues to increase the development of new products to ensure that refractory materials can be applied to more industrial areas in the future. If you have any needs for refractory materials, please contact us and we will reply to you as soon as possible!