1. What is the high-temperature structural strength of refractory materials?
High-temperature structural strength is a key performance indicator for refractory materials. It refers to the material’s ability to withstand pressure without deformation under high-temperature conditions. This indicator is typically assessed by its softening-under-load temperature (SRT). SRT is measured by gradually increasing the temperature under a specific pressure, at which the material begins to deform and at the point where its compression deformation reaches 4% or 40%. These two points, known as the SRT onset temperature and the softening point at 4% or 40%. Respectively, provide crucial information about the material’s ability to resist deformation at high temperatures.
It is worth noting that refractory materials typically exhibit high compressive strength at room temperature. For example, ordinary clay bricks can withstand pressures up to 12.5 MPa. While higher-grade refractory bricks can withstand even greater pressures. However, the strength of these materials decreases significantly when the temperature rises. This is because high temperatures cause the fusible components in the refractory bricks to melt prematurely, forming a liquid phase, which significantly reduces their compressive strength.
In kiln masonry, refractory materials must not only withstand high temperatures but also bear a certain weight load. Therefore, high-temperature structural strength is a key criterion for evaluating refractory quality. For example, corundum bricks, with a refractoriness of up to 2000°C, are ideally suited for molybdenum wire furnace tubes, which must withstand temperatures of 1700-1800°C. This is because the molybdenum wire heating element is typically wound around the corundum tube. Requiring the refractory material in the furnace lining to remain stable at high temperatures, preventing softening and deformation to avoid damage or even fracture to the heating element.
2. The high-temperature structural strength of refractory materials includes:
The high-temperature structural strength of refractory materials is a comprehensive performance indicator encompassing multiple aspects, primarily the high-temperature deformation temperature (HDT) and high-temperature mechanical strength.
The HDT is a key indicator, defining the temperature at which the refractory material begins to noticeably deform or collapse during continuous heating under specific pressure conditions. Determining this temperature is crucial for evaluating the stability and service life of refractory materials in high-temperature environments. High-temperature mechanical strength is another essential indicator, measuring the maximum compressive stress a refractory can withstand under specific high-temperature conditions.
This indicator is directly related to whether the refractory can maintain its structural integrity and stability under high-temperature conditions, thereby ensuring its safety and reliability during use. By comprehensively evaluating these two indicators, we can gain a more comprehensive understanding of the performance of refractory materials in high-temperature environments and provide a scientific basis for selecting appropriate refractory materials.