Compressive strength is the limit load that can be borne per unit area, which refers to the ratio of the ultimate pressure stress to surface area that can be borne when the unit area of the object is destroyed, and the unit is Mpa. Flexural strength refers to the ultimate breaking stress when the unit area of the material is subjected to bending moments. Also known as bending strength, modulus of fracture, the unit is Mpa.
There are two concepts of compressive strength of refractory products, one is "normal temperature compressive strength", which is defined as the ratio of the ultimate compressive stress to surface area that can withstand when a unit area object is destroyed at room temperature. The second is "high temperature compressive strength", which is defined as the extreme pressure stress of the refractory product specimen through cultivation and burning to the specified high temperature conditions, and the unit cross-sectional area can withstand the ultimate pressure stress that is not destroyed.
The flexural strength is also divided into two types, which are divided into room temperature flexural strength and high temperature flexural strength according to different experimental temperature conditions. Under the same testing conditions, the flexural strength of the product is positively correlated with the compressive strength, the flexural strength of the room temperature is high, the compressive strength of the room temperature is increased, the high temperature flexural strength is high, and the high temperature compressive strength is also improved.
The use of normal temperature compressive strength and room temperature flexural strength for non-burning refractory products and amorphous refractory materials is one of the main quality indicators. For general refractory products, the pressure resistance at room temperature and the flexural strength at room temperature are not only an important indicator for judging product quality, but also an important technical reference for measuring the process level, raw material gradation and sintering temperature of the product.
For amorphous refractory materials, whether the raw material gradation is reasonable, the amount of the binder added, the difference in additives, the quality of construction vibration and maintenance conditions, all determine the strength of room temperature compressive strength and room temperature flexural strength.
In general, the same material production of stereotyped refractory products, the higher the molding pressure, the higher the sintering temperature, the more liquid phasor, the higher the pressure resistance at room temperature, but the reason for the large amount of liquid phase is also likely to be caused by the higher impurity composition of the material, so it can not simply rely on the level of pressure strength at room temperature as the basis for judging the quality of refractory materials.
The material's room temperature compressive strength and room temperature flexural strength are high, not necessarily high temperature compressive strength and high temperature flexural strength is high, for example, the normal temperature strength of steel is very high, but at a temperature of 1100 ° C, its compressive strength is almost zero, so we can burn the steel red forging into the shape we want.
Since all kinds of refractories are used under high temperature conditions, high temperature compressive strength and high temperature flexural strength reflect the bearing capacity of refractory materials under high temperature conditions and the resistance to the impact, wear, and erosion of liquid slag materials in the furnace, through the high temperature compressive strength index, the performance of the material can be directly judged, which is the key technical indicator, limited by the habits of the mainland refractory industry and the current situation of high temperature compressive strength and high temperature flexual strength detection methods. At present, there is no product in the national and industry standards to make provisions for these two indicators, the current high temperature compressive strength and high temperature flexural strength indicators of the testing concept is mostly seen in the paper and some foreign product requirements, I believe that with the improvement of the development level of the mainland material industry, will appear in the future of various product standards.