To judge the quality of high alumina refractory bricks, we can start from the following aspects:
Appearance inspection: surface flatness and smoothness: high-quality high-aluminum refractory bricks should have a flat and smooth surface, without obvious unevenness or rough granularity. In this way, it can fit better during masonry, reduce gaps, and enhance the overall stability and sealing of the masonry.
Color uniformity: The color of high-aluminum refractory bricks is usually related to the content of alumina in them. Generally speaking, the higher the alumina content, the whiter the color. High-aluminum refractory bricks with uniform color mean that the raw materials are fully mixed, the production process is well controlled, and its strength distribution will be more uniform, and the service life will be longer.
Cracks and pores: Carefully observe the surface of the brick body. There should be no obvious cracks, pores, caves and other defects. Cracks will weaken the strength and integrity of the refractory bricks, causing them to break easily during use; too many pores will affect the density of the refractory bricks and reduce their resistance to high temperature, corrosion and erosion.
Corner integrity: The four corners of the brick should be intact, without missing corners or edges, and the edges should be regular, otherwise it will affect the quality of masonry and the structural strength of the masonry.
Impurity content: Check the impurities on the surface, such as black spots, the less the better. Most of these impurities are iron oxides, which are easily reduced to molten iron and flow out in the high temperature environment of the kiln, destroying the structure of the brick and shortening its service life.
Dimensional accuracy
Meet the specification requirements: Use a ruler to measure the length, width, thickness and other dimensions of the high-aluminum refractory bricks. The deviation should be within the specified tolerance range to ensure accurate matching during the masonry process and ensure the dimensional accuracy and stability of the masonry.
Physical performance testing
Density: Density is one of the important indicators for measuring the quality of high alumina refractory bricks. Generally speaking, the higher the density, the denser the brick body, and its strength, wear resistance, high temperature resistance and erosion resistance are often better. The density can be calculated by weighing and volume measurement.
Compressive strength: High-aluminum refractory bricks with high compressive strength can withstand greater pressure without breaking or deforming easily, and can be tested using a professional pressure testing machine. In high temperature environment, its compressive strength should also meet the use requirements to ensure the normal operation of kilns and other equipment.
Apparent porosity: Refractory bricks with low apparent porosity have good mechanical strength and wear resistance, strong erosion resistance, and are less likely to be damaged by the penetration of slag or molten materials under high temperature conditions.
Refractory performance test
Refractory: Refractory refers to the ability of refractory bricks to maintain structural stability and resist melting at high temperatures, usually expressed by the softening temperature of the refractory cone. The refractoriness of high-aluminum refractory bricks is generally above 1770°C. The higher the refractoriness, the better the quality.
Thermal shock stability: Thermal shock stability is evaluated by repeatedly heating and cooling bricks quickly to observe whether they crack or peel off. High-aluminum refractory bricks with good thermal shock performance can withstand frequent temperature fluctuations without damage, and are more durable in environments with drastic temperature changes such as kilns.
Load softening temperature: Load softening temperature is the temperature at which refractory bricks deform when subjected to load at high temperature. High-quality high-aluminum refractory bricks should have a high load softening temperature and be able to maintain structural stability under high temperature and heavy load.
Corrosion resistance: High alumina refractory bricks may come into contact with various slags, gases and other chemical substances during use, and need to have good corrosion resistance. Through methods such as slag corrosion tests, its ability to resist chemical corrosion can be evaluated. Refractory bricks with strong corrosion resistance are of higher quality.
Chemical composition analysis
Alumina content: The content of alumina (Al₂O₃) in high-aluminum refractory bricks is a key factor affecting its performance. The higher the content, the better the refractoriness, thermal shock resistance and other properties are generally. Common high-aluminum refractory bricks can be divided into different grades such as 55%, 65%, 75%, and 85% according to the alumina content. The appropriate grade of products can be selected according to the specific use environment and requirements.
Impurity content: Excessive impurity content such as iron oxide and calcium oxide will reduce the refractoriness, corrosion resistance and mechanical strength of refractory bricks. Therefore, low impurity content is one of the characteristics of high-quality high-alumina refractory bricks.
