Causes of wear of refractory castables

Causes of wear of refractory castables

The wear of refractory castables is the result of the combined action of many factors. The following is a detailed summary of these factors:

Mechanical Scouring

In high-temperature equipment such as boilers and kilns, refractory castables are frequently subjected to scouring by air, material flow, or molten metal. This scouring action can cause particles on the castable surface to gradually fall off. Especially in environments with high flow rates or high scouring forces, the wear rate of the refractory castable can be significantly accelerated. Therefore, when designing high-temperature equipment, it is important to fully consider the impact of the medium flow rate on the scouring effect on the refractory castable and implement appropriate measures to reduce the scouring rate and minimize the degree of wear.

Thermal Stress

The thermal expansion and contraction caused by temperature fluctuations generate stresses within refractory castables. These stresses can cause cracking or spalling, especially in environments with drastic temperature fluctuations. When high-temperature equipment experiences frequent heating and cooling cycles during operation, the stresses within the refractory castables can fluctuate constantly, leading to structural damage and performance degradation. To minimize the impact of thermal stress on refractory castables, it is necessary to rationally design the equipment’s heating and cooling profiles and select refractory castables with excellent thermal shock resistance.

Slag Erosion

At high temperatures, refractory castables may be corroded by slag. Certain components in the slag may chemically react with the castable, causing structural damage and performance degradation. This chemical reaction often results in the slag dissolving or stripping away particles on the castable’s surface, causing wear. To minimize the effects of slag erosion on refractory castables, it is necessary to select refractory materials with excellent slag erosion resistance and strictly control the quality and uniformity of the construction process.

Gas Erosion

Certain high-temperature gases (such as oxygen and carbon dioxide) may react with components in refractory castables, causing gradual oxidation and wear. This oxidation reaction typically results in the particles on the refractory castable surface being oxidized into a loose oxide layer, which reduces its strength and wear resistance. To minimize the effects of gas erosion on refractory castables, it is necessary to select refractory materials with excellent oxidation resistance and strengthen maintenance and inspection during use to promptly detect and repair cracks and worn areas.

Poor Construction Quality

Poor construction quality is also a major cause of refractory castable wear. Failure to strictly adhere to construction specifications during the construction process can result in poor construction quality and uniformity, which in turn affects the castable’s wear resistance. Therefore, strict adherence to construction specifications is crucial to ensure the quality and uniformity of the castable. Furthermore, professional training and technical guidance are essential for construction personnel to enhance their skills and capabilities.

Improper Design

Improper design can also lead to wear of refractory castables. For example, insufficient number of pins and grabbers, or substandard materials, can cause the grabbers to carbonize and cause the wear-resistant castable to fall out. Furthermore, excessive expansion joints during construction can cause flue gas to flow back into the insulating castable, burning and carbonizing the pins, rendering them ineffective and causing castable to fall out.

Improper Maintenance

Regular maintenance and inspections are crucial to extending the service life of refractory castables. Failure to promptly identify and repair cracks and worn areas can exacerbate wear. Therefore, a comprehensive maintenance and inspection system is essential, with regular inspections and maintenance of high-temperature equipment. During these inspections, the surface condition and structural integrity of the refractory castables should be carefully observed to promptly identify and address potential problems and hazards.

Insufficient wear resistance of the material itself

If the selected refractory castable lacks wear resistance, it will easily wear out during use. Therefore, when selecting a refractory castable, it is important to fully consider the operating environment and working conditions, selecting a refractory material with excellent wear resistance. It is also important to pay attention to other performance indicators of the refractory castable, such as compressive strength, flexural strength, and thermal shock resistance, to ensure that it meets design and operational requirements.

In summary, the causes of refractory castable wear are diverse, requiring comprehensive consideration and optimization from multiple perspectives, including construction, maintenance, material selection, and operating conditions.