Comparative Analysis of the Properties of Corundum Bricks and Chrome-Corundum Refractory Bricks

I. Definition and Classification of Materials
Corundum bricks are defined as high-grade refractory materials with an alumina (Al₂O₃) content exceeding 85%; based on their manufacturing process, they can be classified into two categories: sintered corundum bricks and electrofused corundum bricks.
Chrome-corundum refractory bricks, conversely, are composite refractory materials produced by introducing chromium oxide (Cr₂O₃) into a corundum matrix, followed by high-temperature forming and sintering; they are similarly categorized into two types: fused-cast chrome-corundum bricks and sintered chrome-corundum bricks.

II. Key Performance Differences

1. High-Temperature Resistance
There are significant differences between the two materials regarding their high-temperature performance. Chrome-corundum bricks possess a refractoriness exceeding 1790°C and a refractoriness under load exceeding 1700°C, whereas the typical service temperature for ordinary corundum bricks is generally around 1600°C. Consequently, the high-temperature performance of chrome-corundum bricks is demonstrably superior to that of pure corundum bricks.
2. Room-Temperature Compressive Strength
The room-temperature compressive strength of standard corundum refractory bricks typically ranges from 70 to 100 MPa, whereas that of chrome-corundum bricks can reach upwards of 150 MPa—representing a significant advantage in strength.
This disparity stems from the Al₂O₃-Cr₂O₃ solid solution formed during the firing process: this solid solution establishes robust bonds—between grains, between grains and fine powders, and among the fine powders themselves—thereby effectively enhancing the structural strength of the finished product.

3. Thermal Shock Stability
The thermal shock stability of chrome-corundum bricks is inversely correlated with their Cr₂O₃ content; specifically, chrome-corundum bricks with a lower Cr₂O₃ content exhibit superior thermal shock stability compared to products with a higher content.
In industrial applications, the Cr₂O₃ content of chrome-corundum bricks is typically controlled within the range of 12% to 20%. In particular, AKZ-type chrome-corundum bricks—manufactured with the addition of a small amount of phase-transformation modifiers—demonstrate even more exceptional thermal shock stability.
4. Resistance to Slag Corrosion
Regarding resistance to slag corrosion, the two materials exhibit distinct differences. Corundum bricks are severely susceptible to slag corrosion; molten slag can completely infiltrate the interior of the brick body and permeate along the pores to the surface, resulting in the formation of a brown, altered layer on the brick's exterior.
In contrast, chrome-corundum bricks remain virtually unaffected by slag corrosion; the boundaries between the internal pores and the residual slag are clearly defined, and the depth of slag penetration is extremely shallow. Overall, chrome-corundum bricks outperform corundum bricks in terms of both chemical corrosion resistance against gasification slag and resistance to slag penetration.

III. Application Fields

Based on their distinct performance characteristics, the application fields of these two materials differ. Chrome-corundum bricks are primarily utilized in demanding environments—such as the linings of glass kilns, hot metal pretreatment units, waste incinerators, and gasifiers—where operating conditions are particularly harsh.
Corundum bricks, conversely, are widely employed as linings for various high-temperature furnaces; these include cracking furnaces and reformers in the petrochemical and fertilizer industries, as well as steelmaking furnaces and blast furnaces in the metallurgical sector.

IV. Selection Principles

Each of these two products possesses its own distinct advantages: Chrome-corundum bricks excel in terms of high-temperature resistance and resistance to erosion, though their cost is relatively high. Corundum bricks, while exhibiting slightly lower performance capabilities, offer a significant cost advantage.
In practical engineering applications, material selection should be guided by a rational assessment of specific operating temperatures and the nature of erosive media present. Provided that operational requirements are fully met, the use of corundum bricks in appropriate temperature zones and locations can effectively control production costs, thereby achieving an optimal balance between technical efficacy and economic efficiency.