Characteristics and Properties of Phosphoric Acid Combined Chrome Corundum Refractory Mortar

Chrome corundum refractory mortar serves as a joint material for constructing chrome corundum brick masonry and is also suitable for building with various chromium-containing corundum refractory bricks. This mortar shares the same resistance to erosion and scouring as chrome corundum bricks crafted from the identical material.

Chrome Corundum Refractory Mortar

Phosphate-bonded Chrome Corundum Refractory Mortar

Phosphate-bonded phosphate refractory mortar enhances its strength, thermal shock resistance, wear resistance, and high-temperature toughness. Chrome corundum refractory mortar is made from fused chromium oxide powder, chromium oxide green, and other powders. Chrome corundum phosphate mortar is made by adding an appropriate amount of aluminum dihydrogen phosphate to the chrome corundum mortar to improve its bonding time and high-temperature resistance. The bonding time of refractory mortar is crucial to its performance. Excessively long or short bonding times can affect construction progress and masonry quality.

Therefore, the amount of aluminum dihydrogen phosphate added is crucial; a larger amount increases the bonding time. The viscosity of the aluminum dihydrogen phosphate solution increases with its content. Increasing the amount of aluminum dihydrogen phosphate added during the process increases the concentration and viscosity of the refractory mortar.

Adding aluminum dihydrogen phosphate to chrome corundum slurry forms a spatial network of aluminum phosphate, cross-linking the other components in the slurry. Increasing the amount of aluminum dihydrogen phosphate increases the cross-linking material in the slurry and enhances its bond strength. However, aluminum dihydrogen phosphate has varying degrees of impact on the slurry's bonding time, especially its high-temperature performance. Therefore, adding more aluminum dihydrogen phosphate is not always optimal. While maintaining the overall performance of the slurry, a total amount of 10% to 15% is appropriate.

Adding aluminum dihydrogen phosphate to chrome corundum slurry optimizes and improves various slurry properties, including a significant increase in cold flexural bond strength. This enhanced bonding allows for closer cross-linking between refractory bricks and joint materials, resulting in a longer service life and improved airtightness.

Applications of Chrome Corundum

Chrome corundum is characterized by its high refractoriness, strength, excellent thermal shock stability, and robust corrosion resistance. When integrated into refractory materials to create chrome corundum bricks or castables, its superior wear and corrosion resistance become particularly evident. It is widely utilized in the metallurgical, glass, carbon black, and petrochemical industries. In recent years, its application in hazardous waste rotary kilns has yielded remarkable results.

Chrome corundum bricks and castables are composed of a continuous solid solution of Al₂O₃ and Cr₂O₃, devoid of eutectics. Both types of materials exhibit a refractoriness exceeding 1790°C and a refractoriness under load surpassing 1700°C, categorizing them as high-end refractory materials. Their strength, wear resistance, and corrosion resistance outperform those of high-purity corundum, brown corundum, white corundum, and other refractory castables and bricks.

High-performance chrome corundum bricks and castables typically possess a room-temperature compressive strength exceeding 150 MPa. During the firing process, Al₂O₃-Cr₂O₃ solid solutions form between particles, between particles and fine powder, and between fine powders. This solid solution effectively bonds the particles and fine powders, significantly enhancing strength and corrosion resistance.

Precautions for Using Chrome Corundum

When making these products, Cr2O3 gets mixed into corundum. Interestingly, the more Cr2O3 you add, the worse the thermal shock resistance of the bricks and castables becomes. So, bricks with less Cr2O3 actually handle thermal shock better than those with more. It's important to keep in mind that too much chromium isn't great, as it's bad for health and weakens the product.

As for resisting slag corrosion, chrome corundum bricks and castables do a pretty good job. Cr2O3 doesn’t dissolve much in coal gasification furnace slag and glass melt, unlike other oxides. This means that bricks and castables with Cr2O3 are better at holding up against steel slag, non-ferrous forged slag, coal gasification furnace slag, and hazardous waste slag compared to other materials that melt easily. They’re designed to stop slag from seeping in and forming a layer that could break down the structure. That’s why for furnace linings that face high temperatures and heavy erosion, people often go for chrome corundum materials or bricks.