铝镁碳砖的独特性质

铝镁碳砖，作为精炼炉内衬的关键耐火材料，巧妙融合了镁砂的出色抗渣侵蚀性与碳的低膨胀性及高热导性，从而有效克服了镁砂剥落性不足的弱点。其卓越性能体现在以下几个方面：首先，MgO与C在高温环境下无共熔现象，得益于两者极高的耐高温性——碳的熔点超过3000℃，而MgO的熔点也高达2800℃，共同赋予了铝镁碳砖极佳的耐火性。

(2) 卓越的抗碱性渣蚀性：镁砂对碱性渣和高铁渣具有强大的抵抗力，而石墨则能增大熔渣的润湿角，使得熔渣难以渗透，从而确保变质层保持轻薄。
(3) 铝镁尖晶石的生成与作用：在高温环境下，基质中的Al2O3与MgO反应，生成铝镁尖晶石（MA）。这种尖晶石具有较低的弹性模量和热膨胀系数，能够有效地转移方镁石中的二次MF尖晶石，并伴随体积膨胀，堵塞气孔，进一步抑制熔渣的渗透。
此外，熔渣中的CaO与Al2O3反应，生成高熔点的柱状CA6和少量的CA2。这些矿物的生成会消耗熔渣中的大量CaO，提高熔渣的粘度，从而降低其渗透能力。同时，高温下的基质尖晶石还能捕捉熔渣中的FeO、MnO，形成尖晶石固溶体，进一步提升铝镁碳砖的抗渣性。由于铝镁碳砖具有一定的膨胀性能，使用后的砖缝能够严实闭合，整体性能优异。

Alumina-magnesia carbon bricks are unfired products made from premium high-alumina bauxite clinker, fused or sintered magnesia, and graphite, supplemented with liquid phenolic resin as a binder, through a special process. They offer excellent refractory and corrosion resistance and are widely used as lining materials for high-temperature kilns such as ladles. In my country, alumina-magnesia carbon bricks produced by numerous manufacturers achieve high physical and chemical performance, providing strong support for the refractory protection of ladles and other kilns.

Following the successful development of alumina-magnesia carbon bricks, my country has further explored the development of alumina-magnesia spinel carbon bricks for ladles. By ingeniously incorporating pre-synthesized magnesia-alumina spinel, these bricks significantly enhance their performance, even surpassing comparable alumina-magnesia carbon bricks.

Unique Properties of Alumina-Magnesia Carbon Bricks

Alumina-magnesia carbon bricks, a key refractory material for refining furnace linings, cleverly combine the excellent slag corrosion resistance of magnesia with the low expansion and high thermal conductivity of carbon, effectively overcoming the inherent flaking properties of magnesia. Its excellent performance is reflected in the following aspects: First, MgO and C do not form a eutectic under high temperature conditions. This is due to the extremely high temperature resistance of both. The melting point of carbon exceeds 3000℃, while the melting point of MgO is as high as 2800℃, which together give the aluminum-magnesium carbon brick excellent refractory properties.

(2) Excellent resistance to alkaline slag corrosion: Magnesia has strong resistance to alkaline slag and high iron slag, while graphite can increase the wetting angle of the slag, making it difficult for the slag to penetrate, thereby ensuring that the metamorphic layer remains thin.

(3) Formation and function of aluminum-magnesium spinel: Under high temperature conditions, Al2O3 in the matrix reacts with MgO to form aluminum-magnesium spinel (MA). This spinel has a low elastic modulus and thermal expansion coefficient, and can effectively transfer the secondary MF spinel in the periclase, accompanied by volume expansion, blocking the pores and further inhibiting the penetration of the slag.

In addition, CaO in the slag reacts with Al2O3 to form high-melting-point columnar CA6 and a small amount of CA2. The formation of these minerals consumes a significant amount of CaO in the slag, increasing its viscosity and thus reducing its permeability. Simultaneously, the matrix spinel at high temperatures captures FeO and MnO in the slag, forming a spinel solid solution, further enhancing the slag resistance of the alumina-magnesia-carbon brick. Due to the certain expansion properties of alumina-magnesia-carbon bricks, the brick joints can be tightly closed after use, resulting in excellent overall performance.