铝热还原氮化法一步烧结制备AlON陶瓷研究

One-step preparation of AlON ceramics by aluminothermic reduction and nitridation

以微米Al粉和纳米γ-Al2O3为原料,采用铝热还原氮化法在流动N2中进行了AlON陶瓷的一步反应烧结制备.结果表明,合成纯相AlON的最佳Al含量为11wt%.在1650℃以下Al先和N2反应生成AlN,AlN再在1650℃以上与Al2O3通过固相反应生成AlON,并在1700℃制备了纯相的AlON,但此时块体中的AlON颗粒几乎没有出现烧结,在更高温度下才合并长大形成AlON陶瓷.煅烧温度较低时(≤1700℃),样品表面和内部的物相组成基本相同,但在高温下(≥1750℃)内部仍为纯相AlON而表层却被过度氮化出现AlN杂相.最后用热力学对该现象进行了分析.

A1ON ceramics were prepared by one-step aluminothermic reduction and nitridation methodusing micron-sized A1 and nanoscale 7-A12 O3 powders as the starting materials. The results showedthe optimal A1 content for single-phase A1ON preparation was 11 wt%. At the temperature below1650℃, A1N was primarily produced by direct A1 nitridation. Then A1N reacted with A12 03 formingA1ON at above 1650℃. Single-phase A1ON was synthesized at 1700℃, but the sintering among A1ONparticles was barely observed, which only occurred at higher temperature. For samples calcined at lowtemperature （〈1700℃）, the phase compositions of both interiors and exteriors were basically the same.However, the interiors maintained pure A1ON while the exteriors were over nitrided and A1N impurityappeared at high temperature （≥1750℃）. Such phenomenon was analyzed with emphasis of thermody-namics.