铝热还原氮化法制备ZrN-Al_2O_3-ZrO_2复合粉体

Preparation of ZrN-Al_2O_3-ZrO_2 Composite Powder by Aluminum-thermal Reduction AndNitriding of ZrO_2

ZrO2材料与ZrN和Al2O3复合可提高其制品的热震稳定性，但关键之一是如何获得ZrN—Al2O3-ZrO2复合粉体。实验以d50为7．5μm的Al粉和粒径小于0．1μm的ZrO2粉为原料，采用铝热还原氮化法及热力学、TG-DTA和XRD等分析方法对ZrN—Al2O3-ZrO2复合粉体的制备工艺进行了探讨。结果表明：在Al—ZrO2与N2的反应过程中，Al氮化形成AIN以及ZrO2铝热还原氮化形成ZrN和Al2O3的反应温度，均主要发生在700～1100℃之间，但以后者的反应为主；期间还存在Al2O3固溶到ZrO2中使之形成c—ZrO2的反应，存在AIN与ZrO2形成Zr7O8N4和Al2O3的反应；当温达到900℃时，Al和AIN的衍射峰趋于消失，ZrN和Al2O3的衍射峰随温度升高而增强，至1000～1100℃时试样中的相成分趋于稳定，至1200～1300℃时各物相的衍射峰强趋于稳定；随Al含量由5％增加至25％及1100℃的烧制条件下，ZrN和Al2O3的衍射峰可由弱变强至占绝对优势。在N2气氛和1100～1200℃的温度条件下，采用15～25％的d50=7．5μm的Al粉和75～85％粒径小于0．1μm的m-ZrO2粉，可制备出具有理想相组成的ZrN—Al2O3-ZrO2混合粉体。

ZrO2 material with the combination of ZrN and Al2O3 can improve the thermal shock resistance of tile products. But one of the Keys is how to obtain ZrN-AlzO3-ZrO2 composite powders. In this experiment, A1 powder （d50=5 μ m） and ZrO2 powder （less than 0.1 μ m） were used as raw materials. The preparation of ZrN-Al2O3-ZrO2 composite powders using aluminum-thermal reduction nitridation were studied by thermodynamics, TG-DTA and XRD analysis method . The experimental results reveal that nitridized A1 powder to form AIN and aluminum-thermal reduction nitriding of ZrO2 to form ZrN and Al2O3 mainly occur between 700 - 1100 ℃ during the Al-ZrO2 reaction with N2, which is dominated by the latter reaction. In this process, Al2O3 solid solution in the ZrO2 may also form c-ZrO2. Additionally, the reaction of ZrO2 and AIN may also exist to form ZrTO8N4 and Al2O3. Al and AIN diffraction peaks disappear at 900 ℃ . With temperature rising, ZrN and Al2O3 diffraction peaks will constantly increase. To the 1000 - 1100 ℃ , phase compositions will trend to stabilize in the sample, to the 1200-1300 ℃ , the diffraction peaks intensity of all the phases trend to be stable.With A1 content increasing from 5% to 25% , ZrN and Al2O3 diffraction peak intensity gradually enhance until reaching an absolute advantage under 1100 ℃ firing conditions.The desired ZrN-Al2O3-ZrO2 composite powders can be prepared under the conditions of an atmosphere of N2 and 1100 - 1200 ℃ firing temperature, when 15 - 25% Al powder （d50=5 μ m） and 75 - 85% ZrO2 powder （less than 0.1 μ m） are used as raw materials.