Ultra-rapid microwave sintering of pure and Y2 O3 -doped MgAl2 O4
Ultra-rapid microwave sintering of pure and Y2 O3 -doped MgAl2 O4
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DOI：
10.1111/jace.15788
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发表时间：
2018-06
影响因子：
3.9
通讯作者：
Y. Bykov;S. V. Egorov;A. Eremeev;V. Kholoptsev;I. Plotnikov;K. Rybakov;A. A. Sorokin-A.;S. Balabanov-S.-Balab
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文献类型：
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作者：
Y. Bykov;S. V. Egorov;A. Eremeev;V. Kholoptsev;I. Plotnikov;K. Rybakov;A. A. Sorokin-A.;S. Balabanov-S.-Balab
mgal2o4样品在加热速率为100°C/min和零等温保持的快速过程中微波烧结至接近满密度。实验采用频率为24 GHz、最大功率为6 kW的材料微波处理回旋管系统进行。在自动调节微波功率的预设加热速率下，原始mgal2o4样品（最高烧结温度1650°C）的最大密度约为理论值的95%，而掺1 wt.% Y2O3样品（1700°C）的最大密度约为97%。在固定的微波功率（约3.5 kW）下，在1700℃下获得了相对密度在99%以上的半透明尖晶石样品。高温烧结阶段的持续时间为1.5 ~ 10分钟。提出的致密化增强的机制涉及热不稳定性的发展和晶界处瞬态液相的形成。在超高速微波烧结的高温阶段，样品的比吸收功率估计为27 ~ 80 W/cm3，与直流场辅助闪蒸烧结实验中观察到的值相似。
MgAl2O4samples were microwave sintered to near‐full density in rapid processes with heating rates on the order of 100°C/min and zero isothermal hold. The experiments were carried out using a gyrotron system for microwave processing of materials operating at a frequency of 24 GHz with a maximum power of 6 kW. In the regimes with a preset heating rate sustained by the automatically regulated microwave power, the maximum achieved density was about 95% of the theoretical value in pristine MgAl2O4samples (maximum sintering temperature 1650°C) and about 97% in 1 wt.% Y2O3‐doped samples (1700°C). In the regimes with a fixed microwave power (about 3.5 kW), translucent spinel samples with a relative density above 99% were obtained at 1700°C. The duration of the high‐temperature stage of sintering was 1.5‐10 minutes. The suggested mechanism responsible for the enhanced densification involves development of a thermal instability and formation of transient liquid phases at grain boundaries. The estimated specific absorbed power in the samples during the high‐temperature stage of ultra‐rapid microwave sintering was 27‐80 W/cm3, similar to the values observed in dc field‐assisted flash sintering experiments.