Governing role of the ratio of large platelet particles to ultrafine particles on dynamic and quasistatic compressive response and damage evolution in ice-templated alumina ceramics

This study revealed that the mass ratio of large anisometric particles (platelets) to ultrafine, equiaxed particles strongly influences dynamic and quasistatic compressive response and the process of damage evolution in ice-templated alumina materials. The improved sinterability between particles of significantly dissimilar size and morphology enabled the utilization of a high mass ratio of the particles in harnessing a markedly enhanced level of strength in highly porous ice-templated ceramics. The high volume fraction of platelets increased lamellar bridge density and resulted in dendritic morphology as opposed to lamellar morphology without platelets. All the materials showed strain rate-sensitivity, where strength increased with strain rate. Materials with highly dendritic morphology exhibited the best performance in terms of maximum strength and energy absorption capacity, and the performance improved from quasistatic to dynamic regime. Direct observation of the process of damage evolution revealed the effects of both strain rate and ratio of platelets to ultrafine particles.

本研究揭示，大尺寸各向异性颗粒（platelets，片晶）与超细等轴颗粒的质量比，对冰模板氧化铝材料的动态与准静态压缩响应以及损伤演化过程具有显著影响。尺寸与形貌差异显著的颗粒间烧结性能得到改善，使得可采用较高的颗粒质量比，从而显著提升高孔隙率冰模板陶瓷的强度水平。片晶的高体积分数可提升层状桥接密度，并形成枝晶形貌，而非无片晶条件下的层状形貌。所有受试材料均表现出应变速率敏感性，即强度随应变速率升高而增大。具有高度枝晶形貌的材料在最大强度与能量吸收能力方面表现最优，且其性能从准静态到动态加载区间均有所提升。对损伤演化过程的直接观测表明，应变速率与片晶-超细颗粒质量比均对其产生影响。