Comparison between a Uniaxial Compaction Tester and a Shear Tester for the Characterization of Powder Flowability
Comparison between a Uniaxial Compaction Tester and a Shear Tester for the Characterization of Powder Flowability
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单轴压实试验机与剪切试验机表征粉末流动性的比较
DOI：
10.14356/kona.2008016
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发表时间：
2008
影响因子：
4.1
通讯作者：
M. Poletto
中科院分区：
文献类型：
--
作者：
Luca Parrella;D. Barletta;R. Boerefijn;M. Poletto
使用剪切单元对粉末流动特性进行完整表征是一个漫长而耗时的过程，需要经过专门培训的操作员或昂贵的自动化仪器。由于这些原因，在工业实践中，通常优选使用单轴压实测试仪进行更简单且不太广泛的测量。然而，文献中的先前研究表明，由于两个测试仪中达到的应力状态条件不同，这两种技术的结果不能直接比较。在这项研究中，进行了一项实验活动，使用环剪测试仪 (RST) 和单轴压实测试仪 (UCT) 测量五种不同粉末的流动函数。 UCT 中的壁摩擦效应可以解释粘性较大的粉末产生的不同流动性结果。对考虑壁摩擦的结果进行重新评估，得出碳酸钙粉末的两种实验技术之间基本一致，而其他四种食品粉末仅在低固结水平下一致。在高固结水平下测试的这些粉末中似乎出现了除壁摩擦以外的现象。两种技术结果之间的比较表明，将 UCT 流动函数直接外推到低固结条件可能会导致低估粉末内聚力。
The complete characterization of powder flow properties with shear cells is a long and timeconsuming process that requires specially trained operators or costly automated instruments. For these reasons, in industrial practice, the use of simpler and less extensive measurement by uniaxial compaction testers is often preferred. However, previous studies in the literature indicate that the results of the two techniques are not directly comparable due to the different stress state conditions achieved in the two testers. In this study, an experimental campaign to measure the flow function of five dif ferent powders with a ring shear tester (RST) and a uniaxial compaction tester (UCT) was performed. Different flowability results that arose for the more cohesive powders are explained by the wall friction ef fect in the UCT. Re-evaluation of the results accounting for the wall friction gave substantial agreement between the two experimental techniques for a calcium carbonate powder and only at low consolidation levels for the other four food powders. Phenomena other than wall friction seem to appear within these powders tested at high consolidation levels. The comparison between the results of the two techniques suggests that straightforward extrapolation of the UCT flow functions to a low consolidation condition can lead to an underestimation of powder cohesion.