Compression curve analysis and compressive strength measurement of brittle granule beds in lieu of individual granule measurements--颗粒学报PARTICUOLOGY

Järveläinen, M., Kaleva, A., Kaitajärvi, A., Laakso, J., Kanerva, U., & Levänen, E. (2016). Compression curve analysis and compressive strength measurement of brittle granule beds in lieu of individual granule measurements. Particuology, 29, 60-68. https://doi.org/10.1016/j.partic.2015.10.006

Compression curve analysis and compressive strength measurement of brittle granule beds in lieu of individual granule measurements

Matti Järveläinen ^a *, Aaretti Kaleva ^a, Annikka Kaitajärvi ^b, Jarmo Laakso ^a, Ulla Kanerva ^b, Erkki Levänen ^a

a Department of Materials Science, Tampere University of Technology, PO Box 589, FIN-33101 Tampere, Finland
b VTT Technical Research Centre of Finland, Sinitaival 6, PO Box 1300, FI33101 Tampere, Finland

10.1016/j.partic.2015.10.006

Volume 29, December 2016, Pages 60-68

Received 1 June 2015, Revised 28 August 2015, Accepted 3 October 2015, Available online 22 February 2016, Version of Record 18 November 2016.

E-mail: matti.jarvelainen@tut.fi

Highlights

• Uniaxial compression was used to determine compressive strength of an average brittle granule.

• Compression phenomena of a bed of kaolinite powder were studied using compression curve analysis.

• The method suggested can work for different small and brittle granules.

Abstract

Powders in granulated form are used in various processes to facilitate convenient usage. The durability of the formed granules is a crucial parameter, typically evaluated by the compressive strength of the granules. However, especially for granules with a diameter in the order of tens of microns, statistically relevant testing of individual granules is not a feasible alternative, and in such cases uniaxial bed compression is required.

There has not been consensus on whether uniaxial compression of a granule bed can be used to study the fracture of micron size or brittle granules. In our case study of a bed of sintered kaolinite granules with diameters under 100 μm, we show how the compressive strength of individual granules can be obtained from the compressive measurement of the entire bed by plotting the relative density versus the logarithmic pressure scale.

We compressed the kaolinite powder with different loads; microscopy confirmed that below the analyzed strength the granules are intact, though the granules start to fracture in the curved region on the compression curve. We found that angle-fitting can be used to locate the average compressive strength on the compression curve and to follow the evolution of strength with sintering temperature. The experiments in unison demonstrate that compression curve analysis is applicable for strength analysis of brittle granules.

Graphical abstract

Keywords

Granule; Mechanical characterization; Pressing; Compressive strength; Sintering; Compression curves

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