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Highly Porous 3D Printed Stoneware Ceramic

G.L.S. Marchelli, M.A. Ganter, D.W. Storti

Journal of Ceramic Science and Technology, Vol. 3, No. 1 (2012), pp. 41-48

DOI: 10.4416/JCST2011-00042

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Abstract

Purpose: This paper explores the relationship between Young's modulus and porosity in stoneware ceramic parts fabricated by means of three-dimensional printing (3DP) and post-processed via kiln sintering. Porosity, strain, and bulk density vary according to the parameters of the sintering schedule, which in turn affects the mechanical properties of the 3D printed ceramics. It is useful to have a quantitative understanding of this relationship, however, the range of porosity typical to 3DP ceramics lies beyond the intended range of applicability for existing stiffness-porosity models. Here we present experimental measurements of Young's modulus and porosity, and quantitatively evaluate existing models for applicability in 3DP's high porosity range. Design/Methodology/Approach: Experimental data including strain as a function of peak soak time, e.g. time spent at peak soak temperature, porosity and bulk density as functions of peak soak temperature, and Young's modulus as a function of porosity are presented for 3DP stoneware. A new heating schedule has been adapted to produce lower porosity 3DP stoneware objects to examine the applicability of existing stiffness-porosity relationships. A regression analysis was performed to evaluate the effective range of popular Young's modulus-porosity models. Findings: Strain was found to be highly dependent on time spent at peak soak temperature and was up to 100 % greater than published values produced by a previous heating schedule. Porosity and bulk density were found to be reasonably modeled as linear functions of peak soak temperature for peak temperatures in the range of 1204 ÂºC to 1316 ÂºC. Use of the current heating schedule allowed for lower than typical porosities in the 3DP stoneware, which led to a broader range of data for fitting the stiffness-porosity models. Optimization of the fitting parameters for the highly porous 3DP stoneware resulted in R2 values greater than 0.99, indicating the ability to extend popular models to non-conventionally produced ceramics. Research Limitations/Implications: The 3DP stoneware used exhibited relatively high porosities ranging from 48 % to 64.6 %, and high strain behavior of up to 47 %. Additionally, only strain was explored as a function of peak soak time owing to kiln restrictions; all other variables were measured as functions of peak soak temperature. Originality/Value: This paper provides the first experimental measurements of the dependence of porosity on relevant sintering parameters for 3DP stoneware ceramics. Analysis of the experimental measurements establishes, for the first time, that application of existing stiffness-porosity models in the higher porosity range requires significant parameter adjustments, with the appropriate parameter values being presented.

Keywords

Printed ceramic, stoneware, stiffness, 3DP

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