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The focus of this study is on the physical properties of clay ceramic materials compatible for drinking water filtration. A multiparameter lognormal multivariate regression approach is proposed for assessing the combined effects of quantity of compositional constituent of raw materials used in ceramic manufacture on toughness. The approach was validated for two specimen types (T- and S-specimens) derived from a circular base of the frustum shaped, porous clay ceramic ware (PCCW). The PCCW were manufactured from clay and sieved sawdust mixed at distinct volume fractions. The variation of the porosity and density of the PCCW was studied with respect to the amounts of sawdust and clay used in the manufacturing. The research helped to clearly define the roles of clay and sawdust quantities for strength development in both T- and S-specimen. A generalized experimental approach is proposed for estimation of mechanical properties of clay ceramics as a function of the material constituent fractions. A polynomial relationship was developed between the compressive strength and density of the PCCW material. The statistical model expressions developed herein may be used for the prediction of material and mechanical properties of similar materials, including natural and engineered materials.

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Porous ceramic water filters (CWFs), produced by sintering a mixture of clay and a combustible material (such as woodchips), are often used in point-of-use water filtration systems that occlude microbes by size exclusion. They are also coated with colloidal silver, which serves as a microbial disinfectant. However, the adhesion of microbes to porous clay surfaces and colloidal silver coated clay surfaces has not been studied. This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion force between Escherichia coli bacteria, colloidal silver, and porous clay-based ceramic surfaces. The adhesion of silver and copper nanoparticles is also studied in control experiments on these alternative disinfectant materials. The adhesive force between the wide range of possible bi-materials was measured using pull-off measurements during force microscopy. These were combined with measurements of AFM tip radii/substrate roughness that were incorporated into adhesion models to obtain the adhesion energies for the pair wise interaction. Of the three antimicrobial metals studied, the colloidal silver had the highest affinity for porous ceramic surface (125 ± 32 nN and ∼0.29 J/m2) while the silver nanoparticles had the highest affinity for E. coli bacteria (133 ± 21 nN and ∼0.39 J/m2). The implications of the results are then discussed for the design of ceramic water filter that can purify water by adsorption and size exclusion.

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This paper presents the results of a combined experimental and theoretical study of microstructure and thermal shock resistance of an aluminosilicate ceramic. Shock-induced crack growth is studied in sintered structures produced from powders with different particle size ranges. The underlying crack/microstructure interactions and toughening mechanisms are elucidated via scanning electron microscopy (SEM). The resulting crack-tip shielding levels (due to viscoelastic crack bridging) are estimated using fracture mechanics concepts. The implications of the work are discussed for the design of high refractory ceramics against thermal shock.