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The origin of the nonlinear behavior of the Young's modulus (E) of carbon‐bonded alumina at high temperatures was addressed, based on the microstructural changes observed during processing and their thermo‐mechanical properties. Impulse excitation technique, thermogravimetric analysis, porosity measurement, and scanning electron microscopy were conducted in order to highlight and explain the E behavior. The finite element model of a virtual microstructure was simulated and the results attained are in good agreement with the experimental data. The tests revealed that the Young's modulus of a cured sample heated from room temperature up to 500°C was governed by the release of volatiles. Above this temperature, the thermal expansion mismatch among alumina, graphite, and the carbon matrix is dominant resulting in an increase in the effective Young's modulus. During cooling, crack networks and gaps between alumina particles and the carbon matrix were developed. The former were induced by volatile release and by the graphite's highly anisotropic thermal expansion. The latter was derived by the thermal expansion mismatch between the alumina and the carbon matrix. The closure of the gaps and cracks governed the expansion behavior during the second heating cycle and a nonlinear effective Young's modulus increase as a function of temperature was observed.

Ceramic filters have singular properties such as high permeability and specific surface area associated to low density. Some examples of their use can be found in liquid metal deep filtration, water treatment, air purification, and others. These particular properties are dependent on the filters' manufacturing process. One of the most used techniques to produce filters is the replication method, which provides a tridimensional network of struts and interconnected pores. However, a common issue of all ceramic filters produced by this technique is their low mechanical strength due to the hollow struts and microcracking generated during the thermal decomposition of the sponge. Intending to address this limitation and produce filters with higher mechanical strength, this paper analyzed a modified process route for manufacturing filters. Samples of preheated Al2O3 filters were vacuum infiltrated with ceramic suspensions (Al2O3 and SiO2) of different solids concentrations (15‐40 wt%), particle size distribution (nano to micrometric size) at distinct processing times (1‐5 minutes). The data analysis indicated that the best balance among mechanical strength, mass, and strut thickness was achieved by infiltration with SiO2 colloidal suspension (40 wt%) per 1 minute. SEM analysis confirmed that the struts were filled and microcracks were sealed with colloidal particles.

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