Fracture toughness enhancement of ceramic materials through multilayered ceramic composites has been developed since 1990. Toughening mechanisms are based mainly on delamination, deflection, bifurcation or crack arrest effect. Delamination and crack deflection occur by means of weak interfaces. Bifurcation (and deflection as well) and crack arrest effects are result of residual stresses arising from the thermal expansion coefficient mismatch or phase transformation on alternating layers. The main manufacturing methods of these composites are slip casting of two ceramic materials, and stacking and pressing of ceramic tapes obtained by tape casting or rolling technics, followed by suitable sintering process. This review aims to present general aspects of research performed around the theme so far. It is verified that occurs the enhancement of ceramic toughness and reliability with this technic, so it is possible to enlarge its range of application in engineering.

In the context of energy economy and thermal comfort, phase change materials (PCMs) have many useful applications. In this study, type A zeolite was tested as a matrix for impregnating obtaining a PCM-impregnated zeolite. A sample of type A zeolite was analyzed by X-ray diffraction (XRD) and X-ray fluorescence (XRF). The porosity was evaluated by scanning electron microscopy. Following that, an apparatus was mounted for vacuum impregnation to incorporate calcium chloride hexahydrate (CaCl2.6H2O), which is a PCM, in the pores of the zeolite. The impregnation and the retention of the phase change material in zeolites were assessed using Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS) on the scanning electron microscopy (SEM) and Differential Thermal Analysis (DTA) to simulate thermal cycles testing to determine the thermal behavior of the compound. The results of the XRD and FTIR analyses showed that CaCl2.6H2O remains in the zeolite phase after the impregnation and the thermal cycling performed on the material shows that there is a positive influence on the thermal behavior of the impregnated material. Varying the amount of the studied PCM between 0 and 30 wt%, different grout boards were constructed. The thermal behavior of the PCM-impregnated zeolite compared to the reference material (pure zeolite) showed an effective temperature difference (38.1 to 33.9 °C), which can lead to significant energy savings.

The coal extraction generates large amounts of coal waste. Powders of this waste can be pressed with the addition of binder in order to obtain ceramics, such as ceramic membranes. In this case, polymeric fibers can be used to increase permeability. This work aims to study the permeability of ceramic structures composed by coal waste and different amounts of polymeric fibers. The compositions were homogenized, pressed and thermally treated at 1050 °C. Samples were characterized in relation to porosity determination, permeability and microstructural features. The results showed that the permeability increased with the increase of the fiber content. However, the composition containing 0.5 vol% of polypropylene fibers showed the best results for using in aerosol filtration permeability.