Being a versatile ceramic, which can be used in various applications, cordierite has always been subject to optimization and research. Nevertheless, the corrosion resistance of the ceramic, synthesized from natural zeolite, has not been widely investigated. In this study, cordierite with 2:2:5 compositions of MgO/Al2O3/SiO2, respectively, was obtained from the natural zeolite. Following sintering at 1250°C for 1 h, of cordierite with 10 and 20% amount of added zirconia (ZrO2), the mechanical properties exhibited proportional amelioration, accompanied by an enhanced homogeneity and reduced microcracks. The corrosion properties were investigated via the weight loss method in 2 vol. % and 5 vol. % HCl acid solutions maintained for up to 480 h at 25, 50, and 75°C. The corrosion kinetics were evaluated from corrosion curves, followed by a calculation of the activation energies of corrosion. The results revealed that ZrO2 addition enhances the resistance, with an optimum observed for the 10% zirconia doped cordierite samples, with varying activation energies between 113 kJ/mol for 5 vol. % HCl acid solution and 119 kJ/mol for 2 vol. % HCl acid solution.

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In this work, a mathematical model for simulating the thermochemical boronizing process is presented. The diffusion model used in this paper is based on Fick’s laws by solving the mass balance equation of the (FeB/Fe2B) interface. In this developed model, the effect of boride incubation times during the formation of Fe2B layers on Armco iron was considered. To demonstrate the validity of our calculations, the simulation results are compared with experimentally obtained data on borided Armco iron, which allowed us to verify the validity of the model. Therefore, a good concordance was observed when comparing the experimental parabolic growth constants taken from the literature with our simulated values of the parabolic growth constants from the present diffusion model. From this study, it has been found that the incubation time has a very important influence on the evolution of the kinetics of the boride layers.

Carbothermal reduction and nitridation (CRN) method, used for the synthesis of nitride-based ceramic powders, is an effective and economic technique that has been widely investigated. In this study, a CRN-based novel approach, denominated as dynamic/thermochemical method (DTM), has been used to synthesize submicron high-purity aluminum nitride (AlN) powders with equiaxed-sized particles. DTM is a modified CRN method in which the reaction takes place in a controlled atmosphere using a rotary tube furnace, allowing the synthesis of fine particle-size powders in a relatively short time. Following the DTM process, homogeneous submicron AlN powders were synthesized from a mixture of aluminum hydroxide (Al(OH) 3 ) and carbon black at 1450 • C for 1.5 h. Furthermore, dynamic synthesis parameters, as well as the use of ammonia (NH 3 ) and propane (C 3 H 8 ) gas mixtures instead of carbon black and nitrogen, were investigated.