Papers by Author: M.I. Pech-Canul

Abstract: This paper presents results of the microstructure characterization and evaluation of physical and mechanical properties of Al/SiC_p composites intentionally containing the Al₄C₃ phase prepared by pressureless infiltration, as well as results of treating the composites by the hybrid system chemical vapor deposition (HYSYCVD) route using Na₂SiF₆ as solid precursor. It also contains thermodynamic feasibility calculations (using the HSC 6.1^TM program) of possible reactions between the SiF_{x (x=1-4)} gas species (produced during the thermal decomposition of Na₂SiF₆), Al₄C₃ and N₂ in the atmosphere. The composites were fabricated using an L4 Taguchi experimental design, infiltrating SiC_p porous preforms at 1100 and 1200 °C in ultra high purity (UHP) argon and nitrogen (ArN₂) atmosphere for 90 and 120 min, with the Al-6Si-16Mg (wt. %) alloy. The specimens were characterized by XRD, SEM and EDS. Results show that the composites exhibit a surface hardness between 63.95 and 86.5 (HR30T) and Young´s modulus up to 118.2 GPa. Application of a post-processing stage by HYSYCVD led to the elimination of Al₄C₃ and the formation of a coating of stable phases on the composites surface. The experimental results confirm the thermodynamic feasibility of the proposed chemical reactions.

Abstract: Fe2O3 thin films were obtained on glass substrates by the ultrasonic spray pyrolysis technique; additionally, a thermodynamic analysis on the Fe2O3 formation from different precursor salts was performed. In this work, the influence of the deposition temperature is related with the structural, optical, and morphological properties of the iron oxide films. The present results reveal that amorphous thin films are obtained at temperatures lower than 350° C, while polycrystalline films with the maghemite structure are formed at higher temperatures.