Oxidation Behavior of Nanostructure CrAlN Thin Films

Nirun Witit-anun — 2025-03-13

In this research, the nanostructure chromium aluminium nitride (CrAlN) thin films were prepared on silicon (100) substrate by reactive DC magnetron sputtering technique with Cr-Al alloy target and then annealing in air at different temperatures (500 - 900 °C) to investigate the oxidation behavior. The films' oxidation rate and oxidation activation energy were also calculated using parabolic relations and the Arrhenius equation. The X-ray diffraction (XRD) indicated that a solid solution CrAlN structure was found for the as-deposited thin film whereas the mixed oxide phase of Cr₂O₃ and Cr₅O₁₂ structures were discovered in the XRD spectra upon oxidation temperature at 800 °C. The XRD patterns were verified by the Energy dispersive X-ray spectroscopy (EDS) examination, which demonstrated the obvious increase of oxygen concentration at oxidation temperature from 800 °C due to the oxidation mechanism. The oxidation behavior was also confirmed by field-emission scanning electron microscopy (FE-SEM) analysis which the grain aggregation was observed while the cross-sectional microstructure of the thin films revealed that a very thin dense oxide layer was formed on the CrAlN layer. The oxide thickness increased from 648 nm to 1044 nm with increasing annealing temperature. The thin films began oxidizing above 800 °C, resulting in a porous structure. It was discovered that the as-deposited thin film exhibited a high-temperature oxidation resistance at 800 °C. The oxidation rate increased from 1.43 × 10^-13 to 3.78 × 10^-13 cm/s² and was obtained from an annealing temperature of 800 °C. The oxidation activation energy calculated from the Arrhenius plot was 99.85 kJ/mol. The nanoindentation technique also reported that the hardness of the films decreased from 15.92 to 0.03 GPa through the annealing temperature.

Evaluating a Small-scale Membrane Technology for Removing Salinity in Village Water Supply at Dan Kuntot, Nakhon Ratchasima

Saranbhak Chuersuwan — 2025-03-13

This study evaluates the use of a solar-powered membrane separation device to remove salinity from a village water supply in Dan Kuntot District. Water quality from surface water, freshwater, and tap water were tested for pH, temperature, turbidity, salinity, conductivity, and total dissolved solids (TDS). The results showed that surface water had high levels of salinity (1.6-2.1 ppt), conductivity (3495-3982 µS/cm, and TDS (2097-2351 mg/L). The surface water had a pH in the range of 5.7 to 6.2, temperatures of 27.6 to 29.3 Celsius, and turbidity of 6.8 to 10.1 NTU. The freshwater from the village water supply had a comparable pH (5.5-6.9). Turbidity levels were low (0.25-0.27 NTU). Conductivity and TDS levels were a bit lower to 3342-3415 µS/cm and 2005-2049 mg/L, respectively. Salinity levels remained high, 1.6 ppt. The village water treatment process cannot remove salt molecules. The tap water had an undetected salinity level after the freshwater passed through the membrane device. Conductivity and TDS were much lower, ranging from 14 to 19 µS/cm and 9 to 12 mg/L, respectively. The solar-powered small membrane separation could remove salinity as high as 2.1 ppt down to undetected level. The device could separate salt molecules using membrane technology, significantly reducing salinity levels in the tap water. Conductivity and TDS levels were also considerably lower in the tap water, with more than a 99 percent reduction. However, the produced water had low pH levels. Adding alkalinity would bring the pH close to neutral.

Suan Sunandha Science and Technology Journal

Oxidation Behavior of Nanostructure CrAlN Thin Films

Evaluating a Small-scale Membrane Technology for Removing Salinity in Village Water Supply at Dan Kuntot, Nakhon Ratchasima