Sakdanuphab, Rachsak
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Sakdanuphab, Rachsak
Alternative Name
Sakdanuphab, R.
Sakdanuphab, Rachasak
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Email
rachsak.sa@kmitl.ac.th
15 results
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Item type:Publication, Advanced AlN/SiO2/AlN multilayer coatings for protecting gold-like decorative surfaces: Improved hardness and color stability(2025-12-01); ; This study explores the development of multilayer AlN/SiO<inf>2</inf>/AlN thin film coatings to enhance tarnish resistance, surface hardness, and color stability of gold-coated silver substrates for decorative use. Gold films were deposited via electroplating, followed by multilayer coatings using reactive magnetron sputtering. The SiO<inf>2</inf> thickness was systematically varied while maintaining fixed AlN layers. Optical evaluations using CIE Lab parameters confirmed that the specimen with a 110-min SiO<inf>2</inf> layer exhibited acceptable color difference (ΔE < 5). X-ray photoelectron spectroscopy (XPS) revealed stable Al–N and Si–O bonds with minimal oxidation. Nanoindentation tests showed a significant hardness increase, reaching 7.02 ± 0.62 GPa. After 240 days of ambient exposure, multilayer-coated samples showed no visible discoloration or sulfur-induced degradation, unlike uncoated and electrochemically coated samples. These results confirm that AlN/SiO<inf>2</inf>/AlN multilayers effectively improve the durability and aesthetic stability of gold-like surfaces, offering a promising solution for long-term decorative applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simultaneous Seebeck coefficient and electrical conductivity enhancement of GeSbTe films via Sn addition(2022-06-15); ; Sn-added GeSbTe (GST) thin films were deposited using a co-magnetron sputtering technique. The effects of varying the Sn content through a variable Sn target sputtering power and post annealing at 673 K were investigated. The DC power density applied to the GST target was controlled at 50 W, while the power density of the Sn target was increased from 0 W to 40 W. The results demonstrate the coexistence of the fcc-GST, hcp-GST and SnTe phases in the Sn-added GST thin films. The substitution of Sn at the Ge-site increases the crystallization speed and leads to defects and lattice disordered local arrangement in the GST films, causing the Seebeck coefficient to increase. The SnTe phase was created as a result of the high Sn content in the sample due to the over-doping limit of Sn into the GST structure. The presence of SnTe in Sn-doped GST films increased the electrical conductivity. The maximum power factor of 17.0 μW/cmK<sup>2</sup> at 450 K was obtained at an Sn content of 14.7 at%. These results indicated that the thermoelectric properties of Sn-doped GST films were improved via the formation of an appropriate amount of SnTe composite. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Sputter-deposited AlN coatings for enhanced tarnish resistance and mechanical durability of silver jewelry(2026-04-01); ; ; Silver jewelry is prone to surface tarnishing caused by sulfur-containing species in ambient environments. In this study, a transparent aluminum nitride–based thin film was deposited by magnetron sputtering and evaluated as a protective barrier against silver tarnishing. Sheets of 99.9% pure silver were coated under various nitrogen flow conditions to optimize film composition and performance. An appropriate nitrogen flow rate of 25 standard cubic centimeters per minute (sccm), corresponding to an N₂/Ar gas ratio of approximately 1:1, was identified for forming AlN-rich films, while an AlN-based film thickness in the range of 80–110 nm was found to be suitable for jewelry protection. X-ray photoelectron spectroscopy analysis showed that insufficient nitrogen availability suppresses complete nitridation, resulting in residual metallic aluminum, which readily reacts with residual oxygen and moisture, increasing the oxygen content in the films. At an N₂ flow rate of 25 sccm, metallic aluminum was suppressed and the films were dominated by Al–N bonding with minor oxygen incorporation, accompanied by the development of a polycrystalline structure. Nanoindentation measurements performed on the 110 nm-thick film yielded a peak hardness of approximately 3.6 GPa, indicating enhanced mechanical durability compared with uncoated silver. Comparative evaluation of color difference, mechanical hardness, tarnish resistance, and environmental durability demonstrated improved performance of the AlN-coated silver. Finally, the practical applicability of the coating was demonstrated by depositing AlN-based films onto large and intricately designed silver jewelry items, indicating compatibility with industrial-scale processing. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Optimizing Waste Heat Conversion: Integrating Phase-Change Material Heatsinks and Wind Speed Dynamics to Enhance Flexible Thermoelectric Generator Efficiency(2024-01-01); ; ; Flexible thermoelectric generators (FTEGs) have garnered significant attention for their potential in harnessing waste heat energy from various sources. To optimize their efficiency, FTEGs require efficient and adaptable heatsinks. In this study, we propose a cost-effective solution by integrating phase-change materials into FTEG heatsinks. We developed and tested three flexible phase-change material thicknesses (4 mm, 7 mm, and 10 mm), focusing on preventing leaks during operation. Additionally, we investigated the impact of wind speed on the output performance of FTEGs with a flexible phase-change material heatsink. The results indicate that the appropriate flexible phase-change material thickness, when integrated with considerations for wind speed, demonstrates remarkable heat-absorbing capabilities at phase-change temperatures. This integration enables substantial temperature differentials across the FTEG modules. Specifically, the FTEG equipped with a 10 mm thick flexible phase-change material heatsink achieved a power density more than four times higher when the wind speed was at 1 m/s compared to no wind speed. This outcome suggests that integrating phase-change material heatsinks with relatively low wind speeds can significantly enhance flexible thermoelectric generator efficiency. Finally, we present a practical application wherein the FTEG, integrated with the flexible phase-change material heatsink, efficiently converts waste heat from a circular hot pipe into electricity, serving as a viable power source for smartphone devices. This work opens exciting possibilities for the future integration of flexible thermoelectric modules with flexible phase-change material heatsinks, offering a promising avenue for converting thermal waste heat into usable electricity. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Post-ball-milling-assisted solid-state synthesis of Bi4O4SeCl2: A low thermal conductivity material(2025-02-01); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhanced thermoelectric properties of Cu2Se via Sb doping: An experimental and computational study(2023-02-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of real working environment/formation of oxide phase on thermoelectric properties of flexible Sb2Te3 films(2019-09-01); ; Flexible Sb<inf>2</inf>Te<inf>3</inf> thin films, for thermoelectric generator applications, were deposited by DC magnetron sputtering. As-deposited films were annealed in air to simulated a realistic operating environment. The oxidation behavior of the films was studied by monitoring their phase change on exposure to air at different temperatures between 50 and 300 °C for annealing times from 1 to 15 h. Oxidation of Sb and Te formed Sb<inf>2</inf>Te<inf>4</inf> and TeO<inf>2</inf> phases when annealing above 100 °C and Sb<inf>2</inf>Te<inf>3</inf> decomposed into oxide phases at an annealing temperature of 250 °C for 15 h. The thermoelectric performance decreased as the content of Sb<inf>2</inf>O<inf>4</inf> and TeO<inf>2</inf> phases increased. These findings show the limitations of Sb<inf>2</inf>Te<inf>3</inf> films operating in air without vacuum or a protective environment. We propose that the kinetic growth of oxide formation on the Sb<inf>2</inf>Te<inf>3</inf> thin films depend on chemical activation energy and oxygen diffusion through the oxide barrier by the variation of annealing temperature and annealing time, respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhancement of thermoelectric properties in rapidly synthesised β-Cu2Se using optimized Cu content and microwave hybrid heating(2024-01-15); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhanced thermoelectric properties of bismuth telluride via Ultra-Low thermal conductivity BOSC compound addition(2024-12-01); ; This study aimed to enhance the thermoelectric properties of bismuth telluride by adding Bi<inf>4</inf>O<inf>4</inf>SeCl<inf>2</inf> (BOSC). Commercial N-type bismuth telluride was mixed with BOSC powder in varying concentrations. As the BOSC content increased, the carrier concentration also rose due to chlorine atoms acting as donor impurities. Despite this increase, the power factor values of the samples with BOSC additives did not significantly differ from those of the bare bismuth telluride sample. However, the total thermal conductivity decreased significantly with the addition of BOSC, reaching a minimum value of 0.54 W·m<sup>–1</sup>·K<sup>–1</sup> at 150 °C for the sample with 1 wt% BOSC. Notably, the ZT value for the sample with 1 wt% BOSC was about 0.86, which is four times higher than that of the bare bismuth telluride sample. Our findings demonstrate superior thermoelectric performance, indicating a more efficient modification of thermoelectric properties through the addition of BOSC to the bismuth telluride matrix. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simultaneous stoichiometric composition and highly (00l) orientation of flexible Bi2Te3thin films via optimising the DC magnetron sputter-deposition process(2019-01-30); ; Simultaneous stoichiometric composition and highly (00l) orientation of flexible Bi<inf>2</inf>Te<inf>3</inf> thin films were investigated under the DC magnetron sputtering parameters. Stoichiometric Bi<inf>2</inf>Te<inf>3</inf> and highly (00l) orientation structure was obtained by sputtering conditions, preheat temperature at 350 °C, and working pressure of 1.8 × 10<sup>−3</sup> mbar. This designed structure of layered compact feature with stoichiometry provide the relatively high mobility. The maximum carrier mobility of 118 cm<sup>2</sup>/V was observed for highly (00l) film. The electrical conductivity of thin film has been greatly enhanced, to a maximum of about 14.90 × 10<sup>3</sup> S/cm at 50 °C. This value is higher than those of hot-pressed or spark plasma sintering n-type Bi<inf>2</inf>Te<inf>3</inf> bulk alloys. The maximum power factor of 12.5 × 10<sup>−3</sup> W/m.K<sup>2</sup> was obtained at 300 °C.