Rudradawong, Chalermpol
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Preferred name
Rudradawong, Chalermpol
Alternative Name
Rudradawong, C.
Main Affiliation
Email
chalermpol.ru@kmitl.ac.th
18 results
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Item type:Publication, High temperature electrical and thermal properties of activated bamboo charcoal/C12A7 mayenite composite prepared by carbon diffusion process(2019-03-15); Activated carbon from bamboo charcoal (BC) was diffused into the C12A7 mayenite compound via carbon diffusion process for synthesizing BC and C12A7 composite (BC/C12A7 composite). The BC/C12A7 composite was fabricated by carbon diffusion at holding time 5, 10 and 20 h for investigating electrical and thermal properties at high temperature. Result of XRD revealed the C12A7 structure and confirmed by Raman spectrum. Obtained energy gap showed at 4.93, 5.26, 5.19 and 5.09 eV at holding times of 0, 5, 10 and 20 h, respectively. Electrical conductivity significantly increased with increasing temperature and increased as a function of increasing holding time. Carrier concentration showed approximately 1.27 × 10 <sup>17</sup> , 1.32 × 10 <sup>17</sup> and 2.76 × 10 <sup>17</sup> cm <sup>−3</sup> of 5, 10 and 20 h, respectively. Temperature dependence of thermal conductivity showed as proportion of T <sup>−1</sup> due to phonon-phonon scattering of Umklapp process. The thermal conductivity decreased from pristine C12A7 approximately 0.4 W m <sup>−1</sup> K <sup>−1</sup> in all BC/C12A7 composite samples. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tuning the thermoelectric performance of flexible copper selenide thin films through sputtering pressure and hybrid microwave annealing(2025-10-10); - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Dual optimization of ZT and output power in bulk Bi2Te3 through metal-assisted chemical etching(2026-03-01); ; Nguyen, Duc NamThermoelectric materials offer a promising route for sustainable energy harvesting by directly converting waste heat into electricity, enabling compact, solid-state, and environmentally friendly energy solutions. Among them, bismuth telluride (Bi₂Te₃) stands out as the benchmark material for near-room-temperature applications due to its excellent electronic transport properties and commercial maturity. However, achieving high-performance in bulk or thick-film Bi₂Te₃ remains a formidable challenge. Conventional strategies such as doping, alloying, and nanoinclusion, while successful in thin films, often fail to translate effectively to bulk systems due to issues like pore collapse, poor uniformity, and degraded electrical connectivity. These limitations hinder the formation of efficient phonon-scattering architectures without compromising charge transport, resulting in limited improvement in the thermoelectric figure of merit (ZT). In this study, we present a novel and scalable nanoengineering strategy that applies metal-assisted chemical etching (MACE) to fabricate nanoporous surface layers on bulk Bi₂Te₃ for the first time. Unlike conventional nanostructuring techniques, MACE enables the formation of oriented nanostructures via a simple wet-chemical process, offering high tunability, low cost, and compatibility with large-area substrates. To reduce interfacial resistance, nickel was subsequently electrodeposited onto the nanostructured surface, forming a conformal contact layer that improves charge extraction and output performance. By systematically tuning the MACE duration, the optimized nanostructured Bi₂Te₃ sample exhibited a 2.3-fold improvement compared to the pristine bulk sample. Furthermore, due to the increased surface area from the nanoporous architecture, the internal resistance and output power of the nanostructured Bi₂Te₃ devices demonstrated 25-fold and 5.8-fold improvments, respectively, relative to the untreated sample. These remarkable improvements are attributed to the synergistic effect of enhanced phonon scattering within the nanoporous layer and improved charge transport enabled by the conformal nickel coating. This work not only introduces a powerful nanostructuring route for Bi₂Te₃ but also establishes a practical platform for high-performance, thick-film thermoelectric devices. The findings offer deep insight into the structure, property, and performance relationships governing thermoelectric efficiency and pave the way toward the scalable fabrication of next-generation thermoelectric modules for real-world applications such as industrial waste heat recovery and self-powered electronics. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Positive ionic conduction of mayenite cement Ca12Al14O33/nano-carbon black composites on dielectric and thermoelectric properties(2020-03-01); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Optimal AIN film deposition conditions for enhancing surface corrosion resistance and silver appearance(2026-05-01); ; ; This study investigates the development of AlN thin-film protective coatings for enhancing the corrosion resistance, surface hardness, and color stability of Ag 925 substrates used in decorative and wearable applications. AlN coatings were deposited by reactive DC magnetron sputtering, and the influences of working pressure and film thickness on bonding chemistry, oxygen incorporation, optical appearance, and artificial-sweat corrosion resistance were systematically evaluated. Increasing the working pressure promoted Al–O bond formation and noticeable surface discoloration, consistent with enhanced oxygen uptake that disrupted the near-surface Al–N bonding network. In contrast, films deposited within a moderate pressure window (2.5–7.5 × 10<sup>−1</sup> Pa) exhibited minimal color change (ΔE < 3), maintained stable Al–N bonding characteristics, and achieved a hardness of approximately 5.2 GPa. Film thickness further governed the protective performance: ultrathin AlN layers provided only limited resistance, whereas coatings thicker than ~ 300 nm significantly improved surface resistance, as supported by the reduced chloride-induced discoloration (ΔE decreased from ~ 33.6 to ~ 11) and the effective suppression of Ag and Cu oxidation, as confirmed by FE-SEM/EDS analysis. These results demonstrate that both an optimal working pressure regime and a sufficiently thick coating (> 300 nm) are essential for achieving long-term color stability and corrosion resistance in wearable silver applications. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Energy-saving synthesis and β-phase enhancement of Cu2Se thermoelectric materials via the microwave hybrid heating technique(2021-10-25); ; ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, High-performance flexible thermoelectric generator based on silicone rubber and cover with graphite sheet(2024-01-05); ; ; Junlabhut, PrasoppornHarvesting thermal energy through a flexible thermoelectric generator (FTEG) offers an excellent micro-power solution for energizing node sensors in the realm of Internet of Things (IoT) and wearable electronics. Nonetheless, current FTEG suffer from drawbacks including low efficiency, significant thermal resistance, and complex manufacturing procedures. In this study, a high-performance FTEG using silicone rubber was designed and fabricated using a straightforward process. The finite-element method was used to optimize the copper electrode thickness, and the bendable substrate layers with various thermal conductivity were studied for the first time. The copper electrode thickness of 0.1 mm was selected because it offers high flexibility and bendability while still providing a relatively high-power output. The 5 × 5 cm<sup>2</sup> FTEG device was fabricated and covered with a bendable substrate. Silicon rubber (0.08 Wm<sup>−1</sup>K<sup>−1</sup>), silicon rubber added 5% graphene (0.14 Wm<sup>−1</sup>K<sup>−1</sup>), and graphite sheets (15 Wm<sup>−1</sup>K<sup>−1</sup>) were used as bendable substrates. The FTEG cover with graphite sheets has a maximum output voltage of 1.1 V under a temperature difference (ΔT) at 65 °C. Its maximum output power is 162.4 mW, corresponding to a power density of 6499.1 µW/cm<sup>2</sup> under the same above ΔT. The experimental findings indicated that integrating a bendable substrate with high thermal conductivity and electrical insulation properties enhances the performance of the FTEG. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of Ga-substitution for Fe sites of delafossite CuFe1-xGaxO2 (X = 0.0, 0.1, 0.3, 0.5) on thermal conductivity(2016-03-05); This work aimed to study the effect of the Ga<sup>3+</sup>-substitution of Fe<sup>3+</sup> sites in CuFeO<inf>2</inf> delafossite on its thermal conductivity. CuFe<inf>1-x</inf>Ga<inf>x</inf>O<inf>2</inf> (x = 0, 0.1, 0.3, and 0.5) samples were synthesized and their phase structure and ionic composition were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The thermal conductivity of the samples was measured at a high temperature range of 298-573 K. The XRD results confirmed that the samples were pure phase delafossite with hexagonal structure space group: R3m while the EDX results showed composition atomic percent of Ga 100% of x = 0.1, 93% of x = 0.3 and 90% of x = 0.5 and the XPS results revealed Cu<sup>1+</sup> and Cu<sup>2+</sup>, Fe<sup>2+</sup> and Fe<sup>3+</sup>, and Ga<sup>3+</sup> ion states in the structure. The Ga-substitution decreased the thermal conductivity of the samples below that of nondoped CuFeO<inf>2</inf>. The high substitution sample (x = 0.5) exhibited the lowest thermal conductivity, 2.5 W/mK at 573 K. Ga substitution into Fe sites affected the lattice thermal conductivity partly through phonon scattering processes arising from mass difference and lattice strain. - 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, Flexible thermoelectric cooler with optimized fill factor and radiative cooling integration for energy-efficient wearable thermal management(2025-12-01);