Sakdanuphab, Rachsak

Preferred name

Alternative Name

Sakdanuphab, R.

Sakdanuphab, Rachasak

Main Affiliation

College of Advanced Manufacturing Innovation

rachsak.sa@kmitl.ac.th

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Figures of merit of low-cost CuAl0.9Fe0.1O2 thermoelectric material prepared at different solid state reaction sintering temperatures
(2015-01-01)
Sakulkalavek, Aparporn
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Thonglamul, Rungnapa
;
Sakdanuphab, Rachsak
In this study, we investigated a CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> compound prepared at two different sintering temperatures in order to find out the effects of sintering temperature on the compound's figure of merit of thermoelectric properties. The thermoelectric CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> compounds were prepared from high purity grade Cu<inf>2</inf>O, Al<inf>2</inf>O<inf>3</inf> and Fe<inf>2</inf>O<inf>3</inf> powders. The mixture of these powders were ground and then pressed with uniaxial pressure into pellets. The pellets obtained were sintered in the air at 1423K and 1473K. X-ray diffraction (XRD) patterns showed a single phase of CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> with rhombohedral structure, R3¯m, along with a trace of CuO second phase. Moreover, the XRD peaks of the sample sintered at 1423K indicated that more Fe3+ atoms replaced Al3+ atoms in this sample than they did in the sample sintered at 1473K. The average grain size of the CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> compound prepared increased with increasing sintering temperature, whereas its mean pore size and porosity decreased with increasing sintering temperature. The dispersed small pores markedly decreased the thermal conductivity of the compound, while the Fe3+ substitution of Al3+ increased its electrical conductivity. The highest figure of merit (ZT) found was 0.021 at 973K in the CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf> sample sintered at 1423K. Our findings show that this low-cost material with a reasonable figure of merit is a good candidate for thermoelectric applications at high-temperature.
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Effect of annealing temperature on thermoelectric properties of bismuth telluride thick film deposited by DC magnetron sputtering
(2020-07-15)
Kianwimol, Supasak
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Sakdanuphab, Rachsak
;
Chanlek, Narong
;
Harnwunggmoung, Adul
;
Sakulkalavek, Aparporn
We report the thermoelectric properties of thick bismuth-telluride (Bi<inf>2</inf>Te<inf>3</inf>) films deposited on polyimide substrates by DC magnetron sputtering and annealed at various temperatures (150–350 °C). The influence of annealing temperature on the microstructure and electronic structure of thick Bi<inf>2</inf>Te<inf>3</inf> films is discussed. In this work, the annealed film at 250 °C has the best thermoelectric property due to highest electrical conductivity and Seebeck coefficient. The main effect of annealing temperature was really helpful to improve crystalline structure and enhance carrier mobility, whereas the carrier concentration was reduced due to the volatile of tellurium atom during annealing. Chemical states of bound and unbound atoms (Bi, Bi3+, Te, and Te2‐) on the surface play an important role in electrical properties. The exceed temperature caused the micro-crack formation and affect carrier transport by the scattering. The power factor of Bi<inf>2</inf>Te<inf>3</inf> deposited by DC magnetron sputtering and annealed at 250 °C is comparable to the power factors of thick Bi<inf>2</inf>Te<inf>3</inf> film deposited by various deposition techniques. The output power of single-leg, thick, thermoelectric Bi<inf>2</inf>Te<inf>3</inf> film annealed at 250 °C as a function temperature generated a power of 0.98 μW at a temperature difference of 50 °C.
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Achieving thermoelectric improvement through the addition of a small amount of graphene to CuAlO2 synthesized by solid-state reaction
(2018-07-15)
Daichakomphu, Noppanut
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Sakdanuphab, Rachsak
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Harnwunggmoung, Adul
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Pinitsoontorn, Supree
;
Sakulkalavek, Aparporn
In this work, delafossite CuAlO<inf>2</inf> powders with graphene (0.00–0.20 wt%) were synthesized by a solid-state reaction method. X-ray diffraction and transmission electron microscope results indicated that graphene was segregated in CuAlO<inf>2</inf> as a split phase, such as composite material. A little addition of graphene content reduces the thermal conductivity and increases the carrier concentration because the graphene generates many point defects and aided carrier-phonon scattering. The CuAlO<inf>2</inf> with graphene content of 0.05 wt% shows the maximum electrical conductivity of 470 S/m at 700 K. In addition, the maximum value for ZT of 0.0045 was recorded at 575 K with the graphene/CuAlO<inf>2</inf> composite (0.05 wt%). Therefore, in brief, this study has highlighted the benefits of combining delafossite CuAlO<inf>2</inf> with a small amount of graphene as a potential route for achieving highly efficient thermoelectric materials.
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Structural, morphological and adhesion properties of coFeB thin films deposited by DC magnetron sputtering
(2013-10-29)
Ibuki, Chuleerat
;
Sakdanuphab, Rachasak
In this work the effects of amorphous (glass) and crystalline (Si) substrates on the structural, morphological and adhesion properties of CoFeB thin film deposited by DC Magnetron sputtering were investigated. It was found that the structure of a substrate affects to crystal formation, surface morphology and adhesion of CoFeB thin films. The X-Ray diffraction patterns reveal that as-deposited CoFeB thin film at low sputtering power was amorphous and would become crystal when the power increased. The increase in crystalline structure of CoFeB thin film is attributed to the crystalline substrate and the increase of kinetic energy of sputtering atoms. Atomic Force Microscopy images of CoFeB thin film clearly show that the roughness, grain size, and uniformity correlate to the sputtering power and the structure of substrate. The CoFeB thin film on glass substrate shows a smooth surface and a small grain size whereas the CoFeB thin film on Si substrate shows a rough surface and a slightly increases of grain size. Sticky Tape Test on CoFeB thin film deposited on glass substrate indicates the adhesion failure with a high sputtering power. The results suggest that the crystalline structure of substrate affects to the atomic bonding and the sputtering power affects to intrinsic stress of CoFeB thin film. © (2013) Trans Tech Publications, Switzerland.
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Figure of merit improvement of delafossite CuAlO2 with the addition of Fe and graphene
(2019-11-01)
Daichakomphu, Noppanut
;
Harnwunggmoung, Adul
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Chanlek, Narong
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Sakdanuphab, Rachsak
;
Sakulkalavek, Aparporn
This study investigated the synthesis of delafossite CuAlO<inf>2</inf> with Fe and graphene through a solid-state reaction method. The results of X-ray diffractometry showed that graphene was insoluble in delafossite CuAlO<inf>2</inf> while Fe was substituted into Al sites, expanding the d-spacing. From X-ray photoelectron spectroscopy, graphene induced excess oxygen in the delafossite CuAlO<inf>2</inf> structure via C–O–Cu bonds and improved the electrical conductivity. In addition, the thermal conductivity was reduced due to generation of point defects, phonon-phonon Umklapp and carrier-phonon scattering. The addition of Fe and graphene in CuAlO<inf>2</inf> shows an improvement of ZT to 0.0114 at 573 K. This is attributable to its increase in charge carrier density, as well as a decrease in thermal conductivity. This study highlights the benefits of combining Fe and graphene in delafossite CuAlO<inf>2</inf> as a prospective process for attaining a high figure of merit thermoelectric materials.
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Effects of iron doping on the oxidation/reduction properties of delafossite CuAlO2 synthesized via a solid-state reaction
(2020-06-01)
Daichakomphu, Noppanut
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Sakulkalavek, Aparporn
;
Sakdanuphab, Rachsak
CuAlO<inf>2</inf> has received a wealth of interdependent research associated with hydrogen-based catalysis in the chemical industry. Herein, Fe-doped CuAlO<inf>2</inf> is demonstrated to reduce the redox temperature for delafossite CuAlO<inf>2</inf>. Time-resolved X-ray absorption spectroscopy and hydrogen temperature-programmed reduction were used to characterize the redox properties, respectively. Delafossite CuAlO<inf>2</inf>, with and without Fe doping at 10 at% (CuAl<inf>0.9</inf>Fe<inf>0.1</inf>O<inf>2</inf>), was synthesized via a one-step solid-state reaction method. The results demonstrate that the redox temperature can be reduced by ~ 60 K for the 10 at% Fe-doped catalyst. The findings of this contribution offer a new approach to circumvent the high temperatures associated with the redox processes, and furthermore, offer a design basis for the development of new catalyst systems with enhanced regeneration abilities.
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Enhanced thermoelectric properties of bismuth telluride via Ultra-Low thermal conductivity BOSC compound addition
(2024-12-01)
Theekhasuk, Nattharika
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Somdock, Nuttakrit
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Voraud, Athorn
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Limsuwan, Pichet
;
Sakdanuphab, Rachsak
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–1·K–1 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.
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Strong electron–phonon coupling and predicted high superconducting transition temperature of MXenes revealed in 2H-Mo2N under biaxial stress
(2024-12-15)
Kotmool, Komsilp
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Tsuppayakorn-aek, Prutthipong
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Bovornratanaraks, Thiti
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Kaewmaraya, Thanayut
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Sakdanuphab, Rachsak
Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (T<inf>c</inf>). This work theoretically reports strong electron–phonon coupling (EPC) and high T<inf>c</inf> (≈38 K) of 2H-Mo<inf>2</inf>N under biaxial stress, with excellent mechanical properties. EPC and T<inf>c</inf> are elucidated upon dynamically stable strain range. At 0% strain, EPC constant (λ) and T<inf>c</inf> are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with λ over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced T<inf>c</inf>. The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The λ’s of Mo<inf>2</inf>NH<inf>2</inf> and Mo<inf>2</inf>NO<inf>2</inf> are reduced, and T<inf>c</inf> drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.
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A Study on the Laser Bending of AISI303 Stainless Steel Sheets under Active Heat Control Temperature
(2024-09-01)
Boonpuang, Ruksakul
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Sakulkalavek, Aparporn
;
Sakdanuphab, Rachsak
In this paper, a novel approach called active heat control (AHC) is proposed to determine effective parameters in the laser bending process on AISI303 sheets. This approach has the advantages of precise control during the bending process, ensuring the temperature limit of the metal sheet. Three process parameters, material thickness, surface temperature, and laser scanning speed, are varied to investigate their effects on bending angles and to optimize the process. A full factorial design of experiment method with 72 experiments was executed using a direct diode laser with active heat control on AISI303 sheets. Analysis of Variance (ANOVA) results indicate that all three parameters have a significant impact on the bending angle. The bending angles increase with the decrease in material thickness and laser scanning speed while the increase of temperature results in the increase of bending angle. Results showed that the AHC laser forming can effectively increase the bending angle with shorter time compared with constant power laser bending method. Moreover, it is crucial to control a consistent temperature at a lower level 500 °C, to minimize the burning edge effect of AISI303 sheets while still achieving effective bending. The findings of this study show the benefits of adopting AHC in manufacturing processes that demand cleanliness.
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Study of corrosion properties of carbon steel, 304 and 316L stainless steels in sulfuric acid and their degradation products
(2023-01-01)
Khamme, Eakapoj
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Sakdanuphab, Rachsak
In this study, corrosion properties of carbon steel and stainless steels, and degradation of sulfuric acid by the corrosion mechanism are presented. Carbon steel (CS), 304 stainless steel (SS304), and 316L stainless steel (SS316L) specimens were analyzed through their electrochemical response by using a potentiostat measurement. The specimens were submerged in concentrated 98 wt.% of H<inf>2</inf>SO<inf>4</inf> acid for 0 day to 60 day. The degradation of H<inf>2</inf>SO<inf>4</inf> was determined by its volume change, turbidity, and color due to the corrosion mechanism. Corrosion rate of CS, SS304 and SS316L specimens are 43.237 mm/year, 0.420 mm/year and 0.086 mm/year, respectively. After 60 days, the weight-loss of CS, SS304 and SS316L specimens are 48 wt%, 33 wt% and 0.1 wt%, respectively. Corrosion resistance of the materials are influenced by the passive oxide layer that forms on its surface and associated with electrochemical activity or semiconductive composition. The degradation of H<inf>2</inf>SO<inf>4</inf> acid was observed due to the corrosion process of specimens and related to the turbidity and volume increase while the wt% concentration of H<inf>2</inf>SO<inf>4</inf> acid decreases. In order to make material choices that enable continuous and safe operation of the process, it is important to understand the corrosion mechanism changes.

Sakdanuphab, Rachsak

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