Tunthawiroon, Phacharaphon

Preferred name

Alternative Name

TUNTHAWIROON, Phacharaphon

Tunthawiroon, P.

Main Affiliation

School of Engineering

phacharaphon.tu@kmitl.ac.th

Now showing 1 - 10 of 29

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Optical Properties of CuCdS Thin Film Prepared by Vacuum Thermal Evaporation Technique
(2023-01-01)
Hankoy, Montree
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Treetornkeerati, Paramapat
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Fungfuang, Natasia
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Khlayboonme, S. Tipawan
;
Kitiwan, Mettaya
This study reports on the synthesis and characterizations of copper cadmium sulfide (CuCdS) thin films prepared using the vacuum thermal evaporation technique with copper sulfide and CdS as precursors in a 1:1 molar ratio. The structural properties of the thin films were analyzed using X-ray diffraction (XRD) which revealed that the main composition of the thin film was CdS with the preferred orientation of the (101) plane. The optical properties were examined using UV–Vis spectrophotometry. The photosensitivity of the films was determined using I–V measurements performed with a two-probe technique. The prepared CuCdS thin films have high optical transmittance of 92%.
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Effect of Si on Microstructure and Corrosion Behavior of CoCrMo Alloys
(2018-06-04)
Peaubuapuan, Chonlawit
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Tunthawiroon, Phacharaphon
;
Kanlayasiri, Kannachai
;
Yuangyai, Chumpol
The aim of this research was to investigate the effect of silicon (Si) on the microstructure and corrosion behavior of CoCrMo alloys. The concentration of Si added in CoCrMo alloys was 0.1, 0.5 and 1 wt %. The corrosion behavior of the present alloys was investigated using potentiodynamic polarization measurements. The normal saline solution with 0.9 wt % was used as an electrolyte. Polarization curves obtained from the polarization test were used to evaluate in terms of corrosion current density (i<inf>corr</inf> ), corrosion potential (E<inf>corr</inf> ) and corrosion parameters that be used to compute corrosion resistant property of CoCrMo alloys. The microstructure of a sample during the polarization test was compared using X-ray diffraction (XRD) and optical microscope (OM). The results indicated that the increase in Si slightly changed the microstructure of CoCrMo alloys and could enhance the resistance to corrosion of CoCrMo alloys in NaCl solution. In addition, the reduction of Cr and Mo concentration in CoCrMo alloys was found to be a significant influence on the decrease in corrosion resistance.
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Characterization of intermetallic phase in as-cast Si-doped Co-Cr-Mo alloys
(2019-10-28)
Tunthawiroon, P.
;
Chiba, A.
This research aims to investigate the effects of Si concentrations on the microstructure and formation of the intermetallic phase of Co-Cr-Mo-xSi alloys. The Si concentration (x) was varied between 0.1, 0.5, 1.0, 3.0 and 5.0 wt%. The microstructure and intermetallic phase of the solution heat-treated Co-Cr-Mo alloys were characterized using SEM-EDX, XRD and TEM. The microstructure analysis revealed that Si concentration played a role in the evolution of intermetallic phase precipitating in Co-Cr-Mo alloys. Two types of intermetallic phased were found in the Si-doped Co-Cr-Mo alloys. The σ phase was identified in the alloys containing Si between 0.1-1.0 wt% while the increase in Si (3.0-5.0Si) contributed to the formation of the χ phase. The calculated lattice parameters of the intermetallic phase precipitated in the 3.0Si and 5.0Si alloys correlated well with those of Co<inf>5</inf>Cr<inf>3</inf>Si<inf>2</inf> phase.
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Possibility of metallic cobalt formation in the oxide scale during high-temperature oxidation of Co-27Cr-6Mo alloy in air
(2023-01-01)
Wongpromrat, Patthranit
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Tunthawiroon, Phacharaphon
;
Bumrungthaichaichan, Eakarach
;
Ponpo, Phisan
;
Nilsonthi, Thanasak
Co-based alloys are known to be high oxidation-resistant material and used in several high temperature applications. During high temperature oxidation, duplex oxides containing Co and Cr were formed. It was thermodynamically elucidated that when the growing scale was thick enough, the partial pressure of O<inf>2</inf> in the scale dropped. Then, the reduction of CoO occurred for promoting O<inf>2</inf> which was responsible for Cr<inf>2</inf>O<inf>3</inf> production. This work experimentally proved this point by in situ char-acterising Co-27Cr-6Mo at high temperatures in air by X-ray diffractometer in a grazing incident mode and metallic Co was confirmed to be formed by the reduction of CoO consistent with the image taken and analysed by field emission scanning electron microscope, energy-dispersive X-ray, and electron backscatter diffraction. Furthermore, the change in lattice parameter and the phase transition were observed when the temperature was altered.
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Effects of Surface Finishing Techniques on Properties of NiTi Coil Spring Actuators
(2025-01-01)
Premwattananarakul, Natakorn
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Srirussamee, Kasama
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Tunthawiroon, Phacharaphon
;
Kumnorkaew, Theerawat
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Phukaoluan, Aphinan
This research aims to investigate the effects of surface finishing techniques on phase transformation, topography, and recovery force of NiTi coil springs designed for actuator applications. The NiTi wire, with a diameter of 1 mm, was fabricated into a helical spring with an index of 9 and 20 active coils. The spring was subsequently annealed at 550 °C for 30 min and then quenched in water. The surface finishing techniques applied to the NiTi springs included chemical etching, mechanical polishing, and sand blasting. It was observed that mechanical polishing had a strong impact on topography than both chemical etching and sand blasting. After mechanical polishing, the topography of NiTi coil springs slightly changed compared to the annealed spring. The examined surface was smooth and glistening, with a surface roughness R<inf>a</inf> of 0.175 ± 0.006 µm, nearly identical to that of the annealed spring R<inf>a</inf> of 0.116 ± 0.021 µm. Chemical etching produced a surface oxide, yet the surface became rough due to an uncontrollable chemical reaction, i.e., the R<inf>a</inf> value obtained from chemical etched surface (1.177 ± 0.156 µm) was higher than that of the mechanically polished spring. Meanwhile, sand blasting provided a blue-shaded surface corresponding to an excessive R<inf>a</inf> of 1.952 ± 0.204 µm. The DSC results revealed two peaks of R-phase and martensite transformation in the cooling curve, with only austenite transformation appearing on the heating curve. According to the DSC curve, all surface finishing techniques can reduce the latent heat and affect the associated phase transformations. Consequently, the recovery force of the spring was increased by 2–5 times the initial length. The maximum stiffness (k) of 0.129 N/mm and recovery force for the surface-finished springs were provided by mechanical polishing, while the minimum values of 0.104 N/mm were yielded by sand blasting. All experimental findings offer a framework for the development of actuator springs enhanced through each surface finishing technique.
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Fabrication and characterization of lightweight aggregates with expanded perlite and NPK nutrient incorporation
(2025-06-01)
Rungrueng, Panadda
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Hankoy, Montree
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Kitiwan, Mettaya
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Keawprak, Nittaya
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Tunthawiroon, Phacharaphon
This study focuses on the development of porous lightweight aggregates incorporated with NPK fertilizer as a sustainable nutrient carrier for agricultural applications. The integration of expanded perlite (EP) as a pore-forming agent enabled the production of lightweight aggregates (EP-LWAs) at lower sintering temperatures (900 °C) while maintaining high porosity and water absorption properties, reducing energy consumption compared to conventional high-temperature ceramic processing. The optimized EP-LWAs exhibited a bulk density of 1.15 g/cm3, porosity of 46.09 %, and water absorption of 40.28 %, ensuring enhanced nutrient retention capacity. The fertilizer incorporation process was achieved using a simple vacuum infiltration technique, effectively loading the pellets with 1.2 % nitrogen (N), 2.6 % phosphorus (P), and 1.2 % potassium (K), surpassing typical soil nutrient levels and exhibiting comparable NPK content to organic fertilizers. These results highlight the potential of EP-LWAs as an energy-efficient and eco-friendly planting materials, offering a cost-effective for sustainable agriculture, green roof, and vertical gardening applications.
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Modification of Al2O3-Based Membranes with Carbon Black for Enhanced Hydrogen Permeation
(2025-11-01)
Hankoy, Montree
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Rodchom, Mana
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Vichaphund, Supawan
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Atong, Duangduen
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Zhang, Jianfeng
This work presents the development and characterization of alumina–carbon black (ACB) composite membranes for enhanced hydrogen separation performance. A series of membranes containing 0–3.0 wt.% carbon black was fabricated via high-temperature sintering and systematically investigated with respect to their structural, morphological, mechanical, and gas separation properties. The addition of carbon black significantly influenced membrane microstructure, promoting pore network formation, increasing specific surface area, and enhancing gas transport. Gas permeation tests using H<inf>2</inf> and N<inf>2</inf> revealed that all ACB membranes exhibited higher hydrogen permeance than the pure Al<inf>2</inf>O<inf>3</inf> membrane. Notably, the ACB3.0 specimen demonstrated the highest H<inf>2</inf> permeance of 508 × 10−6 mol m−2 s−1 Pa−1 at 303 K, which is nearly four times greater than the unmodified membrane. At an elevated temperature (773 K), H<inf>2</inf>/N<inf>2</inf> selectivity improved with increasing carbon black content, with ACB3.0 achieving a maximum selectivity of 3.82, exceeding the theoretical Knudsen value, suggesting a synergistic contribution of Knudsen diffusion and surface diffusion. These results demonstrate that carbon black is a cost-effective and versatile additive for modifying ceramic membranes, offering a promising route for advancing hydrogen purification technologies in industrial applications.
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Characterization of oxide films on wrought Co–Cr–Mo–xSi alloys exposed to high-temperature oxidation
(2021-10-01)
Tunthawiroon, Phacharaphon
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Kitiwan, Mettaya
;
Srirussamee, Kasama
;
Li, Yunping
;
Yamanaka, Kenta
Co-based alloys are currently being used in a wide range of high temperature applications owing to their high resistance to oxidation and corrosion. However, their oxidation-induced degradation could still occur during the long-term exposure to high temperature. Thus, the continuous development of oxidation-resistant Co-based alloys is of crucial importance. In this research, the influence of Si addition on the oxidation behavior of Co–Cr–Mo–xSi alloys under the isothermal oxidation treatment at 700 °C in air was investigated. The Si concentration (x) was varied from 0.1 to 5.0 wt.%. Surface morphologies and chemical compositions of the oxide films formed were analyzed by using SEM-EDS and XPS. The chemical compositions obtained from the surface analysis revealed that Si has played a role in the stabilization of Cr oxides on the surface of Co–Cr–Mo–xSi alloys. With increasing Si concentration, Co-oxide formation on the alloy surface was suppressed by the presence of Cr-oxide due to the selective oxidation of Cr atoms. Furthermore, SiO<inf>2</inf> was both found along the grain boundaries and interfaces between the outmost oxide layer and matrix. It was also found that the oxide thickness was reduced with increasing Si concentration. This was a result of the formation of stable Cr-oxide and SiO<inf>2</inf> sub-layer that became a barrier inhibiting the inward and outward diffusion of O and Cr.
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Evidence for chromium, cobalt and molybdenum volatilisations during high temperature oxidation of Co-27Cr-6Mo Alloy
(2022-07-01)
Wongpromrat, Patthranit
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Galerie, Alain
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Thublaor, Thammaporn
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Chandra-ambhorn, Walairat
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Ponpo, Phisan
A Co-27Cr-6Mo alloy was oxidised in pure O<inf>2</inf> between 800 and 1000 °C for durations up to 96 h. The flow rate was varied between 2 and 5 cm.s–1. In these conditions, volatilisations of chromium, cobalt and molybdenum were observed. The chromium volatilisation values were in good agreement with calculations assuming (CrO<inf>3</inf>)g volatilisation limited by diffusion in the gas boundary layer. On the contrary, the measured flux of evaporated Co was higher than the calculated Co volatilisation flux from the metallic Co. The theoretical relation between the solid Co particle size and its vapour pressure was suggested to help explaining such difference.
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Xps analysis of oxide formed on the surface of co-28cr-6mo-1si alloy oxidized at 550 ºc
(2020-01-01)
Tunthawiroon, Phacharaphon
;
Kitiwan, Mettaya
;
Wongpromrat, Patthranit
;
Chiba, Akihiko
This work investigated the influence of oxidation durations on the formation of oxide on the surface of wrought Co-28Cr-6Mo-1Si alloy. The iso-thermal oxidation was individually performed in air at 550ºC for 4, 12 and 24 h. For comparison, the surface of the non-oxidized Co-28Cr-6Mo-1Si alloy was concurrently examined. The chemical compositions of the non-oxidized and oxidized alloys were principally analyzed via X-ray photoelectron spectroscopy (XPS). The XPS results revealed that the surface of the non-oxidized alloy enriched in Cr-oxide. After oxidation treatment, the Co-oxide, existing as Co2+ state was observed coexisting with two Cr-oxide states, Cr3+ and Cr4+. The low concentrations of Mo6+ were also observed on the oxidized alloy surface. With the increase in oxidation durations, the Co-oxide was suppressed by Cr-oxide. The XPS depth profile analysis indicated that the thickness of the oxide film increased with increasing the oxidation duration.

Tunthawiroon, Phacharaphon

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