Tunthawiroon, Phacharaphon

Preferred name

Alternative Name

TUNTHAWIROON, Phacharaphon

Tunthawiroon, P.

Main Affiliation

School of Engineering

phacharaphon.tu@kmitl.ac.th

Now showing 1 - 7 of 7

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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
;
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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Characterization of oxide films on wrought Co–Cr–Mo–xSi alloys exposed to high-temperature oxidation
(2021-10-01)
Tunthawiroon, Phacharaphon
;
Kitiwan, Mettaya
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Srirussamee, Kasama
;
Li, Yunping
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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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Comparative study of vacuum arc-remelting and spark plasma sintering processes on microstructure and corrosion behavior of Cp-Ti for biomedical implant applications
(2025-11-01)
Kunbuala, Neeraphat
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Srirussamee, Kasama
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Phamornnak, Chinnawich
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Tunthawiroon, Phacharaphon
;
Hankoy, Montree
Titanium (Ti) and its alloys are widely used for biomedical applications due to their excellent mechanical properties and biocompatibility. However, the selection of an appropriate manufacturing process is critical to ensuring the optimal performance of Ti-based implants. This study investigates the effects of two fabrication methods –vacuum arc remelting (VAR) and spark plasma sintering (SPS) – on the microstructure and corrosion behavior of commercially pure titanium (Cp-Ti). VAR-Ti ingots were fabricated using arc-melting with multiple remelting cycles, whereas SPS-Ti specimens were sintered from Ti powders under pressure and pulsed current in a high-vacuum environment. Both specimens were subsequently heat-treated at 800 °C and furnace cooled. Microstructural characterization revealed coarser grains and porosity in VAR-Ti, while SPS-Ti showed refined, uniform α-phase structures. Electrochemical tests, including OCP, polarization, EIS, and ICP-MS, indicated slightly enhanced corrosion resistance in SPS-Ti, attributed to its defect-free microstructure. XPS analysis confirmed TiO<inf>2</inf> surface formation on both samples. Additionally, both materials exhibited high ductility and excellent biocompatibility, with cell viability exceeding ISO 10993-5 thresholds. These findings highlight the advantage of SPS in producing defect-minimized Cp-Ti with improved corrosion behavior for biomedical applications.
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Influence of mouthwash rinsing on the mechanical properties of polymeric ligature ties used for dental applications
(2021-07-02)
Phukaoluan, Aphinan
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Khantachawana, Anak
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Dechkunakorn, Surachai
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Anuwongnukroh, Niwat
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Tunthawiroon, Phacharaphon
Mouthwashes are used during dental treatments to mitigate the complications caused by poor oral hygiene. However, these solutions also affect the properties of dental appliances, including those used in orthodontics. This point has been investigated in this study focusing on the changes in mechanical properties of polymeric orthodontic ligature ties. Commercial ties from four brands were characterized in terms of their maximum forces and displacement, delivery forces, molecular structures, and microscopic morphology. These properties were compared against the ties, which were rinsed with commercial mouthwashes from three manufacturers. The results showed that mouthwash rinsing significantly reduced the maximum bearable forces of ligature ties by up to 73.1%, whereas the reduction in their maximum displacement was up to 74.5% across all tested brands. Significant changes in microscopic morphology of ligature ties were observed after mouthwash rinsing, but not their molecular structure. Furthermore, mouthwash rinsing also reduced the delivery forces from ligature ties by between 20.9 and 32.9% at their first deformation cycle. It can be concluded from this study that mouthwashes have significant impact on the mechanical properties of polymeric orthodontic ligature ties and could also potentially affect the overall efficacy of orthodontic and other dental treatments.
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The Addition of Fluoride to the Eggshell-derived Hydroxyapatite: A Preliminary Study
(2021-01-01)
Uthayaphamornwat, Vilasinee
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Suksap, Arissara
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Khantachawana, Anak
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Kitiwan, Mettaya
;
Srirussamee, Kasama
Dental caries are one of the major oral health problems, which could be mitigated by addressing the dental defects. Hydroxyapatite (HA) is commonly used for tooth and bone replacement due toits similar properties as the native hard tissues. Natural sources with abundant availability, such as eggshells, could be used to synthesize HA. Moreover, with the presence of fluorine in HA, it was suggested that the performance of this material could be enhanced in terms of material stability and anti-caries properties. This preliminary study aims to compare two methods used to produce fluoride-added HA from eggshells, which are pH cycling and wet precipitation methods. The molecular structure, crystal structure, particle appearance and chemical compositions of the obtained samples were characterized. The results suggested that pH cycling has provided samples with higher fluorine content, more crystalline structure and less CO3than those obtained from wet precipitation method. Therefore, pH cycling method appears to be more suitable for further processing and characterization of the fluoride-added HA samples derived from eggshells.
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Characterization of Fluoride-added Hydroxyapatite Derived from Eggshells for Dental Application
(2023-01-01)
Uthayaphamornwat, Vilasinee
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Khantachawana, Anak
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Kitiwan, Mettaya
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Srirussamee, Kasama
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Tunthawiroon, Phacharaphon
Hydroxyapatite (HA) is one of the potential biomaterials used for treating dental defects. It can be incorporated with fluoride to enhance its anti-caries properties, though other properties could be dependent on processing technique. Hence, this study aims to characterize the influence of sintering on the properties of fluoride-added HA derived from eggshells. FTIR and XRD techniques are used to characterize the chemical and crystal structures of the samples, whilst dissolution test is carried out to characterize material degradation in the acidic environment. The results show that sintering increased the crystallinity in both HA and fluoride-add HA (F-HA) samples, which corresponds with the enhanced stability during the dissolution test. Moreover, it is also found that the addition of fluoride could further stabilize the material structure, though the impurities found in all the samples still need to be minimized. These findings suggest that sintering and fluoride addition could potentially enhance anti-caries properties of eggshell-derived HA, which could be beneficial for dental application in future subject to further process optimization and analysis.
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Influence of the Oxide Film on the Performance and Corrosion Resistance of TiNiCu Shape Memory Alloys as the Heat Engine Actuator
(2024-10-01)
Phukaoluan, Aphinan
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Srirussamee, Kasama
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Khantachawana, Anak
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Chuchonak, Monthon
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Tunthawiroon, Phacharaphon
Shape memory alloys (SMAs) are utilized as an actuator for the heat engine to harvest energy from low-temperature geothermal sources, such as hot springs, which convert thermal energy into mechanical work. However, the alloy processing and engine design still require optimization to improve performance and durability. To discuss their potential as heat engine actuator, this study investigated the influence of oxide films on the TiNiCu SMAs in terms of surface and structural properties, recovery forces, and corrosion resistance. The results show that the surfaces of the etched samples were relatively coarser than those unetched with lower oxygen content. With the presence of oxide film, the Austenite Finish Temperature (Af) temperature of the unetched SMAs was lower with R-phase transformation. Also, it provided higher recovery force at above Af temperature (as high as 8.3 N at 70-mm displacement). Furthermore, the corrosion resistance of the unetched SMAs was higher than the etched samples, as analyzed by open-circuit potential and linear polarization in natural spring water at 70°C. These findings imply that the presence of oxide film could be beneficial for the SMAs when used as an actuator for heat engines, although it may require further study to investigate its impact on the fatigue behavior of the alloys.

Tunthawiroon, Phacharaphon

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