Tunthawiroon, Phacharaphon

Preferred name

Alternative Name

TUNTHAWIROON, Phacharaphon

Tunthawiroon, P.

Main Affiliation

School of Engineering

phacharaphon.tu@kmitl.ac.th

Now showing 1 - 9 of 9

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Effect of Si on Microstructure and Corrosion Behavior of CoCrMo Alloys
(2018-06-04)
Peaubuapuan, Chonlawit
;
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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Effects of Surface Finishing Techniques on Properties of NiTi Coil Spring Actuators
(2025-01-01)
Premwattananarakul, Natakorn
;
Srirussamee, Kasama
;
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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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.
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Effects of Si concentrations on microstructure and mechanical properties of as-cast Co-Cr-Mo alloys
(2019-10-28)
Tunthawiroon, P.
;
Chiba, A.
This research investigates the effects of different Si concentrations on the microstructure and mechanical properties of Co-Cr-Mo-xSi alloys. The Si concentration (x) was 0.1, 0.5, 1.0, 3.0 and 5.0 wt%. The mechanical properties of the experimental heat-treated Co-Cr-Mo-xSi alloys was determined by hardness and tensile tests. The microstructure was analyzed using SEM. The microstructure analysis revealed that Si concentration played a role in the formation of the intermetallic phase of Co-Cr-Mo-xSi alloys. The presence of the intermetallic phase significantly decreased the ductility of the experimental alloys. However, the hardness was improved and was increased directly proportional to the fraction of the intermetallic phase precipitating in the Co-Cr-Mo-xSi alloys.
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Effect of expanded perlite on physical and mechanical properties of cement mortar
(2021-09-15)
Patthanavarit, Jira
;
Kitiwan, Mettaya
;
Keawprak, Nittaya
;
Tunthawiroon, Phacharaphon
This study presents an investigation of the physical and mechanical properties of the cement mortar containing expanded perlite as a filler material. The effects of perlite replacement contents and compressive molding force on bulk density, water absorption, and flexural strength were observed. In the mixture of mortar, the content of sand was replaced with perlite ranging from 0 to 15% by weight. The specimen was pressed under the uniaxial force varied from 20 to 40 kN then de-molded and cured in the humidity for 28 days. With the increase in perlite content from 0 to 15 wt%, the bulk density decreased from 2118 kg/m3 to 1586 kg/m3 while the water absorption increased from 7.4% to18.7%. All composites showed a low thermal conductivity in the range of 0.10-0.27 W/m K. The specimen without perlite had a flexural strength in the range of 10.7-14.2 MPa, while that of sample containing perlite was 7.8-12.5 MPa. The cement mortar composite containing 10 wt% expanded perlite and molding at 40 kN showed the highest flexural strength of 12.50±1.36 MPa while the bulk density and water absorption were 1773 kg/m3 and 1.40 %, respectively. The results of this research can be used as a guideline for further development in building materials such as lightweight roof tile, lightweight brick, and ceiling tile.
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Effects of copper content in Sn-based solder on the intermetallic phase formation and growth during soldering
(2018-06-04)
Mookam, N.
;
Tunthawiroon, P.
;
Kanlayasiri, K.
This research has studied the effects of copper contents in the Sn-based solder (i.e. Sn-0.7Cu, Sn-1.0Cu, and Sn-3.0Cu) on the intermetallic phase formation and the growth during soldering. In the experiments, reflow soldering was performed at 350 °C with the Cu substrate by using three solders for various soldering times of 10, 20, 40, 60, 120, 240 and 480 s. XRD data have shown that the η-Cu<inf>6</inf>Sn<inf>5</inf> and ϵ-Cu<inf>3</inf>Sn phases with hexagonal crystal structure were present between the solder and the substrate. The presence of ϵ-Cu<inf>3</inf>Sn phase was found only when the substrate was soldered for at least 240 s. The Cu content in solder had significant effects on the intermetallic growth with long term soldering time. In addition, the diffusion coefficient was correlated to the Cu content in the solder.
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The Addition of Fluoride to the Eggshell-derived Hydroxyapatite: A Preliminary Study
(2021-01-01)
Uthayaphamornwat, Vilasinee
;
Suksap, Arissara
;
Khantachawana, Anak
;
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
;
Khantachawana, Anak
;
Kitiwan, Mettaya
;
Srirussamee, Kasama
;
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.

Tunthawiroon, Phacharaphon

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