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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
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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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Comparative Analysis of the Effects of Cracking and Corrosion using Numerical Model for Bridge Monitoring System
(2023-04-01)
Chairungruangsri, Phitchaya
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Sinsamutpadung, Natdanai
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Saiprasertkit, Kawin
Bridge monitoring system can be used to remotely assess bridge conditions and reduce an inspection gap. Steel box girder bridges suffer from cracking and corrosion damage. A system consists of displacement and strain sensor can be used to monitor these damages. A finite element model of the bridge has been created. A various level of structural damage was introduced to the model in form of cracks in the RC deck, and corrosion in steel girders. Then, a conventional truck load has been applied in the model. Thus, the severity of the damage can be observed based on the deflection and strain value at the critical section of the bridge. As a result, the relationship between damage level and monitoring deflection and strain index has been established. In addition, the proper location of bridge monitoring sensors can be determined by using the result of this study.
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Effect of Homogenization on Anodic Film and Electrochemical Behavior of an A535 Alloy After Sealing with Stearic Sealant
(2022-01-01)
Chankitmunkong, Suwaree
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Eskin, Dmitry G.
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Limmaneevichitr, Chaowalit
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Pandee, Phromphong
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Kengkla, Nattarat
Almag 35 (A535) is a commercial aluminum alloy intended for a number of marine components, which is mainly justified by its excellent castability and corrosion resistance. However, the most important factor for corrosion resistance is the formation of intermetallics that can lead the defects in the oxide film and substrate, as well as activate the corrosion reaction. The characteristics of a sealant on the anodic film were investigated in this work. The alloy was subjected to homogenization at 400 °C for 5 h to improve the uniformity of the anodic oxide film due to the decreased number of intermetallics as a result of dissolving in the matrix. It also improved the hardness of this alloy. Electrochemical measurements were conducted to investigate the corrosion behavior. The effects of intermetallics and stearic sealing on the characteristics of the oxide layer are discussed. The decrease in the number of intermetallics can lead to reduced corrosion current density (I<inf>corr</inf>) and increased potential corrosion (E<inf>corr</inf>), which results in a lower corrosion rate of this alloy.
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The investigation of corrosion behavior of electrodeposited Co-Fe alloys surface with phase and 3D reconstruction of image using TIE and TPE
(2018-01-01)
Srisuwan, Thanthanat
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Somphonsane, Ratchanok
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Sutthiruangwong, Sutha
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Buranasiri, Prathan
In this research, phase retrieval using transport of intensity equation (TIE) and transport of phase equation (TPE) have been used for determine the surface of corrosion behavior of electrodeposited Co-Fe alloys, an important component in hard disk drive. Without interferometer as used in digital holography technique, by using TIE and TPE, our observing setup is simple and compact. The experimental results show the capability of TIE and TPE for observing the pitting corrosion. The pitting corrosion of Co-Fe image results have also shown. The dynamic process of microstructure surface system would be conducted and may be applied to hard disk drive industry in the future.
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Corrosion behavior of electrodeposited Co-Fe alloys in aerated solutions
(2017-05-01)
Chansena, A.
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Sutthiruangwong, S.
Co-Fe alloy is an important component for reader-writer in hard disk drive. The surface of the alloy is exposed to the environment both in gas phase and in liquid phase during manufacturing process. The study of corrosion behavior of Co-Fe alloys can provide useful fundamental data for reader-writer production planning especially when corrosion becomes a major problem. The corrosion study of electrodeposited Co-Fe alloys from cyclic galvanodynamic polarization was performed using potentiodynamic polarization technique. The composition of electrodeposited Co-Fe alloys was determined by X-ray fluorescence spectrometry. The patterns from X-ray diffractometer showed that the crystal structure of electrodeposited Co-Fe alloys was body-centered cubic. A vibrating sample magnetometer was used for magnetic measurements. The saturation magnetization (M<inf>s</inf>) was increased and the intrinsic coercivity (H<inf>ci</inf>) was decreased with increasing Fe content. The corrosion rate study was performed in aerated deionized water and aerated acidic solutions at pH 3, 4 and 5. The corrosion rate diagram for Co-Fe alloys was constructed. It was found that the corrosion rate of Co-Fe alloys was increased with increasing Fe content in both aerated deionized water and aerated acidic solutions. In aerated pH 3 solution, the Co-Fe alloy containing 78.8% Fe showed the highest corrosion rate of 7.7 mm yr−1 with the highest M<inf>s</inf> of 32.0 A m2 kg−1. The corrosion rate of the alloy with 23.8% Fe was at 1.1 mm yr−1 with M<inf>s</inf> of 1.2 A m2 kg−1. In aerated deionized water, the alloy with the highest Fe content of 78.5% still showed the highest corrosion rate of 0.0059 mm yr−1 while the alloy with the lowest Fe content of 20.4% gave the lowest corrosion rate of 0.0045 mm yr−1.
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Silicon nitride thin films deposited by reactive gas-timing magnetron sputtering for protective coating applications
(2015-01-01)
Khemasiri, N.
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Paleeya, N.
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Sae-tang Phromyothin, D.
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Horprathum, M.
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Porntheeraphat, S.
Silicon nitride is a promising alternative to carbon based materials for protective coatings, owing to its compatibility with existing silicon-based microfabrication. The complexity of the fabrication processes and contaminations hamper fine-tuning to obtain desirable coating properties. We have explored the reactive gas-timing rf plasma sputtering technique for silicon nitride thin film deposition as an alternative method to fine-tune the film properties. The gas-timing technique controls the on-off sequence of the sputtering gas (Ar) and the reactive gas (N<inf>2</inf>) during deposition. We focus this investigation to the effect of the Ar:N<inf>2</inf> gas timing ratio (10:0, 10:1, 10:3, 10:5, 10:7 and 10:10) on the composition, the morphology, the corrosion resistance, and the hardness properties of the films, in comparison to the films deposited by conventional reactive sputtering with Ar-N<inf>2</inf> gas mixture. These deposited silicon nitride films were characterized by Auger electron spectroscopy, Raman spectroscopy, and atomic force microscopy. The chemical resistance was measured by the electrochemical corrosion test in sulfuric acid, while the hardness properties were obtained by nanoindentation. The results reveal that although the nitrogen content in the films increases only slightly when the N<inf>2</inf> timing is prolonged, the corrosive current of the films decreases abruptly. A thin passivating oxidized layer is found to play a major role in the corrosion resistance. In contrast, the hardness properties exhibit a uniform variation with the N<inf>2</inf> timing. The gas-timing sequence may induce morphological changes the underlying silicon nitride films. The highest hardness obtained by the gas-timing technique almost doubles that produced by the conventional mixed gas sputtering. Thus the reactive gas-timing technique suggests a new route to selectively control the properties of silicon nitride films with minor modification to existing microfabrication processes.
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Changes in structural, morphological, and corrosion properties of CrN thin film effected by varying N2 pressure In the sputtering process
(2015-01-01)
Wongtanasarasin, Wichuda
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Sakdanuphab, Rachsak
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Suwansukho, Kajpanya
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Sakulkalavek, Aparporn
In this study, we investigate a facet of the fabrication process of chromium nitride (CrN) film intended as a protective coating for pineapple blades. CrN thin films were deposited on unpolished stainless steel substrates (AISI304) by DC reactive magnetron sputtering in Ar+N<inf>2</inf> gases. In principle, the proportion of nitrogen partial pressure to the total pressure in the sputtering process should have considerable effects on the CrN film's chemical composition, its crystal structure, its hardness, and its corrosion resistance. We tested this supposition out by using several different nitrogen partial pressures in the sputtering process and observed the films deposited. The coatings were deposited at five different nitrogen partial pressures of 4.0×10-4 mbar, 8.0×10-4 mbar, 1.2×10-3 mbar, 1.6×10-3 mbar, and 2.0×10-3. The deposition times were controlled to achieve 5-μm thick films in each deposition. The films were analyzed by several analytical methods, such as X-ray diffraction (XRD), scanning electron microscope, micro-hardness and potentiostat in pineapple juice. The XRD spectra of the films showed face-centered cubic structure with (200) preferred orientation, positively identifying them as Cr<inf>2</inf>N and CrN thin films. The calculated d-spacing and lattice parameter of the CrN films increased with increasing nitrogen partial pressure; the ranges were 0.283-0.287 nm and 0.491-0.497 nm, respectively. The cross-section morphology of the CrN films reveals the columnar grain growth with a high density. The crystal structure and the grain texture correspond with the hardness property. The films corrosion potential, an indicator of their corrosion property, was varied from -0.14 to -0.05 volts with varying nitrogen pressure. The most corrosion resistant and the good hardness were the film fabricated at the nitrogen partial pressure of 1.2×10-3 mbar.
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The influence of N2 partial pressure on color, mechanical, and corrosion properties of TiN thin films deposited by dc reactive magnetron sputtering
(2015-01-01)
Nimnual, Pisitpat
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Sakulkalavek, Aparporn
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Sakdanuphab, Rachsak
Multi-functional thin films have gained increasing importance in a decorative application. Among the available material, titanium nitride (TiN) thin film is interesting due to its golden color and mechanical resistance. Beside their properties, the corrosion property of TiN films is mainly considered in order to extend the life time. In this work, the TiN thin films were deposited on 3×3 cm2 Si(100) substrates by dc reactive magnetron sputtering technique. The effects of N<inf>2</inf> partial pressure (P<inf>N2</inf>) on deposited film properties such as microstructure, surface morphology, color, mechanical and corrosion properties were investigated. We found that the crystal structure of the TiN films exhibit the (200) preferred orientation. The color of TiN films change from gold-yellow to gold-red colors by increasing of N<inf>2</inf> partial pressure that could be explained by Drude model. The TiN films have smoother surface when the N<inf>2</inf> partial pressure increases. Standard corrosion tests in artificial sweat solution show the corrosion current density (i<inf>corr</inf>) in the range between 0.25 to 4.25 μA/cm2 and the polarization resistance increases with increasing of N<inf>2</inf> partial pressure. The highest hardness of the film is approximately 40 GPa with elastic modulus of 340 GPa. We conclude that N<inf>2</inf> partial pressure corelates with color, mechanical property and corrosion resistance of TiN films, which were optimized to use in decorative application.
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Corrosion characterization of high moment magnetic material coated with diamond-like carbon
(2013-11-04)
Supadee, Laddawan
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Chatruprachewin, Santi
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Suriya-Amaranont, Chaba
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Titiroongruang, Wisut
In order to increase data storage density of hard drive, DLC overcoat thickness was decreased to allow read/write head to come closer to magnetic alloy of the disk, andwith maintaining the main purpose of the overcoat to provide good corrosion and mechanical protection for the underlying magnetic recording film under unfavorably environmental conditions and occasional reactions. Base on that the edges of topography will be weak point for deposition films cause of shadow effect during the process, it's hard that deposition atomic will stay at the concave and convex of topography. DLC coverage performance at the edge of 3D topography becomes high sensitive with limited DLC films thickness. Currently the 3D profile of magnetic material that needs to protect with DLC, is about 2 nanometers with subnanometres DLC thickness. The enormous of data shrew corrosion pattern was usually happened at the edge of topography. Thus, the accelerated test or indirect methodology was applied for DLC integrity. This investigation was explore the methodology to verify the weakness of DLC films especially at the topography edges which is difficult for any direct metrology tools can pursue. With pore resistance, which related to the film structure, the electrochemical impedance indicated that DLC/Si3N4 is a suitable choice to against corrosion. However topography surface influence to DLC coverage. Controllable surface for DLC deposition also needed well defined. Two types of step height was created as 1 nm and 2 nm on (100) silicon substrate. The 20Å DLC film thickness was deposited on the silicon substrate with promised technique, Filtered Cathodic Vacuum Arch (FCVA). After this process the aluminum (Al) was deposited on the surface of DLC film by using evaporation technique. The silicon substrate was driven to Al surface thro pin holes on the DLC film at 577OC. To detect the pin holes on the DLC film, the aluminum layer was removed by using wet etch chemical process. The SEM image indicates that the square pitting at the edge of DLC film obtained for 2nm step height was around 2nm depth. The latest experiment in this investigation to characterize 2.3 T magnetic moment material degradation with DLC/Si3N4 coating, was performed with electrochemical impedance spectroscopy and AFM. The material with DLC overcoat after exposed to H2SO4 for 30 min, polarization resistance was increased for 2 times from uncoated material. Alternative charge transfer capacitance was reduced as desirable charge current. © (2013) Trans Tech Publications, Switzerland.
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Environmental treatment for perfect spray photoresist morphology and analysis
(2013-10-29)
Supadee, Laddawan
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Chatruprachewin, Santi
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Titiroongruang, Wisut
A homogeneous photoresist for IC or read-write data storage head fabrication requires a certain flowing of the resist film on the topography surface for at least few micrometers, thus defining certain minimal resist viscosity for the remaining solvent concentration for spraying technique. The high photoresist solvent evaporates during flight (between spray nozzle and substrate) prevents the droplets from sticking to the substrate and causes a rough surface. The limitation of very low photoresist viscosity for micro droplets spraying is a drawback of the technique. Because of very low viscosity of spray coating resist, nitrogen in spray coating system will act as 2 functions. First is for spread photoresist to be micro droplets. In the same time nitrogen can dry the small droplet before locating to substrate and perform obstacle for UV exposure. The unsatisfied resist was protected UV light during exposure cause pattern deformation. The study was investigated the particles which always found on finished photoresist surface spraying, and aimed to find the solution to decrease or eliminate dry droplet. EDX identified element of the obstacle particles is photoresist. They are dry resist ball about 1 - 6 um size. The selected chemicals for the investigation to dilute or dissolve the resist ball, IPA, acetone and mixing solution between 70% IPA and 30% acetone. Acetone is most effective. The proper time for dissolve dry resist ball with slight photoresist degradation is 40 s, very short because of high vapor pressure of acetone at room temperature. There is a trade-off between resist surface smoothness and reflow characteristics. Final resist thickness with the acetone vaporization condition will be achieved 7.5 um as expectation with less corner coverage problem. SEM and AFM images were confirmed that morphology after acetone vapor exposure was improved. Surface roughness was reduced for 3 times to 8 nm with acetone vaporization environment. The end of this study was include on corrosion characterization for magnetic CoFe alloys underlying photoresist to explore the method to determine photoresist type in future manufacturing which necessary to run the process with sensitive material. With AZ4999 spray photoresist protection indicated corrosion rate of CoFe films was reduced for 100 times compare to bare films. © (2013) Trans Tech Publications, Switzerland.

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