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Sputter-deposited AlN coatings for enhanced tarnish resistance and mechanical durability of silver jewelry
(2026-04-01)
Sudsawad, Kanyarat
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Somjaijaroen, Natthawirot
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Somdock, Nuttakrit
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Sakdanuphab, Rachsak
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Sakulkalavek, Aparporn
Silver jewelry is prone to surface tarnishing caused by sulfur-containing species in ambient environments. In this study, a transparent aluminum nitride–based thin film was deposited by magnetron sputtering and evaluated as a protective barrier against silver tarnishing. Sheets of 99.9% pure silver were coated under various nitrogen flow conditions to optimize film composition and performance. An appropriate nitrogen flow rate of 25 standard cubic centimeters per minute (sccm), corresponding to an N₂/Ar gas ratio of approximately 1:1, was identified for forming AlN-rich films, while an AlN-based film thickness in the range of 80–110 nm was found to be suitable for jewelry protection. X-ray photoelectron spectroscopy analysis showed that insufficient nitrogen availability suppresses complete nitridation, resulting in residual metallic aluminum, which readily reacts with residual oxygen and moisture, increasing the oxygen content in the films. At an N₂ flow rate of 25 sccm, metallic aluminum was suppressed and the films were dominated by Al–N bonding with minor oxygen incorporation, accompanied by the development of a polycrystalline structure. Nanoindentation measurements performed on the 110 nm-thick film yielded a peak hardness of approximately 3.6 GPa, indicating enhanced mechanical durability compared with uncoated silver. Comparative evaluation of color difference, mechanical hardness, tarnish resistance, and environmental durability demonstrated improved performance of the AlN-coated silver. Finally, the practical applicability of the coating was demonstrated by depositing AlN-based films onto large and intricately designed silver jewelry items, indicating compatibility with industrial-scale processing.
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Multi-phase structure electrospun CNF@Ag/Mn/Bi/Fe composite nanofiber enhanced supercapacitor behavior
(2025-02-15)
Sinprachim, Tanayt
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Klompong, Narit
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Chanlek, Narong
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Kidkhunthod, Pinit
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Maensiri, Santi
This study presents the development of carbon-based multiphase metal oxide nanocomposites (CNF@MO<inf>x</inf>; M = Ag, Mn, Bi, and Fe) incorporating silver, manganese, bismuth, and iron nanoparticles within polyacrylonitrile (PAN)-derived carbon nanofibers. These nanocomposites were fabricated via the electrospinning technique with metal oxide concentrations of 10, 20, and 40 %w. This was followed by annealing in an argon atmosphere. The resulting nanofibers exhibited diameters ranging from 559 to 830 nm, with embedded nanoparticles measuring from 9 to 21 nm. Comprehensive characterization revealed that the nanofibers possessed uniform morphology, high porosity, and robust thermal stability. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) confirmed the valence states of the metal oxides (Ag⁰, Bi³⁺, Mn²⁺, Mn³⁺, Fe²⁺, and Fe³⁺), which are integral to redox reactions and charge storage mechanisms. Among the fabricated composites, CNF@Ag/Mn/Bi/Fe-20 demonstrated the best electrochemical performance, achieving a specific capacitance of 156 F g−1 at a scan rate of 2 mV s−1 and outstanding cycling stability with a capacity retention of over 96 % after 1400 charge-discharge cycles. The synergistic combination of double-layer capacitance and pseudocapacitance mechanisms in these nanofibers represents a significant improvement over conventional electrode material. This study highlights CNF@Ag/Mn/Bi/Fe nanocomposites as highly promising candidates for advanced energy storage applications, particularly in supercapacitor technologies.
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Enhancing the anti-tarnish and mechanical properties of gold-coated silver sheets for decorative applications using TiO2 film protection
(2024-12-01)
Khanwaeo, Sarocha
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Srirach, Pisan
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Limsuwan, Pichet
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Sakulkalavek, Aparporn
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Sakdanuphab, Rachsak
This study explores an innovative method to enhance the anti-tarnish and mechanical properties of gold-coated silver sheets, targeting decorative applications through the TiO<inf>2</inf> film coatings. The research focuses on gold films with a thickness of approximately 100 nm, and TiO<inf>2</inf> films ranging from 10 to 31 nm. It was observed that the color of the multilayer coatings exhibited significant sensitivity to variations in thickness, indicating that a TiO<inf>2</inf> coating with a thickness around 20 nm could be optimally applied to the gold film, maintaining an acceptable ΔE value. X-ray photoelectron spectroscopy analysis demonstrated the TiO<inf>2</inf> film's potential to inhibit the formation of Ag<inf>2</inf>S on the surface, thereby enhancing tarnish resistance. Furthermore, the application of a 20 nm TiO<inf>2</inf> layer reduced the friction coefficient from 0.28 to 0.24 for gold-coated silver. Durability tests involving 1,000 abrasion cycles revealed that the gold film without TiO<inf>2</inf> protection experienced delamination, with only about 57 % of the coated area remaining intact. In contrast, the samples protected with a TiO<inf>2</inf> layer retained approximately 90 % of the coating, underscoring the effectiveness of TiO<inf>2</inf> in preserving the structural integrity and appearance of the gold-coated silver sheets.
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Flexible and fully transparent WORM memory devices based on Ag nanoparticles blended with poly(ethylene-co-vinyl acetate)
(2019-12-01)
Onlaor, Korakot
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Thiwawong, Thutiyaporn
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Tunhoo, Benchapol
Silver nanoparticles (Ag NPs) blended with poly(ethylene-co-vinyl acetate) (EVA) were used as an active layer to fabricate flexible and fully transparent memory devices by using the spin-coating method followed by the thermal roll lamination technique with the structure of ITO/EVA:Ag NPs/ITO. The devices exhibited a non-volatile write-once-read-many-times (WORM) memory type and possessed current bi-stability with ON/OFF current ratio within the range of 104-105 at a reading voltage of +1 V. The data continuous read operations reached more than 10 h, which revealed the stability of the memory devices over a long period of time. The conduction mechanisms of the memory device could be explained by theoretical models and proposed by electron trapping at the trapping center of Ag NPs inside the EVA matrix. In addition, the memory device showed a fast response of 231 ns and was fully transparent with maximum transmittance of the device at 83.2%. Further, the devices could be operated under the bending condition of more than 0.83% strain.
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Multilevel conductance switching and carrier transport mechanisms of memory devices based on an ITO/PVK:Ag nanoparticles/Al structure
(2018-01-25)
Onlaor, Korakot
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Thiwawong, Thutiyaporn
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Tunhoo, Benchapol
Multilevel conductance switching was achieved using silver nanoparticles (Ag NPs) embedded in poly(9-vinylcarbazole) (PVK) with a structure of ITO/PVK:Ag NPs/Al. The current-voltage (I-V) curves of the memory devices at low reading voltages showed three distinguished states of current. The memory devices exhibited non-volatile rewritable memory characteristics. The carrier transport mechanisms of the devices in each state were analyzed by theoretical models based on the experimental I-V data. In addition, retention time measurements showed clearly three current states with good data retention properties. From the retention times test, the average values of ON/OFF, ON/intermediate (INTERM) and INTERM/OFF current ratios of the memory devices were 1.7 × 106, 3.5 × 102 and 5.0 × 103, respectively.
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Silver thin films deposited by compact magnetron sputtering system
(2010-02-08)
Promros, N.
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Paosawatyanyong, B.
A compact dc magnetron sputtering system capable of silver thin films depositions was designed and constructed. The novel small footprint sputtering head with target diameter of 52 mm was constructed utilizing powerful neodymium alloy magnet. Silver metal was sputter-deposited under various powers. Plasma parameters were analyzed by using the sweeping-bias single langmuir probe. The electron temperatures of the plasma glow were constant at approximately 2 eV even with the increasing of input power whereas plasma density increases with the increasing of the input power. The X-ray diffraction analysis (XRD) and scanning electron microscope (SEM) were used to study the crystalline structure and the surface morphology of the obtained silver thin films. Crystalline orientations of (111) and (200) in the silver films deposited on slide glass substrates were revealed from XRD pattern. The highest degrees of (111) and (200) orientations was obtained at the sputtering power between 0.228 and 0.265 Wxcm-2. Sub-micron crystalline silver grain structure were observed using SEM micrographs. Facetted grain size and deposition rate of silver thin films increases as the sputtering power increases. © (2010) Trans Tech Publications.
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Ag-doped TiO2 immobilized on Al2O3 bead as oxidation catalyst
(2007-01-01)
Jaroenworaluck, Angkhana
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Supothina, Sitthisuntorn
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Chumnanklang, Rung Arun
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Juengsuwattananon, Kannikar
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Jinawath, Supatra
Ag-doped TiO<inf>2</inf> catalyst employed as the oxidation catalyst candidate was prepared by two methods, co-precipitation and dip coating method. Co-precipitation method was conducted by adding AgNO<inf>3</inf> into the titanium precursor before gelation and then the obtained solution was coated on the alumna beads. Dip coating method was conducted by coating the first layer on alumina beads with titanium precursor followed by coating the second layer with AgNO<inf>3</inf>. The fired Ag-doped TiO<inf>2</inf> coated on alumina beads was used as catalyst for catalytic oxidation of methanol and carbon monoxide by using oxygen as oxidizing agent in a gas-phase reactor. The methods of catalyst preparation were found to affect the catalytic efficiency. Dip coating method showed better oxidation reaction as Ag-doped TiO<inf>2</inf> catalysts were well dispersed on the alumina beads.
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Ag-doped TiO2 immobilized on Al2O3 bead as oxidation catalyst
(2007-01-01)
Panyathanmaporn, Thammarat
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Jaroenworaluck, Angkhana
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Supothina, Sitthisuntorn
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Chumnanklang, Rung Arun
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Juengsuwattananon, Kannikar
Ag-doped TiO<inf>2</inf> catalyst employed as the oxidation catalyst candidate was prepared by two methods, co-precipitation and dip coating method. Co-precipitation method was conducted by adding AgNO<inf>3</inf> into the titanium precursor before gelation and then the obtained solution was coated on the alumna beads. Dip coating method was conducted by coating the first layer on alumina beads with titanium precursor followed by coating the second layer with AgNO<inf>3</inf>. The fired Ag-doped TiO<inf>2</inf> coated on alumina beads was used as catalyst for catalytic oxidation of methanol and carbon monoxide by using oxygen as oxidizing agent in a gas-phase reactor. The methods of catalyst preparation were found to affect the catalytic efficiency. Dip coating method showed better oxidation reaction as Ag-doped TiO<inf>2</inf> catalysts were well dispersed on the alumina beads.

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