Silver Nanopowder Research Articles

Ultrasonic Vibration assisted Silver Integration by Powder Mixed EDM for Antibacterial Surfaces

Powder mixed electrical discharge machining (PMEDM) with silver nano-powder has demonstrated its potential capability in antibacterial surface modification. Analyses in the cross-sectional layer showed that silver was mainly integrated near the topmost surface layer, and its content is reduced within the layer towards the substrate. However, to achieve a long-term antibacterial efficacy, silver needs to be deeply integrated in the modified layer.Previous studies indicated that ultrasonic vibration (UV) assisted PMEDM can homogenize the silver content in the deposited layer. In this study, the effect of UV on the silver distribution within the modified layer is investigated. Ti6Al4V workpieces were stimulated by UV with a frequency of 22.3 kHz and an amplitude of 2.5 µm. Hydrocarbon-based dielectric fluid, mixed with silver nano-powder with concentrations up to 15 g/L, were internally flushed through a hollow tool with a pressure of 4 bar. PMEDM without UV was investigated for comparison. The layer thickness, micro-cracks and the cross-sectional distribution of deposited silver were analysed by confocal microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Results indicate that applying UV leads to the highest silver content in the middle region of the layer, a significant decrease of micro-cracks and a slight reduction of the layer thickness.

Silver-integrated EDM processing of TiAl6V4 implant material has antibacterial capacity while optimizing osseointegration

Periprosthetic joint infections (PJI) are a common reason for orthopedic revision surgeries. It has been shown that the silver surface modification of a titanium alloy (Ti–6Al–4V) by PMEDM (powder mixed electrical discharge machining) exhibits an antibacterial effect on Staphylococcus spp. adhesion. Whether the thickness of the silver-modified surface influences the adhesion and proliferation of bacteria as well as the ossification processes and in-vivo antibacterial capacity has not been investigated before. Therefore, the aim of this work is to investigate the antibacterial effect as well as the in vitro ossification process depending on the thickness of PMEDM silver modified surfaces.The attachment of S. aureus on the PMEDM modified surfaces was significantly lower than on comparative control samples, independently of the tested surface properties. Bacterial proliferation, however, was not affected by the silver content in the surface layer. We observed a long-term effect of antibacterial capacity in vitro, as well as in vivo. An induction of ROS, as indicator for oxidative stress, was observed in the bacteria, but not in osteoblast-like cells. No influence on the in vitro osteoblast function was observed, whereas osteoclast formation was drastically reduced on the silver surface. No changes in cell death, the metabolic activity and oxidative stress was measured in osteoblasts.We show that already small amounts of silver exhibit a significant antibacterial capacity while not influencing the osteoblast function. Therefore, PMEDM using silver nano-powder admixed to the dielectric represents a promising technology to shape and concurrently modify implant surfaces to reduce infections while at the same time optimizing bone ingrowth of endoprosthesis.

Assessing the Dispersion Stability of Antimicrobial Fillers in Photosensitive Resin for Vat Polymerization 3D Printing.

Polymers are widely used in healthcare due to their biocompatibility and mechanical properties; however, the use of polymers in medical products can promote biofilm formation, which can be a source of hospital-acquired infections. Due to this, there is a rising demand for inherently antimicrobial polymers for devices in contact with patients. 3D printing as a manufacturing technology has increased exponentially in recent years. Surgical guides, orthotics, and prosthetics, among other medical devices, created by vat polymerization have been used in hospitals to treat patients. Biocompatible resins are available for these applications, but there is a lack of antimicrobial resins, which would further improve the technology for clinical use. The focus of this study was to assess settling of candidate antimicrobial metal and metal oxide fillers in vat polymerization resin to determine which fillers were compatible with the resin. Dispersion stability was assessed by measuring settling over the maximum print duration of the medium priced desktop 3D printers to evaluate printability of 17 potentially antimicrobial resins. Eight materials displayed settling behavior during the test period: molybdenum oxide, zirconium oxide nanopowder, scandium oxide, zirconium oxide, titanium oxide, tungsten oxide, lanthanum oxide, and magnesium oxide. No settling was observed for manganese oxide, magnesium oxide nanopowder, titanium oxide nanopowder, copper oxide, silver oxide, zinc oxide nanopowder, zinc oxide, silver nanopowder, and gold nanopowder during the test period. This method could be applied to assess settling of other fillers introduced into 3D printing resins before actual printing.

A Fluorinated Polyimide Based Nano Silver Paste with High Thermal Resistance and Outstanding Thixotropic Performance.

Because of high conductivity, acceptable cost and good screen-printing process performance, silver pastes have been extensively used for making flexible electronics. However, there are few reported articles focusing on high heat resistance solidified silver pastes and their rheological properties. In this paper, a fluorinated polyamic acids (FPAA) is synthesized by polymerization of the 4,4'-(hexafluoroisopropylidene) diphthalic anhydride and 3,4'-diaminodiphenylether as monomers in the diethylene glycol monobutyl. The nano silver pastes are prepared by mixing the obtained FPAA resin with nano silver powder. The agglomerated particles caused by nano silver powder are divided and the dispersion of nano silver pastes are improved by three-roll grinding process with low roll gaps. The obtained nano silver pastes possess excellent thermal resistance with 5% weight loss temperature higher than 500 °C. The volume resistivity of cured nano silver paste achieves 4.52 × 10-7 Ω·m, when the silver content is 83% and the curing temperature is 300 °C. Additionally, the nano silver pastes have high thixotropic performance, which contributes to fabricate the fine pattern with high resolution. Finally, the conductive pattern with high resolution is prepared by printing silver nano pastes onto PI (Kapton-H) film. The excellent comprehensive properties, including good electrical conductivity, outstanding heat resistance and high thixotropy, make it a potential application in flexible electronics manufacturing, especially in high-temperature fields.

Preparation of silver nanopowders and its application in low temperature electrically conductive adhesive

Printable electrically conductive adhesive with high electrical conductivity and good mechanical properties has a broad application prospect in electronic devices. In order to explore the preparation method of high-purity nanometal conductive filler for conductive adhesive, silver nanopowders were prepared by DC arc plasma method. The silver nanopowders present a spherical structure and the average particle size is 55 nm. In this paper, a high performance electrically conductive adhesive (ECA) was prepared. This ECA was fabricated by mixing silver nanopowders with epoxy resin and screen-printed to a required shape. It was found that the ECA can be solidified through a low temperature sintering method in the air at 150 °C for 10 min. The electrical and mechanical properties of above ECA were investigated and characterized. The ECA filled with 75 % silver nanopowders exhibits excellent performances, including high electrical conductivity (9.8 × 10−3 Ω·cm) and high bonding strength (8.3 MPa). Based on the performance characteristics, the ECA applications in flexible printed electrodes and interconnecting materials are demonstrated.

Graphene–Silver Hybrid Nanoparticle based Organic Phase Change Materials for Enhanced Thermal Energy Storage

Due to the intermittent nature of solar energy, researchers and scientists are working to develop thermal energy storage (TES) systems for effective utilization of solar energy. Phase change materials (PCMs) are considered to be promising materials for TES. In this study, organic paraffin RT50 and graphene silver (Gr:Ag) nanopowder are adopted as TES material and thermal property enhancers. Microstructure and morphological behavior as well as chemical, optical, and thermal stability of the prepared composite PCM are visually investigated using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy, thermal conductivity analyzer, differential scanning calorimeter (DSC). and thermogravimetric analyzer (TGA). Furthermore, based on the outstanding thermal performance of the composite, an extended investigation on the thermal and chemical properties are evaluated for 500 thermal cycles to ensure their reliability. Results show the thermal conductivity of RT50 improved by 53.85% when Gr:Ag nanopowder is dispersed at a weight percent of 0.8 (RT50-0.8Gr:Ag). The change in latent heat value of the composite sample is less than 3%, which is significant for effective thermal energy storage. The thermal decomposition of RT50 is slightly improved from 300 °C to 330 °C. To ensure a reliable and passive technique for thermal energy storage within solar thermal application devices, such as solar air heaters and solar photovoltaic thermal systems, using nanoparticle enhanced PCMs at the range of a 50 °C melting point are a current research hotspot.

Electrokinetic analysis of water oxidation on alumina supported silver oxide nanopowders

This research intended to synthesize γ-Al2O3 supported Ag2O nanopowders (xAg2O/Al2O3, x = 1–5%) in five different compositions for alkaline water electro-oxidation reaction (WEOR). Electrochemical investigations including cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were performed to examine the electrocatalytic potential of the synthesized nanomaterials. Performed electrochemical (EC) studies designated Ag2O/γ-Al2O3 as a robust electrocatalyst for WEOR. Standard benchmarking protocols were employed to appraise the activity of synthesized catalysts. All catalyst materials exhibited comparable activities by achieving an overpotential of nearly 300 mV at 10 mAcm−2. Results demonstrated that an increase in Ag2O contents reduced the charge transfer resistance (Rct) and augmented EC surface area, ensuing in reduced onset potential (0.98 V vs. Ag/AgCl) and a small Tafel slope (TS) of 0.85 V dec−1. EC analysis revealed high WEOR performance at all Ag2O/γ-Al2O3 modified electrodes, however maximum diffusion coefficient (Do; 6.5 × 10−6 cm2s−1), mass transport coefficient (mt; 7.63 × 10−4 cm s−1), rate constant (ko; 2.4 × 10−4 cm s−1) and low Rct (101 Ω) was observed for 5% Ag2O/γ-Al2O3. This study scheme has proved to be cost-effective synthesis of Ag2O/γ-Al2O3 catalysts providing better fallouts for activity and stability for water oxidation at ambient conditions.

Developments in Powder Mixed EDM and its perspective Application for targeted Surface Modification

Although widely studied over the few decades, there are conflicting theories on the discharge mechanisms of powder mixed electrical discharge machining (PMEDM). Additionally, the dielectric flow plays a vital role in the distribution of powder particles in the machining gap, which significantly affects the powder deposition to the modified surface. In this paper, the literature on PMEDM surface modification is thoroughly reported. The conflicting mechanisms and the effects of PMEDM main machining conditions, such as powder and electrical parameters on improving mechanical and antibacterial properties as well as biocompatibility of the surface, have been discussed. To verify the separation mechanism of the discharge in PMEDM, single discharge investigations have been performed when silver nano-powder is mixed into the hydrocarbon-based dielectric fluid to modify Ti6Al4V surfaces. Surface topography, chemical composition as well as the deposited silver content and distribution over the crater surface when using positive and negative polarities are analyzed and discussed. Current waveforms of PMEDM and EDM without powder at varying discharge energies as well as with and without ultrasonic vibration assistance are recorded and analyzed. For the transfer of fundamental results to a perspective application, CFD simulation is used to calculate the flow field of the dielectric fluid and analyze the velocity and distribution of the nano-powder within the working gap of a setup with internal flushing. The results show that PMEDM is a potential technology for machining medical devices with simultaneous antibacterial surface modification.

IV-curve and structural studies of the composite mixture of reduced graphene oxide and silver nanopowders

IV-curve and structural studies of the composite mixture of reduced graphene oxide and silver nanopowders

Effect of Silver Nanopowder on Mechanical, Thermal and Antimicrobial Properties of Kenaf/HDPE Composites.

This study aims to investigate the effect of AgNPs on the mechanical, thermal and antimicrobial activity of kenaf/HDPE composites. AgNP material was prepared at different contents, from 0, 2, 4, 6, 8 to 10 wt%, by an internal mixer and hot compression at a temperature of 150 °C. Mechanical (tensile, modulus and elongation at break), thermal (TGA and DSC) and antimicrobial tests were performed to analyze behavior and inhibitory effects. The obtained results indicate that the effect of AgNP content displays improved tensile and modulus properties, as well as thermal and antimicrobial properties. The highest tensile stress is 5.07 MPa and was obtained at 10wt, TGA showed 10 wt% and had improved thermal stability and DSC showed improved stability with increased AgNP content. The findings of this study show the potential of incorporating AgNP concentrations as a secondary substitute to improve the performance in terms of mechanical, thermal and antimicrobial properties without treatment. The addition of AgNP content in polymer composite can be used as a secondary filler to improve the properties.

Sonochemical synthesis of welded titanium dioxide-silver nanocomposite as a 3-dimensional direct ink writing printed cathode electrode material for high-performance supercapacitor

Using a facile ultra-sonication method, Ag nanoparticles are embedded into TiO2 nanoparticles, and the as-developed composite material is 3D printed through direct ink writing (DIW) process as an electrode material for supercapacitor. The as-printed TiO2–Ag composite electrode displayed a lower contact angle value of 32.2°, with higher surface energy of 76.32 mJ m−2. The electrochemical performance of the TiO2 nanoparticles incorporated with silver nano-powder is improved significantly in-comparison to pristine TiO2 nanoparticles. The significant improvement in the electrochemical performance of the TiO2 nanoparticles with the incorporated silver nano-powder is due to the synergistic interaction between the TiO2 nanoparticles and the silver nano-powder developed through sonochemical process. The plain TiO2 and TiO2–Ag composite printed electrode revealed a maximum specific capacitance (specific capacity) values of 148.43 (56.84 mA h mg−1) and 257.8 (122.96 mA h mg−1) F g−1 at 1 A g−1, respectively. TiO2–Ag composite printed electrode also maintained a capacitance retention of 58.3% at a higher current density of 10 A g−1. The electrochemical impedance spectroscopy study also confirms that the incorporation of silver nano-powder into TiO2 nanoparticles reduces charge transfer resistance (Rct). The TiO2–Ag nanocomposite electrode shows excellent long-term cycling stability with 96% of capacitance retention after 3,000 continuous GCD cycles. Moreover, TiO2–Ag//AC based asymmetric supercapacitor device is developed which delivers a high energy density of 26.72 W h Kg−1 at minimum power density of 655.61 W kg−1. These results indicate a high potential of the as-printed TiO2–Ag composite electrode material for energy storage applications.

Reduced Graphene Oxide Nanosheets Decorated with Copper and Silver Nanoparticles for Achieving Superior Strength and Ductility in Titanium Composites.

Graphene and its derivates are extensively applied to enhance the mechanical properties of metal matrix nanocomposites. However, their high reactivity with a metal matrix such as titanium and thus the limited strengthening effects are major problems for achieving high-performance graphene-based nanocomposites. Herein, reduced graphene oxide nanosheets decorated with copper or silver (i.e., Cu@rGO and Ag@rGO) nanopowders are introduced into Ti matrix composites using multiple processes of one-step chemical coreduction, hydrothermal synthesis, low-energy ball milling, spark plasma sintering, and hot rolling. The Cu@rGO/Ti and Ag@rGO/Ti nanocomposites exhibit significantly enhanced strength with superior elongation to fracture (846 MPa-11.6 and 900 MPa-8.4%, respectively, basically reaching the level of the commercial Ti-6Al-4V titanium alloy), which are much higher than those of the fabricated Ti (670 MPa-7.0%) and rGO/Ti composites (726 MPa-11.3%). Furthermore, fracture toughness values of the M@rGO/Ti composites are all significantly improved, that is, the highest KIC value is 34.4 MPa·m1/2 for 0.5Cu@rGO/Ti composites, which is 20.28 and 51.5% higher than those of monolithic Ti and 0.5rGO/Ti composites, respectively. The outstanding mechanical properties of Ag@rGO/Ti and Cu@rGO/Ti composites are attributed to the effective load transfer of in situ formed TiC nanoparticles and the formation of interfacial intermetallic compounds between the rGO nanosheets and Ti matrix. This study provides new insights and approach for the fabrication of metal-modified graphene/Ti composites with a high performance.

Facile synthesis of multifunctional Ag-nanocomposite poly(HIPE) foam via emulsion template method

Designing efficient nanoparticle-based stabilizer that is suitable for achieving an interconnected porous monolith still remains a challenge. Herein, Ag-nanocomposite poly high-internal phase emulsion (HIPE) template was readily obtained by O/W HIPE, co-stabilized by silver nano powders (Ag-NPs) and polyvinyl pyrrolidone. Cyclohexane as oil phase, N, N′-methylenebisacrylamide as a crosslinking agent, and free-radical copolymerization of acrylamide (AM) and 2-acrylamide-2-methyl propane sulfonic acid (AMPS) were used in the water phase, which was initiated by potassium persulfate. Thus, Ag-nanocomposite copolymer poly(HIPE)s [Ag/P(AM-co-AMPS)] were obtained via a one-pot synthesis method. The effects of Ag-NP content and different internal phase volume on the porous composites were investigated. The morphology and structures of the composites were characterized, and the average pore size was measured to be approximately 60 μm. Furthermore, the catalytic activity was studied via catalytic degradation of the methylene blue (MB). The decolorization of the MB solution can be completed within 8 min by using the composites containing 5 wt% Ag-NPs. The composite poly(HIPE)s had certain antibacterial activity against E. coli and S. aureus bacteria (9 mm zone of inhibition). Moreover, a compression electric sensitivity (GF = 2.05) was exhibited with an enhanced electrical conductivity. Thereby, a facile approach to multifunctional macroporous Ag-nanocomposite poly(HIPE) was presented.

Additive Manufacturing of Electronics from Silver Nanopowders Sintered on 3D Printed Low‐Temperature Substrates.

Additive manufacturing is more widely used these days in aerospace, power industry, and automotive. The latest reports indicate that electronics can be produced with this technique. This approach requires the development of new materials for the fabrication of conductive metallic layers on polymers. Herein, a hybrid technique based on fused deposition modeling, direct‐write, and selective laser sintering is demonstrated, for the fabrication of structural electronics. Highly conductive paths are obtained with conductivity values up to 3.2·106 S m−1 in a single printing and sintering additive process. The influence of process parameters is evaluated with several 3D printed polymer substrates affecting the electrical conductivity of the printed conductive paths and circuits. The developed hybrid technique allows performing selective thermal sintering of metallic pastes on polymer substrates exhibiting the value of melting temperatures much lower than the sintering temperature of the silver paste. This phenomenon can be explained with the proposed hypothesis that the activation energy of the sintering process of metallic paste and degradation of polymer substrate plays a key role in obtaining functional conductive metallic paths on polymer substrates. Application of the developed process is demonstrated with a simple human interface device and a circuit with light‐emitting diodes and power source.

Preparation and properties of silver nanopowders and composites based on a radiation-chemical method

Silver nanopowders with specific surface area up to 39.1 cm2/g, as well as alumina powders coated with silver consisting of nanoparticles with sizes of 50 and 80 nm, were produced by a radiation-chemical method. The influence of the number of OH groups of polyhydric alcohols on the specific surface area of obtained silver nanopowders is shown in the first time. The coating area of the oxide base can be varied from 2-3%–40%. Antibacterial properties of the composite have been studied on wine yeast, as well as E. coli and S. aureus bacteria. The results of the study of photocatalytic properties of the composite showed its potential.

EVALUATION OF MICROLEAKAGE OF SILVER NANOPARTICLE-ADDED PIT AND FISSURE SEALANT IN PERMANENT TEETH (IN-VITRO STUDY)

Introduction: Silver has long been recognized for its antimicrobial effect on a wide spectrum of microorganisms. Consequently, silver nanoparticles became among the most common therapeutic nanoparticles under research in the field of caries prevention. Pit-and-fissure sealants are among the major components in the field of caries prevention which could have an additional antibacterial benefit through silver nanoparticles addition. Objectives: The aim of the study was to evaluate, in-vitro, the marginal seal of silver nanoparticle-added pits and fissure sealant in comparison to the conventional sealant in permanent teeth. Materials and methods: Thirty sound premolar teeth extracted for orthodontic purposes were randomly assigned into two main groups; Group I (n=15) for silver nanoparticle-added ClinproTM sealant and Group II (n=15) for the conventional ClinproTM sealant. Silver nanoparticle-added sealant was prepared by mixing the contents of one syringe of ClinproTM sealant to silver nanopowder of particle size 50-80nm at a concentration of 6.25μg/ml. For microleakage testing, after sealant application and thermocycling for 500 thermal cycles, the sealed teeth was immersed into 1% methylene blue solution for 24h, sectioned longitudinally in a bucco-lingual direction and then examined under stereomicroscope for dye penetration assessment at x60 magnification. Results: Using Mann Whitney U test there was no statistically significant difference in microleakage between both groups (P= 0.325) Conclusion: Addition of silver nanoparticles to pit-and-fissure sealant did not affect its sealing ability.

Screen-printed activated carbon/silver nanocomposite electrode material for a high performance supercapacitor

Activated carbon has been investigated intensively during the past few decades as an electrode material for supercapacitors because of its excellent capacitive properties, especially its double layer capacitance. However, the presence of inaccessible micropores in activated carbon lower its electrochemical performance and hinders its use in industrial applications as an effective electrode material for supercapacitors. In this article, we have incorporated silver nano-powder into activated carbon through unique screen-printing fabricating method to enhance its electrochemical performance. The activated carbon/silver (AC/Ag) electrode material has shown lower contact angle of 43°, better surface energy of 63.70 mJ cm−2 and high specific capacitance of 194 F g−1 with 89% of capacitance retention after 1000 cycles. These results demonstrate that screen-printed AC/Ag electrode material is a potential candidate for high performance supercapacitor applications.

New Brush Copolymers as an Effective Dispersant for Stabilizing Concentrated Suspensions of Silver Nanoparticles.

Silver nanopowders (nano-Ag) have extremely high surface energy and are generally difficult to have an effective dispersant for their dispersion stabilization. This study proposes two brush copolymers that show a strong preference for adsorption on the nano-Ag surface via their backbone, while their side chains extend into the dispersion solvent for particle stabilization. After adding only 5 wt % (based on the mass of nano-Ag) of the proposed dispersants, the nano-Ag particles can be stably suspended without settling for at least 2 months. Besides, 5 wt % of these dispersants can well stabilize at least 40 wt % nano-Ag dispersed in di(ethylene glycol) ethyl ether, which is a common solvent for conductive inks and pastes. For applications, a thin film cast using the dispersed nano-Ag shows greatly improved surface flatness as compared to that made without the dispersant, and a low electrical resistivity of 2 × 10-5 Ω cm is obtained after the film is annealed at 170 °C for 20 min.

Synthesis and Antimicrobial Activity of Metal-Containing Linseed Oil-Based Waterborne Urethane Oil Wood Coatings

In this study, the antimicrobial agents of mono(hydroxyethoxyethyl)phthalate (M(HEEP)2) with different metal of M = Zn, Mn, Pb, and Ca were synthesized from diethylene glycol (DEG), phthalic anhydride (PA), and divalent metal acetates including calcium acetate, zinc acetate, manganese acetate, and lead acetate, respectively. The waterborne urethane oil (WUO) dispersions synthesized from linseed oil, diisocyanates (hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)), dimethylolpropionic acid at NCO/OH molars of 0.9, by acetone processing method were described as in our previous report. The M(HEEP)2 antimicrobial agents as well as the commercial nanosilver powder were added into WUO dispersions as the antimicrobial coatings. The effects of various antimicrobial agents and dosages (0.0, 0.2, 0.6, 0.8, 1.0, 2.0, and 4.0 phr) on antimicrobial activity of WUO films against gram-negative bacterium of Escherichia coli, gram-positive bacterium of Staphylococcus aureus, brown-rot fungus of Gloeophyllum trabeum, and white-rot fungus of Lenzites betulina were assessed. In addition, the film properties of the best antimicrobial WUO coatings were also examined. The results showed that the antimicrobial agents of mono(hydroxyethoxyethyl) phthalate M(HEEP)2 (M = Zn, Mn, Pb, and Ca) powders should certainly be synthesized by FTIR, 1H-NMR, 13C-NMR, and energy-dispersive X-ray spectroscopy (EDS) identifications and the yields of them were 43–55%. The results also revealed that the WUO film synthesizing with HDI films containing Zn(HEEP)2 of 2.0 phr and Pb(HEEP)2 of 0.4 phr had the best antibacterial activity for E. coli and S. aureus, respectively. The IPDI films containing Zn(HEEP)2 of 1.0 phr had the best antibacterial activity for both E. coli and S. aureus. For antifungal activity, the WUO film synthesizing with HDI films containing Pb(HEEP)2 of 0.8 phr and Zn(HEEP)2 of 2.0 phr as well as IPDI films containing Mn(HEEP)2 of 0.2 phr and Zn(HEEP)2 of 4.0 phr had the best performances against G. trabeum and L. betulina, respectively. Comparing with commercial nanoAg powder, the Zn(HEEP)2 and Pb(HEEP)2 had a superior antifungal efficiency for G. trabeum and L. betulina, while it had a slightly inferior efficiency in the antibacterial activity for E. coli and S. aureus. On the properties of WUO films, adding metal-containing antimicrobial agents could slightly enhance the thermal stability, but lowered the gloss of all films, however, the Tg value increased for HDI film and decreased for IPDI film. In addition to this, they had no significant difference in the film properties including hardness, impact resistance, bending resistance, adhesion, mass retention, and light-fastness between the WUO films with and without adding antimicrobial agents.

Evaluation of Zirconia Nanofiller and Brass Alloy Assembly by X-Ray Radiography

Zirconia samples were linked with brass alloy using different nanofiller types. These nanofillers were formed with different concentrations of copper, silver, and titanium nanopowder metals. They were prepared by mixing powders, compacting them by pressure, and sintering them by tube furnace with argon atmosphere at 1200 °C for 50 min. Zirconia/brass assemblies were joined in a vacuum furnace with the pressure of 2 × 10−5 torr at 900 °C for 15 min. X-ray radiography was used to evaluate and detect the defect in the contact area. Some defects were detected. The shear test was achieved to determine the joint strength. Finally, a relationship was found between X-ray radiography and the shear test.