Different Concentrations Of Ag Research Articles

Synergistic effects of micronanobubbles and AC/Ag–TiO2 nanocomposites in photocatalytic process

The AC/Ag–TiO2 nanocomposites were prepared by sol-gel method using different concentrations of Ag. Comprehensive characterization of the crystalline structure, surface morphology, elemental composition, and optical properties of the AC/Ag–TiO2 photocatalysts was carried out using XRD, FTIR, SEM, EDX, TEM, and UV–vis DRS techniques. Consequently, a detailed investigation into the photocatalytic degradation of Indigo Carmine (IC) and Reactive Black 5 (RB5) dyes was conducted, thoroughly examining the involved photocatalytic mechanisms. The study revealed promising outcomes, particularly with the hybrid photocatalyst AC/0.5%Ag–TiO2, showcasing enhanced characteristics in both photooxidation and absorption processes, thereby boosting overall efficacy for IC (70.15%) and RB5 (69.9%). Remarkably, the introduction of small air bubbles significantly improved the removal efficiency of IC and RB5 dyes, achieving removal levels of 93.66% and 88.66%, respectively. The utilization of these micro-nanobubble systems (MNBs) resulted in notably higher first-order reaction constants compared to scenarios without MNBs, indicating the pivotal role of the photocatalyst in dye removal processes. Additionally, the photocatalyst showed unmatched efficacy in eliminating the pesticide carbaryl, attaining 100% removal with and without the presence of MNBs. Moreover, the AC/Ag–TiO2 photocatalyst exhibited significant inhibition of both gram-positive and gram-negative pathogenic bacteria, showcasing its capability to curb their growth even without MNB aeration. This underscores its potential for applications in environmental remediation and microbial control.

The ratiometric fluorescent sensor based on the mixture of CdTe quantum dots and graphene quantum dots for quantitative analysis of silver in drinks.

Silver nanoparticles can be used in antibacterial packaging or disinfection. Research has shown that sugary fluid induces the leaching of silver nanoparticles into water, which may be harmful to humans. Single wavelength fluorescence analysis has been used for quantitative analysis of silver nanoparticles but suffers from low specificity and poor anti-interference ability. In this paper, a ratiometric fluorescence sensor system (GCS) was used for the detection of Ag+, which realized both visual detection and quantitative analysis of silver in drinks. The color changes of GCS with different concentrations of Ag+ are distinguishable and easy to analyze. There is also a good linear relationship between the concentrations of Ag+ and varieties of F424 nm/F570 nm, and the lowest detection limit reached 0.2266nmol/L. This GCS shows good selectivity and recovery and could be used for the detection of Ag+ in drink samples.

(TiZrNbTaMo)N nanocomposite coatings embedded with silver nanoparticles: imparting mechanical, osteogenic and antibacterial traits to dental implants

Designing highly osteogenic and effective antibacterial biomaterials with a prolonged service life for oral implants remains an ongoing challenge. In this work, the multi-element (TiZrTaNbMo)N high entropy nitride (HEN), with different concentrations of Ag, was co-deposited onto surgical grade commercially pure titanium by a reactive sputter-deposition technique using a double cathode glow discharge plasma system. The effects of Ag concentration on the microstructure and mechanical properties of the HEN-Ag nanocomposite coatings were investigated by various testing methods. Potentiodynamic polarization measurements were used to evaluate the corrosion resistance of the coatings in simulated body fluid. The antibacterial activity of the HEN-Ag nanocomposite coatings against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) strains was examined based on the bacterial inhibitory zones and bacterial killing efficiency. The cytocompatibility and osteogenesis activity of the HEN nanocomposite coatings using MC3T3-E1 cells were evaluated by a CCK-8 assay and an alkaline phosphatase quantitative assay. These studies demonstrate that the Ag-free HEN coating was composed of a face-centered-cubic (FCC) nitride phase, which displays good mechanical properties, anti-corrosion performance and osteogenic function, but no antibacterial properties were observed. In contrast, the HEN0.9Ag0.1 coating, composed of amorphous/nanocrystalline high-entropy nitride embedded with silver nanoparticles ∼10 nm in diameter, displays good mechanical and anti-corrosion performance, together with the excellent cell compatibility and antibacterial performance, which offer potential for providing outstanding protective efficiency for dental implants. Although the HEN0.8Ag0.2 nanocomposite coating exhibited superior antibacterial efficacy, potential for in vitro cytotoxicity was identified.

Antifungal Activity of Nontoxic Nanocomposite Based on Silver and Reduced Graphene Oxide against Dermatophytes and Candida spp.

Dermatomycoses are typical hair, skin, or nail infections caused mainly by dermatophytes and nondermatophytes: Trichophyton, Microsporum, Epidermophyton, and Candida. In addition to the esthetical impact, pain, and nail deformity, these mycoses can be a source of severe disease. The high cost of treatment, toxicity, and the emergence of resistant infectious agents justifies research into new drugs. This work evaluates the fungicidal activity of nanocomposites (NCs) based on reduced graphene oxide (rGO) loaded with silver (Ag) nanoparticles (rGO/Ag) against clinical isolates of dermatophytes and Candida species. This is an unprecedented study in which, for the first time, hybrid nanocompounds based on Ag/rGO were tested against Epidermophytom, Microsporum, and Trichophyton species (dermatophytes agents). In this paper, we synthesize rGO using different concentrations of Ag by hydrolysis of metal salt AgNO3 and follow the growth of nanocrystals on sheets of rGO provided by the NaBH4. The NCs were analyzed by X-ray diffraction analysis, and the NC morphology, silver distribution on the rGO surface, and crystalline information were investigated by transmission electron microscopy. Antifungal susceptibility assay was performed by the microdilution method based on modified Clinical and Laboratory Standards Institute (CLSI) protocol. Time-kill kinetics was conducted to monitor the effect of the composite to inhibit fungal cells or promote structural changes, avoiding germination. The toxicological evaluation of the NCs was born in an in vivo model based on Galleria mellonella (G. mellonella). Minimum inhibitory concentration (MIC) values of the rGO/Ag NCs ranged from 1.9 to 125 μg/mL. The best inhibitory activity was obtained for rGO/Ag12%, mainly against Candida spp. and Epidermophyton floccosum. In the presence of sorbitol, MIC values of rGO/Ag NCs were higher (ranging from 15.6 to 250 μg/mL), indicating the action mechanism on the cell wall. Both yeast and dermatophytes clinical isolates were inhibited at a minimum of 6 and 24 h, respectively, but after 2 and 12 h, they had initial antifungal interference. All hybrid formulations of rGO/Ag NCs were not toxic for G. mellonella. This study provides insights into an alternative therapeutic strategy for controlling dermatomycoses.

Silver decoration of Cr2O3 nanoparticles: Facile preparation of Cr2O3 nanoparticles and Ag–Cr2O3 nanocomposites and characterization of their antibacterial activity and ability to photocatalytically degrade organic wastes under visible light

An eco-friendly, single-step process was adopted for the preparation of Cr2O3 nanoparticles (CR-NPs), and different concentrations of Ag were doped into the CR-NPs through liquid impregnation to synthesize a series of Ag-CRNPs composites. In order to prevent agglomeration, chemical transformation, and weak adhesion of Ag to CR-NPs, a mechanical process of circular-motion grinding and high-temperature treatment in a sealed condition were used. Well-defined heterojunctions were successfully formed between Ag and CR-NPs. In comparison to the CR-NPs, the Ag-doped CR-NP composites exhibited excellent performance in photocatalytic and antibacterial applications. Under visible light (VL), the best-performing composite (2 %-Ag decorated CR-NPs) showed 96 %, 79 %, and 57 % decomposition of methylene blue, Congo red, and tetracycline, respectively, in 100 min, which was attributed to a synergetic effect in the composites. The rate constant of the photocatalytic reaction is 14 times higher than that of the reaction without a photocatalyst. The enhanced efficiency was attributed to a reduced bandgap, prolonged retention of photogenerated electron–hole pairs, an increased amount of active spots, and increased absorption of VL. Similarly, the best-performing composite exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with zones of inhibition of 15.4 and 15.1 mm, respectively. The 2 %-Ag decorated CR-NPs were the most efficient and exhibited robust recyclability until the fifth cycle (≥90 %). The photocatalytic activity was primarily driven by reactive oxygen species, holes and hydroxyl radicals.

Photochemical preparation, characterization and formation kinetics of riboflavin conjugated silver nanoparticles

Riboflavin conjugated silver nanoparticles (RF–AgNPs) have been synthesized by photoreduction of Ag+ ions and characterized by UV–visible, X-ray diffraction (XRD), FTIR spectroscopy, spectrofluorimetry, dynamic light scattering (DLS) and atomic force microscopy (AFM). The RF–AgNPs exhibit a typical surface plasmon resonance (SPR) peak at 422 nm due to the interaction of RF and AgNPs. FTIR studies indicate the appearance of an intense absorption peak at 2920 cm–1 due to the interaction of RF and Ag. AFM studies indicate that the RF–AgNPs are spherical and polydisperse in nature (57–73 nm), which nicely complement the hydrodynamic radii (57.9–72.2 nm) measured by DLS. None of the tested concentrations (1-250 µg mL−1) of RF–conjugated AgNPs show any adverse effect on normal mouse fibroblast and cancerous non-small lung carcinoma cell lines. At acidic pH (2.0–6.2) aggregation of RF–AgNPs occurs due to an increase in the ionic strength of the medium. The rates of formation of RF–AgNPs on UV and visible light irradiation have been determined in the pH range of 8.0–10.5 and at different concentrations of Ag+ ions. The photochemical formation of RF–AgNPs follows a biphasic first–order reaction probably due to the formation of AgNPs in the first phase (fast) and the adsorption of RF on AgNPs to yield RF–AgNPs in the second phase (slow).

Silver Nanoparticles Stabilized with a Chitosan Shell: Physical-Chemical Properties and Features of the Toxic Effect in Vivo

The results of investigating the in-vivo toxicity and safety of colloidal solutions of chitosan–silver nanocomposites with different concentrations of Ag (0.19, 1.9 mg/mL) obtained by the “green chemistry” technique via the chemical reduction of silver nitrate with chitosan under hydrothermal conditions are presented. The synthesized samples possess high aggregative stability (the values of their ζ potential are 37.3 ± 0.2 and 43.2 ± 2.5 mV) and pronounced antimicrobial properties against Staphylococcus aureus, Salmonella dublin, and Escherichia coli (inhibition zones of 11–16 mm). It is found that the nanocomposites are not very dangerous in the case of acute intragastric administration, are relatively safe in the case of intraperitoneal administration, and do not possess dermal irritation. A hydrosol of the nanocomposite with a high concentration of silver (1.9 mg/mL) induces reversible eye irritation in laboratory animals as well as has a pronounced sensitizing action, inducing the development of an allergy by the delayed hypersensitivity mechanism.

The effects of Ag concentration on toluene gas sensing performance of Ag NPs decorated on g-C3N4 sheets

In this study, Ag nanoparticles (NPs) were decorated on graphitic carbon nitride (g-C3N4) sheets with different concentrations of Ag (1%, 3%, and 5%) using a co-precipitation method as a selective toluene gas sensor. The X-ray diffraction (XRD) patterns of the samples indicated that Ag NPs did not affect the phase of the g-C3N4 nanocomposites. The Ag NPs were well dispersed on the g-C3N4 sheets, as shown by transmission electron microscopy (TEM) images. The optical characterization results revealed that Ag NPs decreased the bandgap of g-C3N4 nanocomposites. The results of gas sensing indicated that compared to the pristine g-C3N4 sheets, sensors based on Ag NPs decorated g-C3N4 sheets exhibited a stronger response to toluene due to the formation of more defects and active sites on the surface of g-C3N4 sheets. Moreover, the 5%Ag/g-C3N4 nanocomposite exhibited the highest response and selectivity to 50 ppm toluene at 200 °C (25.4% and 61.3%, respectively). In addition, 5%Ag/g-C3N4 nanocomposite demonstrated a faster response/recovery time and superior long-term stability than the other sensors.

Efficient photoelectrocatalytic conversion of CO2 to formic acid using Ag-TiO2 nanoparticles formed on the surface of nanoporous structured Ti foil

Global warming and adverse climate change, which have been intensified by a strident increase in carbon dioxide (CO2) emissions, have necessitated the development of alternative techniques to reduce the disproportionate concentration of CO2 in the atmosphere. The photoelectrochemical reduction of CO2 is a technique of lowering the energy required to convert greenhouse gases into useful end products. Herein, we have manufactured an innovative, cost-effective silver (Ag) decorated anatase TiO2 (TO-Agx; ‘x’ stands for different concentration of Ag) nanoparticles which created on the 3D nanoporous structured surface of a thin titanium foil (Ti-foil) by the assist of chemical treatment with hydrogen peroxide (H2O2) and different concentrations (1, 5, 10, 20 mM) of silver nitrate (AgNO3) solution and followed by calcination at 500 °C. As-prepared samples were analyzed by several characterization techniques such as XRD, XPS, TEM and Raman spectroscopy. Among various samples (TO, TO-Ag1, TO-Ag5, TO-Ag20), the TO-Ag10 sample were exposed a supreme photocurrent density of 83.2 µA/cm−2 (86.1% higher than TO sample which is untreated with AgNO3 solution). Because of its high photocurrent density, the sample TO-Ag10 were selected as the electrode material for photoelectrochemical CO2 reduction reaction and a lowest reduction onset potential (−1.018 V) was observed on linear sweep voltammetry analysis in the presence of light with Ag/AgCl reference electrode. 1H NMR analysis of the product solution exposed the production of formic acid as a single product of CO2 reduction reaction after the chronoamperometric electrolysis were carried out more than 6 h. The maximum faradaic efficiency (73%) and formic acid yield (193 µmol cm−2 h−1) were found at an applied potential of −1.2 V (vs. Ag/AgCl reference electrode) for TO-Ag10 photocathode.

Photoreduced Ag+ surrounding single poly(4-cyanostyrene) nanoparticles for undifferentiated SERS sensing and killing of bacteria

Developing a rapid, low cost and sensitive sensing strategy for undifferentiated detection and fast killing of bacterial pathogens are critical to alleviating bacteria infections. Here, we propose a direct photoreduction method to synthesize the SERS tag by integrating poly(4-cyanostyrene) nanoparticles (NPs) and silver ions, which are applied as bio-sensing system for bacteria sensing and fast killing. Under a focused laser spot, silver ions on the surface of the poly(4-cyanostyrene) NPs could be photoreduced into Ag NPs, thereby causing the Raman signal amplification of poly(4-cyanostyrene) NPs up to 40 times, and there is a good linear correlation between the Raman intensity of poly(4-cyanostyrene) NPs and different concentrations of Ag+. Moreover, 4-mercaptophenylboronic acid, performing the same recognition function for both the Gram-positive and Gram-negative bacteria, is used as bridge between the bacteria and Ag+ by the inherent chemical bonding. Based on further constructed bio-sensing system, we achieved the quick count and killing of both Gram-positive bacteria, e.g., Staphylococcus aureus (S. aureus), and Gram-negative bacteria, e.g., Escherichia coli (E. coli). Notably, the sensing strategy can detect at least ∼100 cells of E. coli, ∼10 cells of S. aureus and ∼10 cells of their mixture in less than 40 min. The detection accuracy for actual samples can also reach over 80% and the bacteria were entirely killed by Ag+ after the detection, avoiding bacterial contamination in the environment. This novel method is anticipated to perform as a simple yet effective tool for fast and sensitive bacteria counting and killing.

Performance of simple green synthesized Ag incorporated TiO2 nanoparticles based photoanodes by doctor-blade coating as working electrodes for dye sensitized solar cells

In this work, TiO2 and Ag doped TiO2 nanoparticles with different concentrations of Ag (0.01 M, 0.03 M, and 0.05 M) were synthesized by facile green synthesis method using grapefruit extract as solvent/reducing agent. X-ray diffraction patterns and the Raman spectra of the prepared material exhibited anatase phase with tetragonal crystal structure. No specific peaks corresponding to Ag nanoparticles were observed, which further confirms the Ag doping in TiO2. FESEM images reveal the nanorods and spherical shaped morphology of the TiO2 and Ag-TiO2 nanoparticles respectively. UV–Visible spectrum illustrates that absorption edge was shifted towards the visible region and from the photoluminescence spectroscopy quench in the fluorescence intensity was observed for the Ag doped TiO2 samples compared to bare TiO2 sample. Using the prepared TiO2 nanoparticles and Ag doped TiO2 nanoparticles, two different dyes such as natural dye and commercial dye (N719) as sensitizers, photo anodes were prepared. DSSCs were constructed using the prepared photoanodes, and its performance was examined. The silver doped TiO2 nanoparticle showed an efficiency η of 2.66% for MK dye and 6.42% for N719 dye with 0.03 M of silver doping. Improvement of the visible light absorption and the decrease in photogenerated electron hole pair recombination, increment of the oxygen vacancy in the Ag-TiO2 are found to be the key factors for the enhancement of the electrical properties of the DSSCs.

Synthesis of Ag Decorated TiO2 Nanoparticles for Ammonia Gas Sensor Application

In this research, nanometer size clusters of TiO2 have been successfully synthesized through sol-gel method. Further, at different concentration of Ag were further deposited on TiO2. After successful deposition of TiO2: Ag the gas sensing performance of the sample has been studied at different exposure of NH3(ammonia) gas. Analysis has been done via XRD to evaluate the grain sizes of the nanoparticles and calculated 18 nm for TiO2 and 12 nm for 5% Ag doped TiO2. EDS has been conducted, ensured that Ag has been successfully decorated on the superficial of TiO2. The formation of nano size particles has been confirmed by TEM analysis. FTlR analysis confirmed the existence of TiO2 and Ag. The surface state emission of TiO2: Ag nanoparticles can be seen in the PL spectrum at 383 nm, 450 nm, and 465 nm. As the exposure of NH3 gas increases from 50 to 250 ppm, the impedance range displayed a decrease in semicircle radius, which was then marginally increased. The variance in resistance also contributed to the gas sensing properties due to grain boundaries, in accordance to impedance spectroscopy review.

Effect of annealing temperatures on performance of DSSCs fabricated using Ag or Pd@C@ZnO composites as photoanode materials

ZnO nanorods have been synthesized with microwave treatment and co-precipitation method. Different concentrations of Ag@C and Pd@C nanospheres prepared by hydrothermal method were loaded onto ZnO nanorods. The sample obtained was characterized by x-ray diffraction (XRD), UV–vis reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and Energy dispersive X-ray spectroscopy (EDX). The metal content did not change the peak position deducing that prepared materials were of high purity. Different types of cells were prepared to check the effect of noble metal content on the optical property on ZnO and annealed at different temperatures. The cells were tested in a conventional architecture sing Pt counter electrode and I-/I-3 electrolyte. The dye sensitized solar cells (DSSCs) based on Ag@C-ZnO photoanode including 50 mg Ag annealed at 500 °C was found to be more efficient among all DSSs with an efficiency of 3.60% and a current density of 7.87 mA/cm2 with a fill factor of 59.3%. While DSSC based on Pd@C-ZnO photoanode including 50 mg Pd with the same conditions was observed to possess 1.93% efficiency with current density 6.01 mA/cm2 and fill factor of 42.9%. The enhancement in ZnO efficiency is attributed to the reduction in electron hole recombination and increase in photo-generated e-/h+ due to presence of noble metals and valonea.

Ag-grafted on ZnO nanorod arrays using UV-assisted irradiation for enhanced SERS behavior in CV detection

Introduction: Semiconductor-based surface-enhanced Raman scattering (SERS) substrates with high stability and reproducibility have become one of the essential analytical tools in the analysis of chemical and biological at trace levels. Herein, a growth of the hexagonal-wrapped ZnO nanorod arrays decorating with Ag nanoparticles (AgNPs) at different concentrations of Ag was proposed.
 Methods: The crystallinity, morphology, chemical composition, and optical properties of the prepared samples were investigated by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Raman system, respectively.
 Results: The results revealed that the SERS performance of ZnO NRs incorporating with AgNPs exhibited higher detection of crystal violet (CV) probe molecules at a low concentration of 10􀀀8 M than that of the pristine ZnO NRs. This effect originates from the localized surface plasmonic resonance of AgNPs that could cause a strong electromagnetic field and synergistic effects of Ag, ZnO, and CV molecules in ZnONRs@Ag/CV SERS system.
 Conclusion: These outcomes reveal that AgNPs play a crucial role in enhanced SERS performance for chemical and biological detection of ZnO substrate.

Increase of SRG modulation depth in azopolymers-nanoparticles hybrid materials

Thin films of azopolymer-nanoparticles hybrid materials were fabricated with poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl] (PAZO) and different concentrations of Ag and AgAu nanoparticles (NPs). By illuminating the films with polarized interference patterns, surface relief gratings (SRGs) were recorded. It was found that for some concentrations of NPs their modulations and diffraction efficiency were higher than the obtained for PAZO films without NPs. The effect was mainly explained by the increase of the free volume available for the photoisomerization for certain concentrations of NPs. The dependence of the diffraction efficiency on concentration was directly related to changes in modulation depth. When doping with NPs, the maximum efficiency increases more than two times the efficiency without NPs.

Histological assessment of the local effect of different concentrations of aminoguanidine hydrochloride on bone healing in rats

Nitric oxide (NO) has several functions in bone healing and affects bone metabolism. Selective inducible NO synthase (iNOS) inhibitors can be used to assess the efficacy of NO for healing of bone defects. This study sought to assess the local effect of different concentrations of aminoguanidine hydrochloride (AG), a selective iNOS inhibitor, on bone healing in rats. In this animal experimental study, 72 rats were divided into six groups of control, placebo, 5% AG, 10% AG, 15% AG, and 20% AG. A bone defect measuring 5 mm × 5 mm was created in the femur. The defect remained empty in the control group. In the placebo group, neutral gel was placed in the bone defect, and in the remaining four AG groups, different concentrations of AG were applied to the defects. Bone healing was assessed histologically. The healing score in the six groups was analyzed by the Kruskal-Wallis test. A P < 0.05 was considered statistically significant. The healing score in 20%, 15%, 10%, and 5% AG groups was significantly higher than that in the neutral gel and control groups (P < 0.01). Among the four groups of AG, 20% concentration showed better results, but the difference was not significant. Four concentrations of AG caused greater bone healing compared to the other two groups. Selective iNOS inhibitors such as AG can be used to promote local bone healing.

Antibacterial activity and in vitro cytotoxicity studies of Ag-doped CaO nanoparticles

CaO nanoparticles can be used in different fields, such as medical and food, some studies suggest that they have poor antimicrobial properties. In this work, CaO nanoparticles doped with different concentrations of Ag were synthesized by the sol-gel method, to improve their antimicrobial activity. Cytotoxicity was also determined by MTT assay. The results of this study showed that it was possible to increase the antimicrobial activity of the CaO nanoparticles by doping them with different concentrations of Ag. According to a cytotoxicity study, a percentage of cell viability above 70% was obtained, thus the nanoparticles of CaO doped with Ag are candidates to be used in medical and food applications.

Green Synthesis, Characterization &amp; Antibacterial Studies of Silver (Ag) and Zinc Oxide (Zno) Nanoparticles

Green synthesis nanoparticles were considered as an alternative effective resource instead of chemically engineered metal oxide nanoparticles. Using leaf extracts for green synthesis, essential for the reduction and oxidation process of the metals. Phyllanthus niruri (L.) and Aristolochia indica (L.) leaf extracts were used to synthesize yellowish brown coloured silver (Ag) and white coloured zinc oxide (ZnO) nanoparticles. Synthesized green nanoparticles characterized by different spectroscopic analysis (XRD, XPS, FTIR, PL) and TEM. Characterization results confirmed the particles morphology, size, structure and also their optical and photonic properties. Three different concentrations of Ag and ZnO NPs were analysed against three (gram positive) and five (gram negative) bacteria. Increased levels of green synthesized Ag and ZnO NPs showed increased zone of inhibition than amoxicillin (positive control). Our study proved that the green synthesized Ag and ZnO NPs showed similar unique physical and chemical properties with metal oxide nanoparticles but less toxic while their discharge into the ecosystem.

Preparation and Tribological Behavior of Ti2AlNb/Ag Self-Lubricating Composites

In this paper, Ti2AlNb-based composites with different concentrations of Ag were fabricated by ball milling and spark plasma sintering (SPS). Microstructural evolution and phase compositions of the composites were further analyzed. The MS-T3001 friction wear tester was used to evaluate the friction performance of the Ag/Ti2AlNb self-lubricating composites. Results showed that the composites exhibit better anti-friction and anti-wear performance comparing with pure Ti2AlNb alloy. As the Ag wt.% increased, the coefficient of friction (COF) and wear rate of the composites were all decreased. Compared with pure Ti2AlNb, the COF and wear rate of Ti2AlNb-15 wt.%Ag self-lubricating composites at room temperature were decreased approximately 42 and 46%, respectively. The self-lubricating mechanisms of the composites were further discussed, and the silver-rich friction film formed on the friction surface under compression stress was regarded as the main anti-friction and anti-wear factors.

Silver doped glasses from the system BaO/SrO/ZnO/SiO2 – The influence of Sb, Sn, and Ta on the formation of core-shell structures

Three glasses from the base system BaO/SrO/ZnO/SiO2 have been synthesized using conventional melt quenching technique and different concentrations of Ag, Sn, Sb, and Ta. After two-step heat treatments, two glasses showed volume crystallization, while the third glass crystallized solely from the surface. The different crystallization mechanisms were studied by differential scanning calorimetry and both scanning and transmission electron microscopy. It was found that the formation of LEAZit (Low Expansion Alkaline Earth Zinc Silicates) volume crystals runs parallel to the formation of core-shell structures inside the glassy matrix. Such a core-shell structure consists of a metallic Ag core, which is surrounded by a shell composed of Zn2SiO4. Into this crystalline phase, Sb, Sn, as well as Ta can be incorporated. Glasses without Sb show the formation of metallic and spherically shaped Ag particles without any shell, being unsuitable to trigger volume crystallization in the studied glasses. Hence, the presence of Ag, Sn, Sb, or Ta in a suitable ratio is decisive for the nucleation and crystallization mechanism of the studied glasses.