Papers by Keyword: Ag

Abstract: Mixture powders with different ratio of Ag/γ-TiAl were deposited on titanium alloy by low presure plasma spray and thermal treatment was applied to convert the mixture coatings into Ti-Al-Ag ternary ones. The experimental results indicated that the oxidation resistance of ternary coatings was better than sheer γ-TiAl coating and increased with increasing Ag from 2at.% to 4at.% at 700 and 800°C. The outside oxide scale consisted of alumina and a small amount of rutile due to the insufficient diffusion of Ag in γ-TiAl.

Abstract: The ageing behavior of AZ80+xAg (x=0;0.3;0.5) magnesium alloys at different temperature were systematically investigated using optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Experimental results demonstrate that the trace amount of Ag accelerated the precipitation of Mg₁₇Al₁₂ phase during ageing at 200°C, AZ80+0.5Ag achieved the peak hardness of 89.7HV after holding for 12h, compared with 80.8HV after 28h for the Ag-free alloy. However, when ageing at high temperature (250°C), the promotion response of Ag was totally vanished. The tensile property of the peak aged alloys at ambient temperature increased with Ag addition, as well as the tensile property at elevated temperature. Further investigation indicates that Ag addition suppresses the discontinuous precipitates, which account for the enhanced property of Ag-containing alloy.

Abstract: Mist-atomization deposition method was applied in order to grow ZnO nanoparticles on Au-seeded glass substrates acting as seeded template. Ag doped ZnO thin films were deposited on ZnO seeded templates by solution-immersion method. The influence of Ag doping content on the optical and Raman scattering properties of ZnO films were systematically investigated by UV-Vis transmittance measurement measured by ultra-violet visible spectroscopy (UV-Vis) and Raman scattering spectrum measured by Raman spectroscopy under room temperature. From UV-Vis transmittance measurement, the incorporation of Ag dopant to the ZnO makes the transmittance wavelength shifted to the shorter wavelength as compared to the pure ZnO. From Raman spectra, 4 cm^-1 downshift is observed in Ag-doped thin films as compared to pure ZnO thin films. This Raman peak shift shows that a tensile stress existed in the Ag-doped ZnO film.

Abstract: In this paper, a novel anti-bacterial agent of Ag-deposited silica-coated Fe₃O₄ magnetic nanoparticles was prepared by a template-activated strategy, which possess a silica coated magnetic core and silver nanoparticles on the outer shell. The as-synthesized nanoparticles have been characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX). The obtained products exhibited dispersibility and high magnetization, which also show a good recycling antibacterial activity, and the antibacterial rates against Escherichia coli was all 100 % for 3 cycles.

Abstract: A new sensor with Pt and Ag mixture paste on the surface to act as the sensing electrode (Ag) and catalyst (Pt) to oxidized SO₂ to SO₃ for sulfur dioxide was fabricated. The effect of auxiliary phase on the sensing properties has been investigated and the device with auxiliary phase showed better performance and the effect of operating temperature has also been studied. It shown that 500°C would be more suitable than 600°C for the device gas test.

Abstract: A number of nonequilibrium nanocrystalline fcc solid solutions Cu_1-x-Ag_x (x = 0,1; 0,2; ... 0,9; 1,0) were obtained by mechanical alloying of powders by the use of high pressure torsion. Chemical homogeneity, microstructure, mechanical properties and thermostability were studied. The obtained alloys were found to be characterized by a positive excess over Vegard law, ~ 20 nm grain sizes, a microhardeness of 4.5-6 times higher than the Cu and Ag one and brittle type of the fracture surface. In situ shear stress vs. strain measurements and energy-power parameters estimation were performed. A decomposition of nonequilibrium solid solution induced by a thermal influence begins from close to room temperatures and finishes completely at heating up to 500°С accompanied by collective recrystallization development.

Abstract: Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2at.% and the same as, respectively. Ag or Cu added alloy showed higher maximum hardness than base alloy. The particle shape and rod shape precipitates were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased higher than that of base alloy.

Abstract: The Ag-assisted electroless etching of p-type silicon substrate in HF/H₂O₂ solution at room temperature was investigated. In this work, the effects of HF, H₂O₂ and their volume ratio on morphology and growth of p-type silicon substrate surface by using metal assisted etching were investigated in order to produce a highly efficient antireflecting structure. The Ag metal particles were deposited onto Si wafer by electroless deposition from a metal salt solution including HF. The experimental results show that the growth rate and morphology of the pores formed on the Ag metalized Si surfaces are strongly dependent on the volume ratio of HF and H₂O₂.

Abstract: The effect of Cu or Ag addition on 2 step aging in Al-Mg-Si alloy has been investigated to understand precipitation for this alloy. The maximum hardness of two step aged alloy was higher with increasing pre-aging time for Al-Mg-Si alloy. There was no remarkable difference between the peak-hardness of the Ag addition alloy with and without pre-aging. The hardness decreased once for the Ag addition alloy aged at 473K just after pre-aged at 343K for 600ks and then increased to the peak hardness with increasing aging time, which means the reversion of the Ag addition alloy.

Abstract: Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. Ag or Cu added alloy showed higher maximum hardness than Ag or Cu free alloy. The η’ phase were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased than Ag or Cu free alloy.