Phase equilibria in the ternary Ag-Au-Ga system: Isothermal sections at 250°C and 450°C

The ternary Ag-Au-Ga system seems to be interesting in jeweller’s craft as a joint. Moreover, the ternary systems based on gold and silver have found applications in the dental industry. A literature overview of the Ag-Au-Ga system shows that the information about phase equilibria of this system does not exist. In the present work, phase equilibria in the Ag-Au-Ga ternary system have been studied by using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) analysis and X-ray diffraction analysis (XRD). Twenty two annealed alloys in the 10-70 at.% Ga region have been investigated. Obtained experimental results were compared with the predicted isothermal sections at two temperatures (250°C and 450°C). No ternary compounds are found

The application of viscoelastic damping materials to control the vibration of magnets in a synchrotron radiation facility

The Advanced Photon Source at Argonne National Laboratory is a facility signed to produce extremely brilliant x-rays for materials, chemistry, and medical research. In this facility, positrons are first produced and accelerated to energy levels of 7-GeV. The positrons are then injected into a 1104-meter circumference storage ring where they circulate, for periods up to 18 hours, and emit high-intensity x-rays as the circulating beam is oscillated by insertion devices. The beam is positioned and its size controlled by large electromagnets. The magnets are mounted on 200 individual girder assemblies, with each assembly having several magnets mounted on it. Of prime concern are the girder assemblies supporting the quadrupoles, or focusing, magnets. These magnets must satisfy very stringent vibration criteria, with motion restricted to less than a micron over a broad frequency range. Therefore, amplification at resonant frequencies of the girder assemblies must be minimized. To accomplish this, various viscoelastic damping materials and their placement in the system were evaluated. As a result of the study, dynamic magnification factors were reduced to a value of five with no detectable increase in static deflection. The damping materials and methods used to accomplish this in massive systems of 7,500 kg or greater, where the displacements are on the of 0.1 micron or less, will be useful for many less demanding situations

Passive vibration damping of the APS machine components

The accelerator and beamline components of the APS have stringent vibration criteria in order to meet the beam stability requirements. For instance, the vibration amplitude of the storage ring quadrupoles is restricted to 0.11 {mu}m (rms) over a frequency range of 4--50 Hz. Damping pads, consisting of thin viscoelastic f`ilms sandwiched between stainless steel plates, have been designed for passive vibration damping. Results presented in this paper show that the damping pads under the storage ring girder-magnet assemblies reduced the vibration amplification factor Q from over 100 to 8. The broad band rms motion of the magnets was reduced by a factor of 2.5 to 3. Preliminary results for a monochromator housing show a potential use of such damping pads for vibration control of beamline components. Radiation and creep effects on the damping pads` performance are considered

Activity and diffusivity of oxygen in the liquid dilute BixSb1-x solutions

The diffusivity and activity coefficient of oxygen in liquid antimony, bismuth and antimony-bismuth alloys were determined from coulometric titration experiments, which were performed in the temperature range from 985 to 1185 K. The diffusivity in pure metals (in cm2/s) is: Dbi,O =(9.04 ± 1.82)∙10-3 exp (-49115±1809/RT) DSb,O(2.87±0.22)∙10-4 exp (-16720±677/RT). The standard free energy of solution of oxygen in liquid antimony, bismuth and antimony-bismuth alloys according to the reaction ½ O2 (g) = O (infinite dilution) is calculated. The activity coefficient of oxygen was calculated at 1085 K as a function of the alloy composition. It was demonstrated that Wagner's model with one adjustable parameter h gave a satisfactory description of the experimental data

Właściwości termodynamiczne i równowagi fazowe w układzie trójskładnikowym Cu-Pb-Fe

Using experimental data available in the literature, two binary systems, namely Cu-Pb and Fe-Pb were recalculated. Next, accepting Cu-Fe phase diagram assessment as given by Ansara and Jansson, the ternary Cu-Fe-Pb system was analyzed. Calculated equilibrium lines and thermodynamic functions are compared with existing experimental data. Good agreement was found between the calculated diagram and the experimental results. Having the system optimized, functional dependences of the logarithms of the activity coefficients on temperature and concentrations for Cu, Fe and Pb in the liquid solution are given.Dwa układy podwójne Cu-Pb oraz Fe-Pb zostały powtórnie zoptymalizowane używając danych eksperymentalnych dostępnych w literaturze. Następnie, akceptując optymalizacje układu Cu-Fe opublikowana przez Ansare i Janssona, poddano analizie trójskładnikowy układ Cu-Pb-Fe. Obliczone linie równowagi faz oraz funkcje termodynamiczne zostały porównane z dostępnymi danymi eksperymentalnymi. Uzyskano dobrą zgodność pomiędzy policzonym układem a danymi eksperymentalnymi. Korzystając z wyników optymalizacji, zostały podane zalezności logarytmu współczynnika aktywności w funkcji temperatury oraz Cu, Fe i Pb w funkcji stężenia dla w roztworze ciekłym

Two-phase flow and pressure drop in flow passages of compact heat exchangers

Two-phase flow experiments were performed with air/water mixtures in a small rectangular channel measuring 9.52 {times} 1.59 mm (aspects ratio equal to 6), for applications to compact heat exchangers. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities (0.0002 to 1), and in the case of flow pattern data, a large range of mass fluxes (50 to 2,000 kg/m{sup 2}s). A flow pattern map, based on visual observations and photographs of the flow patterns, is presented and compared with a map developed for a rectangular channel of the same aspect ratio but with dimensions twice those of the test channel, and with a map developed for a circular tube with the same hydraulic diameter of 3 mm. Pressure drop data are presented as a function of both mass quality and Martinelli parameter and are compared with state-of-the-art correlations and a modified Chisholm correlation. 13 refs

Determination and characteristics of the transition to two-phase slug flow in small channels

Two-phase pressure drop was measured in a small horizontal rectangular channel (hydraulic diameter = 5.44 mm). The two-phase fluid was an air/water mixture at atmospheric pressure tested over a mass flux range of 50 to 2000 kg/m{sup 2}{center_dot}s. Two-phase flow patterns were identified and an objective method was found for determining the flow pattern transition from bubble or plug flow to slug flow. The method is based on an RMS pressure measurement. In particular, it is shown that the transition is accompanied by a clear and abrupt increase in the RMS pressure when plotted as a function of mass quality. Use of the RMS pressure as a two-phase flow pattern transition indicator is shown to have advantages over pressure-versus-time trace evaluations reported in the literature. The transition is substantiated by a clear local change in slope in the curve of two-phase pressure drop plotted as a function of either Martinelli parameter or mass quality. For high mass fluxes, the change in slope is distinguished by a local peak. Some degree of substantiation was found in previous work for both of the results (the RMS pressure change and the local pressure drop change) at the transition to slug flow

Phase relations near ternary eutectic point in the Ag-In-Sb system

The results of the phase relations near ternary eutectic point in the Ag-In-Sb system are investigated in this paper. Phase equilibrium calculation was done using Thermocalc software and experimental DTA results for the chosen alloys in the isopleths with molar ration of In:Sb = 7:3; 9:1 and 1:1. The structural characteristics of these alloys have been investigated using light optic microscopy and scanning electron microscopy, while hardness measurements have also been done. Solidification path for three ternary alloys located on three different investigated isopleths was calculated using Pandat software