Palladium-silver alloys

Palladium-silver alloy has greater resistance to fretting. Inlays are common, and coatings will be adopted as deposition processes improve. ... 

The disappearance of the paramagnetism of palladium-silver alloys (rich in Pd) when the ratio (H + Ag)/Pd = 0.6 (24) illustrates that the effect of both these alloying" elements in palladium is additive and each one contributes essentially in the same way to the change of magnetic susceptibility of palladium. 

Silver-palladium alloys, see Palladium-silver alloys... 

Selective gas permeation has been known for generations, and the early use of palladium silver-alloy membranes achieved sporadic industrial use. Gas separation on a massive scale was used to separate U from U using porous (Knudsen flow) membranes. An upgrade of the membranes at Oak Ridge cost 1.5 billion. Polymeric membranes became economically viable about 1980, introducing the modern era of gas-separation membranes. H2 recovery was the first major application, followed quickly by acid gas separation (CO2/CH4) and the production of N2 from air. 

Soma-Noto Y, Sachtler WMH. 1974. Infrared spectra of carbon monoxide adsorbed on supported palladium and palladium-silver alloys, J Catal 32 315. 

Uemiya, S., T. Matsuda, and E. Kikuchi, Hydrogen permeable palladium-silver alloy membrane supported on porous ceramics, /. Membr. Sci., 56, 315,1991b. 

Palladium-silver alloy membranes, 15 813-814 Pall rings, 1 28 8 770... 

Siloxane compounds, in vitreous silica manufacture, 22 414 Siloxane materials, 20 240 Siloxane oligomers, in silicone polymerization, 22 555-556 Siloxanols, silylation and, 22 703 Silsesquioxane hybrids, 13 549 Silsesquioxanes, 15 188, 22 589-590 SilvaGas process, 3 696, 697 Silver (Ag), 22 636-667. See also Silver compounds. See Ag entries Argentothiosulfate complexes Batch desilverizing Lead-silver alloys Palladium-silver alloy membranes analytical methods for, 22 650-651 applications of, 22 636-637, 657-662 as bactericide, 22 656, 657, 660 barium alloys with, 3 344 in bimetallic monetary system, 22 647-648 in cast dental gold alloys, 8 307t coke formation on, 5 266 colloidal precipitation color, 7 343t colloidal suspensions, 7 275 color, 7 334, 335... 

The reversible absorption was observed to proceed in presence of either metallic palladium or in palladium-silver alloys much less hydrogen was absorbed in Cu sponge (1 vol. Cu 0.6 vol. H.), and not at all in Os-Ir. The reaction of hydrogen with palladium, so being described by Graham, was ... 

It should be noted that, in the interpretation of activity patterns of alloy catalysts, extreme care is needed to ensure that the surface composition is known. It has been shown [321,322] with copper—nickel alloys, which show two phases in the composition range 2—80% copper, that, within this miscibility gap, the surface composition remains constant at 80% Cu—20% Ni, independent of the nominal bulk composition. Furthermore, the surface composition may vary depending upon the catalyst pretreatment [322], No miscibility gap occurs with palladium—gold or palladium-silver alloys [323]. 

H. Palladium. Palladium (mp 1,SS2°C), is soft and ductile but work-hardens. At elevated temperatures, the diffusion of hydrogen through palladium is rapid, which forms the basis of a method for the purification of hydrogen. The best performance is obtained from a palladium-silver alloy containing about 18% silver because, unlike pure Pd, this alloy does not undergo a phase transition in the presence of hydrogen. Palladium is not as inert as platinum and is attacked by sulfuric and nitric acids. 

Zinc Chloride Hydrocracking—Batch Autoclave Work. All tests were made in a 316 stainless steel, 300-ml rocking autoclave. The equipment, the product work-up, analytical and calculational procedures used are all identical to those previously described (1). A constant hydrogen partial pressure was used in each run by monitoring it with a palladium-silver alloy probe within the authoclave. The sensitivity of the probe response was increased as compared with prior work by heat treating at... 

A striking property of many interstitial metal hydrides is the high rate of hydrogen diffusion through the solid at slightly elevated temperatures. This mobility is utilized in the ultra-purification of H2 by diffusion through a palladium-silver alloy tube. 

Jayaraman V., Lin Y.S. Synthesis and hydrogen permeation properties of ultrathin palladium-silver alloy membranes. J.Membr.Sci 1995 104 251-262. 

A FIRST-PRINCIPLES STUDY OF HYDROGEN DISSOLUTION IN VARIOUS METALS AND PALLADIUM-SILVER ALLOYS... 

Palladium silver alloys admit of receiving a high polish, and retain their bright surface. An alloy containing 38 per cent, of palladium, the remainder being silver, was formerly used for dental purposes. 

We are not going here to discuss the rf-likc energy bands of metallic transition elements except for two pioneer studies (237,238) and an important demonstration (239) that palladium-silver alloys behave as if individual I(Pd4d) and I(Ag4d) remain distinct. Watson and Perlman discuss gold and its alloys in great detail in the present volume. Many authors (240—245) have studied the valence region of... 

One of the earliest applications of membrane to shift equilibrium was developed by Wood(5) (1960). He showed that by imposing a nonequilibrium condition on a hydrogen-porous palladium silver alloy membrane, an otherwise stable cyclohexane vapor is rapidly dehydrogenated to cyclohexene. 

G.L. Holleck, Diffusion and solubility of hydrogen in palladium and palladium>silver alloys, J, Phys. Chem, 74 503 (1970). 

E. Kikuchi and S. Uemiya, Preparation of supported thin palladium-silver alloy membranes and their characteristics for hydrogen separation. Gas Sep. Purif. 5 261 (1991). 

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