Palladium alloyed with gold

Hardy and Linnett (59) studied the heterogeneous recombination of atomic hydrogen at room temperature on nickel and nickel alloy foils. They did not find any similarity to the behavior of palladium and its alloys with gold studied earlier (35). There was no evidence that, as a result of exposure to atomic hydrogen, hydride was formed in any metal catalyst investigated with a resulting change in the activity of the initial parent metal catalysts. 

The full analogy with palladium and its alloys with gold should thus be emphasized once more. 

Occurrence and History.—Palladium occurs native along with platinum in Brazil,1 St. Domingo, and the Urals. It is also found alloyed with gold as the mineral porpesite, the name being derived from Porpez in Brazil. Of tliis alloy the following may be taken as a typical analysis 2 ... 

An alloy is made by mixing two or more melted metals. The solid mixture has properties different from those of the individual metals. Palladium is commonly alloyed with gold, silver, and copper. The alloys... 

Palladium is now being used more in industry than hitherto, often as a substitute for platinum. Sometimes medals are struck in it. Alloyed with gold it is used as a substitute for platinum. Gold with 20 per cent palladium is completely white and is sometimes used in expensive jewellery under the name white gold . 

A second information is provided by the market of precious metals for electronics applications. In the United States, the largest volume in 1992 was for silver powders and flakes with 249 tons, second were silver-palladium alloys with 31 tons, followed by palladium, gold, and platinum with 6.2, 3.1, and 0.8 tons, respectively. The paste and ink formulations loaded with 60-80% of precious metals included a metal value exceeding 180 million, and the added value for the producers of powders and flakes was approximately 30-32 million. The companies making the conductive pastes added approximately 100 million to the final products. This means that in the US alone the total market was over 300 million for conductive adhesives and pastes, inferring a worldwide production worth over 1 billion dollars. The most important manufacturers of multilayer ceramic capacitors and other discrete devices using large quantities of conductive materials are located in Japan and South-East Asia. 

Copper [7440-50-8] Cu, produces a reddish color and reduces the melting pokit of the alloy. It produces heat-treatable compositions with gold, platinum, and palladium that result ki kicreased hardness, strength, and generally improved physical properties. The tarnish resistance of the alloy is usually decreased. The gold—copper, Au—Cu, system is the fundamental system of many dental gold alloys. Copper has a useful range of 0—20 wt %. 

Palladium and Palladium Alloys. Palladium is used in telephone equipment and in electronics appHcations as a substitute for gold in specific areas. Palladium is plated from ammoniacal and acid baths available along with chelated variations as proprietary processes. One typical alkaline bath uses 8 g/L diammine-dinitropalladium, 100 g/L ammonium nitrate, and 10 g/L sodium nitrite. The pH is adjusted to 9—10 using ammonium hydroxide, and the bath is operated at 100 A/m at 50° C. If ammonium sulfamate, 100 g/L, is used in some baths to replace the nitrate and sodium nitrite salts, the bath is mn at lower temperature, 25—35°C, and a pH of 7.5—8.5. A palladium—nickel alloy, 75% Pd, is plated from a bath having 6 g/L palladium from the same salt, 3 g/L nickel from nickel sulfamate concentrate, and 90 g/L ammonium hydroxide. The bath is operated at 20—40°C with 50-100 A/m/... 

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... 

A. Sieverts, E. Jurish, A. Metz, Solubility of hydrogen in sohd alloys of palladium with gold, silver, platinum, Z. Anorg. Chem. 91 (1915) 1 5. 

Low force/low voltage separable connectors used in computers, and other electronic devices, are typically plated with gold or palladium over a barrier layer of nickel. The tail ends of these connectors, which are usually joined to the device by soldering, are plated with a tin-lead alloy, or pure tin. 

Composition of Native Gold.—Nativo gold is neveT quite pure, behig almost invariably alloyed with silver, and containing frequently small proportions of copper and iron. In Siberia it is often associated with platinum, and in the Gongo Soco mines in Brazil, on alloy of gold and palladium of a pale yellow color is sometimes found. In Columbia a somewhat similar... 

The exchange reaction of methane with deuterium has been found to show a decrease in specific activity upon alloying of palladium with gold (82), reflecting the decrease in number of reactive surface metal atoms upon alloying. 

Fig. 6. Activation energy of carbon monoxide oxidation over nickel oxide on gold-palladium alloys (24). (Copyright by Akademische Verlags-Gessellschaft. Reprinted with permission.)...

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