Gold wetting

Chromium/gold Wet chemical etching Cathode sputtering Glass isotrope... 

As a somewhat anecdotal aside, there has been an interesting question as to whether gold is or is not wet by water, with many publications on either side. This history has been reviewed by Smith [119]. The present consensus seems to be that absolutely pure gold is water-wet and that the reports of non wetting are a documentation of the ease with which gold surface becomes contaminated (see Ref. 120, but also 121). The detection and control of surface contaminants has been discussed by White [121] see also Gaines [122]. 

Atre S V, Liedberg B and Allara D L 1995 Chain length dependenoe of the struoture and wetting properties in binary oomposition monolayers of OH and CHj-terminated alkanethiolates on gold Langmuir 3882-93... 

DiMilla P A, Folkers J P, Biebuyck H A, Harter R, Lopez G P and Whitesides G M 1994 Wetting and protein adsorption of the self-assembled monolayers of alkanethiolates which are supported on transparent films of gold J. Am. Chem. Soc. 116 2225-6... 

Dry chlorine reacts with most metals combustively depending on temperature alurninum, arsenic, gold, mercury, selenium, teUerium, and tin react with dry CI2 in gaseous or Hquid form at ordinary temperatures carbon steel ignites at about 250°C depending on the physical shape and titanium reacts violendy with dry chlorine. Wet chlorine is very reactive because of the hydrochloric acid and hypochlorous acid (see eq. 37). Metals stable to wet chlorine include platinum, silver, tantalum, and titanium. Tantalum is the most stable to both dry and wet chlorine. 

Mercuric Sulfate. Mercuric s Af2iX.e.[7783-35-9] HgSO, is a colorless compound soluble ia acidic solutions, but decomposed by water to form the yellow water-iasoluble basic sulfate, HgSO 2HgO. Mercuric sulfate is prepared by reaction of a freshly prepared and washed wet filter cake of yellow mercuric oxide with sulfuric acid ia glass or glass-lined vessels. The product is used as a catalyst and with sodium chloride as an extractant of gold and silver from roasted pyrites. 

The BLM layer uses a glue layer of chromium or titanium. These metals stick well to other metals and most dielectrics, but they are not solderable. Copper, nickel, and silver have been used as the solder-wetting layer for BLM in appHcations involving 95% lead—5% tin solders. Gold is commonly used as the oxidation layer on account of its resistance to oxidation and its excellent solderabiUty. 

The contact between the aluminium layers and the ceramic substrate requires a joining material which will wet both metal and ceramic, and solders such as the conventional Pb-Sn alloy have been used which are molten during the annealing process. The contact between the solder and the aluminium layer is frequently unsatisfactoty because of the intervention of the AI2O3 layer, and a practical solution appears to be to place drree layers of metal clrromium in contact widr the aluminium, copper in contact with the clrromium, and gold between the copper layer and the solder. 

Treatment of slimes for economic recovery of silver, gold, selenium, tellurium, and other trace elements requires fusion and oxidation in a furnace. The furnace gases are exhausted through a wet scrubber followed by an ESP to recover the metals. 

Processes, other than wet processes, in which metal articles (other than gold, platinum or iridium) are ground, abraded or polished using mechanical power, in any room for more than 12 hours per week 6 months... 

CO conversions over Au/Ce02 catalyst were measured in the dry and wet condition as shown in Fig. 1. Similar to other supported gold catalysts, Au/Ce02 catalyst showed higher CO conversions in the presence of water vapor than in the absence of it at the same temperature. Catalytic activities for CO oxidation over Au/Ce02 catalysts prepared at different calcinations temperature were compared in the dry and wet condition as shown in Fig. 2. Au/Ce02 catalyst calcined at 473 K showed the highest initial CO conversion in the absence of water vapor. However, the CO conversion decreased steadily and reached a steady-state value over this catalyst. 

Figure 16.7 Schematic drawing of the asymmetric electrode pattern. The gold electrode was covered with a Fc-alkanethiol monolayer. The wetting of the gold electrode was switched from wetting to repulsive and vice versa by changing the electrochemical potential of the electrode.

Figure 16.10 show pictures of the nitrobenzene droplets on the gold electrode covered with Fc-monolayer in aqueous solution when Vbias (0.35 V) was applied. The potential of the substrate was measured by two wires in contact with the substrate. It was clearly shown that the position of the wetting boundary moved when PofFset was changed, as shown in Figure 16.10b-d. 

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