Cu amalgams

Dental amalgams have been in use for more than a thousand years (Waterstrat, 1990). Amalgams are still a very important class of material for dental restoration, in spite of corrosion problems with mercury release because the amalgams offer an advantageous combination of properties with respect to processing and use (Watts, 1992 Waterstrat and Okabe, 1994). These 

---

In all methods, except that of Troisdorf, the resulting MF is of greyish color due to the presence of small quantity of free Hg. Such MF is not suitable for loading into caps made of Cu or Cu-contgalloys such as brass or bronze. This is because free Hg attacks Cu forming a Cu amalgam, and this will react with MF to form Cuprous Fulminate which is less stable and more sensitive than MF... 

Alloy formation is of great technological importance. Indeed, the Bronze Age, Iron Age, and other epochal historical transformations are characteristically identified with metallurgical advances in alloying. Well-known binary or ternary alloys that underlie aspects of modem life include bronze (Cu/Sn), brass (Cu/Zn), stainless steel (Fe/Ni/Cr), coinage and jewelry metals (Au/Ni, Ag/Cu), amalgams (Hg/Ag/Cu), and aluminum can material (Al/Mn), among many others. 

In seawater, Zn, Cd, Pb, and Cu amalgamate quasi-reversibly with Hg. Thus, these metals are routinely analyzed. Nonroutine methods for the analysis of many more transition metals in seawater by either cathodic or anodic stripping are being developed daily. Also, because of the low concentration of trace metals in oceanwater ( 1 jixg/L), the stripping process is routinely carried out in the differential pulse (DP) mode, a process that enhances the metal-related component of the current over the background. Calibration of the cell (and of the analysis) is carried out by adding known... 

In the dispersed-phase amalgam an additional phase of an eutectic of the Ag—Cu system and a reaction ring (2one) of Cu Sn [12019-69-1] around the residual silver alloy particles has been detected. If 10% gold is added to conventional alloys at the expense of the silver content, non-y2 amalgams are... 

Selection. The widely used cathode materials iaclude Hg, Pb, Al, Zn, Ni, Fe, Cu, Sn, Cd, and C. Because of mechanical iaconvenience, mercury is not an attractive electrode material for large cells. The preferred material is lead or an amalgam. Because Pb is soft and has a tendency to deform, however, it presents some mechanical problems. The problems can be overcome by hot dip or electroplating on steel, copper, or other rigid base material. 

Fig. 3. Evans-diagram for the cementation of Cu2+ and Pb2 with zinc amalgam of different zinc content. If the zinc concentration in the mercury employed for this special extraction technique is low, the anodic zinc-dissolution current density may be diffusion controlled and below the limiting cathodic current density for the copper reduction. The resulting mixed potential will lie near the halfwave potential for the reaction Cu2+ + 2e j Cu°(Hg) and only Cu2 ions are cemented into the mercury.

Silver was formerly extracted by cyanide solution of Ag2S, the resulting Ag(CN)2 being treated with zinc to afford the metal roasted ores could also be extracted with mercury to give silver amalgam. Presently much silver is extracted by workup of the anode slime from the preparation of non-ferrous metals (Pb, Cu) pure silver is obtained by electrolysis of AgN03. 

About 20 amalgam-forming metals, including Pb, Sn, Cu, Zn, Cd, Bi, Sb, Tl, Ga, In and Mn, are easily measurable by stripping strategies (ASV and PSA) based on cathodic deposition onto mercury electrodes. Additional metals, such as Se, Hg, Ag, Te and As are measurable at bare solid electrodes such as carbon or gold. 

In many instances electrogravimetry must be preceded by a separation between metals suitably this can be an electroseparation by means of constant-current electrolysis as previously described, but more attractively an electroseparation by means of controlled-potential electrolysis at a mercury pool or sometimes at an amalgamated Pt or brass gauze electrode. In this way one can either concentrate the metal of interest on the Hg or remove other metals from the solution alternatively, it can be a rougher separation, i.e., the concentration of a group of metals such as Fe, Ni, Co, Cu, Zn and Cd on the Hg whilst other metals such as alkali and alkaline earth metals, Be, Al, Ti and Zr remain in solution151. In all these procedures specific separation effects can be... 

The way that the stripping analysis is performed in practice is much more sophisticated. After the solution has been exhausted, all of the copper (as Cu (Hg) amalgam) resides on the surface of the mercury drop. The potential of the drop is changed from cathodic to anodic (we say that we have stepped the potential), and the copper is all oxidized back to Cu and the charge determined - as oxidation-The potential chosen should be more positive than E for the analyte couple by at least 0.2 V. 

H20 col prisms (from w) expl on heating in a flame and from strong impact. Was prepd by treating Ba fulminate with an excess of cuprous chloride in w. Ba fulminate may be obtained by shaking Hg fulminate with Ba amalgam under w. Its uses were not specified (Ref 1 Ref 2, p 2757) Copper(l)-calcium Fulminate, Ca [Cu(CNO)3]. ... 

Copper(l)-sodium Fulminate, Na [ Cu(CNOz)] col crysts (from hot w), expl more violently than disodium salt on heating or impact. Was prepd by treating dil Na fulminate soln with cuprous chloride at 80°(Ref 1 Ref 2, pp 2754-55) Copper(l)strontium Fulminate, Sr [Cu(CN0)4]t 2HjO col microscopic crysts, expl violently on heating or on impact. Was prepd by warming Sr fulminate in w with cuprous chloride. Sr fulminate was obtd by shaking Sr amalgam with Hg fulminate in w (Ref 1 Ref 2, p 2755)... 

---