Gold-cadmium alloy

Goldbeater Gold-beryUium Gold bronzes Gold-cadmium alloys Gold-calcium alloy... 

Swedish researcher Arne Olander observes a gold-cadmium alloy that can be bent while cool but returns to its original shape after heating—a shape-memory alloy. 

The shape memory effect was first discovered at the end of the 1940s in a gold-cadmium alloy. Since this extraordinary effect was recognized in the early 1950s as being caused by a martensitic transformation, new and improved shape memory alloys have been found. As prices for shape memory alloys are dropping, more and more commercial apphcations ranging from aviation to medicine - make use of the functional properties of those materials. In this contribution we will focus on the new and innovative field of actuator applications. 

The development of new alloys as a means of modifying existing electrodeposits for example the production of hard gold by alloy codeposition of copper, cadmium etc. to yield 23 or 18 carat alloys, or the use of zinc alloys for improved electrogalvanised coatings. 

Figure 8. Gold-cadmium-copper alloy obtained by dissolution of CdS in molten Au-Cu alloy. The black earthy deposit is easily separated from the...

The so-called white gold alloys were introduced to resemble platinum when that metal was prohibitive in price, and their use in jewellery has been very successful. The earliest white gold contained. gold, nickel and zinc. Gold-palladium alloys are easier to work and with 20 per cent of the latter element are completely white, but the high price of palladium militates against their use except in the most expensive jewellery. Green, blue and purple alloys are also easily made by addition of cadmium, iron and aluminium respectively. 

By adding copper and/or cadmium salts to the neutral electrolyte, gold-copper-cadmium alloys can be plated. 

The most noteworthy and extensively researched shape-memory materials are shape-memory alloys (SMAs). Olander first discovered and reported in 1932 a novel metallic transformation of gold-cadmium (AuCd) alloy, whose pseudoelasticity triggered imusual macroscopic deformation [12]. The discovery of the SME in equiatomic nickel-titanium (NiTi) alloy, which is well known as nitinol, represented a paradigm shift in the SMA field. 

Tables 8.6 and 8.7 list a representative range of colored and white karat gold brazing alloys, respectively. The silver, copper, cadmium, zinc, nickel, indium, and gallium additions serve to...

Until recently, many of the gold brazing alloys contained cadmium as an alloying element, which offered the advantages of acting as a melting point depressant and, simultaneously, imparting... 

Cadmium-free gold solder alloys, G. Normandeau, Gold Technology, 1996, 18, 20-24. 

Table 9.2 shows the compositions and melting ranges of three 18 kt cadmium-free solder alloys and two containing cadmium compared with the solidification range for a typical 18 kt yellow gold casting alloy. 

G. Normandeau, 1989. Cadmium-free gold brazing alloys. In Proceedings of the Santa Fe Symposium on Jewelry Manufacturing Technology, ed. D. SchneUer, 179-209. Albuquerque, NM Met-Chem Research. 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

Electroplated Metals and Alloys. The metals electroplated on a commercial scale from specially formulated aqueous solutions iaclude cadmium, chromium, cobalt, copper, gold, iadium, iron, lead, nickel, platinum-group metals, silver, tin, and ziac. Although it is possible to electroplate some metals, such as aluminum, from nonaqueous solutions as well as some from molten salt baths, these processes appear to have achieved Httie commercial significance. 

Features of the method Most metals can be deposited by this technique, usually on to steel or copper alloys as substrates. The most commonly deposited metals are nickel, chromium, tin, copper, zinc, cadmium, gold and silver. 

Other alloys Other copper alloys can be plated, including copper-tin-zinc (Alballoy) , copper-nickel , copper-cadmium , copper-gold and copper-lead . 

---