Gold mechanical properties

Dentistry. Most casting alloys meet the composition and properties criteria of specification no. 5 of the American Dental Association (37) which prescribes four types of alloy systems constituted of gold—silver—copper with addition of platinum, palladium, and 2inc. Composition ranges are specified, as are mechanical properties and minimum fusion temperatures. Wrought alloys for plates also may include the same constituents. Similarly, specification no. 7 prescribes nickel and two types of alloys for dental wires with the same alloy constituents (see Dental materials). 

Table 5. Mechanical Properties of Cast Gold Alloys ...

In the following we present an experimental study of gold atomic contacts formed in various aqueous electrolytes under electrochemical potential control. We will focus in particular on the electrical and mechanical properties of the electrochemical nanojunctions, as well as on their interplay in the presence/absence of various adsorbates (e.g., H2, C104, S042-, Cl-, Br-, and I-) [209, 210]. 

Besides the manufacture of jewellery, gold is used in electronics, dentistry, brazing alloys, the aerospace industry, etc. For several applications gold is alloyed with other metals in order to improve its mechanical properties. 

Uses. The unalloyed metal cannot be directly used owing to its bad mechanical properties and its high oxidability. Several thallium alloys are used as semiconductors or ceramic compounds it may be used as additive to gold, silver or copper contacts in the electronic industries. Thallium is dangerously toxic. 

The materials normally used in the construction of working electrodes are platinum, gold, mercury and carbon. However, there have been recent attempts to use more sophisticated materials such as superconductors (as will be discussed in Chapter 10, Section 1), but at moment, due to their poor chemical and mechanical properties, they are not very promising electrode materials. 

Carbon is widely used in the catalytic processes of the chemical industry due to its unique characteristics, such as chemical inertness, high surface area and porosity, good mechanical properties and low cost. It is used for the production of chlorine and aluminum, in metal refining (gold, silver, and grain refinement of Mg-Al alloys) as well as for the electrolytic production of hydrogen peroxide and photoelectrochemical water splitting. 

Conducting (conjugated) polymers have a unique set of properties The electronic properties of metals and semiconductors and the processing advantages and mechanical properties of polymers. It is the and that makes conducting polymers special materials. There are, after all, many excellent metals for example, copper, nickel, silver and gold, to name but a few. Similarly, there are many excellent semiconductors. Indeed, the sophisticated modem electronics industry uses silicon as the semiconductor of choice. It would be difficult to improve on the quality of copper as a metal or silicon as a semiconductor. 

Fig. 14,— Variation in Mechanical Properties on Annealing after 300 % Gold Work.)...

After plating, the first test of deposit was controlling the mechanical adhesion of Cu layers using the adhesive tape test. All films passed successfully this test whereas films obtained from an acid CUSO4 solution never passed the same test. The excellent mechanical properties of Cu films deposited from alkaline cyanide solutions is therefore presumably related to some specific interactions between the CN ions and the Si surface as recently observed for the electrodeposition of gold on n-Si from KAu(CN)2 solutions (6). 

Au-Cu-Ag alloys based on the inter-metallic phases CuAu and CujAu have found applications in dentistry because of their extremely high corrosion resistance, their advantageous mechanical properties such as high strength and ductility, and their decorative gold color (Yasuda, 1991). These alloys age-harden as a result of complex ordering and decomposition reactions by which the phases CujAu I, CuAu I, CuAu II, and an Ag-rich tXj phase are formed, depending on the composition. 

The main disadvantage of phenolic resins is their intrinsic yellow to brown color. As a result they cannot be used for colored and white paints. They can only be used for decorative coatings in a few cases (e.g., gold lacquers). Phenolic resins have favourable mechanical properties and a high chemical resistance. Paint systems that are optimally adjusted to the requirement profile can be developed by suitable formulations. 

---