Copper-zinc alloy solution

Standard Test Methods for Use ofMattsson s Solution of pH 7.2 to Evaluate the Stress Corrosion Cracking Susceptibility of Copper—Zinc Alloys, ASTM G 37-85, American Society for Testing and Materials, Philadelphia, Pa., 1992. 

Wilde, B. E. and Teterin, G. A., Anodic Dissolution of Copper-Zinc Alloys in Alkaline Solutions , Brit. Corrosion J., 2, 125 (1967)... 

Alloys of copper and zinc can be obtained by combining the molten metals. However, zinc is soluble in copper up to only about 40% (of the total). When the content of a copper/zinc alloy contains less than 40% zinc, cooling the liquid mixture results in the formation of a solid solution in which Zn and Cu atoms are uniformly distributed in an fee lattice. When the mixture contains more than 40% zinc, cooling the liquid mixture results in the formation of a compound having the composition CuZn. The solid alloy consists of two phases, one of which is the compound CuZn and the other is a solid solution that contains Cu with approximately 40% Zn dissolved in it. This type of alloy is known as a two-phase alloy, but many alloys contain more than three phases (multiple-phase alloys). 

DEZINCIFICATION. A form of electrolytic corrosion observed in sume brasses where the copper-zinc alloy goes into solution with subsequent redepnsition of the copper. The small red copper plugs thus formed in the brass are usually porous and of low strength. In recent years, the term dcziticilicalion lias also been applied in a more general sense to signify any metallic corrosion process that dissolves one of the components from an alloy. 

Stress-corrosion cracking of copper-zinc alloys can occur in environments other than ammoniacal solutions (Ref 114, 147, 151, 152). Included are nitrogen-bearing compounds such as amines and aniline, as well as sulfates, nitrates, nitrites, acetates, formates, and tartrates. These environments can produce tarnish films of Cu20 similar to the films formed in ammoniacal solutions. Both the rate of formation and... 

Milosev, I. and T. Kosec, Electrochemical and spectroscopic study of benzotriazole films formed on copper, copper-zinc alloys and zinc in chloride solution. Chemical and Biochemical Engineering Quarterly, 2009. 23(1) p. 53-60. 

The most widely used group of copper alloys is the brasses, which are basically copper-zinc alloys. The resistance of brasses to corrosion by aqueous solutions does not change markedly as long as the zinc content does not exceed about 15 % above 15 % zinc, dezincification (or deaUoying) may occur. Selective removal of zinc leaves a relatively porous and weak layer of copper. 

Ammonium hydroxide solutions also attack copper-zinc alloys. Alloys containing more than 15 % zinc are susceptible to see when stressed and exposed to ammonium hydroxide, although it also is experienced by the copper-beryllium alloys which are zinc-free. The stress may be due to applied tensile service loads or to unrelieved residual tensile stresses. 

ASTM G 37 (Practice for Use of Mattsson s Solution of pH 7.2 to Evaluate the Stress Corrosion Cracking Susceptibility of Copper-Zinc AUoys) is an accelerated stress corrosion cracking test environment for brasses (copper-zinc alloys). The use of this test environment is not recommended for other copper alloys since the results may be erroneous, providing completely misleading rankings. This is particularly true of alloys containing aluminum or nickel as deliberate alloying additions. 

Conditions of the environment that favor dezincification are high temperatures, stagnant solutions, especially of acid, and porous inorganic scale formation. Other factors that stimulate the process are increasing zinc concentrations and the presence of both cuprous and chloride ions. As the dealloying proceeds a porous layer of pure or almost pure copper is left behind. This reaction layer is of poor mechanical strength. The dezincification process on copper-zinc alloys is therefore very detrimental. 

Alloying metals with impurities results in a reduction in the thermal conductivity, for the same reason that the electrical conductivity is decreased (Section 18.8) namely, the impurity atoms, especially if in solid solution, act as scattering centers, lowering the efficiency of electron motion. A plot of thermal conductivity versus composition for copper-zinc alloys (Figure 19.4) displays this effect. 

Silver-copper, energy of solutions, 142 Silver-gold, excess entropy, 132, 136 excess free energy, 136 Silver-lead, alloy (AgsPb5), calculation of thermodynamic quantities, 136 Silver-zinc, alloy (Ag5Zn5), 129... 

Copper(l) cyanide is used in copper plating of nickel, chromium, zinc alloys, steel, and other metals or alloys. Such copper plating imparts brightness, smoothness, hardness, and strength. The cyanide solution employed for copper electroplating consists of copper cyanide and sodium cyanide. Other apph-cations of this compound are as an insecticide, a catalyst in polmerization, and as an antifouling agent in marine paints. 

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