Brass - Copper and Zinc

Central and Northern Europe developed its own brass manufacture concurrently with the increased knowledge of zinc and its ores (see Chapter 33 Zinc). 

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Alloys of nonferrous metals, primarily the brasses (copper and zinc) and the bronzes (copper and tin), can cause an air pollution problem during melting and casting. The type and degree of emissions depend on the furnace and the alloy. Control systems consist of hoods over the furnaces and pouring stahons to collect the hot gases, ducts and fans, and baghouses or ESPs. 

An alloy is a metallic compound having two or more elements. An alloy can also be a solution. The components of an alloy generally are themselves metals. Carbon, a non-metal being the exception. Alloys are produced by melting the required combination of metals. Alloys were known and used extensively in the ancient world. Brass (copper and zinc) and bronze were two important alloys used then. 

The metals zinc and cadmium should be avoided because of their high vapor pressures. Metals that include zinc and cadmium alloys such as brass (copper and zinc) and some silver solders (cadmium) should also be avoided for the same reasons. It is possible to obtain cadmium-free silver solder and brazing materials that use tin, lead, and indium for vacuum use. Some steel screws are cadmium-coated and also must be avoided. 

Bronze contains two elements, but it is not a compound. The elements are both metals, namely copper and tin, but they are not chemically combined in bronze. Bronze is a mixture of metals, an alloy the two metals can be separated. The percentages of copper and tin in bronze can vary considerably, depending on how much of each you add together. The properties of bronze depend on the relative amounts of the two metals. Another very common alloy is brass (copper and zinc). In compounds, the ratio of the elements present is always the same value and fixed. 

The structure of caesium chloride is included here because, although it is not close packed, it is often confused with, and written as, body centred when it is not. The structure of caesium chloride is shown in Figure 1.17. The chloride ions are on the cube comers and the ion at the centre is a caesium. In Section 1.4 we saw that a body-centred cubic lattice refers to an identical set of points with identical atoms at the comers and at the centre of the cube. This means that the stmcture of caesium chloride is not body-centred cubic. Many alloys, such as brass (copper and zinc) possess the caesium chloride structure. 

Like many transition metals, zinc has been known in impure form since ancient times. Brass (copper and zinc) coins were used by Egyptians and Palestinians as early as 1400 B.C.E. The first purification of zinc probably occurred during India in the thirteenth century C.E. Although the origin of the name is unknown, it has been suggested that it derives from the German word Zincke, meaning spike or tooth. ... 

CHEMICAL PROPERTIES nonflammable gas extremely stable to heat, even up to 2000°C reacts with water to form sulfurous acid (H2SO3) catalytically oxidized by air to sulfur trioxide (SOj) will slowly oxidize from sulfurous to sulfuric acid reacts with alkaline materials such as sodium and potassium reacts with some active metals like aluminum, brass, copper, and zinc may corrode aluminum corrosive when dissolved in water as sulfurous acid FP (NA) LFL/UFL (NA) AT (NA) HC (NA) HF (-320 kJ/mol liquid at 25°C, -296.8 kJ/mol gas at 25°C). 

Brass Copper and zinc are used to form brass, an alloy. Briefly explain why these two metals form a substitutional alloy and not an interstitial alloy. 

Alloys are most often made using the transition metals such as iron, or chromium for example. Since they form hard and strong materials with high melting points and high boiling points, they are often used for machinery and other structures that require strength and endurance. Commonly used household alloys include both bronze (copper and tin) and brass (copper and zinc). The transition metals can form alloys with one another and with... 

Examples Sodium, aluminium, iron, mercury and brass (copper and zinc) Diamond, polyethene, nylon, silicon dioxide and graphite Iodine, methane, hydrogen chloride, water, benzoic acid, ethanol, ammonia and fullerenes Sodium chloride, magnesium oxide, calcium fluoride and sodium carbonate... 

Alloys are usually divided into ferrous and non-ferrous alloys. Ferrous alloys include the steels, which are alloys of iron containing up to 2% carbon. The majority of non-ferrous alloys are based on copper. Familiar alloys of copper are brass (copper and zinc) and bronze (copper and tin). Bronze is an alloy that people have used considerably over long periods of history. 

Solid solution Solid Solid Brass (copper and zinc) and other alloys... 

A typical m el ter iastalled in a medium sized brass foundry contains 4500 kg of brass and its inductor is rated 500 kilowatts. Brass is an alloy containing copper and zinc. Zinc vaporizes at temperatures weU below the melting temperature of the alloy. The channel iaductor furnace s low bath temperature and relatively cool melt surface result in low metal loss and reduced environmental concerns. Large dmm furnaces have found use in brass and copper continuous casting installations. 

Adhesives in the Tire Industry. Cobalt salts are used to improve the adhesion of mbber to steel. The steel cord must be coated with a layer of brass. During the vulcanization of the mbber, sulfur species react with the copper and zinc in the brass and the process of copper sulfide formation helps to bond the steel to the mbber. This adhesion may be further improved by the incorporation of cobalt soaps into the mbber prior to vulcanization (53,54) (see Tire cords). 

Ammonia Used in refrigeration, chemical processes such as dye making, explosives, lacquer, fertilizer Textiles, chemicals Corrosive to copper, brass, aluminum, and zinc high concentration producing chemical burns on wet sldn... 

The components of an alloy are the elements which make it up. In brass, the components are copper and zinc. In monel they are nickel and copper. The components are given the atomic symbols, e.g. Cu, Zn or Ni, Cu. 

Striking of a smear or thin coating of alloy on rusty steel with a hammer. The glancing impact of stainless steel, mild steel, brass, copper-heryllium hronze, aluminium copper and zinc onto aluminium smears on rusty steel can initiate a thermite reaction of sufficient thermal energy to ignite flammahle gas/vapour-air atmosphere or dust clouds. 

Lucey concludes from his electrochemical studies that dezincification involves anodic dissolution of both copper and zinc followed by the cathodic deposition of copper, and on this basis he has explained why arsenic is capable of inhibiting dezincification of a-brass but not of a 3-brass. 

When dezincification occurs in service the brass dissolves anodically and this reaction is electrochemically balanced by the reduction of dissolved oxygen present in the water at the surface of the brass. Both the copper and zinc constituents of the brass dissolve, but the copper is not stable in solution at the potential of dezincifying brass and is rapidly reduced back to metallic copper. Once the attack becomes established, therefore, two cathodic sites exist —the first at the surface of the metal, at which dissolved oxygen is reduced, and a second situated close to the advancing front of the anodic attack where the copper ions produced during the anodic reaction are reduced to form the porous mass of copper which is characteristic of dezincification. The second cathodic reaction can only be sufficient to balance electrochemically the anodic dissolution of the copper of the brass, and without the support of the reduction of oxygen on the outer face (which balances dissolution of the zinc) the attack cannot continue. 

Brasses Brasses are basically alloys of copper and zinc, containing between about 10 and 45 l o Zn, but many other additions are made and the resulting alloys are the most complicated of all the copper-base series. The singlephase (a) brasses, containing up to about 37 7o Zn in the binary alloys, may have additions of 1% Sn (Admiralty brass), 2 7o A1 (aluminium-brass), or... 

The most important non-ferrous metals for handling water are lead, copper and zinc the last, however, is used chiefly as a protective coating on steel or alloyed with copper to form brass. 

Two mixtures. On the left is brass, a homogeneous mixture of copper and zinc. On the right is a piece of granite, a heterogeneous mixture that contains discrete regions of different minerals (feldspar, mica, and quartz). 

FIGURE 16.41 The atomic radii of copper and zinc are similar, and atoms of one element fit reasonably comfortably into the lattice of the other element to give the range of alloys that we know as brass. 

The /3-alloys are different in nature from the 7-alloys and the a-manganese and /3-manganese structures discussed above, in that they are not complex structures, but are simple, being based upon the body-centered arrangement. /3-Brass, for example, has either a disordered structure, above 480°K, the copper and zinc atoms in essentially equal number being distributed largely at random over the points of a body-centered cubic lattice, or an ordered structure, below 300°K, with copper and zinc at the positions 000 and, respectively, of the cubic unit. Moreover, the physical properties of /3-brass are not those that indicate a filled zone structure. 

Brass (alloy of copper and zinc) used for ship s propellers, screws, wind instruments. 

Many studies have reported the effects of metals on general soil microbiological processes. Metals including cadmium, chromium, copper, lead, mercury, nickel, and zinc have been reported to inhibit many of the microbial processes listed above. Metal toxicity in the environment ultimately decreases litter decomposition, which can be measured by the rate of mass loss. Both copper (0.5 mg Cu g4 soil) and zinc (1.0 mg Zn g 1 soil) were shown to decrease the rate of decomposition of unpolluted Scots pine needle litter near a brass mill in Sweden.61 Duarte et al.63 also determined that copper and zinc toxicity reduced leaf decomposition rates and fungal reproduction. Other metals, such as cadmium, nickel, and lead, have also been reported to decrease litter decomposition.77... 

Copper is a metallic element brass is an alloy or mixture of the metallic elements copper and zinc. The surfaces of copper and brass items tarnish with prolonged exposure to air, particularly in moist environments with high carbon dioxide (CO2) or sulfur dioxide (SO2) concentrations (see color Fig. 5.2.1). The compounds that form on the surface, ranging in color from black to blue to dark green, dissolve readily in acidic solutions. Vinegar contains acetic acid, ketchup contains tomatoes rich in ascorbic acid (Vitamin C), and onions contain malic acid and citric acid. All of these foods provide variable amounts of acid to dissolve the tarnish on copper surfaces. 

When this system was studied over time, it was found that the marker wires move toward each other. This shows that the most extensive diffusion is zinc from the brass (an alloy of zinc and copper) outward into the copper. If the mechanism of diffusion involved an interchange of copper and zinc, the wires would not move. The diffusion in this case takes place by the vacancy mechanism described later, as zinc moves from the brass into the surrounding copper. As the zinc moves outward, vacancies are produced in the... 

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