Copper 3 , zinc 12 , aluminium

Two methods are used to obtain casts used for later mass production (1) wax casting and (2) vulcanised rubber casts. The casts used in jewellery and costume jewellery are almost always made from steel, although copper, zinc, aluminium and tin-bismuth casts are also used. 

About 20% of the total import bill of a country like Britain is spent on engineering materials. Table 2.2 shows how this spend is distributed. Iron and steel, and the raw materials used to make them, account for about a quarter of it. Next are wood and lumber - still widely used in light construction. More than a quarter is spent on the metals copper, silver, aluminium and nickel. All polymers taken together, including rubber, account for little more than 10%. If we include the further metals zinc, lead, tin, tungsten and mercury, the list accounts for 99% of all the money spent abroad on materials, and we can safely ignore the contribution of materials which do not appear on it. 

However, the object of this section is to outline the principles which govern atmospheric corrosion, and the emphasis is placed on metals whose atmospheric corrosion is of economic importance. These include iron and steel, zinc, copper, lead, aluminium and chromium. 

Contact of brass, bronze, copper or the more resistant stainless steels with the 13% Cr steels in sea-water can lead to accelerated corrosion of the latter. Galvanic contact effects on metals coupled to the austenitic types are only slight with brass, bronze and copper, but with cadmium, zinc, aluminium and magnesium alloys, insulation or protective measures are necessary to avoid serious attack on the non-ferrous material. Mild steel and the 13% chromium types are also liable to accelerated attack from contact with the chromium-nickel grades. The austenitic materials do not themselves suffer anodic attack in sea-water from contact with any of the usual materials of construction. 

Very small amounts of copper taken into solution may cause considerable corrosion of more anodic metals elsewhere in the system, particularly zinc , aluminium , and sometimes steelSmall particles of copper deposited from solution set up local cells that cause rapid pitting. 

Little information is available about the corrosion of metals in concrete, although it seems likely that all Portland cements, slag cement and high-alumina cement behave similarly Concrete provides an alkaline environment and, under damp conditions, the metals behave generally as would be expected e.g. zinc, aluminium and lead will react, copper is unaffected, while iron is passivated by concrete. 

Thermal conductivity can be as low as one-eighth that of solid metal in the case of steel 7 W/m°C. The electrical resistance (specific) of copper, zinc and silver is about twice that of the cast metal, and of aluminium as much as five times, depending on spraying conditions. Adhesion in tension should... 

Most of the information available on the mechanism of action of inhibitive anions relates to iron, which will be discussed in some detail, and followed by brief accounts of zinc, aluminium and copper. 

Recent developments have also been reported in the inhibition of zinc , aluminium and copper . ... 

The selective net loss of a component such as zinc, aluminium or nickel from copper-base alloys sometimes occurs when these alloys corrode. Early studies of the phenomenon were done by simple immersion. More recently, however, the potential-pH dependence of de-alloying has been examined , and it appears that this approach can provide a much more detailed understanding of the mechanism. Future experimental work is expected to include potentiostatic and potentiodynamic techniques to a much greater extent. 

Discussion. Various metals (e.g. aluminium, iron, copper, zinc, cadmium, nickel, cobalt, manganese, and magnesium) under specified conditions of pH yield well-defined crystalline precipitates with 8-hydroxyquinoline. These precipitates have the general formula M(C9H6ON) , where n is the charge on the metal M ion [see, however, Section 11.11(c)]. Upon treatment of the oxinates with dilute hydrochloric acid, the oxine is liberated. One molecule of oxine reacts with two molecules of bromine to give 5,7-dibromo-8-hydroxyquinoline ... 

D. Benzoin-a-oxime (cupron) (VII). This compound yields a green predpitate, CuC14Hu02N, with copper in dilute ammoniacal solution, which may be dried to constant weight at 100 °C. Ions which are predpitated by aqueous ammonia are kept in solution by the addition of tartrate the reagent is then spedfic for copper. Copper may thus be separated from cadmium, lead, nickel, cobalt, zinc, aluminium, and small amounts of iron. 

Fluoride, in the absence of interfering anions (including phosphate, molybdate, citrate, and tartrate) and interfering cations (including cadmium, tin, strontium, iron, and particularly zirconium, cobalt, lead, nickel, zinc, copper, and aluminium), may be determined with thorium chloranilate in aqueous 2-methoxyethanol at pH 4.5 the absorbance is measured at 540 nm or, for small concentrations 0-2.0 mg L 1 at 330 nm. 

Trinitrophenol can only be stored safely in the form of a paste with water. Lead, mercury, copper, zinc, iron and nickel salts are sensitive to impact, friction and heat. Sodium, ammonium and amine salts give rise to explosions. When it was poured on to a cement floor, trinitrophenol formed a calcium salt that detonated when it came into contact with shoes. Trinitrophenol salts in the form of moist paste are stable. Aluminium salt is not explosive, but combusts spontaneously when in contact with water. 

Aluminium-copper-zinc alloy (Devarda s alloy)... 

Several ions (e.g., manganese, iron (II), iron (III), cobalt, nickel, copper, zinc, cadmium, lead, and uranyl) react with pyrocatechol violet, and to some extent are extracted together with aluminium. The interferences from these ions and other metal ions generally present in seawater could be eliminated by extraction with diethyldithiocarbamate as masking agent. With this agent most of the metal ions except aluminium were extracted into chloroform, and other metal ions did not react in the amounts commonly found in seawater. Levels of aluminium between 6 and 6.3 pg/1 were found in Pacific Ocean and Japan Sea samples by this method. 

After adjusting to 2 mol 1 1 in hydrochloric acid, 500 ml of the sample is adsorbed on a column of Dowex 1-XS resin (Cl form) and elution is then effected with 2 M nitric acid. The solution is evaporated to dryness after adding 1M hydrochloric acid, and the tin is again adsorbed on the same column. Tin is eluted with 2 M nitric acid, and determined in the eluate by the spectrophotometric catechol violet method. There is no interference from 0.1 mg of aluminium, manganese, nickel, copper, zinc, arsenic, cadmium, bismuth, or uranium any titanium, zirconium, or antimony are removed by ion exchange. Filtration of the sample through a Millipore filter does not affect the results, which are in agreement with those obtained by neutron activation analysis. 

Jones and Isaac 16 ) compared atomic absorption spectroscopy and spark emission spectroscopy for the determination of several elements in plant tissue. By comparing results statistically using a t-test, no significant differences were found for calcium, manganese, iron, copper, zinc, and aluminium, but significant differences were found for potassium and magnesium at the 0.01 % level. Breck162) made a similar comparison study for 15 elements. 

Attractive metallic effects can be obtained by incorporating very thin, small flakes of aluminium, copper or copper/zinc alloys in otherwise transparent surface coatings. The metal flakes act as tiny mirrors within these paints, which are particularly effective on the curved surfaces of cars since the colour changes with the angle from which the surface is viewed. The orientation of the flakes within the paint film also changes the colour seen by the eye, so that careful dispersion of the metal components of the paint is essential. 

It consists in a deposition of ions from an electrolyte onto the cathode in an electrolytic cell, under the influence of an applied potential. Usually the process is accompanied by material dissolution from the anode. The electrowinning from aqueous solutions is an important commercial method for the production (and/or refinement) of many metals, including, for instance, chromium, nickel, copper, zinc. As for the electrodeposition from non-aqueous solutions, the primary production of aluminium, electrodeposited from a solution of A1203 in molten cryolite, is a typical example. Other metals which may be regularly reduced in a similar way are Li, Na, K, Mg, Ca, Nb, Ta, etc. 

Individually indexed alloys or intermetallic compounds are Aluminium amalgam, 0051 Aluminium-copper-zinc alloy, 0050 Aluminium-lanthanum-nickel alloy, 0080 Aluminium-lithium alloy, 0052 Aluminium-magnesium alloy, 0053 Aluminium-nickel alloys, 0055 Aluminium-titanium alloys, 0056 Copper-zinc alloys, 4268 Ferromanganese, 4389 Ferrotitanium, 4391 Lanthanum-nickel alloy, 4678 Lead-tin alloys, 4883 Lead-zirconium alloys, 4884 Lithium-magnesium alloy, 4681 Lithium-tin alloys, 4682 Plutonium bismuthide, 0231 Potassium antimonide, 4673 Potassium-sodium alloy, 4646 Silicon-zirconium alloys, 4910... 

Metals, usually brass but also, for example, a more-expensive stainless steel if a higher tensile strength is needed. The insert metal must be compatible with the plastic material. For example, polyamide absorbs moisture, which leads to the steel rusting copper is a oxidation catalyst for polyolefins zinc, aluminium and brass are not compatible with polyacetals... 

Reactions with metals. When mercury fulminate is boiled with water containing metallic suspensions, the majority of metals (e.g. aluminium, zinc, copper), form their fulminates and mercury is precipitated. Reaction can also occur at room temperature, except with nickel. Other metals may be ranged according to increasing reactivity silver, tin, bismuth, cadmium, iron, lead, copper, zinc, brass, aluminium. With aluminium, the reaction takes only a few hours, yielding a large amount of A1203. 

---