Aluminium wire, coated

A third type of electrode is the very simple coated aluminium wire described by Vytfas [18], made in the laboratory from an aluminium wire coated in thick PVC, as follows. 

Sensing electrode. Aluminium wire coated with a membrane by dipping repeatedly into a solution of 0.09 g PVC and 0.2 ml 2,4-dinitrophenyl octyl ether in 3 ml tetrahydrofuran (caution flammable toxic vapour) and allowing the solvent to evaporate between treatments. 

Aluminium can be deposited from complex organic solutions if sufficient precautions are taken, and such coatings are now being produced commercially in North America. Two of the systems on record are (1) aluminium trichloride and lithium aluminium hydride dissolved in diethyl ether used at 40°C and 50A/m, and (2) aluminium chloride, n-butylamine and diethyl ether used at 20°C and 970 A/m. Deposits of 0-010 mm can be obtained on mild steel or copper at 20°C and 970 A/m using aluminium-wire anodes and nitrogen or argon atmospheres. 

Gilbert, P. T., Lecture, Assoc. Beige pour L tude et L Emploi des Mat6riaux, June (1954) Moss, A. R., Arc Plasma Technology, Welding Institute Autumn Meeting, London (1963) Spra Aluminium Coatings, brochure published by Aluminium Wire and Cable Co. Ltd., Swansea... 

Provided the solution is at least 0.1 M in hydrogen ion, betaines can be titrated potentiometrically with NaTPB. Vytfas et al. [18] successfully titrated cocodimethylbetaine, cocoamidopropylbetaine and an imidazoline derivative with NaTPB using the coated aluminium wire described in section 3.6.3. The potential changes at the end-point were not very large, and the method would probably be useful mainly for fairly pure samples such as raw materials rather than for products. 

The smallest metal particle is a single atom. In recent years atoms of metallic elements have attracted a great deal of interest. First, their formation by evaporation of the bulk element has been studied extensively. It is possible to evaporate metals that vaporize under vacuum at temperatures below 2000°C by using electrical resistive heating of ceramic crucibles (such as aluminium oxide coating on a tungsten wire basket). The metals listed below all evaporate nicely using this method. All but Sn, As,... 

The melting point of aluminium (660°C). The operating temperature usually reaches 750-850°C in pretreatment and 700°C in the bath, causing a loss in tensile properties of cold-drawn wire. On the other hand, if cold-worked material which is to be subsequently annealed is used in this process the annealing and coating operations may be combined, with obvious economic advantage. 

Where the end use of the product is known, there is usually preference to use either zinc or aluminium, both technically and because of the works problems associated with use of an alloy (identification, separation of overspray). However, in some countries (such as the United States) where there has been a recent-surge in anti-corrosion uses of metal spraying, a zinc-15%-aluminium alloy wire has been widely used. The original commercial experience was with 65-35% alloys used in powder form. Both have many of the advantages of the parent metals. At one time, the zinc-5%-aluminium alloy was also of interest. These alloy coatings may prove particularly satisfactory for sprayed coatings on articles where service conditions are not known in advance. 

Spray-aluminised coatings are used for exhaust valves in automobile engines, exhaust and silencer systems (double and triple life), tyre moulds, gas ducting, heat-treatment pots, furnace ladles, carburising boxes and fans handling hot gases. Similar applications utilise Calorised and hot-dip aluminised coatings. Hot-dip aluminised steel wire has been used in steel-cored aluminium conductors for overhead transmission lines. For some... 

Intermediate alloy compositions include a zinc-15%-aluminium alloy for metal spraying (higher aluminium contents are unsuitable for spraying wire) and a zinc-30%-aluminium-0.2%-magnesium-0.2%-silicon coating (Lavegal) for sheet. 

The anodes (see Fig. 145) consist of aluminium rod with platinum side arms on whioh platinum wires are arranged in 8 turns. The aluminium support is thoroughly coated with rubber. Current density at the anode varies between 100 to 150 A per sq. dm. (In war-time Germany current density was increased to 200 A per sq. dm. because of the shortage of platinum). 

Kelley, V. 1. (1975). Atmospheric Corrosion Investigation of Aluminium-Coated, Zinc-Coated and Copper-Bearing Steel Wire and Wire Products. A Twelve-Year Report. ASTM STP 585, ASTM, Philadelphia, 89 pp. 

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