Magnesium joining

Weldments subjected to corrosive attack over a period of time may crack adjacent to the weld seams if the residual stresses are not removed. Gas—tungsten arc welding and gas—metal arc welding ate recommended for joining magnesium, the former for thinner materials and the latter for thicker materials. Maintaining a protective atmosphere is a critical issue in welding these alloys. 

Joining Magnesium, form 141-524, The Dow Chemical Co., Midland, Mich., 1990. 

Magnesium anodes are usually built into the object to be protected through isolating sockets or holes (see Fig. 20-6) and joined to them with cables. They must be readily accessible and easily exchangeable for convenient control [4]. The directions for use have to indicate the necessity for an inspection after 2 years of operation. During operation, control can be exercised by electrical measurements (current, resistance). In addition, acoustic and optical methods exist to determine the amount of anode consumption [4]. The life of the anodes is usually more than 5 years (see Section 6.6). 

Higher resolution aluminium-27 and silicon-29 NMR spectroscopy of glasses and crystals along the join calcium magnesium silicate-calcium aluminium silicate (CaMgSijOj-CaAljSiO,). American Mineralogist, 71, 705-11. 

Electrical contact between the electrode and connecting wires can be made with solder if the electrode is a refractory metal, while lower-melting-point metals such as lead, and reactive metals such as magnesium, should be joined to a connection lead with commercially available conductive silver paint . Contact to ITO-coated electrodes will similarly require this conductive paint. 

Above LKJ lies the area of saturation with magnesium sulphate, which passes into bd on the vertical plane, the line of saturation for that salt by itself. Only here we have to take account of the conversion of heptahydrate into hexahydrate, which for the pure salt takes place at 48"" (point g). That point must therefore be joined to k by a line which represents saturation with both hydrates, and divides... 

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