Manganese-bronze
This bronze, manufactured by P. M. Parsons, England, for every purpose for which gun-metal has heretofore been employed, and for which object it constitutes an eminently superior alloy, is made by adding from 1 to 2 per cent manganese to the common bronzes of copper, tin, and zinc. It is largely used for propeller-blades, sheathing, bearings, piston-rings, etc., and is said to be 60 per cent stronger than gun-metal, and will wear three times as long. See BRONZE; BRASS.
Manganese-copper is used as a strengthener to bronze and brass. The density, ductility, and tensile strength of the metal is increased, as it prevents the formation of copper and tin oxides. The alloy is made from copper 70, manganese 30, of which composition sufficient must be used to bring the mixture up to the required degree of hardness. A very hard bronze is made by using from 3 to 6 per cent. A suitable mixture for bearings would be copper 80, tin 6 1/2, zinc 4 1/2, manganese-copper 9.
A hardness resembling steel is produced by increased quantities of cupro-manganese, or manganese-copper. See COPPER; BRONZE; BRASS.