alloys, bronze


Значение термина alloys, bronze в knolik


alloys, bronze - Alloys, Bronze
alloys, bronze - This alloy has been known and employed since very remote ages. It was used exclusively by the ancients for making swords and other sharp instruments, for coinage, statues, and many other useful and ornamental purposes. It is composed of copper and tin, sometimes with the addition of a little zinc and lead. Great variations are made in the proportions of the two chief constituents, according to the nature of the application for which it is destined. For statuary, the proportions used by the Brothers Keller, the most noted bronze-founders of modern times, were copper, 91.40; zinc, 5.53; tin, 1.70; and lead, 1.37. The bronze coinage of this country contains 95 parts copper, 4 of tin, and 1 of zinc. The addition of a little zinc to the alloy is an advantage, but too much diminishes its tenacity; lead is objectionable, owing to its tendency to sink after casting, thus destroying the homogeneity, of the alloy. The metals should be melted rapidly to prevent loss of metal by oxidation, and the melted mass should be covered with a layer of charcoal, and kept constantly stirred. The operation is generally carried on in refractory crucibles, heated in a reverberatory furnace of suitable form. The cooling in the moulds must be as rapid as possible, in order to prevent the separation of the metals.

The composition of different kinds of bronze is shown below:

For edge-tools: 100 parts copper, 14 tin; when properly tempered, this alloy is capable of taking nearly as fine an edge as steel.

For gilding: (1) copper, 82 parts; zinc, 18; tin, 3; lead, 1½; (2) copper, 83; zinc, 17; tin, 2; lead, 1; (3) copper, 70; zinc, 25; tin, 2; lead, 3. Nos. 2 and 3 represent extremes.

For medals: (1) copper, 89 parts; tin, 8; zinc, 3; this alloy takes a sharp impression by stamping; (2)(Chaudet) copper, 95 parts; tin, 4 or 5.

For mortars: copper, 93 parts; lead, 5; tin, 2.

Ornaments. (a) Copper, 82 parts; tin, 3 parts; zinc, 18 parts; and lead, 2 parts.

(b) Copper, 83 parts; zinc, 17 parts; tin, 1 part; lead, ½ part.

For statuary: (1) copper, 88 parts; tin, 9; zinc, 2; lead, 1; (2) copper, 82½; zinc, 10½; tin, 5; lead, 2; nearly the proportions of the celebrated statue of Louis XV.; (3) copper, 90; tin, 9; lead, 1; (4) copper, 91; tin, 9; (5) copper, 91.4; zinc, 5.6; tin, 1.6; lead, 1.4; (6) copper, 89.35; tin, 10.05; zinc, 0.5; lead, 0.1.

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