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alloys, german silver

Значение термина alloys, german silver в knolik

alloys, german silver - Alloys, German Silver
alloys, german silver - - This alloy is much used as a substitute for silver; it is composed of copper, zinc, and nickel. The proportions of the three metals are various. When intended as a substitute for silver, they are 50 parts copper, 25 zinc, and 25 nickel; castings, such as candlesticks, etc., are made of an alloy containing 60 parts of copper, and 20 of each of the other two constituents. German silver is harder than silver, and susceptible of a high polish. It is of a greyish-white colour; fuses at a bright-red heat, the zinc being volatilised in the open air. The three metals, in a state of division and intimately mixed, may be melted together in a crucible, having copper at the top and bottom. The whole is covered with a coating of fine charcoal, and strongly heated in an air furnace with a strong draught. Or the copper and nickel may be first melted in the crucible, fragments of hot zinc being afterwards added. To aid the fusion of the nickel, the mixture should be well stirred. Lead is sometimes added, also iron, for the purpose of whitening the alloy.

Actual analyses of various kinds of German silver (including Argentan, Maillechort and Packfong) show the following proportions:

(a) Copper, 50 parts; nickel, 20; zinc, 30; very malleable, and takes a high polish.

(b) Copper, 50 parts; nickel, 26; zinc, 24; good imitation of silver.

(c) Copper, 41 parts; nickel, 18;zinc, 41; rather brittle.

(d) Copper, 50 parts; nickel, 25;zinc, 25; good imitation of silver;white and malleable.

(e) Copper, 60 parts; nickel, 25;zinc, 20; for rolling and wire; verytough and malleable.

(f) Copper, 40½ parts; nickel, 31½; iron, 2½; zinc, 25½; made from Hillburghausen ore; equal to best Chinese sample.

(g) Equal parts of copper and nickel; recommended by Pelouze as being superior to any alloys containing zinc.

(h) Copper, 55 parts; nickel, 24; zinc, 16; tin, 3; iron, 2; white metal spoon, sold as German plate.

(i) 10 parts copper shavings and 4 parts arsenic in alternate layers, covered with salt, make a white alloy almost resembling silver.

(k) Copper, 50 lb.; zinc, 25 lb.; nickel, 25 lb.

(l) Copper, 50 lb.; zinc, 20 lb.; nickel (best pulverised), 10 lb.

(m) Copper, 60 lb..; zinc, 20 lb.; nickel, 25 lb. Used for spoons, forks, and table ware.

(n) Frick's. 53.39 parts copper, 17.4 nickel, 13 zinc.

(o) Copper, 60 lb.; zinc, 20 lb.; nickel, 20 lb.; lead, 3 lb.; iron (that of tin plate being best), 2 lb.

(p) In melting the alloy for German silver, it is difficult to combine a definite proportion of zinc with the compound of nickel and copper previously prepared. In fusing the three metals together there is always a loss of zinc by volatilisation, which may be lessened by placing it beneath the copper in the crucible. The best method is to mix the copper and nickel, both in grains first, place them, thus mixed, in the crucible, when melted add the zinc and a piece of borax the size of a walnut. The zinc will gradually dissolve in the fluid copper, and the heat may be raised as their fluidity increases. In this instance, as in all others of forming alloys, it is profitable to mix the oxides of the various metals together, and reduce the munder the protection of a suitable flux. The metal nickel can be produced only from pure oxide of nickel; and, as purity of the alloy is essential to good quality, the common commercial zinc is not sufficiently pure for forming argentan. Copper cannot well be used in the form of oxide, but grain copper or wire-scraps will serve equally as well.

Рядом со словом alloys, german silver в knolik

alloys, fusible plug

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alloys, gold artificial

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