Henley's Twentieth Century Formulas, Recipes and Processes. Various

preparing these alloys, the great volatility of cadmium must be taken into account. It is customary to prepare first the alloy of silver and copper, and add the cadmium, which, as in the case of the alloys of silver and zinc, must be wrapped in paper. After putting it in, the mass is quickly stirred, and the alloy poured immediately into the molds. This is the surest way to prevent the volatilization of the cadmium.

      Silver, Copper, Nickel, And Zinc Alloys.

      —These alloys, from the metals contained in them, may be characterized as argentan or German silver with a certain percentage of silver. They have been used for making small coins, as in the older coins of Switzerland. Being quite hard, they have the advantage of wearing well, but soon lose their beautiful white color and take on a disagreeable shade of yellow, like poor brass. The silver contained in them can be regained only by a laborious process, which is a great drawback to their use in coinage. The composition of the Swiss fractional coins is as follows:

	20 centimes	10 centimes	5 centimes
Silver	15	10	5
Copper	50	55	60
Nickel	25	25	25
Zinc	10	10	10

      Mousset’s Alloy.

      —Copper, 59.06; silver, 27.56; zinc, 9.57; nickel, 3.42. This alloy is yellowish with a reddish tinge, but white on the fractured surface. It ranks next after Argent-Ruolz, which also contains sometimes certain quantities of zinc, and in this case may be classed together with the alloy just described. The following alloys can be rolled into sheet or drawn into wire:

	I	II	III
Silver	33.3	34	40.0
Copper	41.8	42	44.6
Nickel	8.6	8	4.6
Zinc	16.3	16	10.8

      Japanese (Gray) Silver.

      —An alloy is prepared in Japan which consists of equal parts of copper and silver, and which is given a beautiful gray color by boiling in a solution of alum, to which copper sulphate and verdigris are added. The so-called “mokum,” also a Japanese alloy, is prepared by placing thin plates of gold, silver, copper, and the alloy just described over each other and stretching them under the hammer. The cross sections of the thin plates obtained in this way show the colors of the different metals, which give them a peculiar striped appearance. Mokum is principally used for decorations upon gold and silver articles.

      Silver-zinc.

      —Silver and zinc have great affinity for each other, and alloys of these two metals are therefore easily made. The required quantity of zinc, wrapped in paper, is thrown into the melted and strongly heated silver, the mass is thoroughly stirred with an iron rod, and at once poured out into molds. Alloys of silver and zinc can be obtained which are both ductile and flexible. An alloy consisting of 2 parts of zinc and 1 of silver closely resembles silver in color, and is quite ductile. With a larger proportion of zinc the alloy becomes brittle. In preparing the alloy, a somewhat larger quantity of zinc must be taken than the {77} finished alloy is intended to contain, as a small amount always volatilizes.

      Imitation Silver Alloys.

      —There are a number of alloys, composed of different metals, which resemble silver, and may be briefly mentioned here.

      I.—Warne’s metal is composed of tin 10 parts, bismuth 7, and cobalt 3. It is white, fine-grained, but quite difficult to fuse.

      II.—Tonca’s metal contains copper 5 parts, nickel 4, tin 1, lead 1, iron 1, zinc 1, antimony 1. It is hard, difficult to fuse, not very ductile, and cannot be recommended.

      III.—Trabuk metal contains tin 87.5, nickel 5.5, antimony 5, bismuth 5.

      IV.—Tourun-Leonard’s metal is composed of 500 parts of tin and 64 of bell metal.

      V.—Silveroid is an alloy of copper, nickel, tin, zinc, and lead.

      VI.—Minargent. Copper, 100 parts; nickel, 70 parts; tungsten, 5 parts; aluminum, 1 part.

      VII.—Nickel, 23 parts; aluminum, 5 parts; copper, 5 parts; iron, 65 parts; tungsten, 4 parts.

      VIII.—Argasoid. Tin, 4.035; lead, 3.544; copper, 55.780; nickel, 13.406; zinc, 23.198; iron, trace.

      SOLDERS: See Solders.

      Steel Alloys: See Also Steel.

      For Locomotive Cylinders.

      —This mixture consists of 20 per cent steel castings, old steel springs, etc.; 20 per cent No. 2 coke iron, and 60 per cent scrap. From this it is stated a good solid metal can be obtained, the castings being free from honeycombing, and finishing better than the ordinary cast-iron mixture, over which it has the advantage of 24 per cent greater strength. Its constituents are: Silicon, 1.51; manganese, 0.33; phosphorus, 0.65; sulphur, 0.068; combined carbon, 0.62; graphite, 2.45.

      Nickel steel is composed of nickel 36 per cent, steel 64 per cent.

      Tungsten steel is crucible steel with 5 to 12 per cent tungsten.

      Stereotype Metal.

Lead	2 parts
Tin	3 parts
Bismuth	5 parts

      The melting point of this alloy is 196° F. The alloy is rather costly because of the amount of bismuth which it contains. The following mixtures are cheaper:

	I	II	III	IV
Tin	1	3	1	2
Lead	1	5	1.5	2
Bismuth	2	8	3	5 Скачать книгу В начало < 49 50 51 52 53 54 55 56 57 58 > В конец