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The nickel-plating of aluminum
268
CURRENT ToPics.
[J. F. I.
The 'Nickel-plating of Aluminum. E. TASSILY. (Rev. de M~tallurgie, xi, 67o-673.)--None of the large number of the methods which have been patented for nickel-plating aluminum appears to give satisfaction in practice. Generally, the nickel is deposited on an intermediate coat of copper, zinc, or iron, but even then the adherence leaves much to be desired. A method recently patented by Carnac permits the direct deposition of an adherent coating of nickel which can be polished, will stand hammering and heating, and, in fact, the result behaves so much like an alloy that the author has been led to call it aluminum-nickel. The method consists in passing the metal through a bath of boiling potash, brushing with milk of lime, soaking for some minutes in a o.2 per cent. potassium cyanide solution, and, finally, treating in a bath of 5oo gm. HC1, 5o0 gin. water, and I gm. of iron until the A1 assumes a mottled metallic appearance. After each operation the metal is well washed in water. Nickelling is carried out in the ordinary way in a bath containing 5° gm. nickel chloride, 20 grn. boric acid, and Iooo c.cm. of water, using a current at 2.5 volts and a density of I amp./dm. 2 The success of the process appears to depend on the thorough cleaning and the fact that a thin layer of iron is deposited on the A1 from the ferruginous bath. That there is a layer of iron on the metal is proved by the /act that on testing by means of the magnetic balance the susceptibility of metal which has been through this bath is I4 times as great as that of the metal which has simply been boiled in potash. Microscopic examination of the surface reveals the presence of small cells in which the Ni is deposited during electrolysis, the process being assisted by the formation of numerous small couples. The resulting product resists the action of moist air, hot and cold acids and alkalies, hot concentrated salt solutions, alcohol, and does not permit the sweating of petrol. Compared with pure A1, the tensile strength is increased, the coefficient of expansion decreased, while the density is only slightly increased. It can be applied in railway construction, shipping, the manufacture of instruments, cooking utensils, and so on. Fuel Saving through Proper Dimensioning of Steam Piping. GILUEAUME. (Feuerungstechnik, vol. xi, No. I4.)--This article argues that fuel can be saved by using higher steam velocities in pipes ; the limit for safety with reciprocating engines is 82 to 98 feet per second. The Berlin Electricity Works Company carried out experiments and obtained considerable saving in fuel by eliminating pipes which had been put in to reduce the fall of pressure. Formula~ are discussed with the results of experiments.
PRESS OF ] . B. L I P P I N C O T T C O M P A N Y PHILADELPHIA
CURRENT ToPics.
[J. F. I.
The 'Nickel-plating of Aluminum. E. TASSILY. (Rev. de M~tallurgie, xi, 67o-673.)--None of the large number of the methods which have been patented for nickel-plating aluminum appears to give satisfaction in practice. Generally, the nickel is deposited on an intermediate coat of copper, zinc, or iron, but even then the adherence leaves much to be desired. A method recently patented by Carnac permits the direct deposition of an adherent coating of nickel which can be polished, will stand hammering and heating, and, in fact, the result behaves so much like an alloy that the author has been led to call it aluminum-nickel. The method consists in passing the metal through a bath of boiling potash, brushing with milk of lime, soaking for some minutes in a o.2 per cent. potassium cyanide solution, and, finally, treating in a bath of 5oo gm. HC1, 5o0 gin. water, and I gm. of iron until the A1 assumes a mottled metallic appearance. After each operation the metal is well washed in water. Nickelling is carried out in the ordinary way in a bath containing 5° gm. nickel chloride, 20 grn. boric acid, and Iooo c.cm. of water, using a current at 2.5 volts and a density of I amp./dm. 2 The success of the process appears to depend on the thorough cleaning and the fact that a thin layer of iron is deposited on the A1 from the ferruginous bath. That there is a layer of iron on the metal is proved by the /act that on testing by means of the magnetic balance the susceptibility of metal which has been through this bath is I4 times as great as that of the metal which has simply been boiled in potash. Microscopic examination of the surface reveals the presence of small cells in which the Ni is deposited during electrolysis, the process being assisted by the formation of numerous small couples. The resulting product resists the action of moist air, hot and cold acids and alkalies, hot concentrated salt solutions, alcohol, and does not permit the sweating of petrol. Compared with pure A1, the tensile strength is increased, the coefficient of expansion decreased, while the density is only slightly increased. It can be applied in railway construction, shipping, the manufacture of instruments, cooking utensils, and so on. Fuel Saving through Proper Dimensioning of Steam Piping. GILUEAUME. (Feuerungstechnik, vol. xi, No. I4.)--This article argues that fuel can be saved by using higher steam velocities in pipes ; the limit for safety with reciprocating engines is 82 to 98 feet per second. The Berlin Electricity Works Company carried out experiments and obtained considerable saving in fuel by eliminating pipes which had been put in to reduce the fall of pressure. Formula~ are discussed with the results of experiments.
PRESS OF ] . B. L I P P I N C O T T C O M P A N Y PHILADELPHIA