ELECTRODEPOSITED €-BRASS BY H. KERSTEN* AND JOSEPH
MA AS^
Introduction The crystal structure of brass made by fusing together zinc and copper has been the subject of a number of investigations' which have shown that such brass probably has five different structures (known as a, /3, y, E, and Q), all stable a t room temperature. Alloys of zinc and copper have been electrodeposited from mixtures of their cyanides dissolved in a solution of potassium or sodium cyanide, since 1841.~It has recently been shown that a-brass having a structure agreeing with that of a fused alloy of like composition may be deposited from such a solution.* This paper shows that e-brass, agreeing reasonably well in composition and structure with fused e-brass may also be deposited from a cyanide bath. Experimental The electrolysis was carried on in a one-liter beaker with stainless steel anode and cathode, each 5 X I O cm in size, j cm apart. The sides of the anode and cathode not facing each other were covered with a thick sheet of celluloid so that no current could flow from the back of the anode or to the back of the cathode. Stainless steel was used as an anode because it was practically insoluble in the electrolyte and as a cathode because the deposit did not adhere well and could be stripped for analysis. A bath having the following composition was made: Zinc cyanide.. . . . . . . . . . . .. 4 0 gm, Sodium cyanide.. . . . . . . . . . s o gm, Sodium carbonate.. . . . . . . . .30 gm, (anhydrous)
To this was added small quantities of copper cyanide to determine a region in which the e-brass could be deposited. A new bath was used for each sample plated. For all the experiments the current density was held a t z amperes per square decimeter and the bath temperature a t 50°C. The x-rays were supplied by a gas tube4 having an iron target. The samples were clamped in the reflection spectrograph5shown in Fig. I , in which the x-rays, after gassing through the slits in the tube a t the left, strike the
* Dept.
t
of Physics, University of Cincinnati, Cincinnati, Ohio. Dept. of Engineering Chemistry, University of Cincinnati, Cincinnati, Ohio.
2176
H. KERSTEN AND JOSEPH MAAS
I
Ei".
I
X-my spectrograph
by adding copper cyanide I O the bath given in a previous paragraph is given in Table I .
ELECTRODEPOSITED €-BRASS
2177
Samples 3, 4, 5 and 6 showed the +structure. Fig. z shows the reflection photograph for sample 5 compared with fused c-brass of nearly the same composition and with the computed positions of the diffraction lines. The fused €-brass was annealed for 9 days at 360°C, before the picture was taken. It is evident that the two photographs show structures nearly the same. The electrodeposited sample did not give as sharp lines as the annealed fused sample. Some of the lines to be seen on the original negatives have been lost in the reproduction. The authors wish to express their thanks to Dr. Earl F. Farnau for the loan of samples of fused brass of various compositions.
References References are given in Wyckoff: “The Structure of Crystals,” and. Ed., 212 (1931). * Gore: “The Art of Electro-Metallurgy,” 278 (1877). 3 Nakamura: Sei. Papers Inst. Phys. Chem. Research (Tokyo), 2, 287-92. (1925). Kersten: Rev. Sci. Inst., 3, 145-50.(1932). 6 Kersten: Rev. Sei. Inst., 3, 384 (193z).. 1
