An Important Development in the Treatment of Metals
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IN a report to the French Academia des Sciences, M. Leon Gullet, head of the Ecole Centrale des Arts et Manufacturers, describes an interesting discovery which may have an important bearing upon workshop practice in the motor industry.
M. Mahoux, chief of the LorraineDietrich experimental department, related some time ago to M. Gullet that when treating some pieces of steel by nitration, in the immediate neighbourhood of a wireless apparatus, he obtained results which differed appreciably from the normal. M. Gullet became interested and himself carried out experiments both in the Lorraine laboratories and at another engineering works near Paris. The results already obtained have been surprising.
A sample of chrome-nickel steel as employed for aero-engine crankshafts was treated by nitration under ordinary c40 conditions and under Brinell test gave a hardness of 380 and a resilience of 9 kilog-m. A second sample of the same steel was then treated by nitration in the presence of an electric oscillator and gave a hardness of 1,033 and a resilience of 12 kilog-m.
The penetration of the case-hardening, moreover, which in the first instance amounted to only 1-100 mm., reached a depth of no less than 35-100 ram. under the influence of the electrical oscillations.
Other experiments gave equally ,interesting results, one, in particular, relating to the treatment of " stainless " steel. The specific variety of this metal employed contained 3 per cent. carbon, 20 per cent chromium and 8 per cent. nickel. Under ordinary conditions it was not possible to obtain any high degree of hardness, but when treated under the influence of electric waves, the steel, after nitration, gave 1,035 under Brinell test.
Further experiments opened up another field of usefulness for the discovery. In the chromium plating and nickel-plating of steel by means of the ordinary electrical process, it was found possible to obtain an actual penetration of the steel at relatively low temperatures by the employment of oscillating waves of a certain frequency.
M. Guillet in collaboration with General Ferrie, also of the Academy of Science, is now conducting experiments at the Eiffel Tower.
The theory suggested by M. Gullet in explanation of the phenomenon is that the electrons composing the steel are put into an unusual state of vibration by the wireless waves and thus allow a greater degree of penetration by other metals than they do in normal circumstances.