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Engineers Develop Intense Heat So As To Study Properties of Rarest Metals

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A new program of research into the scientific "no man's land" of rare metals, to study the basic physical properties and possible industrial uses of most of the forty metals as yet little understood or exploited, war announced today at the Harvard Graduate School of Engineering.

The research is made possible through the development of an "electron bombardment" furnace, in which metals have been heated, without contamination up to temperatures of bout 1500 degrees Fahrenheit, or nearly half that of the sun. Much higher temperatures could be easily reached by this apparatus, the Harvard scientists say.

The inventor is Dr. Ralph R. Hultgren, instructor in Metallurgy who is now completing the equipment after a year's work.

The most important feature of the new furnace is that contamination of the metal under study, by carbon or other impurities, can be entirely eliminated. The familiar carbon are reaches as high temperatures as the electron furnace; but as an experimental device the carbon arc is less effective because of uncontrollable carbon contamination.

The only factor limiting the temperature in the new Harvard furnace is the melting point of the crucible. The best crucibles obtainable at present are made of tantalum, lined with thorium oxide. Both substances melt at about 5000 degrees Fahrenheit.

In the new furnace, such metals as vanadium, titanium, columbium, zirconium, and the platinum group, which have been difficult to study because of their very high melting points, can be melted into very pure alloys. Then, through X-ray photographs, significant students can be made of the individual peculiarities of molecular structure and other physical characteristics.

Electron bombardment has been utilized by scientists for intense heats before now, but the new Harvard furnace is the first application of this method to metallurgy.

In experimental tests Dr. Hultgren has successfully molted iridium at 4230 degrees Fahrenheit; platinum at 3200 degrees; and pallodium at 2790 degrees. Ruthenium was heated to 440 degrees Fahrenheit and "sintered" a little but did no melt.

These preliminary experiments have indicated that out of the fifty-five metallic elements, only six have melting points beyond the reach of the Harvard apparatus in its present state. These are carbon, melting at 6300 degrees Fahrenheit; tungsten, at 6066 degrees; rhenium, at 5400 degrees; tantalum, at 5130 degrees; osium, at 4860 degrees and molybdenum at 4716 degrees.

Of the fifty-five metallic groups, only fifteen have been extensively utilized utilized. From ancient times, gold, silver, Iron, copper, tin, zinc, lead, and mercury have been used. And within recent years the aluminum, antimony, bismuth, cadmium, chromium, cobalt, and nickel groups have also found uses.

There still remain forty metal groups whose alloy characteristics have yet to be studied, and whose possible industrial application is still in its infancy. Their development may mean as much to industry as the relatively recent development of such alloys as stainless steel, or tungsten carbide used in high speed machinery.

The working parts of the Harvard electron furnace are a small cylindrical metal cup, or crucible about one half inch in diameter and height; and two filament wires on opposite sides of the crucible.

In operation, the metal to be melted is placed in the crucible, and an air tight cylindrical hood, about 10 inches in diameter by 15 inches in height, is placed over all the parts. By a powerful vacuum pump, the pressure under the hood is reduced to about one billionth of ordinary atmospheric pressure.

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