"Titanium can no longer be considered a rare metal, even though the modern era of its production came into being only a few years ago. The first discovery of titanium was in 1791 by an English clergyman, the Reverend William Gregor, and the name titanium became universally adopted when so called by a German mineralogist, Martin Klaproth, who rediscovered titanium three years later. Not until 1887 was the relatively pure, 75 percent, metal prepared by L. F. Nilson and O. Pettersson, whose experiments were repeated in 1910 by M. A. Hunter. Hunter is given credit for producing the first metallic titanium pure enough to be malleable while cold. However, since that time progress was somewhat more rapid, and there are several accounts in the German literature of relatively pure ductile titanium being prepared as far back as 1925.
The chief reasons for the enthusiasm being shown for titanium, are its fortunate combination of desirous physical and chemical properties, and its relative abundance. Ductile titanium and its alloys possess a good combination or strength, lightness, high proportional limit, high modulus or elasticity, high electrical resistivity, high melting point, low coefficient or thermal expansion, low thermal conductivity, and good corrosion resistance. F. W. Clarke in his survey or the relative abundance of elements for the U.S. Geological Survey, placed titanium as being ninth, 0.529 percent, in abundance in elements of the earth's crust. That is, twenty times as abundant as all the copper, nickel, zinc, tin, lead and molybdenum combined. Also, titanium is found concentrated in sufficiently large deposits for economical mining and recovery.
The strength-weight ratio of some of the alloys of titanium is high, well above that or any other structural material. While elemental titanium ranks only after aluminum, iron and magnesium as a structural metal. Then too, the strength is retained well at moderately elevated temperatures where aluminum and magnesium have lost much of their strength. Titanium may also be hot forged, machined about as easily as stainless steel, and spot or arc welded in an inert atmosphere.
The corrosion resistance of titanium is good, and compares favourably with stainless steel. It is not attacked by the atmosphere, and has excellent resistance to sea water, humid and saline atmospheres, and nitric acid. While at present not enough conclusive evidence has been gathered to place the corrosion resistance exactly, it seems at least to be on a level with chromium and nickel.
While several papers have been published within the past year or two on the corrosion of pure titanium, these papers dwell on corrosion rates in various acids of different concentrations, and are not too much concerned with the mechanism of the corrosion process. In view of this, it was thought worthwhile to continue the study or titanium corrosion a step further, and to determine if an addition agent would have any effect on the corrosion rate, when added to an acid in which pure titanium was relatively unaffected.
As it has been found that pure titanium is most rapidly attacked by hydrofluoric acid 1) and attacked very slowly by sulphuric, nitric, and hydrochloric acids, it was decided to add ammonium fluoride to these slower attacking acids. This would serve the purpose of introducing a fluorine ion in controlled, limited amounts, in sufficient quantity to remove the corrosion resistant surface layer or the titanium, and then give the ordinarily ineffective acids an opportunity to attack the titanium surface now exposed. This would show if there is a skin effect on the surface of the titanium, the skin being highly corrosion resistant. At the same time other investigations would be carried out to try and determine the mechanism by which the titanium is attacked"--Introduction, pages 1-3.
Schlechten, A. W.
Straumanis, Martin E., 1898-1973
Materials Science and Engineering
Ph. D. in Metallurgical Engineering
Missouri School of Mines and Metallurgy
xiii, 203 pages
© 1952 Charles Burroughs Gill, All rights reserved.
Dissertation - Open Access
Titanium -- Metallurgy
Corrosion and anti-corrosives
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Electronic OCLC #
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Gill, Charles Burroughs, "A study of the dissolution of titanium in acids with ammonium fluoride added" (1952). Doctoral Dissertations. 987.