782
INDUSTRIAL AND ENGINEERING CHEMISTRY LITERATURE CITED
(1) Am. Soc. Testing Materials, “BSTM Standards,” D 609-45T,
Philadelphia, Pa., 1941, revised 1945. (2) Ibid., D 823-45T, procedure B, 1945. (3) Bacon, R. C., Smith, J. J., and Rugg, F. M., IND. ENG.CHEM., 40, 161 (1945).
(4) Barr, N. F., and Schneider, K. W., U. S. Patent 2,426,917 (September 1947). (5) Chem. Eng. Netus, 29, 1205 (1951). (6) McClure, H. B., Ihid., 29, 749 (1951). (7) McCuen, C. L., Ihid.,29, 746 (1951). ( 8 ) Mattiello, J. J., “Protective and Decorative Coatings,” Vol. IV, chapter by H. F. Payne, New York, John Wiley & Sons, 1944.
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(9) AMunger,H. P., Chem. Eng. N e w s , 29, 648 (1961). (10)Powell, 9. T., and Lossberg, L. G. yon, Chem. Eng. P ~ o g r . ,45, (11) (12)
300 (1949). Uhlig, H. H., Chem. Eng., 59, No. 6, 314 (1952). Vander Valk, C. J., Ofleial Digest Federation Paint & I‘nrnish Production Clubs, 292 (May 1949).
RECEIVEDfor review January 10, 1952. ACCEPTED September 19, 1952. For material supplementary to this article order Document 3843 from dmerican Documentation Institute, X Library of Congress, Washington 2 5 , D . C., remitting $2.75 for microfilm (images 1 inch high on standard 35-mm. motion picture film) or 87.50 f o r photocopies ( 6 X 8 inches) readable without optical aid.
Embrittlement of Zirconium and Tantalum in Hydrochloric Acid LEX B. GOLDEN, I. ROY LANE, JR., AND WALTER L. ACHERMAN U . S. Bureau of Mines, College Park, Md.
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UTSTANDING resistance to chemical corrosion is one of the most attractive properties of zirconium. This metal is similar to tantalum in acid corrosion-resistant properties and is superior in alkali resistance. It is probable that in the near future zirconium and some of its alloys will replace tantalum for specific uses in the chemical industry. A much greater potential supply of zirconium is available, especially within the borders of this country and it can be produced at a much lower price per pound than tantalum. Since the specific gravity of zirconium is only 6.5 as compared to 16.6 for tantalum, differences in price on a unit-volume basis are even greater. There have been a number of investigations of the corrosion resistance of zirconium and tantalum but practically none on zirconium alloys. Hoyt (9) and the Corrosion Handbook ( 4 ) described the corrosion resistance of tantalum toward a number of chemical reagents. The Fansteel Metallurgical Corp. has published descriptive literature on the properties of tantalum, including corrosion data ( 6 ) . Taylor ( 1 4 ) tested tantalum, niobium (columbium), zirconium, and titanium in a number of reagents and showed that tantalum was completely resistant. Alnutt (I), Gillett ( 7 ) , and Raynor (12) compared the relative corrosion resistance of zirconium and tantalum. Brumbaugh (Z), Gee ( 6 ) , Golden (8), and the Corrosion Handbook (3)give data showing the corrosion resistance of zirconium in acids, bases, and salts. Kroll (10, 11) stated that the good corrosion resistance of zirconium against hydrochloric acid suggests its use in chemical equipment and that zirconium could be used in the hydrochloric acid industry, replacing tantalum, if it could be made cheap enough in malleable form. RaJrnor ( I S ) pointed out that in addition to excellent acid-corrosion resistance, zirconium will withstand hot, concentrated caustic solutions and probably will find many applications requiring resistance to both acid and basic conditions. Waggaman (16) stated that zirconium appears equal or superior to tantalum in corrosion resistance to concentrated mineral acids and has the additional advantage of being lighter in ?$-eight,more plentiful, and cheaper, to produce. Mentioned among possible substitute uses for tantalum are metal parts coming into contact with acids such as mixers, conversion heaters, stills, pipes, valves, and tank linings. This paper describes the results obtained with zirconium, zirconium alloys, and tantalum exposed to the corrosive action of
concentrated hydrochloric acid. These tests were made in sealed glass tubes a t elevated temperatures and pressures, EXPERIMENTAL METHODS AND MATERIALS
The apparatus used consisted of sealed tubes approximately 16 inches long and made from heavy walled borosilicate glass tubing (24mm. outside diameter X 4-mm. wall), which contained the concentrated hydrochloric acid and the samples under test. These glass tubes were placed inside 18-inch sections of 2-inch diameter iron pipe which were then capped a t bot,h ends. B slot approximately 3/4 inch n-ide and 4 inches long was made in one end of the pipe to relieve any abnormal pressures developed in the event of failure of the sealed glass tube. The iron pipes containing the sealed glass tubes were placed vertically, slotted ends up, in a constant temperature oil bath. The oil level of the bath was adjusted to approximately the level of the acid in the sealed glass tubes. During the test the group of iron pipes was covered with a large, inverted stainless steel container as a safety precaution. Three different types of zirconium were furnished by the Northwest Electrodevelopment Laboratory of the U. S. Bureau of Mines, Albany, Ore. These were: 1. Ordinary purity met,al, induction-melted in grapl?ite, sheath-rolled at 850’ C., the sheath removed and the zirconium rolled at, 600” C., the oxide removed by sandblasting, the sheets pickled in a solution of 1% hydrofluoric and 1% nitric acid, and then cold-rolled. 2. High purity metal induction-melted in graphite and in the form of hot-rolled sheets. 3. High purity arc-melted metal (melted in a water-cooled copper container using a tantalum tipped elect,rode in a helium atmosphere) in the form of hot-rolled sheets. Also supplied were t.rvo high purity zirconium alloys inductionmelted in graphite and containing, respectively, 1 .OS% tant,alum and 3.70% niobium (columbium). These alloys were finished to size by cold-rolling. The terms ordinary and high purity refer to the hafnium content of the metal. Ordinary purity zirconium usua.lly contains 2 to 2.5% hafnium, whereas the high purity metal contains less than 0.1% hafnium. The tant,alum metal iised was in the annealed condition and was obt,ained from the Fansteel Metallurgical Corp.
The Northwest Elect.rodevelopment Laboratory of the Bureau of Mines also made available a series of 103 arc-melted zirconium alloys. These binary alloys contained different percentages of silver, nickel, aluminum, silicon, tungsten, molybdenum. anti-
INDUSTRIAL AND ENGINEERING CHEMISTRY
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mony, iron, copper, manganese, cobalt, tantalum, cerium, chromium, and beryllium. Twenty-gram compacts of all the alloys were prepared from accurately weighed metal powders of the best quality available and minus 10-mesh, X-grade zirconium chips of the following composition: Chemical Analysis, P.P.M. N 20 Fe 1500 C 100 A1 20 AI Sb Bi Sn cu Pb
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