V O L U M E 23, N O . I , J U L Y 1 9 5 1
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Recent Investigations in the Infrared Spectrum. J. LECOMTE, intensities for successive harmonics at different temperatures. The Laboratoire des Recherches Physiques h la Sorbonne, I’UniversitQde fine structure, between 1.5 and 1.9 I* approximately, of the vibrationParis, Paris, France rotation spectra of the halogen derivatives of methane and hydrogen sulfide was obtained by Mathis. She has already published a satisThe spectra of metallic metaborates, the general formula of which factory interpretation for the band in water vapor at 2.6 and 1 . 8 7 ~ is BOzMe (Me = monovalent metal), taken by the powder method which she has resolved very well, and is currently attempting to explain the very numerous lines obtained for the other compounds. reveal the presence of other groups, probably BlO7 and Boa (Duval and Lecomte). I t has been possible by the same method to follow Gauthier again has set about to study the harmonic bands and combination bands in the near-infrared with different aliphatic the modifications of structure as the sample is heated (Dupuy). hydrocarbon and liquid benzene by means of a grating spectrograph. The spectra of minerals (chiefly carbonates) currently are being studied with polarized radiation together with the spectra of crystalHis interpretations are now applied to the study of chemical reactions in the liquid state. Finallv, Larnaudie has calculated the position line powders and powders prepared synthetically having the same of the 32 fundamental vibrations of cyclohexane, and the agreement chemical composition, in an effort to identify the observed bands with experiment proves very satisfactory (determination of force (Louisfert). Vincent is, at present, carrying out theoretical and experimental studies on the intensities of the absorption bands of and interaction constants). This study is now being extended t o gases (HCI and CO) and plans to measure the variation of the other derivatives of cyclohexane.
Symposia on Analysis and Metallography of Titanium and on Surfaces W. C. MCCRONE, Armour Research Foundation, Illinois Institute of Technology, Chicago 16, Ill., A. F. KIRKPATRICK, American Cyanamid Co., Stamford, Conn. HESE consecutive Symposia on hnalysis and MetallogTraphy of Titanium and on Surfaces formed the fourth of an annual series of symposia sponsored by the Armour Research Foundation of Illinois Institute of Technology. The Symposium on Analysis and Rletallography of Titanium was held on June 11, 12, and 13; the Symposium on Surfaces was held June 14, 15, and 16. All sessions met in the Sheraton Hotel, Chicago, 111. Searly 400 people representing many branches of chemistry, physics, metallurgy, and engineering registered. After introductory remarks and a welcome from H. A. Leedy, Director, Armour Research Foundation, the Symposium on Analysis and Metallography of Titanium was conducted in five sessions designated as: Analytical Methods for Commercial Titanium, Analytical Methods in Titanium Alloy Development, Determination of Oxygen in Titanium, Instrumental Methods for Titanium and Its Alloys, and Metallography of Titanium and Its A4110ys. The moderators for these sessions were, respectively: Steven Urban, Yational Lead Co.; E. J. Center, Battelle Memorial Institute: E. J. Chapin, Saval Research Laboratory, Washington, D . C.; B. F. Scriber, Sational Bureau of Standards; J. R. Long, Xational Research Council; and W. L. Finlay, Ren-Cru Titanium, Inc. These moderators were aided by panels made up of active workers in the various fields. The panel members presented semiformal summaries of the various subjects under discussion. As has been the practice in these symposia, the audience informally and spontaneously participated in the discussions. The questions and contributions greatly enhanced the value of the symposium to those attending. The cochairmen of the Titanium Symposium, Julian Glasser and Max Hansen, are to be commended for organizing the first full-scale symposium on analytical methods for titanium and its alloys and on the metallography of these materials. The importance of titanium and its alloys, principally because of their high strength-to-weight ratio, has brought this metal in less than 5 years to a developmental stage that took 50 years for aluminum. Unfortunately, the analytical methods for titanium and its alloying elements have not kept pace with the engineering developments. Because so many laboratories are proceeding so rapidly in the development of analytical methods, there is no hope for publication as a means of exchanging information a t this stage and a symposium with ample discussion time was shown during this week to be the answer to this need. The first session on analytical methods for commercial titanium and commercial alloys opened with some orienting remarks and a discussion of sampling methods by Steven Urban of the National Lead Co. Further discussion covered the analysis of titanium sponge and the determination of carbon, tungsten, manganese, chromium, iron, and aluminum in titanium ingot and commercial
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alloys. Of these the determination for iron by ammonium thiocyanate is excellent in Ion concentrations and in the absence of chromium; the determination for chromium b y the ammonium persulfate method is satisfactory if titanium is kept in solution; the combustion for carbon is routine if high temperatures, particularly with the new dielectric heating furnaces, are used; with care the manganese determination by oxidation to permanganate and titration with sodium arsenite are satisfactory; the cinchonine method for tungsten gives low results; and aluminum may be determined chemically, using cupferron, or spectrographically. Chromium can also be determined simultaneously by the latter technique. In the Monday afternoon session covering analytical methods in titanium alloy development, chemical methods for nickel, cobalt, copper, niobium, tantalum, molybdenum, vanadium, and beryllium were discussed. Sickel can be determined either gravimetrically or photometrically, copper by electrodeposition, and cobalt colorimetrically using Sitroso-R salt a t 520 millimicrons. Additional work is needed on the other elements covered. The use of neutron activation techniques has been applied to tungsten and chlorine in titanium where the sensitivities are 0.03 and 0.003 microgram, respectively. These methods may be useful for the analysis of spectrographic standards or for special homogeneity experiments; however, the application to routine analysis depends, of course, on the availability of high intensity neutron sources. Titanium, as the metal, has the unusual ability to dissolve oxygen and other gases to an amazing degree with attendant effects on the physical properties. The importance of being able to determine the oxygen content in titanium resulted in a full morning session devoted to this subject. The moderator, Edwin J. Chapin, was able to present a well-coordinated discussion from his discussion leaders and the audience. It was decided that the results obtained by the much, and probably justly, maligned vacuum fusion method depend on the skill, ingenuity, and patience of the operator. It is hoped that a simpler and more trustworthy method may be developed in the future. Spectrographic approaches, a neutron activation technique, a mass spectrometric method, two fluorinations, and a hydrogen chloride procedure were all presented as hopeful possibilities. Much work remains to be done, however, on the determination of oxygen in titanium. The Tuesday afternoon session on instrumental methods of analysis for titanium and its alloys dealt more with possibilities than eventualities but was complete with an evaluation of each of several physical analytical methods by authorities in their use. The potentialities of x-ray fluorescence, polarography, the emis-
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sion spectrograph, electron microscopy, and electron diffraction were all ably covered. On Wednesday the discussion turned to metallography which was to serve as a bridge between the analytical discussions of the previous two days and the Symposium on Surfaces of the succeeding three days. Metallography is an analytical tool since the various solid phases can be recognized and often measured quantitatively by a real analysis. At the same time the metallographer is interested in polishing and etching techniques in addition to light and electron microscopy, all of which were more completely discussed on Thursday and Friday. The metallography of titanium was included in order to bring together people from both research and industry, to discuss informally and freely the many problems confronting this relatively new metallurgical field. Formal presentations by experts on subjects such as metallographic techniques, interpretation of microstructures of titanium and its alloys, kinetics of structural changes occurring during heat treatment, etc., were followed by stimulating and informative discussions. These discussions, possibly even more than the more formal parts of the meeting, resulted in the free exchange of information and a better understanding of the many problems related to the metallography of titanium, in particular, and the industrial development of titanium, in general. The large attendance a t the meeting, and the active discussion, reflected the fact that although there is a great interest in this new, promising material, there are also many attendant problems to be solved before it can find wide commercial application. During the session on metallography, i t was emphasized that titanium is a very difficult material for study. Its allotropic transformation, tendency to smear and flow, susceptibility to cold working, weak diffraction, and strong fluorescence with x-rays, and the unknown effects of impurities contribute to the difficulties of the preparation and examination of specimens. The various methods for cutting, grinding, polishing, and etching metallographic specimens were compared. The general opinion was that electrolytic polishing and etching offered the most promise. With these techniques, the production of surface artifacts is minimized. There was considerable discussion of various chemical etchants that can be used. The present status of the metallographic structure of pure and commercial titanium was summarized. A great deal of information remains to be determined on the nature and identity of impurities. A session was spent in consideration of the various aspects of the transformation kinetics of titanium and its alloys. Time-temperature curves like those for austenitic transformations in ~teelshave been and are being determined for titanium alloys and are being applied to metallurgical treatments. The cochairmen, TV. C. McCrone and C. F. Tufts, organized the program so that the session on metallography successfully connected this symposium with the Symposium on Surfaces. After a welcome and introductory remarks by K. W. Miller, Assistant Director of Research, Armour Research Foundation, the Symposium on Surfaces was conducted in four sessions designated as: Formation of Surfaces, Geometry of Surfaces, Structure of Surfaces, and Problems and Applications. The moderators for these sessions were, respectively: C. S. Smith, Institute for the Study of Metals, University of Chicago; E. J. Abbott, Physicists Research Co.; Georg Hass, Fort Belvoir; and J. J. Bikerman, Merck & Co. A discussion group consisting of five or six commentators aided the moderators. This symposium differed from the former in that no extended summaries of the subject matters were presented; instead, an outline of the topics to be considered was presented a t the start of each session and the commentators initiated the discussion. Progress was governed largely by comments and questions from the audience. The first session on the formation of surfaces was characterized by the attention to metals as would be expected from the influence of the preceding Bymposium. Considerable time R*as
ANALYTICAL CHEMISTRY spent in discussion of the mechanism of polishing and abrading, and the influence of these procedures on the observed structures of surface layers. The relatively new technique of ion bombardment a t low pressures for the preparation of metallic surfaces was reviewed. A surface may be cleaned, etched, and brightened by controlling the accelerating voltage and the gas pressure. Although optical contrast is usually not good, it can be enhanced by the process of “heat tinting,” a-hich is the introduction of air into the vacuum chamber and the subsequent formation of oxide films. -4s it has been found that the sample surface may reach a temperature of 700” C., it is necessary that the temperature effect must not be overlooked when this procedure is being considered for sample preparation. Tilting of the sample with respect to the ion beam results in a great increase in the rate of action. Ion bombardment yields surfaces that are excellent for examination by electron diffraction. Fractographic techniques were shown to be of value in the examination of crystals, metals, and resins. Fractographic examination of silicon carbide crystals produced evidence that was in complete agreement with the stepwise spiral growth that had been observed with the high temperature microscope. Electron micrographs of replicas of fracture surfaces of resins generally shov detail that allow a determination of the number of resinous phases present, the distribution of fillers, and an estimation of the macromolecular weight. The session on the geometry of surfaces covered a large number of ways to examine surfaces. These ranged from a simple adaptation of the Foucault “knife-edge” test for low power microscopical examination, through phase and interference microscopy, multiple reflection interferometry, stereoscopic examination with both the optical and electron microscopes, to the tracer point methods of the machine shop. Tracer point and profilometer methods are now being applied to surfaces other than metals, such as linoleum and paper. C. P. Saylor summarized the highlights of the colloquium on Nicroscopical Phase and Interference Contrast recently held in Paris. He briefly described some of the newer microscopes using the principles of phase change and interference for improving contrast. A n w lens system for increasing the working distance of a normal objective mas described by Francesco Scandone of Officine Galileo. Progress is being made in the development of the two-step microscope of Gabor and of the point emission microscope of Rlueller. Both instruments offer the promise of the availability of high resolving power: however, serious technical difficulties niust be overcome before they can become of general use. The session on the structure of surfaces included a discussion of the application of electron and x-ray diffraction, spectroscopy, microscopy, and other techniques. It was re-emphasized that each instrument or method is not universal in its application but must take its place in conjunction with all possible methods of approach to a problem. Investigations are in progress of the use of higher voltages, greater than 30 to 60 kv., for electron diffraction. The diffraction patterns obtained are essentially the same as those obtained with the normal voltages. Five hundred kilovolts have been used with good results for specimens up to 6 to 7 A. in thickness. Sometimes these higher voltages produce changes in the specimens. The session on problems and applications covered the range of the following subjects: friction, wear, gloss, luster, wettability, adsorption, adhesion, lubrication, and catalysis. There was considerable discussion of friction. The present status of the fundamental thinking on this subject was summarized. Apparently, the basic concepts are controversial, for there was an active, but good natured, discussion. These two symposia were thoroughly successful in carrying out the tradition of the annual series of symposia sponsored by the Armour Research Foundation. I t is certainly hoped that the series will be continued through the years.
