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were known as produced in crucibles that the same would spontaneously emerge from electric furnaces. It required patience, skill, experimentation, and study, and at one time we were almost ready to abandon the process. But human skill, guided by the best tradition and experience and aided by improved facilities of production and science, won. Another important field in which electric furnaces have given a good account of themselves is in the production of superior ferro-alloys for further use in steel-making. We are apt to overlook this improvement in products, but as a matter of fact many of our present-day steels could not be produced with the ferro-alloys of twenty-five years ago. PRODUCTION O F CASTINGS AND FORGINGS-Jve have dealt mainly with the metallurgists’ development of new alloy steels, but must not overlook branches of the ferrous industry engaged in the production of steel, malleable, and gray-iron castings and drop forgings. The application of scientific methods of heat control to these fields of industry has revolutionized production, both qualitatively and quantitatively. Non-Corrosive Steels
The last contribution of metallurgy to the motor industry which we will mention is the development of non-corrosive steels. Just as the leading types of structural alloys antedated the automotive industry, so the development of non-corrosive steels was far in advance of the demand-not of the needfor losses caused by corrosion have long been with us and the national loss on account of corrosion has been estimated a t a staggering figure. Metallurgists responded to the need faster than buyers created a demand. Regular stainless iron and steel are of about ten years’ standing, while the
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nickel-chrome and nickel-chrome-silioon steels have been available in the United States almost as long. Only within the past year or two have really large and important uses been made of them in chemical plant, oil refinery, and other equipment of similar nature. Their indirect importance to the motor industry is doubtless greater than their direct use in automotive parts, yet in the manufacture of valves, pump-shafts, body trim, and fenders, there is in the aggregate a great field for their direct employment. A Tribute to the Analytical Chemist
I n our enumeration of the contributions of chemistry, we must not forget the splendid work of those patient, conscientious men-the analytical chemists. Their contributions of rapid and accurate methods of analysis and their honesty and faithfulness in the use of those methods have been of incalculable worth to the industry; yet they probably receive less recognition, either financially or otherwise, than any other class of professional men. To the chemistsincluding metallurgists-the automotive manufacturers must always be under everlasting obligations for their contributions, theoretical and practical, to the success of this colossal industry. Conclusion
The flight of Lindbergh was a great exhibition of personal stamina, courage, and confidence made possible by generations of science, years of skilful engineering, and the conscientious manufacture and intelligent selection and use of materials for which we chemists may modestly take some credit and press on to greater things in the days to come.
Miscellaneous Nonferrous Metals and Alloys’ By H. W. Gillett2 BUREAU OF STANDARDS, WASHINGTON, D. C.
INCE modqrn means of automotive transportation, such as automobiles, trucks, busses, motorcycles, airplanes, and airships, will assay better than 95 per cent metallic, and even motor boats contain much metal, it is proper that the uses of the various metals and the service the chemist has rendered in connection with them should be described. Steel occupies the most prominent position, but nonferrous alloys likewise demand attention.
S
Scope of Paper
This paper is to deal with the odds and ends of the nonferrous alloys. We have, then, to consider the miscellaneous nonferrous metals essential to automotive transportation, the purposes they serve, and the chemist’s or metallurgist’s contribution to the automotive industry in respect to them. One cannot say much about steel for automotive uses without speaking of alloy steel, nor about modern methods of machining without speaking of high-speed steel, and the alloying elements for these steels are nonferrous. Thus, in alloy steel, and to a certain extent in alloy cast iron, we find chromium, manganese, molybdenum, silicon, nickel, vanadium, tungsten, and cobalt. The aluminum alloys, beside that metal, may contain copper, silicon, magnesium, and manganese. Metals that are electroplated for automotive uses are nickel, copper, zinc, chromium, silver,
* Published by permission of the Director of the National Bureau of Standards. 2 Senior metallurgist, Bureau of Standards.
and cadmium. Storage 6atteries use lead and antimony and spark plugs use nickel and manganese. Copper and its alloys make up the bulk of the nonferrous materials here discussed. It is estimated that approximately 15 per cent of the country’s output of copper goes into automotive construction. Other metals and alloys used comprise a very little tungsten in lamp filaments and timer contacts, lead fuses, lead-tin solder, the tin-copperantimony or lead-tin-antimony alloys in the babbitt or white metal bearings, many zinc-base die castings and possibly a lead lining for the gas tank, and a magnesium alloy diaphragm in the horn. A dozen or fifteen nonferrous elements serve definite purposes in any modern means of automotive transportation. Copper
Copper is used in the electrical system because of its electrical conductivity, in the radiator because of its resistance to corrosion, and in the gas and oil lines largely because of the latter property since rust would clog them. The ability of copper to be drawn, rolled, or stamped fits i t for all these uses, as well as for gaskets. No other material is so suitable for many of these purposes, especially for piping, since copper has a unique combination of ability to stand severe cold-working in forming, of suitable mechanical properties (sufficient strength and the ability to be bent without damage), and of resistance to corrosion.
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Copper deoxidized by phosphorus will stand severe working, as in making tubing, better than the old-time tough pitch copper, and tubing specifications now recognize this. Brass
Wrought brasses also are readily formed and hence are used in many parts, such as headlight rims and reflectors, lamp bases, carburetor parts, tire valves, grease fittings, hubcaps, and, together with Invar, in the bimetallic strip used in thermostatic valves. Door handles and similar fittings may be forged, or hotpressed, from brasses of the Xuntz metal type, and then plated, or may be made from monel metal. Brass or bronze castings appear in the bearings and bushings, the carburetor, the water-pump. and various fittings, such as priming cocks. Bronze may be used in the timing gears, in the rear axle, if the car is worm-driven, and in parts of the steering gear. Motor boats naturally use much brass and bronze to defeat corrosion. Beside the various cleats, rails, and small fittings, the propeller is nonferrous, usually of manganese bronze. Manganese bronze or aluminum bronze are sometimes used as airplane fittings where strength and resistance to corrosion must be combined. Aluminum bronze serves as valve seats in some aircraft engines. Anti-Rust Material
Wherever rust would injure or deface the car or aircraft, and where aluminum alloys are not admissible, recourse must be had to the use of nonferrous plating as protection, or to some anti-rust metal. Such anti-rust metals, when the part is exposed so that appearance is a factor, may be one of the chromium or chromium-nickel irons or steels, or, among nonferrous alloys, monel metal, or nickel-plated brass, for example. The use of nickel-plated steel bolts and screws in places that offer crevices where moisture can collect, notably around the wind shield, and of ordinary steel in the windshield frame itself is quite inadequate. Those automobile designers, and there are many of them, who continue to use materials in such places that will give unsightly rust stains in a few months, are doing slovenly work. The automobile is no longer used merely on bright Sunday afternoons. It is used daily in all weather and must withstand longer and more continued exposure to the elements. Nowadays, when a garage costs as much as the car, many people even get along without a garage. Such owners certainly, and probably a large proportion of the others, would prefer to pay the slight extra initial expense for monel metal or some other suitable nonrusting material. Chemical and Metallurgical Control
QuALITY-The service of the chemist and metallurgist has been twofold. He has made possible the attainment of uniform high quality, through control of raw materials and of manufacturing processes and through inspection for compliance with specifications. Chemical and metallurgical control of the nonferrous materials entering into automotive transportation is farther advanced, both in the automobile plants themselves and in the plants supplying parts, than in many other industries. This ii largely due to the general use of the standards of the Society of Automotive Engineers. PRIcE-The chemist has also played a large part in the many developments which have kept metal prices down. For example, copper is selling at pre-war prices because flotation and leaching have made commercial the exploitation of vast amounts of low-grade ore. ELECTRICAL D ~ v ~ c ~ s - T helectrolytic e zinc process has played its part in making available larger amounts of pure
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zinc. The working out of the electrolytic zinc process, which requires an extreme degree of purification of the solutions, has been the chemist's job. The Cottrell precipitator saves metals that used to go up the stack, prevents damage from smelter fumes, and cheapens the cost of production of various metals. Electric melting of brass lowers the volatilization and other metallic losses and produces brass for wrought forms and for castings cheaper than the old fuel-fired furnaces. These electrical devices might be credited to electrical engineering, but the moving spirits in their development were actually chemists. KICKELAND ITSALLOYS-The chief use of nickel in days gone by was in armor plate. Naval limitation reduced the output in armor, and it was necessary for the nickel producers to seek other outlets. Application t o various industries, especially chemical industries, carried out largely by chemists, has provided those outlets and kept the cost of nickel down. Nickel. together with chromium, performs a service in the production of the automobile, even though it appears in a car or a plane in very small proportion compared to copper or aluminum. The heat-treatment of steel and of duralumin is very largely done in electric furnaces with nickel-chromium resistors and controlled by thermocouples of nickel-aluminum and nickel-chromium. Without the precise temperature control made possible by the modern pyrometer, greater factors of safety mould have to be used to allow for non-uniformity of the heat-treated product, excess weight would have to be carried, and more paid for a less satisfactory product in both automobiles and aircraft. Similarly, on the score of cost of production, automatic heat-treatment with low labor cost is facilitated by the ease of control of the electric furnace with its nickel-chromium resistor. Even when automatic heat-treating fuinaces are fuel-fired so that the resistor is not used, heat-resisting alloys are required and these again are generally of the nickel-chromium group. The nickel-chromium alloys were developed by chemists. TUNGSTEK LAMPFILAMENTS-one of the notable achievements of physical chemistry is in the tungsten lamp filaments. Those who can recall the old carbon filaments or the early tungsten filaments can realize the far cry between them and a filament that will stand the jouncing it gets on the road in an automobile. Admixture of small amounts of thoria allows the control of grain growth and the production of essentially single crystal filaments of ductile tungsten which have high mechanical strength. Drawn to very fine wire, presentday tungsten has more than twice the strength of the strongest steel wire. Methods for mechanical working of tungsten had to be developed before it was a satisfactory substitute for platinum in contact points. DIE CAsTIxGs-zinc base die castings, &ch as may be found on the top of the vacuum tank, and in various fittings. and meter cases, used t o be prone to crack and swell in tropical climates because of intercrystalline oxidation. Now that the influence of traces of certain impurities on these alloys has been established those troubles are avoided, and die castings, requiring scarcely any machine work and hence reducing the cost of production of the parts, are freely used for timer cases, instrument cases, parts of carburetors and vacuum tanks, and for small brackets and fittings. The ability to produce such parts from a reasonably corrosion-resistant alloy, which has sufficient strength and is made up c h i d y of zinc, the cheapest nonferrous metal-and to do it either in a single operation so that no machining whatever is required or with extremely little machining-is an important advance in decreasing the cost of production. Quite complicated parts may be die-cast astonishingly true to dimensions and, even if machining is needed, only a light
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cut need be taken, and the alloy machines with great ease. that of lubrication and is very complex, bringing in such Of course the cost of making the die is high and large numbers questions as that of the adsorption of the oil by the metal, of identical castings have to be made to bring the die cost on which there is much speculation but too little definite per piece below the cost of casting and machining other types informa tion. \T’Ea~-lf-hen pressures are very high, as in worm gears, of castings, but the automotive industry does require these wear and pitting of the worm or the gear may be excessive. large numbers. Intercrystalline attack of spark plug wires has been traced Small additions of nickel to the gear bronze are said to be to sulfur in the fuel. The deleterious effect of tiny traces of advantageous. I n this, as in all wear problems, much more sulfur in nickel alloys themselves is overcome by the use of a information is needed. The study of wear, of fatigue of metals, of corrosion and little magnesium or manganese. FATIGUE OF & f ~ ~ a ~ s - T effect h e of repeated stress on the of resistance t o high temperatures, are all being actively progressive failure, or fatigue of metals, has been studied, carried on by chemists and metallurgists, both from the and the behavior of ferrous materials is beginning to be immediate and practical point of riew, and from that of understood. Sonferrous materials have been studied to a fundamental theory. lesser extent. The latest development along this line deals Application of Other Sciences with combined fatigue and corrosion, or “corrosion-fatigue,” HOWwide the metallurgical chemist’s horizon is and how which may be the cause of many hitherto unexplained failures. This is especially important in seaplanes. Steels many branches of science he uses in working out the fundathat are subjec.t to corrosion fail at astonishingly low stresses mental theories applying to alloys can be seen by glancing when combined repeated stress and corrosion occur, ac- through any copy of Chemical Abstracts. SPECTROSCOPY AND ATOMICPHYsIcs-The spectroscopist cording to the findings of Dr. McAdam of the Naval Experiment Station, while the corrosion-resistant nonferrous alloys and the atomic physicist are studying subatomic phenomena in metals. These scientific detectives dealing with the inshow up well in comparison. finitely small, under the handicap of being able to touch or Unsolved Problems to see nothing at all of what they are dealing with and having ALLOYS FOR STORAGE BATTERIES-There are some phases to draw conclusions from circumstantial evidence only, on which much more metallurgical information is needed. are studying quanta, energy levels, electrons and protons, Storage battery makers claim that they cannot stamp out in the attempt to find out horn the atom is put together. battery plates but must cast them; otherwise the plates CRY~TALLOGRAPHY-N~X~ in line comes the crystallograwill not stand up properly. This needs more proof than has pher, who shoots a beam of x-rays a t metallic crystals and yet been adduced. Moreover, the choice of the particular by the way that beam is reflected and the lines or spots it gives compositions of alloys used by various battery makers seems on his x-ray spectrograph, finds out how the atoms are arto be based on empirical observation. It is a t least possible ranged and spaced in the crystal. He can follow the orientathat a study of alloys for storage battery construction might tion of the crystal as it is distorted in cold-working processes lead to reduced cost. and can tell whether it is broken up in working or grows SUBSTITUTES FOR TIN-With the limited supply of tin and larger on annealing. He, too, is working below the range the consequent high prices, the finding of satisfactory sub- of visibility under the microscope and has to depend on stitutes for it in bronzes, babbitts, and solders. or in other indirect evidence, but has more opportunity to cross-check his uses which mill release tin for those uses, is still a major findings with other phenomena than has the atomic physicist. problem and one for which no satisfactory solution is in METALLOGRAPHY-Then comes the metallographist, who sight, though cadmium-zinc solders have some promise. now examines metals a t useful magnifications, about 5000 REARINGMETALS-The problem of bearing metals i s in diameters; that is, he sees a given area 25 million times its an unsatisfactory state. Bearing wear is a t least one cause, actual size. Even that does not satisfy him, and he is trying even though a minor one, for deterioration of an automobile ultra-violet light to give still better resolving power in his or aircraft engine. It is being combated to some extent photomicrographs. by oil filters and air cleaners to exclude grit, but the metal&IETALLURGY-The metallurgist now grows single crystals to-metal contact of shaft and bearing in starting, before the of aluminum, zinc, copper, iron, etc., large enough for him oil film has been formed, still produces wear. There is to study the properties of the crystal itself in different evidence that the properties of the shaft and the bearing directions and free from complications caused by crystal need to be complementary, different types of shafts requiring boundaries. different bearing metals. The usual theory as to what He studies the mechanism of the hardening of metals by constitutes a be‘aring metal states that it must have hard heat treatment and by cold-working, using the high power particles in a soft matrix and that a certain combination of microscope and the x-ray spectrograph as well as the older compressive strength and “conformability” is required. methods of attack. Heat treatment for strengthening of Yet if care were taken in the alignment of bearings and in alloys is as essential in dealing with aluminum as with steel, the polishing of the bearing surface comparable to that and heat treatment of some copper alloys is being developed. taken in honing cylinders, it is an open question whether the Elements previously unused are being studied in alloys; “classical” bearing metal is necessarily the best. high strength, high conductivity copper-beryllium alloys Failures of bearings in service were formerly a vital factor are among the latest. in limiting the reliability of aircraft engines. Changes ELECTROCHEMISTRY-The chemist and electrochemist pile in the design of the backing for the actual bearing metal, up theories of corrosion, through the study of the formation so as to give greater stiffness and prevent deformation, of protective films, the consideration of overvoltage, of have overcome this without notable change in the bearing polarization, of aeration, of concentration cells, and so on. metals themselves. The chemist has produced spectroscopically pure zinc with Oil-retaining bearings for fan and other lightly loaded interesting corrosion-resistant properties. bearings have been made by compression of metal and graphConclusion ite powder into a coherent, but porous, mass. There is All the new methods of investigation are being applied to room for improvement in the more heavily loaded bearings as well. The whole problem of bearing metals is tied up with nonferrous mekals and alloys. The new facts and new
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theories enable the chemist more intelligently to control the materials used in automotive transportation, but few really revolutionary advances have been made, within the period in which automotive transportation has become so highly developed, in the nonferrous alloys dealt with in this paper. Most of them were known and rather far developed even before the days of automotive transportation. It was necessary only to adapt them to automotive uses, and to produce them of uniform high quality at reasonable prices. That little of the spectacular can be recorded for the copper and other alloys dealt with in this paper seems to be accounted for by the fact that the older chemists and metallurgists who developed those alloys did a good enough job so that the products were adequate for the demands of the automotive industry. I n the alloy-steel and the aluminum industries the demands of automobiles and aircraft forced great de-
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velopments upon those industries so that spectacular achievements can be recorded in the production of new alloys or those not previously developed commercially. The nonferrous metallurgist has been called upon to solve such problems as how to use more borings in his furnace charge and still make good carburetors, or how to modify the composition of the alloy so it will machine a trifle more readily, rather than to introduce radically new alloys like stainless steel, molybdenum steel, or the aluminum-silicon alloys. Most of the advances in the nonferrous fields that concern automotive transportation and are discussed here, are small hard-won gains resulting from steady plugging along. The chemist and metallurgist have made, and will continue to make, these miscellaneous nonferrous metals and alloys for automotive use a little better, a little more uniform, and a little cheaper.
Aluminum and Its Alloys By Francis C. Frary ALUMINUM COMPANY OF AMERICA, XEWKENSINGTOS, PA.
M
ETALLURGY is essentially a branch of applied chemistry : its problems are fundamentally chemical, although in many cases the greater physical prominence of the mechanical side of a metallurgical problem tends to obscure its chemical features. In the case of the production of aluminum, however, the chemical problems are more prominent and their solution relatively more difficult than in the case of any other common metal. Here it is impractical to use the familiar and chemically simple reduction of the oxide by carbon or carbon monoxide, which plays such a role in the metallurgy of iron, copper, lead, zinc, and tin. We must bring to our aid more powerful chemical reducing agents, such as the alkali metals, or else we must carry out the reduction by electrical means. Deville and others worked along the first of these lines, achieving a technical and commercial success in the reduction of sodium aluminum chloride with metallic sodium, but when Hall found out how to solve the problem along the second line, Deville’s method became commercially valueless because of its intrinsically higher costs. Chemical Problems
The first chemical problem in the electrolytic production of aluminum was to find a solvent in which the electrolysis of aluminum oxide could take place. Hall solved this by the use of molten cryolite. The next great problem was the cheap production of the oxide on a large scale in a state of purity comparable with that of many c. P. chemicals. The sodium aluminate process, as developed by Bayer and worked out in detail by groups of unknown chemists in plant laboratories, was the first real solution of this problem, and has made most of the world’s supply of alumina. A host of other inventors have labored on this problem and presented many and varied alternative solutions of it. While most of their processes are chemically possible, they are practically all commercially impossible in competition with the Bayer process. Hall himself blazed the trail along what appears at present to be the most promising of these other lines of attack-namely, the electrothermal purification of bauxite, and it appears probable that one or more commercial solutions of the problem along this line are now in sight. The production of synthetic cryolite, the chemical problems of the carbon mix for the inert crucible lining, and the prob-
lems of carbon-electrode manufacture have for years engaged the attention of chemists. The aluminum industry probably manufactures and consumes a t least half of the carbon electrodes of the world, and has contributed much to the development of the technic of this industry. Although commercially pure aluminum is used in the wrought condition for molding instrument parts, body parts etc., and can be considerably hardened by cold-working, an important problem has been the development of methods for very largely increasing its hardness, strength, and elastic limit, especially when it is to be used in the form of castings or wrought metal parts which may be highly stressed in service. This has been accomplished by alloying it with small amounts of other metals, especially copper, zinc, silicon, magnesium, and manganese, and by heat-treating some of these alloys. The value of copper and zinc in aluminum-casting alloys has been known for many years, and most of the aluminum castings used in the automotive industry contain one or both of these metals as important constituents. Silicon alloys are now coming into quite extensive use, thanks to the labors of Aladar Pacz, whose “modification” process for these alloys is a good example of the profound effect which the presence of a trace of one element (sodium) may have on the behavior of another (silicon) in an alloy. Magnesium is useful in some classes of heat-treated alloys, and the manganese alloys are found to be particularly resistant to corrosion. Recent Developments The recent development, by Archer and Jeffries, of the proper technic for heat-treating aluminum-copper alloy castings promises to be of great interest to the automotive industry, especially in view of the increasing demand for greater engine reliability for motor busses, etc. Crankcases for the largest fire engines are made of such heattreated castings. Similar castings are replacing the ordinary aluminum castings in engines and other parts for busses, and are becoming of increasing importance in other places in the automotive industry. The development of the high-strength wrought alloys of aluminum, having properties allowing them to replace mild steel, owes its start and much of its success to the pioneer work of a German metallurgist, Alfred Wilm, who dis-
