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By George Tryon, E. A. Barnard

The importance of the conservation of the waste heat contained in copper reverberatory furnace gases was realized very early by those in charge of operation at Anaconda. The first attempt to utilize it was in preheating the air used for combustion of the coal. This was done by forcing the air through ducts surrounding the flue-gas downtake and continued down beneath the furnace hearth to the firebox. Any small advantage gained by the heat transferred from the flue gases was more than offset by the losses sustained in cooling the hearth, therefore this process, after several trials, was soon discarded. It was first used at the Old Works as early as 1893 and again for a comparatively short time on the original furnaces at the Washoe smelter, or present works. Water-tube boilers came into general use very rapidly after 1890. Their adaptability for waste-heat steam generation, as well as the saving to be effected by the production of cheap steam from this source, was soon recognized. The first waste-heat boiler to be used in connection with a matte furnace at Anaconda was installed in September, 1900, at the "Old Lower Works." It consisted of a 100-hp. "Cook," vertical water-tube boiler. This boiler had 65 small perpendicular tubes arranged in concentric circles around a 10-in. tube in the center. These tubes were expanded into 4 ft. 4 in. inside diameter cylindrical steel top and bottom drums which served as the steam and mud drums respectively. This boiler was set in a cylindrical brick housing into which the furnace gases entered just above the mud drum and thence circulated upward around the tubes and steam drum to the stack. This installation proved unsatisfactory, presumably on account of difficulty with dust, and was soon abandoned. However, the possibilities for steam generation were undoubtedly encouraging for shortly afterwards (December, 1900) a 300-hp. Stirling boiler was installed, to be followed by two more in the spring of 1901. The choice of the Stirling type of boiler for application to copper reverberatory furnaces was particularly fortunate, as the arrangement of the tubes appears to combine to a great extent the maximum contact of the gases with the heating surfaces of the boiler and at the same time

Jan 1, 1934

By D. D. Button, L. D. Jaffee

INTEREST in the use of graphite as a high-temperature engineering structural material has recently increased markedly. However, actual use of this material has been limited, in part because information about its high-temperature mechanical properties has been lacking. The information needed includes not only reliable values for the properties, but also how to control these properties. Malmstrom, Keen, and Greenl have reported on the tensile and creep properties of some graphites above 2700° F (1500°C). They observed measurable creep under tensile loading at 4000 OF (2200 °C) and higher, with elongations of about 7 pct at 4500°F. Their typical elongation-vs-time curve showed the normal three stages of creep found for many metals at elevated temperatures. The specimens used were heated by passing an electric current through them. This method of heating caused a significant difference between the surface and axis temperatures, and may have affected the results. More recent work by kattus, in which the specfinens were also heated by their own resistance, showed very little plastic deformation for either slow or fast tensile testing or for creep testing. Work at this Laboratory, already reported,3 showed that for temperatures above 4500 "F and under conditions of slow tensile loading some commercial graphites exhibited elongations up to 20 pct. The work reported here is the continuation of a study of the tensile creep behavior of some commercially available synthetic graphites at temperatures up to 5300°F, and is preliminary to a more systematic investigation of the variables governing the high-temperature mechanical properties of graphite. MATERIALS TESTED The tests were conducted on six blocks from four lots of synthetic graphite bearing four different commercial-grade designations. These blocks were selected because their tensile stress—strain properties had been determined in previous work.3 Table I pre- sents the available information, supplied by the producers, on the processing of these materials. Also included in this Table are the densities and the tensile strengths at room temperature and 4500°F determined by the authors. EXPERIMENTAL TECHNIQUE The furnace used to heat the specimens for testing is shown in Fig. 1. The heating element was a graphite tube, 3-in. OD by 2 1/2 in. ID by 24 in. length. A spiral was cut into the 6-in. center portion of this tube to provide a high-resistance sec-

Jan 1, 1961

By Ray W. Arms

The combination wet and dry coal-cleaning process is not an attempt at a compromise between the wets and the drys nor is its merit confined entirely to the limitation of moisture in the smaller sizes. It is more correctly, and more broadly, an application of the sized-coal cleaning principle adapting itself in an ideal fashion to present day multiple-size preparation practice. The purpose of this paper, therefore, is to call attention to the broader significance of the term "combination wet and dry process" and to mention some of the factors that govern its application. In the narrow sense, when considered apart from the sized-coal cleaning principle, the combination process finds its justification chiefly in the ability to limit the moisture in cleaned coal. Larger sizes of coal offer less superficial area compared with their bulk for the attraction of moisture films. They drain more readily in bins or railroad cars, having more interstitial space for the free flow of water. Therefore, they neither attract nor hold objectionable moisture percentages. In fact, there is so keen a demand for certain washed sizes containing some moisture that hygroscopic salts such as calcium chloride are applied to attract and retain it. When coal deliveries are made on a guaranteed moisture percentage the coarser sizes may be washed and mixed back with the fines without adding greatly to the original moisture but the fines must be dry cleaned or dried to control moisture. Thus in all respects moisture in the coarser sizes is less objectionable than in the fines. The implication of this statement, that moisture is always more or less objectionable, is true. It is safe to say that if dry-cleaning apparatus could be perfected to a point at which its technical results, cost and other aspects would be equal to wet washing, water would no longer be used. As it is, we find that good technical results are more difficult to obtain by dry cleaning than by water. Obviously the use of air tables for coarse coal is not ideal, for it involves the attempt to stratify material in a thin bed on a table surface when the load is only one particle deep. Furthermore, the various air cleaning tables on large sizes require a large volume of air for separation, more power to operate, more dust-collecting apparatus and involve more coal breakage.

Jan 1, 1931

By E. L. Anderson, J. R. Long, R. S. Dean, F. S. Wartman

Titanium has been estimated to comprise about 0.65 per cent of the earth's crust and ranks fourth in abundance among the metallic elements suitable for engineering uses. In spite of this, applications of titanium for structural purposes have not as yet been developed. Its commercial exploitation has been largely confined to the chemical industries and the production of paints and pigments; no doubt because of the difficulties that lie in the way of preparing the pure ductile metal. Published reports, however, indicate that ductile titanium can be prepared and possesses some unique properties. This, together with the occurrence in this country of several important titaniferous deposits, has led the Bureau of Mines to investigate processes for the production of metallic titanium, methods required for its fabrication, and the properties that may be produced in this interesting metal. Methods of Preparing Metallic Titanium Many early investigators claimed to have isolated metallic titanium; but in the light of present knowledge, it seems that they really had produced various mixtures of carbides and nitrides that have a metallic appearance but are brittle, hard, and unworkable. The first metallic titanium pure enough to be malleable when cold was produced by Hunter1 in the early part of the twentieth century. Kroll,~ van Arkel,~ and Fast,4 subsequently confirmed the facts that pure titanium is a. ductile metal and that small amounts of impurities were responsible for previous reports of brittleness. When heated, titanium reacts chemically with various gases, such as hydrogen, oxygen and nitrogen; if the volume of gas thus absorbed is too great, the metal becomes brittle and unworkable. The principal difficulty in making ductile titanium is prevention of such contamination, and the success of a given process may be judged by the completeness with which it solves this difficulty in a practical manner. Of the gases mentioned, hydrogen is the least objectionable, since its absorption by the metal is completely reversible and, although dimensional changes occur and absorption of hydrogen embrittles the metal, the gas may be removed readily by heating in a high vacuum for a short time. On the other hand, the absorption of oxygen or nitrogen results in the formation of permanent solid solutions of the oxide and nitride, which cannot be decomposed by the strongest reducing agentsz with sufticient completeness to restore the inherent ductility of the metal. Because of

Jan 1, 1946

By T. Prof. Egleston

ALL industrial establishments whose operations depend upon chemical reactions use gases. In the simplest case the oxygen of the atmosphere, heated or not, as the case may be, is used, and in other cases, gases which are produced by a special apparatus of more or less complex composition. The manufacturer depends, for the success of his operations, entirely upon having these gases arrive at the right time, in the proper proportions, at the required temperature. It often requires but a slight variation in their composition to make a given process a success or a failure. In most cases the gas used is formed from fuel, and according as variations in its composition are produced by alterations in the manner of charging the grate, not only different, but often directly opposite, results are obtained. The great industrial question of the present time, and one upon which the prosperity of the world depends, is how to get the greatest amount of useful effect from fuel, whether the caloric is used directly or is transformed into horse-power. In almost all industrial pursuits this translates itself into the question of how to construct a fireplace and its adjuncts in such a way that the heat of the flame and of the products of combustion shall be made to produce a maximum effect. Unfortunately, until very recently, except by comparison, there was no means of ascertaining whether the loss of useful effect was 80, 40, or 20 per cent. of the total amount of fuel employed. It seems now strange that there should have been furnaces so constructed as to produce 20 per cent. of carbonic acid in the fireplace, but this has been proved by analysis to have been true. It does seem incredible that, notwithstanding the immense number and variety of furnaces used for different processes, and the great difference in kind, quality, and quantity of fuels consumed, there should formerly have been used for them all, the same stereotyped fireplace, varied only in its dimensions of height, length, and breadth. It is true that, with a good fireman, excellent effects may be, and have been, produced, but the manufacture is here, as in many other cases, dependent on the intelligence of the workman, a very uncertain reliance for capital to rest upon. The workman, unless he receives a prime for fuel saved, or is fined for excessive use of it, may be said

Jan 1, 1874

By L. Sturkey

Quantitative X-ray diffraction studies of the precipitation of thorium in a Mg + 3.3 Th + 0.51 Zr alloy (HK31A) in both the as-cast and cold-worked states show that the precipitation may be described by f = 1 - e(t/T)1/2 over most of the aging period. The effects of cold work and temperature changes are determined. The precipitation of tile equilibrium Mg-Th compotund is Preceded by the formation of a transition phase of higher thorium content, with the cowposition Mg2Th and with a Laves-phase structure. Thorium-containing alloys of magnesium have assumed considerable commercial importance, especially for applications requiring exposures to temperatures greater than 500°F for appreciable lengths of time. The principal commercial wrought alloys in this system are HK31A, containing nominally 3 pet by weight thorium and about 0.7 pet by weight zirconium: and HM21A. containing 2 pet by weight thorium and 1 pet by weight manganese. These two alloys retain a high level of properties even after exposures of 100 hr at 600°F, while the more common alloys containing aluminum and zinc are badly overaged by these conditions. Therefore, in order to obtain some insight into the mechanism by which thorium produces high temperature stability in these wrought alloys, it seems desirable to investi- gate the effect of temperature and mechanical working on the precipitation processes involving thorium. Since the scattering power of a thorium atom for CuKa X-ray radiation is about ten times that for a magnesium atom, the magnesium alloys containing about 3 pet by weight thorium are ideal for quantitative measurements by X-ray diffraction of the amount of Mg-Th compound present at any time. Such quantitative measurements should be of theoretical importance in the study of the effects of time, temperature, and deformation on precipitation and precipitation hardening. Of the two commercial alloys, HM21A and HK31A, the latter is certainly the most suitable for study: In the Mg-Th-Zr2 system, only Mg-Th compounds need be considered, since no ternary compounds or binary Th-Zr3 and Mg-Zr4 compounds exist. The Zr is added to this alloy as a grain refining agent and probably plays a secondary role in precipitation. On the other hand. thorium and manganese form many

Jan 1, 1961

By J. R. Long, E. L. Anderson, R. S. Dean, F. S. Wartman

TITANIUM has been estimated to comprise about 0.65 per cent of the earth's crust and ranks fourth in abundance among the metallic elements suitable for engineering uses. In spite of this, applications of titanium for structural purposes have not as yet been developed. Its commercial exploitation has been largely confined to the chemical industries and the production of paints and pigments; no doubt because of the difficulties that lie in the way of preparing the pure ductile metal. Published reports, however, indicate that ductile titanium can be prepared and possesses some unique properties. This, together with the occurrence in this country of several important titaniferous deposits, has led the Bureau of Mines to investigate processes for the production of metallic titanium, 'methods required for its fabrication, and the properties that may be produced in this interesting metal. METHODS OF PREPARING METALLIC TITANIUM Many early investigators claimed to have isolated metallic titanium; but in the light of present knowledge, it seems that they really had produced various mixtures of carbides and nitrides that have a metallic appearance but are brittle, hard, and unworkable. The first metallic titanium pure enough to be malleable when cold was produced by Hunter1 in the early part of the twentieth century. Kroll,2 van Arkel,3 and Fast,4 subsequently confirmed the facts that pure titanium is a ductile metal and that small amounts of impurities were responsible for previous reports of brittleness. When heated, titanium reacts chemically with various gases, such as hydrogen, oxygen and nitrogen; if the volume of gas thus absorbed is too great, the metal becomes brittle and unworkable. The principal difficulty in making ductile titanium is prevention of such contamination, and the success of a given process may be judged by the completeness with which it solves this difficulty in a practical manner. Of the gases mentioned, hydrogen is the least objectionable, since its absorption by the metal is completely reversible and, although dimensional changes occur and absorption of hydrogen embrittles the metal, the gas may be removed readily by heating in a high vacuum for a short time. On the other hand, the absorption of oxygen or nitrogen results in the formation of permanent 'solid solutions of the oxide and nitride, which cannot be decomposed by the strongest reducing agents2 with sufficient completeness to restore the inherent ductility of the metal. Because of

Jan 1, 1946

By G. A. Croes, N. Schwarz

This paper reports the results of a series of model displacement experiments carried out for measuring the efficiency of the water-drive process. This series forms a continuation and extension of that described by Engel-herts and Klinkenberg. Detailed information has been obtained on the influence of the oil/water viscosity ratio. The results are represented in the form of a diagram from which both the oil recovery and the water/oil ratio can be easily read off as a function of the total production (oil plus water) for all values of the viscosity ratio M between I and 500. These resu1ts are viewed in the light of the two existing theories on water flooding, viz. that of Buckley and Leverett and that of Dietz. It is shown that if the Buckley-Leverett theory applies, the relation between the relative permeability ratio and saturation, which plays a major role in this theory, (.an be calculated with a high degree of accuracy from the results of the model experiments. Dietz's theory is found to be in agreement with the experimental results in a certain range of circumstances. A discussion of the physical background of the Buckley- Leverett and Dietz theories makes it clear why the latter fails to agree with some of the experimental results. INTRODUCTION For an economical exploitation of oil fields both a rational control of natural (primary) recovery processes and a proper application of artificial (secondary) recovery methods are essential. These require detailed information upon the dependence of the relevant flow processes on the variables by which they are governed. Three methods are available for obtaining this information: (1) (statistical) analysis of actual field data; (2) appropriately scaled model experiments; and (3) mathematical analysis of the physical problem. If sufficient data were available, the first method would, in principle, be the most reliable one, although it has the drawback that the basic relationships between the variables involved are to a large extent obscured by the natural inhomogeneities of most reservoirs. The most profitable procedure seems to be: (a) determining the fundamental relations for idealized reservoirs by methods (2) and (3); (b) checking the consistency of the results obtained by these two methods; and (c) establishing the range of applicability of these methods to actual reservoirs by comparison with the data accumulated under (1). In this paper items (a) and (b) are dealt with for the case of homogeneous loose sands initially saturated

Jan 1, 1956

By J. R. Long, E. L. Anderson, R. S. Dean, F. S. Wartman

Titanium has been estimated to comprise about 0.65 per cent of the earth's crust and ranks fourth in abundance among the metallic elements suitable for engineering uses. In spite of this, applications of titanium for structural purposes have not as yet been developed. Its commercial exploitation has been largely confined to the chemical industries and the production of paints and pigments; no doubt because of the difficulties that lie in the way of preparing the pure ductile metal. Published reports, however, indicate that ductile titanium can be prepared and possesses some unique properties. This, together with the occurrence in this country of several important titaniferous deposits, has led the Bureau of Mines to investigate processes for the production of metallic titanium, methods required for its fabrication, and the properties that may be produced in this interesting metal. Methods of Preparing Metallic Titanium Many early investigators claimed to have isolated metallic titanium; but in the light of present knowledge, it seems that they really had produced various mixtures of carbides and nitrides that have a metallic appearance but are brittle, hard, and unworkable. The first metallic titanium pure enough to be malleable when cold was produced by Hunter1 in the early part of the twentieth century. Kroll,~ van Arkel,~ and Fast,4 subsequently confirmed the facts that pure titanium is a. ductile metal and that small amounts of impurities were responsible for previous reports of brittleness. When heated, titanium reacts chemically with various gases, such as hydrogen, oxygen and nitrogen; if the volume of gas thus absorbed is too great, the metal becomes brittle and unworkable. The principal difficulty in making ductile titanium is prevention of such contamination, and the success of a given process may be judged by the completeness with which it solves this difficulty in a practical manner. Of the gases mentioned, hydrogen is the least objectionable, since its absorption by the metal is completely reversible and, although dimensional changes occur and absorption of hydrogen embrittles the metal, the gas may be removed readily by heating in a high vacuum for a short time. On the other hand, the absorption of oxygen or nitrogen results in the formation of permanent solid solutions of the oxide and nitride, which cannot be decomposed by the strongest reducing agentsz with sufticient completeness to restore the inherent ductility of the metal. Because of

Jan 1, 1946

By Adrian C. Dorenfeld

Laboratory data form the basis for the design of flotation circuits. These data, obtained from testing samples of the ore, should show the optimum con- ditions for concentrating the ore and the effects of change in process vari- ables. Among the more important variables commonly met in flotation practice are: Liberation Size-This is the particle size at which substantially all of the valuable minerals are detached from the gangue minerals. Reagent Additions- Experimental data will show the reagents used and their quantity, quality, and point of addition. Pulp Density-This is an important variable in the design of the flotation circuit because it is one of the factors determining the size and number of flotation cells. Flotation Time-The time necessary to make the separation into concentrate and tailing depends on such factors as particle size and reagents used and must be known for determination of the size and number of flotation cells in the plant. Temperature of Pulp-Temperature affects flotation reactions. Water at approximately room temperature is satisfactory for most flotation separations, but some minerals such as fluorspar are best floated in hot water. Type of Circuit-Many types of circuits can be designed, as discussed in detail later. The laboratory tests should provide data for design of the plant circuit best suited to the ore. Water-Knowledge of the quality of the future plant's raw water is important because water quality may drastically affect flotation results. If possible, flotation tests should be made using samples of the water to be used in the plant. Flotation results may vary with seasonal temperatures and with circulation of reclaimed water. Experimentation can show whether it will be necessary to provide for heating, cooling, treating, or reclaiming the water. Uniformity of Ore-The extent of variation of the ore in hardness, grind- ability, mineral content, and floatability should be investigated so that the designer can ascertain methods to overcome problems caused by ore variations. Settling and Filtration Data-To design the plant flotation circuits, settling and filtration rates and ultimate percentage solids of the various products must be determined. Corrosion and Erosion-Corrosion and erosion tests should be made on the flotation pulps, particularly if the pulps are acid or at an elevated temperature, so that suitable materials of construction can then be chosen.

Jan 1, 1962

By A. P. Boller

In the victories of peace as well as of war, the science of engineering has played a prominent, if, indeed, not the leading part. While it might be interesting, and food for profitable thought, to trace the development of engineering from early times in its bearings upon the social betterment of mankind, it will be sufficient on the present occasion to suggest a few thoughts that it is hoped will aid the unprofessional listener to an appreciative consideration of the subject-matter laid down for to-day's discussion, and possibly lead the professional brother to a higher conception of the profession to which he belongs. Since the advent of the railway era, it is difficult to grasp the sequence of historic events that have led to the wondrous derelopment of mechanical science, making possible the civilization that is our daily boast, and opening up a vista of future intellectual and moral advancement among the nations of the earth, 'before which the imagination becomes hopelessly lost. Even now, looking back over a period of only half a century, we often fail to realize the vast change in the relations of individuals and nations to each other., brought about by the results of those mechanical discoveries which, having made the whole world kin, exercise a resistless levelling influence that bears fruit politically in the spread of republican ideas, and morally in the elevation of the individual through the facilities given to the dissemination of Christian ideas and general intelligence. In this view, it seems almost like a work of supererogation for a body of representative men of one department of that science to which the whole world owe. so much, to meet here at the centre of our national life to plead not only for a practical recognition of the national importance of the work to which their lives are devoted, but also for national aid, on a scale beyond that of private effort, to the end that mechanical science may be carried to a higher plane than ever yet attained, each step on the way being of material benefit to every man, woman, and child in the community. Possibly this is strong language, but none too strong when we consider that the work for which we plead is one affecting not only vast scientific and commercial interests, but also human life, to a degree little ap

Jan 1, 1882

By J. E. Elliott, K. O. Miller

Solubility studies were carried out to establish the phase distributions for various Fe-Ni-Pb-C alloys at temperatures where the metallic components exist as liquid solutions. Temperature us composition diagrams for the Ni-Pb, Fe-Pb, Fe-Ni-Pb, and Ni-Pb-C systems are derived by employing various approximations in conjunction with the data. Results are summarized for 1550°C in a quaternary phase diagram of the Fe-Ni-Pb-C system. BECAUSE surprisingly little information has been published on the phase diagrams of the Ni-Pb, Fe-Pb, Fe-Pb-Ni, and Fe-Ni-Pb-C systems, a study of these systems was undertaken to ascertain the important phase relationships in the temperature range of 1300" to 1550°C. Measurements were also made on the carbon-saturated systems in the hope that they would assist in the interpretation of the systems without carbon. This paper reports the results obtained from the simple equilibration of the various liquid and solid phases. EXPERIMENTAL PROCEDURE The experimental technique involved holding appropriati quantities of the metals in an alumina crucible, or in a graphite crucible when saturation of the melt with carbon was desired, for sufficient time at the desired temperature to ensure equilibrium. Then a sample of each liquid phase presen was drawn into a small-bore silica tube. This sample was withdrawn quickly from the furnace, cooled, and sent to the chemical laboratory for analysis. The cell assembly used is shown in Fig. 1. Durin the work on the Fe-Pb-Ni system, it was placed in a furnace wound with 20 pct Rh-80 pct Pt wire. This furnace eventually failed and subsequent studies were carried out between 1350" and 1475°C in a tube furnace heated by silicon-carbide resistance elements. A protective atmosphere of argon with approximately 10 pct hydrogen was supplied to the cell assembly at a gage pressure of 1 in. of water. Hydrogen was passed over palladized alumina and then anhydrous calcium chloride for purification. Argon was purified of oxygen and water vapor by passing it over copper gauze at 550°C and then through a calcium chloride drying column. The gases were mixed and redried before they entered the equilibration cell. Temperature was measured by calibrated Pt/Pt-10 pct Rh thermocouples and a Rubicon Type B potentiometer. The thermocouples were standardized against the melting points of pure nickel

Jan 1, 1961

By A. R. Elsea, C. C. McBride

HIGH-TEMPERATURE alloys, that is, alloys that are strong at high temperatures, have become increasingly important with the development of modern aircraft engines. Many alloys of this type are available. However, metallurgists do not have a clear understanding of the phases or structures which are responsible for these high-temperature properties. If these basic factors were understood, it might be possible to make better or cheaper alloys for service at high temperatures. For this reason, an investigation of the fundamental factors promoting high-temperature strength in alloys was started at Battelle Memorial Institute. This was to have included a study of the relationship between the structure and properties of cobalt-chromium base alloys of the vitallium type. It soon became clear that the structure of vitallium is quite complex and that the equilibrium diagrams which should explain these structures were unreliable. As a result, the cobalt-chromium binary diagram was determined as the first phase of this investigation1. This diagram is shown in fig. 1. During the study of the cobalt-chromium binary system, it was learned that these alloys may pick up considerable nitrogen when melted and heat treated in air. The extent to which nitrogen affects the various reactions in cobalt-chromium base alloys was not known, but there were indications that this impurity might be responsible for some of the erratic test results obtained for vitallium. Consequently, nitrogen was the first ternary addition studied. Thereafter the work was extended to ternary additions of iron and of nickel. This paper describes the investigation of the effects of nitrogen, iron, and nickel upon the reactions in cobalt-chromium alloys with 80:20 and 68:32 cobalt-chromium ratios. Experimental Work Alloy Preparation: A series of cobalt-chromium base alloys containing various amounts of the third element being studied were made for both the 80:20 and the 68:32 cobalt-chromium ratios. Electrolytic chromium, cobalt, and iron, and reagent-grade nickel powder were used as melting stock. Table I contains the chemical analyses of these materials. The charges were melted in alun-dum thimble crucibles which absorbed chromium oxide and effectively deoxidized the melts. These crucibles were supported by close-fitting graphite sleeves so that if they cracked during melting the metal would not be lost. Carbon increases, during

Jan 1, 1951

By Gerard Matthes

WITHIN the last three years, aerial mapping has made wonderful progress. Its three sources of development in North America may be enumerated as follows: (1) The work of the U. S. Army Air. Service and Corps of Engineers at the McCook Experimental Field, Dayton, Ohio. This is generally regarded as the backbone of this class of endeavor in the United States. (2) In Canada, a great deal has been accomplished in a practical way by methods that have not even been tried out in the United States. Under the leadership of the late Doctor Deville, the Dominion Land Surveyors have turned out reconnaissance maps of large areas at very, small cost. (3) Private capital has contributed a great deal toward development of aerial mapping in a practical way in the United States. Prominent in this regard stands the Fairchild Aerial Surveys, Inc. which has spent large sums in research and development work, especially in the construction of aerial cameras. Its camera is, at present, the official camera of the U. S. Army and Navy Air Services, also, of the Canadian and Brazilian governments. Aerial photographic surveying is a flexible process and adapted to a variety of uses. To date, it has proved. of direct practical value for engineering projects such as reservoir and power transmission surveys, railroad location, drainage, harbor front studies; also, for many commercial purposes, tax assessment, city planning, forest surveys, and lawsuits. In a few instances, aerial photographs have been used successfully by geologists as base maps on which to record field observations, thereby dispensing with pacing and compass surveys. There is reason to believe that, eventually, the aerial map will find wide application in the work of geologists. The reason for advancing this opinion is that aerial maps have, in other fields, proved more complete as regards detail than maps made by standard processes of surveying and drafting, and often are more accurate than the latter. At the present time, five distinct uses are being made of aerial photographs: There is the "oblique" photograph taken at an angle with the horizon; it is used extensively for illustrations in newspapers, magazines, and advertisements. Also, for reconnaissance purposes, it has been found of great practical value. For illustrating reports of engineers and geologists, it offers many obvious advantages. In the Canadian Surveys, maps have been compiled from oblique photographs.

Jan 3, 1925

By H. H. Power, Charles R. Houssiere

THE development of effective and dependable methods for drilling through the so-called "heaving-shale" horizons, particularly in the Gulf Coast area, is believed to comprise a major contribution to drilling technology, and to the task of finding and developing our undiscovered oil pools. Many mechanical remedies have been proposed and are in use in troublesome areas for combating heaving shale. However, in conducting a research program it was concluded that the physical and chemical properties of shales should be investigated, and the effect of added chemicals on such properties determined. As a preliminary step, the effect of chemicals on bentonitic suspensions was determined in accordance with recent contributions in the field of ceramics. The most plausible theoretical explanations for the behavior of the clay minerals involved are offered in the paper that follows. It is hoped that subsequent investigation of actual shale from troublesome wells will be aided by the initial work done on bentonitic suspensions of known composition. INTRODUCTION Formations variously designated as "heaving shale," "sloughing shale" and "caving shale" impede and may even preclude drilling of oil wells, particularly in certain parts of the Gulf Coast. In a previous paper1 it has been stated that the development of effective and dependable methods for drilling through these troublesome beds is believed to comprise a major contribution to drilling technology, and to the task of finding and developing our undiscovered oil pools. Since the attack on the heaving-shale problem by mechanical means was principally a matter of field investigation, it was concluded that a research program should be concerned with the physical and chemical properties of heaving shales, and the effect of added chemicals on such properties. It was realized that a study of shales required an advanced knowledge of the behavior of the individual clay minerals. A thorough review of the literature led the authors to the conclusion that very recent contributions2.3 in the field of ceramics furnished the most plausible theoretical explanations for the behavior of clay minerals. Accordingly, these fundamental ideas will be used in an attempt to explain the behavior of more complex systems whose composition and replaceable ions are known. In order to obtain comparable results it was deemed important to select an easily procurable clay of uniform characteristics. Accordingly, Wyoming bentonite, which is marketed under the name of "Volclay,"* was used for the preliminary investigations. The chemical analysis reported by the distribution is given as follows:

Jan 1, 1941

By W. J. Reagan

The problem of increasing output and decreasing percentage of rejections is a vital one in the manufacture of steel of any kind. The making of basic open-hearth steel for use in rolled steel wheels, tires for locomotive and car wheels, and forgings of various kinds, is a highly specialized industry. The increase in weight of railway rolling stock of all kinds, and the high speed that the public demands of transportation facilities, make it imperative that steel for use in this class of material shall be of the highest quality obtainable. During the past few years it has been the writer's good fortune to have opportunity to study the defects in basic open-hearth steel, and also the results obtained by various changes in open-hearth practice, on such defects. The opportunity for study and the details available are rarely found in the manufacture of steel of any kind. It seems reasonable to assume that many of the results determined here can be applied to the production of steel of other types with a decided improvement in quality, a decrease in the percentage of rejections and an increase in output. All of the material described is basic open-hearth steel with the following range of analysis: carbon, 0.50 to 0.85 per cent.; phosphorus and sulfur, 0.04 max.; silicon, 0.15 to 0.35; manganese, 0.50 to 0.75. All of this material is bottom-cast, therefore tapping and pouring temperatures are higher than in top-cast production. Ingots used in this type of work are of standard length with varying diameters. The ingot is known as duodecagonal, or twelve-sided. The standard body length is 88 in. and the hot top length, 14 in. Fig. 1 shows a typical ingot of this type. The diameter varies from 13 to 30 in. Ingots for special forgings, which cannot be made in molds of standard size, are made in molds of various sizes and designs. These ingots are sliced cold, into blocks of various lengths, depending upon the weight of the forging to be made. Fig. 2 shows the ingot after coming from the slicing lathe. Jusf sufficient metal remains between blocks to hold the ingot in one piece while it is being removed from the lathe; then steel wedges are inserted between the blocks and the blocks are broken apart. This affords abundant opportunity for inspection, as the interior of the

Jan 1, 1930

By Gerald Edmunds

The liquidus line on the phase diagram for temperature versus composition of a binary alloy system, representing the boundary between the homogeneous melt and the heterogeneous melt plus solid, besides showing the minimum casting temperature, is useful in determining eutectic compositions and the presence of phase changes such as peritectic transformations and intermetallic compound formation. The liquidus often is determined by the cooling curves of thermal analysis, but supercooling frequently occurs, so that the temperature values are low. An alternative method, the one employed here, consists of determining the composition of samples of the melts from heterogeneous alloys that are at equilibrium. With meticulous attention to fundamentals, this method is capable of yielding values limited in precision only by the temperature control and measurement and analyses. Apparatus By starting, on the one hand, with a supersaturated solution and allowing the excess solute to precipitate, and on the other hand with an undersaturated solution and allowing more of the solute to be dissolved, both processes being carried out at the same temperature, equilibrium may be said to have been approached from both directions; that is, from above and from below. If the analyses show the solutions to contain the same fraction of solute when equilibrium has been approached from above and from below, one is assured that equilibrium has been reached in both determinations. In order to carry out such determinations, it is necessary to have equipment for obtaining and maintaining the proper temperatures; for holding the melt, measuring its temperature, and stirring, sampling and analyzing it. The present work required temperatures from 420° to 900°C. The equipment consisted of: A furnace, which was a vertical alundum tube, 13/4-in. diameter inside and 18 in. long, wound with Nichrome resistance wire, surrounded by a 3-in. i.d. alundum tube wound for 5 in. of length near each end, for compensation of end losses. This muffle was contained in an iron shell with Transite end plates, the intervening space being packed with Sil-O-Cel. The outside dimensions of the furnace were 12 in. in diameter by 181/2 in. in height. Heating current was supplied by three independent variable-voltage transformers (Variac), one connected to each end compensator winding and manually controlled, and one connected to the main winding through a series resistance of 5 ohms. This resistance was short-circuited for

Jan 1, 1944

By Gerald Edmunds

The liquidus line on the phase diagram for temperature versus composition of a binary alloy system, representing the boundary between the homogeneous melt and the heterogeneous melt plus solid, besides showing the minimum casting temperature, is useful in determining eutectic compositions and the presence of phase changes such as peritectic transformations and intermetallic compound formation. The liquidus often is determined by the cooling curves of thermal analysis, but supercooling frequently occurs, so that the temperature values are low. An alternative method, the one employed here, consists of determining the composition of samples of the melts from heterogeneous alloys that are at equilibrium. With meticulous attention to fundamentals, this method is capable of yielding values limited in precision only by the temperature control and measurement and analyses. Apparatus By starting, on the one hand, with a supersaturated solution and allowing the excess solute to precipitate, and on the other hand with an undersaturated solution and allowing more of the solute to be dissolved, both processes being carried out at the same temperature, equilibrium may be said to have been approached from both directions; that is, from above and from below. If the analyses show the solutions to contain the same fraction of solute when equilibrium has been approached from above and from below, one is assured that equilibrium has been reached in both determinations. In order to carry out such determinations, it is necessary to have equipment for obtaining and maintaining the proper temperatures; for holding the melt, measuring its temperature, and stirring, sampling and analyzing it. The present work required temperatures from 420° to 900°C. The equipment consisted of: A furnace, which was a vertical alundum tube, 13/4-in. diameter inside and 18 in. long, wound with Nichrome resistance wire, surrounded by a 3-in. i.d. alundum tube wound for 5 in. of length near each end, for compensation of end losses. This muffle was contained in an iron shell with Transite end plates, the intervening space being packed with Sil-O-Cel. The outside dimensions of the furnace were 12 in. in diameter by 181/2 in. in height. Heating current was supplied by three independent variable-voltage transformers (Variac), one connected to each end compensator winding and manually controlled, and one connected to the main winding through a series resistance of 5 ohms. This resistance was short-circuited for

Jan 1, 1944

By Roman Šejnoha, Karel Mazanec

A pronounced tendency for delayed fracture zoas observed in the martensite structure of low-alloy steels in the as-quenched condition. Cracks of predominantly intercrystalline nature nucleated and propagated at stresses substantially lower than the short-titne tensile strength of- the steels, and were observed even in hydrogen-free speciunens. The occurrence of delayed fractures in the as-quenched condition is interpreted as a supevposition of the effect of free dislocations generated during the martensite transforlnation, and of a weakening of the prior austenite grain boundaries caused by dynamic shocks exerted on the boundaries by growing martensite plates. AN important metallurgical problem, connected with the production and use of high-strength steels, is delayed fracture in martensitic structures. Such fractures occur in quenched steels as a result of prolonged loading with external stresses far lower than the short-time tensile strength of the steel. The same effect can be produced by sufficiently high internal stresses: it is well-known that quenched structures will in some cases crack intergranularly at room temperature if not tempered quickly enough even in the absence of any externally applied stress. In Troiano's papers1,2 on delayed fractures in high-strength steels, the fundamental role of hydrogen migrating under the influence of multiaxial stress towards the nuclei of cracks was found. Fig. 1 shows the typical relationship between stress and the time to fracture found by Troiano in hydrogen-charged high-strength steels. On the other hand, Shurakov 3,4 explains the realization of delayed fractures in martensite as due to a "quasi-viscous" behavior of the austenite grain boundaries immediately after the martensitic transformation. 1) MATERIALS AND EXPERIMENTAL METHODS Two low-alloy steels of commercial purity were used for the experiments reported in this paper. Their chemical composition is shown in Table I. The heats were melted in a laboratory furnace, cast to ingots, forged to bars of 3/4 in. diameter, and annealed. Machined test pieces were heat-treated as follows: Ni-Cr-Mo steel held at 900°C for 30 min and quenched in oil; Mn-Si-Cr steel held at 900°C for 30 min and quenched in water. For the delayed-fracture tests, notched cylindrical test pieces, Fig. 2, stressed in torsion, and unnotched cylindrical tensile-test pieces, 1/4 in. diameter, were used. The specimens were normally loaded with a constant static load 45 min after quenching for the torsional tests and 10 min

Jan 1, 1965

By John W. Cahn

The spinodal has long been regarded as a limit beyond which a homogeneous phase could no longer be metastable. But only recently has it become apparent that a phase beyond the spinodal would decompose by simple diffusional clustering mechanism quite different from the nucleation and growth mechanisms encountered for metastable phases. The theory of spinodal decomposition, which is based on the diffusion equation modified by thermodynamic requirements , is phenomenological, and each parameter can be measured by independent thermodynamic or diffusion experiments. The details of the theory have been carefully verified in a number of simple systems. It appears that the spinodal mechanism is commonly encountered in clustering reactions in solids and glasses. HISTORICAL INTRODUCTION The understanding of the earliest stages of precipitation in alloys has been the subject of three prior Institute of Metals Lectures. In 1932 Paul ~erica' reviewed the puzzling evidence that hardening of duralumin is completed before precipitation of CuAlz takes place and suggested that hardening occurs when the copper atoms "assemble in random groups on lattice positions of the duralumin, not of the CuAlz lattice". He called these random groups knots. This modification of his dispersion hardening theory seemed to fit all the facts, but Merica worried that the required diffusion "is just the reverse of what we deem normal; although quite spontaneous, it proceeds uphill, if you please". The reality of Merica's knots was quickly confirmed by Guinier's' and preston's3 X-ray work and these knots are today known as G.P. zones in their honor. Theoretical justification for uphill diffusion was also quickly provided by Becker and Dehlinger~ who noted that the diffusion coefficient could be negative in certain regions of phase diagrams. The boundaries of such regions could be described by a 90-year-old thermodynamic concept first described by ~ibbs' in 1877 as a limit of metastability for fluid phases, which by 1890 had received the name spinodal (see Appendix A). Spinodal in fluids is as old as nucleation theory. Both appear for the first time in the same paper by Gibbs who called the spinodal the limit of metastability. For the first 50 years, nucleation theory was forgotten and the spinodal was extensively treated in every good thermodynamics textbook.81Q The idea was simple and logical and it was accepted as part of a rigorous thermodynamic development of metastable phases, and for a while it was extensively investigated theoretically.

Jan 1, 1969