Search Documents

By L. C. Weiner

THIS study was undertaken to round out an investigation on the effects of solid environments on the brittle fracture of zinc single crystals.' In the previous work it was demonstrated that the presence of a surface film increased the cleavage strength of crystals whose basal planes were oriented almost parallel to the tensile axis by some 43 pct. This increase was observed to be independent of the type of surface-coating material, as well as of thickness of film above a certain small critical value (about 200 to 300A). These observations were described sat- isfactorily by a dislocation-pile-up-at-a-barrier model of brittle fracture2 in which twins modifying the dislocation path act as barriers, their increase in number and homogeneity of distribution brought about by the presence of the surface film. From previous work reported on the strength of ductile metal crystals as affected by gaseous and liquid environments,3 it may be concluded that the effects of these media are present only when the environment produces a surface film on the initially clean-surfaced crystal, or when it has a disintegrating effect on a previously existing surface layer. Similarly, it might be expected that an increase in cleavage strength of initially clean zinc crystals (xo = 3", A, - 28") will result only when the gas or liquid reacts with the crystal to produce a solid, adherent surface film. Clean-surfaced crystals,l 2 1/12 in. in length, were tested in tension at room temperature in an Instron

Jan 1, 1959

By R. Jr. Schuhmann

PROBLEMS in expressing, interpreting, and using size-distribution data recur in many phases of mineral dressing; therefore it is desirable that size analyses be ex-pressed in such a form, either numerically or graphically, that comparisons can be made readily. The size distribution of comminuted material is a result of a specific physical operation on the material and therefore should be governed by some definite physical principle, or cause-effect relation. Although this principle has not been dis-covered, it has been found that the size distribution of comminuted, homogeneous solids may be expressed by relatively simple mathematical equations. Two equa-tions in particular, proposed by Gaudin1 and by Rosin and Rammler,2 respectively, have stood out, both having wide demon-strated ranges of application. The form and the method of application of the two appear almost irreconcilably different on the surface, but, as will be shown, they are asymptotic in the fine sizes when expressed in the same units. This paper gives the results of a further study of the Gaudin and Rosin-Rammler relations, made with the object of develop-ing a form of size-distribution equation that will be more usable and more signifi-cant-particularly in comminution studies, both for interpreting the nature of size distribution and for evaluating surface. The work is summarized in the following:

Jan 1, 1940

By E. Miller, J. M. Eldridge, K. L. Komarek

Aclivilies of magnesium in liquid Alg-Si alloys have been delermined between 5 and 60 at. pcl Si, close to the melling point of Mg2Si, by an improved isopieslic melhod. Silicon specinrens, held in alumina crucibles and graplrile conlainevs of special design, were healed in a letrlpevalure gvadient and equilibrated with mag-nesilcrrl rapor in a closed lilanium system. The ther-madynamic Junctions were calculated and compared with the thermodyuamic properties of the other three mg- Gvoup IVB systems. Lattice paramelers of three Mg2X compounds were measured. The bonding in the Mg2X compounds is largely covalent with small and uarying amounts of metallic and ionic conlvibutions. The Mg-Si phase diagram1 has one congruent melting compound, Mg2Si, of essentially stoichiometric composition, two eutectics, and very limited terminal solid solubilities. Little information is available on the thermodynamic properties of this system. The free energy of formation of Mg2Si has been determined by the Knudsen cell technique2 in the range 572" to 680oC, by the transportation method3 between 858" and 950oC, and by the electromotive-force method4 in the range 400o to 600°C. Kubaschewski and villa5 and caulfield6 have measured the heat of formation of Mg2Si. An electromotive-force study of magnesium-rich liquid alloys was recently published by Sryvalin el al.7 The present investigation was undertaken to complete a general survey of the thermodynamic properties of the homologous series of Mg-Group IVB systems, i.e., Mg-Pb,a9,Mg-Sn,10,11 mg-Ge,12and Mg-Si. An isopiestic technique, previously developed for similar measurements on liquid Mg-sn11 and Mg-Ge alloys,12 was modified for the Mg-Si system. Specimens of the nonvolatile component, silicon, were contained in dense alumina crucibles placed inside covered graphite crucibles which were heated in a temperature gradient in an evacuated and sealed titanium reaction tube and equilibrated with magnesium vapor of known vapor pressure. The alumina crucibles prevented contact between the highly corrosive liquid Mg-Si alloys and graphite. The graphite cruci- bles effectively preserved the high-temperature equilibrium composition of the liquid alloys containing highly volatile magnesium on termination of the experiments during the quench to room temperature. EXPERIMENTAL PROCEDURE Silicon of semiconductor-grade purity (E. I. du Pont de Nemours and Co., Brevard, N.C.) and 99.99+ pct Mg (Dominion Magnesium Ltd., Toronto, Canada) were used. Graphite crucibles with press-fitted lids were machined from high-density (1.92 g per cu cm) rods (Basic Carbon Corp., Sanborn, N.Y.) which had a maximum ash content of less than 0.04 pct. The alumina crucibles had a purity of 99.7+ pct (Triangle RR grade, Morganite, Inc., Long Island City, N.Y.). In preliminary runs the liquid alloys were contained in graphite crucibles following the exact procedure developed for the Mg-Ge system.'2 These runs failed due to appreciable reaction between the molten Mg-Si alloys and graphite, and the results have been discarded. The procedure was then modified and the Mg-Si alloys were subsequently held in alumina crucibles. For most of the runs alumina crucibles of known weight and approximately 6.3 mm ID, 12.5 mm height, 1.0 mm wall thickness were loaded with weighed amounts of silicon and encapsuled in tightly covered weighed graphite crucibles 5/16 in. ID, 2 in. helght, 3/32 in. wall thickness). The graphite crucibles were machined from rods which were 85 pct of the theoretical density. These crucibles were therefore sufficiently porous so as to permit magnesium vapor to effuse through the silicon under the experimental conditions of approximately 970O to 1220°C and 1 day equilibration time. However, negligible magnesium was lost from the crucible during the quench due to the slow effusion rate through the pores of the graphite. The inner alumina crucible prevented the liquid alloys from contacting the graphite, and the very tightly fitting graphite crucible lids served to retain any magnesium vaporizing from the alloys inside the crucibles during the quenching step.12 The loaded silicon-alumina-graphite cells were positioned, one above another, on a 16-in.-long titanium thermocouple well and tied securely to the titanium tube with thin molybdenum wires held in grooves around the circumference of the graphite crucibles. A thin (0.005-in.) molybdenum strip prevented contact between the graphite crucibles and the titanium. This assembly was lowered into a titanium reaction tube (la in. ID, 16 in. long, $ in. wall thickness) closed on one end which contained a 11/2-in.-long cylinder of magnesium at the bottom. The inner titanium thermocouple well was positioned eccentrically in the large tube because of the eccentric mounting of the cells on the well. Appropriate modifications of the titanium cap"'12 were made to join the inner and outer titanium

Jan 1, 1968

By R. F. Bell, L. W. Eastwood, R. W. James

Among those concerned with the annealing and heat-treating of aluminum and aluminum alloys, it is well known that after co1d-working a coarser grain is usually produced by slow heating than hy more rapid heating. Consequently, for the control of the grain size produced by annealing or heat-treating cold-worked aluminum and aluminum alloys, the heating rate is of considerable practical importance. References in the current literature on the effect of heating rate are numerous, but it appears neither necessary nor desirable to give here a review of the former nark done on this subject. It became evident during some preliminary work on the recrystallizn-tion of aluminium and aluminum alloys that the effect of heating rate depended upon the type of microstructure of the metal. This observation led to the following study of the relationship of the type of microstructure of the alloy to the effect of the heating rate. Materials Investigated Analyses of the aluminum and aluminium alloys investigatted are given in Table 1. Three classes of material are listed, as follows: Class I.— Belonging to the first class are pure aluminium and aluminium containing a second constituent that is soluble in the aluminium matrix at

Jan 1, 1939

By Carl H. Samans

In their recent complete review of the subject of age-hardening,' R. F. Mehl and L. K. Jetter classify the main types of precipitation-hardening alloys under two headings, depending upon the nature of the precipitate and the character of the precipitation. In the alloys falling under the first heading, which display "continuous precipitation" and are typified by the aluminum-copper alloys, "precipitation seems to occur without much regard to grain boundaries and apparently at much the same rate at every point," although an acceleration in regions plastically deformed has definitely been established.2 In the second type of alloys the precipitation is "discontinuous," as in the copper-silver system for example, and "seems to start in restricted regions, primarily those contiguous with the grain boundaries, and to spread inward in an advancing wave." The reasons for the occurrence of these two greatly different types of precipitation are unknown, as are those for many other reactions that take place in the solid state. In the present paper only the first or "continuous" type of precipitation will be dealt with, for which a complete crystallographic mechanism has been worked out for the process of precipitation from a supersaturated solid solution of copper in aluminum. Based upon this mechanism, an explanation of the various property changes found experimentally will be developed in the second paper of this series. In later papers ('discontinuous precipitation" in copper-silver alloys will be explained, and an effort will be made to rationalize the two processes and types of precipitation. Crystallography of the Precipitation Process Through the extensive investigation by R. F. Mehl, C. S. Barrett and F. N. Rhines3 on the Widmanstätten structure in aluminum-rich copper

Jan 1, 1940

By P. A. Beck, M. N. Parthasarathi

In high purity aluminum single crystals grown by the strain-anneal method (primary re crystallization after a small deformation) Lacombel observed sub-boundaries with disorientations of 1 to 3 deg. In commercial and high purity aluminum crystals grown by the same method Tiedema observed sub-boundaries with disorientations of about 20 min of arc, radiating from a =nuclear spot," centrally lo-

Jan 1, 1959

By R. L. Tobie

The degree of automation that has evolved in the dumping and hoisting of ore at the 3A and 3B hoisting shafts of the San Manuel mine is discussed. Motormen underground now dump their own trains at shaft pockets with rotary car dumps which operate semiautomatically. The ore is then drawn out of the 1200-ton shaft pockets into measuring baskets in skip loading stations, loaded into bottom-dump skips, hoisted, and dumped into coarse ore bins on the surface, in a fully automated operation. In an underground control room on the 2075 level midway between 3A and 3B shafts, car dumping, skip loading, and hoisting systems are monitored on lighted control panels which mimic each step in the operation. Here skip loading and dumping are viewed on closed-circuit television.

Jan 1, 1972

By R. F. Bell, R. W. James, L. W. Eastwood

Among those concerned with the annealing and heat-treating of aluminum and aluminum alloys, it is well known that after co1d-working a coarser grain is usually produced by slow heating than hy more rapid heating. Consequently, for the control of the grain size produced by annealing or heat-treating cold-worked aluminum and aluminum alloys, the heating rate is of considerable practical importance. References in the current literature on the effect of heating rate are numerous, but it appears neither necessary nor desirable to give here a review of the former nark done on this subject. It became evident during some preliminary work on the recrystallizn-tion of aluminium and aluminum alloys that the effect of heating rate depended upon the type of microstructure of the metal. This observation led to the following study of the relationship of the type of microstructure of the alloy to the effect of the heating rate. Materials Investigated Analyses of the aluminum and aluminium alloys investigatted are given in Table 1. Three classes of material are listed, as follows: Class I.— Belonging to the first class are pure aluminium and aluminium containing a second constituent that is soluble in the aluminium matrix at

Jan 1, 1939

By Carl H. Samans

In their recent complete review of the subject of age-hardening,' R. F. Mehl and L. K. Jetter classify the main types of precipitation-hardening alloys under two headings, depending upon the nature of the precipitate and the character of the precipitation. In the alloys falling under the first heading, which display "continuous precipitation" and are typified by the aluminum-copper alloys, "precipitation seems to occur without much regard to grain boundaries and apparently at much the same rate at every point," although an acceleration in regions plastically deformed has definitely been established.2 In the second type of alloys the precipitation is "discontinuous," as in the copper-silver system for example, and "seems to start in restricted regions, primarily those contiguous with the grain boundaries, and to spread inward in an advancing wave." The reasons for the occurrence of these two greatly different types of precipitation are unknown, as are those for many other reactions that take place in the solid state. In the present paper only the first or "continuous" type of precipitation will be dealt with, for which a complete crystallographic mechanism has been worked out for the process of precipitation from a supersaturated solid solution of copper in aluminum. Based upon this mechanism, an explanation of the various property changes found experimentally will be developed in the second paper of this series. In later papers ('discontinuous precipitation" in copper-silver alloys will be explained, and an effort will be made to rationalize the two processes and types of precipitation. Crystallography of the Precipitation Process Through the extensive investigation by R. F. Mehl, C. S. Barrett and F. N. Rhines3 on the Widmanstätten structure in aluminum-rich copper

Jan 1, 1940

By E. Stansfield

THIS test was described in a privately circulated First Progress Report on Slacking Characteristics of Coal, by A. C. Fieldner and W. A. Selvig, May 1, 1928. The test was described in detail in U. S. Bureau of Mines Report of Investigation 3055, in November, 1930.1 The test, in brief, is conducted as follows: A sample of freshly mined coal consisting of 18 to 25 pieces approximating 1 ¼ cubes, and weighing 500 to 600 grams, is taken for the test. The sample is subjected to a "blank sieving" of carefully regulated degree, on an 8-in. circular sieve with 0.263-in. square openings; and the undersize and oversize weighed. The oversize is placed on a sheet-iron pan and dried for about 24 hr. in an A.S.T.M. air-drying oven maintained at 30° to 35° C. through which a current of warm air is drawn. The sample is then cooled to room temperature and immersed for one hour in water at the same temperature. The water is then drained off, the sample dried for 24 hr. as before, cooled, sieved as before, and the oversize and undersize weighed. The percentage weight of the undersize, is calculated and reported as the first cycle loss. This loss, corrected by subtracting the percentage loss in the blank sieving, is termed the slacking index. The sample may be subjected to further cycles of wetting, draining, air-drying, sieving and weighing. In a letter (August, 1932) W. A. Selvig approved making the blank sieving on a duplicate sample, rather than on the sample used for the test, where sufficient coal was available. This method is now employed in these laboratories. The accelerated weathering test has been employed in the labora-tories of the Research Council of Alberta, at Edmonton, since 1928, but not found entirely satisfactory as repeat determinations with samples taken from the same or adjacent mines frequently showed serious differ-ences. Differences must be expected as the coal may vary in the seam, and the selection of a typical set of lumps approximating 1 ¼ -in. cubes

Jan 1, 1934

By John Wulff, J. H. Hollomon

SERVICE failures in brass condenser tubes are often due to corrosion. One of the commonest types of corrosion reveals a surface structure of redeposited copper.1 The study of the effect of alloy addition agents in preventing this kind of corrosion has received impetus from the extensive publication of Bengough and May.2 The mechanism of such inhibition gauged from immersion corrosion,' cell corrosion,' and electrolytic potential' measurements is controversial. This controversy may be attributed in part to a lack of definite knowledge5 of the actual nature of the initial films formed in corrosion experiments. In our own corrosion work on copper and 70-30 brass this lack became apparent and necessitated an examination of surface films by X-ray and electron diffraction methods. The present paper is but an introduction to the subject of inhibition and reports the structure of films formed in active corrodents. EXPERIMENTAL PROCEDURE The arsenical coppers and brasses used in this investigation were made by one of the writers* in the plant of the Revere Copper and Brass Co. at Rome, N. Y. Standard commercial melting practice was followed. O.F.H.C. copper and electrolytic zinc were used and all arsenic additions were made by additions of a master copper alloy. The final analyses are given in Table I. Likewise, the extrusion, cold-rolling, and intermediate anneals employed followed standard usage. Final heat-treatments were given to all materials to produce a similar grain size (0.035 to 0.045 mm. for brass and 0.015 to 0.025 for [ ] copper) for the alloys containing various percentages of arsenic. Samples ¼ by ½ by ¼ in. were cut from sheet material resurfaced and finished with 0000 metallographic papers. The surfaces were all degreased in alcohol and benzine before immersion. After immersion in the corrodent, they were washed gently in tap water, dipped first in alcohol and then in pure benzine and allowed to dry in the diffraction apparatus. The reflection electron diffraction apparatus used has been described by Burwell

Jan 1, 1941

By George B. Clark, Edward E. Hornsey

Pulses from large underground explosions which traverse the rock beyond the "fracture" and "plastic" zones do not behave as a spherical elastic model. Observed attenuation is greater than that predicted by the elastic wave equation, and the pulse form changes in a different manner, i.e., it usually lengthens with the first power of the distance. To more clearly define a mathematical real earth-wave model, detailed analyses of the spherical elastic and the Voigt viscoelastic models have been made, and results compared with observed wave forms from large confined chemical and nuclear explosions. TRANSIENT SPHERICAL ELASTIC WAVES Scope of Investigation Transient elastic spherical waves were investigated in detail. However, an elastic model is not, in general, an exact representation of wave propagation in rock. An understanding of transient elastic waves is desirable for gaining insight into explosive-generated wave phenomena because it can be employed for comparison of more complex and realistic models, such as the Voigt model, or others which may simulate real earth waves. The study was concentrated primarily on the peak values of the radial wave parameters : displacement, particle velocity, acceleration, stress, and strain.

Jan 1, 1972

By Arthur Foote

AT THE end of the year 1914, the main North Star incline shaft had reached the 6300-ft. level, and encountered a vein dipping Southwest, or, exactly opposite to the North Star. Subsequent development failed to find the North Star vein continuing beyond this intersection, so the 6300-ft. level proved to be the bottom level of the North. Star vein, and very little ore was found below the 5300-ft. level. The new vein was called No. 1 vein. Development work carried on for the next 10 years discovered a third vein, called No. 2, branching off about 1200-ft. to the east, with a North-south strike and a west dip. No. 1 vein had about 900 ft. of backs above the 6300-ft. level before reaching the boundary line of the property, and No. 2 vein died out about 800 ft. above. During these 10 years, the money spent on development was increased from $54,000 in 1914 to $184,000 in 1924; the ore reserves steadily diminished until it was evident that the mine must close down unless by some means a large tonnage of ore could be developed quickly.

Jan 1, 1930

By Robert Sisselman

Saving time and energy at Consolidation Coal Co.'s Rowland mine is realized by exploiting its coal deposits via three mining methods. Surface, auger and underground techniques are uniquely combined with specialized transport vehicles to coax the coal from seams unduly protected by topography and lithology. These factors account for what is believed to be the swiftest and most economical means of working the Beckley, W. Va., property.

Jan 1, 1970

By Sherwin F. Kelly

Drilling in the Oligocene potash basin of Alsace prior to 1927 had shown important differences of level in the salt beds thus encountered. TO explain this a somewhat unsatisfactory hypothesis of faulting had been advanced. During the latter part of 1926 and the beginning of 1927 our firm was engaged by two organizations1 for the purpose of trying to supplement, by an electrical survey, the geological data this far collected. As a result of this exploration it was possible to affirm that salt dome structures were present in the Oligocene basin of the Upper Rhine, something heretofore absolutely unknown in that region. Two salt domes were actually outlined: one, near Meyenheim, was made the subject of a communication to the Academy of Sciences, by G. Friedel;2 the other, near Hetten-schlag, was briefly discussed by C. and M. Schlumberger3 before the same academy. The purpose of this paper is to indicate the stratigraphic and structural conditions of the area where these salt domes were found; to discuss the results of the electrical survey which led to the location of the domes; and to indicate the new geological outlookwhich such a discovery suggests. Stratigraphy In the southern part of the Rhine graben the Oligocene rests almost directly on the Middle Jurassic and consists, in ascending order, of: 1. Green marls, not salt-bearing, composed of fresh and brackish water deposits. 2. Middle stage, salt-bearing, consisting of lower-schistose marls and upper, variegated marls. 3. Blue marls, not salt-bearing, but including gypsum deposits; hence sediments laid down in a bay more or less connected with the sea.

Jan 1, 1929

By Alden B. Grenninger

The time-honored description of the growth of metal crystals to form polycrystalline aggregates is one in which two important steps are considered: (1) nucleation, and (2) dendritic growth, each dendrite starting from its individual nucleus and resulting (upon slow cooling, assuming no solid phase changes) in a macrograin. This picture of the process of crystallization is incomplete, and it is with the hope of enlarging upon it that the following summary and correlation of experimental results are given. Mosaic Structure For an exact definition of the mosaic structure of metal crystals—if, indeed, one can be found that will hold for all metals—one must await the results of much experimental work in this field. The writer's investigations have been confined almost entirely to copper and a few of its alloys. The following terms are proposed, and will be used in this report: Macromosaic Structure1.—Large-scale mosaic structure; more specifically, mosaic structure of a scale large enough to produce splitting of Laue spots on back-reflection Laue X-ray patterns2. The deviation from exact parallelism of neighboring macromosaics varies from a few minutes to a few degrees3. Just as there are no exact dimension limits for macrograins, so the dimensions of a macromosaic vary considerably. Macromosaic structure may often be seen on copper single crystals if they are examined carefully with critical illumination4. However, back-

Jan 1, 1936

By Francis A. Thomson

But little has been written concerning the camp of Republic. In 1900 Chatard and Whitehead 1 reported the results of some experiments with samples of ore from the Republic mine, and a few years later Fritz Cirkel2 described the construction, operation, and results attained in the mill at the Mountain Lion mine. From time to time brief articles, mostly of a semi-technical nature, have appeared in the Engineering and Mining Journal and other mining periodicals. The general geology of the camp, especially in regard.to its areal features, has recently been ably described by Joseph B. Umpleby.3 To bring to mind the general features of the district it may perhaps be well to review briefly some facts in regard to it, before discussing the treatment of the ore. I. History and Production. The town of Republic is situated in the NW. corner of Ferry county, about 25 miles south of the International Boundary, on the head-waters of the San Poi1 river, in what was formerly the " north-half" of the Colville Indian reservation. On Washington's birthday, 1896, this portion of the reservation was thrown open to mineral location, and within a few weeks important discoveries had been made. The present Eureka mining-district was organized, the camp grew apace, and consignments of ore were shipped by wagon to Grand Forks, 30 miles away; or to Marcus, a somewhat greater distance. It is reported that the first 1,500 tons shipped from the Republic mine uetted the owners $160 per ton, after being hauled

Jan 1, 1913

By R. W. Heckel, R. A. Tanzilli

ANALYTICAL results have previously been presented for the diffusion-controlled solution of a second phase in a finite medium for planar, cylindrical, and spherical geometries.' These results were obtained by numerical methods using digital computer techniques and are applicable not only to the stage of the problem where the unstable phase shrinks to zero size, but also the subsequent stage where the concentration gradients in the matrix phase become negligible (essentially complete homogenization). It is anticipated that the results of such an analysis may be of use to those workers who are interested in the processes

Jan 1, 1970

By Francis P. Sinn

IN the zinc smelting industry the year 1947 seems to have been one of putting one's house in order rather than one of any material technical development or radical change in operating conditions. Labor generally has been in better supply but several plants report a scarcity of skilled workmen. Some plants continue to operate on the basis of a six-day week and will probably continue to do so until labor is more plentiful. Only one plant is known to have operated on a curtailed basis because of labor shortage, but here the difficulty was lack of proper housing facilities. Necessary materials and equipment for much-needed maintenance and modernization have been in short supply so these programs have often been delayed. Laborsaving devices of the "Payloader" type have been more generally used for handling materials. Slab zinc production was discontinued during the last months of the year at Danville, 111. and at Langeloth, Pa. Both of these plants used the Hegeler type of furnaces fired with producer gas. It is understood that the rolling mill and possibly the acid plant at Danville will continue to operate. At Langeloth acid will be produced from

Jan 1, 1948

By R. L. Curfman

In May 1960, six months after conversion of one- half of the Uranium Reduction Co. mill from acid to alkaline leach, severe corrosion was encountered in the 112 stainless steel wash baskets in the resin- in-pulp portion of the uranium circuit. Fortunately the corrosion was limited to the stainless steel screen cloth and bolts. The frames were not affected. Each resin-in-pulp wash basket serves as a container and a vehicle for approximately 40 cu ft of ion-exchange resin. Four baskets are installed in each tank through which uranium-rich solution flows as the baskets move up and down mechanically in the tank. The ion-exchange resin has an affinity for the uranium in the solution which causes it to be deposited on the resin in solid form. By reverse action with different chemical solutions, the uranium may be stripped from the resin for further processing and purifying. This section is the first step in the actual recovery of the uranium.

Jan 9, 1962