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By K. P. Stricker, H. Keddeinis, K. Grebe

Recent investigations by Mannesmann Research have shown that disintegration of sinter with widely varying quality levels is subject to a much more complex set of influences than was previously assumed. It was confirmed that disintegration at temperatures between 300° and 600°C (570°and 1,110°F) is triggered by the degradation of hematite. The specific tendency of hematite to disintegrate is, however, not constant: sinters containing the same amount of hematite can show widely differing disintegration tendencies, depending on structural homogeneity, porosity, and gangue quantity. Sinters with heterogeneous structures transmit stress to the hematite phase and this favors disintegration. Another factor is the brittleness of the glassy silicate phase, which can be influenced even by small modifications of minor gangue constituents.

Jan 1, 1984

By J. Szekely, V. Stanek

Steady state heat transfer and fluid flow rates are predicted for the counter-current contacting of gas and solid streams. For a .fixed pressure drop across the bed the convective heat transfer rate is affected by the gas flow rate, which in turn is affected by the temperature distribution in the system. Variations in bed voidage and in particle size were found to change the predicted temperature profiles quite markedly, in particular when the thermal capacities of the gas and solid streams were equal. IN Part I we examined the effect of step and pulse changes in the inlet gas temperature on transients in the flow of gases through fixed packed beds. Here we shall discuss heat flow and fluid flow interactions in the counter-current heat exchange between packed solids and a gas stream. Counter-current heat exchange in packed beds has been extensively studied. In his now classical paper, Furnas' assumed constant property values and developed a simple analytical. expression for the temperature profiles in the gas and in the solid stream. A highly sophisticated analysis of counterflow systems, allowing for transients and interparticle conduction was developed by Amundsen. In preparing a very readable review of this topic Elliott' also presented a number of elegant solutions, including the case involving heat generation. A great deal of work has been done on the application of these concepts to the modelling of the blast furnace. However, in all this previous work the mass flow of the gas was regarded as a quantity independent of the gas-solid heat exchange process. In the following we shall consider counter-current heat exchange between a gas stream and a packed bed of solids, under conditions where the pressure drop across the bed is specified, rather than the mass flow of the gas. FORMULATION Consider a packed bed, extending from y' = 0 to y' = L, in which moving solids and a moving gas are contacted in a counterflow arrangement. Let cold solids, with an initial temperature Tsi and mass flow GA, enter at y' = L, and hot gas with an initial temperature of Tgi and mass flow Gg enter at y' = 0. In contrast to the problems considered in Part I this system has a nontrivial steady state and we shall restrict our attention to the study of the pressure drop flow relationships and the resultant temperature distributions for steady state conditions. Under these conditions the formulation of the problem requires the statement of the following: 1) heat balance on the gas 2) heat balance on the solids 3) the mechanical energy balance equation and in addition the knowledge of the equation of state, and a functional relationship between viscosity and temperature and an expression for the heat transfer coefficient in terms of the other parameters. On neglecting temperature gradients within the solids and for a constant mass flow of the gas, the solution to this problem is well known.'" The expressions for the temperature profiles of the gas and solid streams may be put in the following form: where Tg and T, denote the dimensionless gas and solid temperatures respectively, y is a dimensionless distance, and R is the ratio of the thermal masses. These quantities are defined as follows: For the particular case of equal thermal mass capacities by the gas and the solid, that is R = 1, the Eqs. [1]and[2] simplify to Eqs. (71 and[8], respectively: i.e., the resultant profiles are linear. As for most practical cases , solutions given by Eqs. [7] and [8] will contain only the inlet temperatures as parameters. For a fixed, predetermined value of C;b the above

Jan 1, 1970

By E. L. Claridge, K. S. Lee

Areal sweep efficiency of oil displacement by enhanced-viscosity water exhibiting pseudoplastic behavior was measured in a Hele-Shaw model representing one-quarter of a five-spot pattern. The pseudoplasticity of polymer solutions and the velocity distribution in the five-spot pattern produced a condition under which the mobility ratio between the displacing and the displaced fluid could not be assigned a single value. Instead, the movement of the displacement front is governed by local mobility ratios which are also time dependent. The areal sweep at breakthrough with polymer solutions was poorer than the sweep obtained with Newtonian fluids of comparable viscosity. However, the areal sweep at 1 PV throughput was greatly improved as compared to flood water without polymer. It was also demonstrated that, even after the oil-cut had declined to a low value during a regular waterflood, switching to polymer flood efficiently swept out the oil remaining in the model. INTRODUCTION The behavior of fluid displacements in isotropic porous media for various patterns of injection and production wells has been extensively investigated.1-7 These investigations all concerned Newtonian fluids, i.e., the viscosity of each fluid was constant regardless of flow rate. The generally unfavorable influence on areal sweep efficiency of higher mobility of the displacing fluid as compared to the mobility of the displaced fluid has been established for both miscible and immiscible fluids. The principle was also established that a close correspondence exists between miscible and immiscible flood front behavior,2, 3 although oil recovery in a waterflood at unfavorable mobility ratio may be less than that observed in a miscible displacement at the same mobility ratio. This is true even when oil recovery is expressed on the basis of movable oil. The reason is that oil saturation only slowly achieves its final value behind the water-flood front in accordance with the Buckley-Leverett8 simultaneous flow relations. It is convenient to use miscible displacements for laboratory simulation of waterflood frontal advance since the interfacial tension forces which are negligible in proportion to viscous forces on a reservoir scale9 are thus made nonoperative in the laboratory model. For miscible displacements, the Hele-Shaw type of model adequately represents a porous medium so long as the appropriate scaling rules5-10 are observed in its design and operation. During simulation of waterflood front behavior in the laboratory by using miscible displacements, the behavior of connate water may ordinarily be disregarded since it is usually indistinguishable from flood water in this process. However, when the flood water is deliberately thickened to improve the mobility ratio between water and oil. the effect on the sweep efficiency due to generation of a connate water bank during the process must be considered. In a uniform porous medium, such a bank is generated11 and efficiently displaced by injection of thickened water.l2 The oil originally in-place at the start of the waterflood is then displaced by connate water followed by thickened water. If the flood water must be thickened to obtain a favorable mobility ratio, the mobility of the oil phase is appreciably less than that of the connate water. Hence, the oil phase is inefficiently displaced by the connate water bank, and a considerable proportion of the oil comes in contact with and is displaced by the thickened waterflood front' A recent study 12 of five-spot displacements using miscible Newtonian fluids in which connate water banks of various sizes were simulated shows that, for connate water banks as large as 40 percent of 1 PV, major improvements in sweep efficiency resulted from use of a thickened

Jan 1, 1969

By W. Mckewan, W. M. Fassell

The oxidation rates of copper have been determined at temperatures from 600" to 900°C in oxygen from 14.7 to 400 psi total oxygen pressure. The oxidation rate of copper is unchanged by oxygen pressures within the range studied. The observed data extend Feit-knecht's conclusion concerning the pressure independence of copper from atmospheric pressure to 400 psi. All samples studied in the above-mentioned temperature and pressure range have both Cu2O and CuO present in the oxide film. NUMEROUS papers have been published on the oxidation of copper, some of which have noted the effect of oxygen pressure on the oxidation rate of copper. It must be noted, however, that no data on the oxidation rates of copper at pressure in excess of 1 atm have been reported in the literature. (Le Chatelier¹ reported that a black oxide of silver was formed at 300°C and 15 atm pressure.) This is likewise true for the other metals. This investigation was initiated to obtain experimental oxidation rate constants for pure metals at elevated temperatures and high oxygen pressure. Copper was selected as the first metal since probably more reliable data are available on its oxidation rates and related physical and chemical properties than for any other metal or alloy. As a general summary, the following conclusions appear well established for the oxidation of copper: 1—The oxide coating consists of Cu2O with a superficial coating of CuO providing the ambient oxygen pressure exceeds the equilibrium pressure for the coexistence of Cu2O and CuO.² The following sequence of phases is then Cu/Cu2O/CuO/O2 (gas). The Cu2O consists of large crystals that have no relation to the orientation of the metal crystals, except for a very thin layer adjacent to the metal." The CuO consists of very fine crystals randomly oriented. If the oxygen pressure is below the equilibrium pressure for the coexistence of Cu2O and CuO, the coating consists of Cu,O only. 2—The rate-determining factor in the parabolic oxidation of copper is the diffusion of Cu+ ions through the Cu,O layer.4,6,7 The Cu+ ions are accompanied by electrons to maintain electrical neutrality. The mechanism of the reaction at the Cu2O/CuO interface and the method of growth of the CuO is in some doubt. 3—On copper, there are three reported pressure effects: (a) At pressures below 0.3 mm Hg oxygen pressure, the oxidation rate increases directly with pressure.', ' .Vxygen starvation at the surface may account for this effect. (b) At oxygen pressures from 0.3 to 63 mm, the oxidation rate increases as the 7th root of the oxygen pressure providing the temperature is such that only Cu2O is present in the film. (c) At pressures from above the equilibrium pressure for the coexistence of Cu2O and CuO (varies with temperature) to atmospheric pressure, the oxidation rate is independent of the oxygen pressure.' Equipment In order to determine the oxidation rates of metals in an oxidizing atmosphere at pressures up to 400 psi, the equipment is somewhat different than for low pressure work as is shown in Figs. 1 and 2. A Leeds and Northrup Micromax recording controller (A) is used to control the temperature of the Ni-chrome furnace winding in conjunction with a Micromax electric drive unit. The drive unit adjusts a 20 amp Variac (variable transformer) to control the power input into the Nichrome furnace winding. Due to the "self heating" of the sample by oxidation, frequently encountered in oxidation rate studies, it is essential that the sample temperature be measured independently. This is done by means of a series of six chromel-alumel calibrated thermocouples located spirally around the oxidizing metal sample. Each thermocouple is partially shielded from the direct radiation of the furnace wall by

Jan 1, 1954

By L. W. Holm, A. K. Csaszar

A series of laboratory experiments was conducted in which oil was displaced from a porous medium by water-driven slugs of alcohols or similar solvents. The solvents used were soluble to some degree in both oil and water and covered the range of solubilities from complete solubility in oil to complete solubility in water. Displacement experiments were conducted on 2-and 3%-in. in diameter consolidated cores and 1-and 2-in. in diameter unconsolidated sand packs. The cores and sand packs ranged in length from 1 to 30 ft, and they were saturated with brine and crude or refined oils. The solvents used included ethyl alcohol, isopropyl alcohol (IPA), tertiary butyl alcohol (TBAI, secondary butyl alcohol (SBA), n-amyl alcohol (NAA), methyl ethyl ketone, acetone and others. It was found that all of the oil present in a porous medium could be miscibly displaced by injecting a slug of mutual solvent and driving it with water. The oil-recovery efficiency was dependent upon (1) the relative solubilities of the solvent in oil and water, and (2) the distance traversed by the flood. For complete oil recovery from cores, a smaller amount of a preferentially oil-soluble solvent was required, compared to the amount of preferentially water-soluble solvent needed. The size of the solvent slug required varied inversely with the linear flooding-path length raised to the 0.65 power. Water-driven dual solvent combinations (an oil-soluble solvent slug followed by a water-soluble solvent slug) were found to effect complete oil recovery with less total solvent than any single solvent used. In these dual-solvent displacement experiments, the slug size required varied inversely with length raised to the 0.55 power. Based upon the experimental results, a theory was developed to describe the displacement of oil and water by mutual solvents, and equations are presented to predict the production history in a linear system. These equations take into account the properties of the solvents and the porous medium. INTRODUCTION Oil-recovery processes which utilize displacing fluids that are miscible with the reservoir fluids have been studied extensively in recent years. Because of the poor contact efficiency and high pressure requirements of the LPG-gas displacement process there has been considerable interest in the alcohol-water process, and a number of studies have been made on the recovery of oil through the use of solvents which are mutually soluble in oil and water. An investigation by Sievert, Dew and Conleyl indicated that the use of mutual solvents would be limited because the presence of water in a porous medium would cause a phase break in the leading edge of the displacing solvent. Their study also showed that, in consolidated cores containing. only oil, the displacement of oil by a water-driven mutual-solvent slug of tertiary butyl alcohol (TBA) was affected by the viscosity ratios of the fluids involved. Gatlin and slobod3 concluded that an isopropyl alcohol (IPA) slug acts as a miscible piston, completely displacing both oil and water until the alcohol content of the mixing zone falls below the concentration necessary to maintain miscibility. Their study was conducted on uniform unconsolidated sand packs. They concluded further that IPA could be used effectively to recover oil from a watered-out sand. In a paper by Taber, Gamath and Reed4 relating an investigation on sandstone cores, it was stated that the displacement of oil by mutual solvents, particularly IPA, was not a miscible displacement and that no improvement in efficiency could be expected with increase in flooding-path length. However, their analytical analysis of the displacement mechanism using TBA is, in fact, one which indicates that the displacement is controlled by miscible mixing. They suggested that the lack of improvement in efficiency with flooding - path

By G. C. Wallick, W. R. Foster, J. G. Savins

A comprehensive review of the salient features of the differentiation method of rheological analysis in Poiseuille flow from its inception circa 1928 is presented. Here no initial assumptions regarding the nature of the function relating rheological parameters to observed kinematical and dynamical parameters are required in the data-analysis process. In contrast, the integration method involves interpreting flow properties in terms of a particular ideal model. It is shown that, although both methods represent modes of solution of the same integral equation, being relatively bias-free, the differentiation method offers a more discriminating procedure for rheological analysis. The application to problems involving plane Poiseuille flow is also described. INTRODUCTION In most instances, the approach to the problem of interpreting the rheological properties of various compositions as they are affected by changes in chemical or physical environment, assaying the characteristics of a particular constituent of a suspension, analyzing flow behavior in terms of interactions between components in a system, to cite but a few examples, has been in terms of what Hersey1 terms the integration method. Briefly, it consists of interpreting flow properties in terms of a particular ideal model. The usual practice of the integration method is to choose a model with a minimum number of parameters because, other things being equal, it is desirable to use the simplest model which will describe the behavior of a real material and yet be mathematically tractable for the requirements of data analysis. This expression is then substituted into an equation which relates observed kinematical and dynamical quantities, such as volume flux Q and pressure gradient ], and angular velocity and torque T, in a capillary and concentric cylinder apparatus, respectively. The rheological parameters appear on integrating, in an expression relating the pairs of observable quantities such as those just given. In many instances a particular model provides a good representation of rheological behavior over a reasonable range of compositional and environmental changes. Just as often, however, it is obvious that the interpretation of rheological changes by the integration method is not providing realistic information about changes in flow behavior. A more general method of interpreting rheological data for a given material is to make no initial assumptions regarding the nature of the function relating rheological parameters to observed kinematical and dynamical quantities, e.g., flow rate and pressure drop in capillary flow or angular velocity and torque in a rotational viscometer. This general method Hersey1 terms the differentia-ation method. Instead of integrating, one differentiates the integral equation with respect to one of the limits, i.e., one of the boundary conditions; the resulting expression contains the same observable quantities just given, their derivatives, and the rheological function evaluated at that boundary. By obtaining these derivatives from experimental data, graphically or by a computer routine, they can be substituted into the differential equation and a graphical form of the function derived. THEORY OF THE DIFFERENTIATION METHOD FOR POISEUILLE-TYPE FLOWS In this introductory paper, two flow cases which are important in viscometry are considered (one for the first time) from the differentiation method of analysis, flow in a cylindrical tube and flow between fixed parallel surfaces of infinite extent, the basic integral equations being formulated in a manner analogous to the way they originally appeared in the literature. In addition, the following ideal conditions will be assumed: (1) an absence of anomalous wall effects, (2) isotropic behavior everywhere, and (3) steady laminar flow conditions. Before proceeding it would seem appropriate to preface the analysis of these flow geometries with the comment that the basic philosophy of the differentiation method could be said to stem directly from the efforts of Herzog and weissenberg2 to indicate systematically the various ways of using

By P. K. Weimer

Coinpletely integrated thin-film circuits inco?,porating more than 1000 active and passive elements have been fabricated reproducibly in the laboratory by evaporation of- all components. A 180-stage modified shift register comprising 540 CdSe TFT's, 360 resistovs, and 180 capacitors was deposited upon a glass substrate during one pump-down of the vacuum systeitl. Experimental units have been operated for more than 5000 hr at temperatures uP to 85°C without failure of any slages. The present pupper reviews the charvactevistics of evaporated thin-film transistors (TFT's) and discusses their application to integrnted circuils. INTEGRATED circuits most widely used today are based upon silicon technology, with the circuits formed on the surface of a block of single-crystal silicon1 or on a block of sapphire 2,3 upon which a thin layer of silicon has been deposited. Transistor patterns and interconnections are defined by photographic procedures using photoresist masking. Large groups of transistors are produced in batches which undergo many processing steps, some of which are carried out at elevated temperatures. Passive elements are formed by treatment of the semiconductor surface or are deposited by evaporation alongside the active elements. The size and complexity of the circuits are limited by defects in the devices and by the size of the available single-crystal chips. Capacitative coupling to the semiconducting substrate may also limit useful size and frequency response of the circuits. An alternative approach to integrated circuits is based upon the deposition by evaporation of all circuit components upon a noncrystalline, insulating substrate such as glass.4 Thin-film field-effect transistors,1'6 known as TFT's, can be deposited in large arrays on glass or plastic substrates at the same time the associated passive elements are being deposited. Although still in the research stage the all-evaporated approach is expected to offer certain advantages for many applications. In particular, the use of thin films upon a noncrystalline substrate offers the prospect of producing complex, large-area circuits not now feasible with single-crystal silicon. Important applications of this type include memory arrays for computers and imaging devices for television. The ease with which the evaporated TFT's can be deposited may permit continuous, automated production methods not possible with high-temperature batch processing. Recent advances7'8 in the fabrication of thin-film transistors have led to greatly improved reproduci-bility and life of the TFT's. Experimental circuits having over 1000 active and passive elements deposited upon a common glass substrate are currently being produced in the laboratory. The present paper reviews recent progress in the development of the TFT and in its application to integrated circuits. I) DESCRIPTION OF THE THIN-FILM FIELD-EFFECT TRANSISTOR The TFT is a field-effect transistor of the type having the control gate separated from the semiconductor by a thin insulating spacer. Although its operation resembles that of the silicon MOS transistorg its construction is based entirely on thin-film techniques. Fig. 1 shows a cross-sectional view of an evaporated TFT deposited upon a glass substrate compared with a silicon MOS transistor deposited upon single-crystal sapphire.3 The semiconductor in the TFT is a poly crystal line layer, of a material which can be readily evaporated, such as cadmium sulfide, cadmium selenide,l0 or tellurium." Silicon monoxide layers have usually served as the gate insulator, but other oxides, sulfides, and fluorides may be used. Film thicknesses range from a few hundred to a few thousand angstroms. The source, drain, and gate electrodes in the TFT are of metal. Qpical source-drain gap dimensions are 0.0003 x 0.030 in., with a gate strip whose width slightly overlaps the source and drain. The source and drain electrodes should make low impedance contacts to the semiconductor. With cadmium sulfide films, gold is a satisfactory material for underlying electrodes, while aluminum is preferable for overlying electrodes.12 Considerable variation in design of the TFT is permissible, with the electrodes being

Jan 1, 1967

By B. L. Averbach, M. Cohen, C. H. Shih

The isothermal formation of martensite is studied in Fe-Ni-Mn and Fe-Mn-C alloys under conditions where the athermal transformation is completely avoided, there being no martensite present at the beginning of the isothermal reaction. The initial rate of martensite formation is extremely low under these conditions, but it increases greatly as soon as some martensite is formed. It appears that true initial characteristics of the isothermal reaction can be studied only in samples wherein the formation of martensite on cooling is completely eliminated. THE phenomenon of isothermal martensite formation is well established1 -" but the observations have been made in the presence of varying quantities of athermal martensite. Complete avoidance of athermal martensite and the formation of martensite under pure isothermal conditions have been reported by Kurdjumov and Maksimova2 in an Fe-Ni-Mn alloy (23 pct Ni, 3.4 pct Mn, and the balance Fe) and have been confirmed by recent experiments of Cech and Hollomon in a similar alloy. In each case, the isothermal transformation rate was a maximum at the beginning of the transformation and decreased as the reaction proceeded. These initial transformation rates were used by Fisher7 for the confirmation of calculated nucleation rates based on classical nucleation theory extended to include the effect of elastic strain energy. Cech and Hollomon have admitted, however, that up to 3 pct martensite formed on cooling in their samples and thus was present at the initiation of their isothermal runs. In this paper, experiments on similar alloys are described, except that care was taken to remove the incidental martensite developed at the surface prior to the isothermal reaction. It is shown here that the reaction rate at the beginning of the strictly isothermal reaction is very low. As soon as some detectable amount of martensite is produced, the transformation rate increases rapidly but ultimately decreases as the reaction proceeds. When martensite is allowed to form isothermally in the presence of about 2 pct of prior martensite, the apparent initial reaction rate is a maximum and corresponds to the observations of Kurdjumov and Maksimova and Cech and Hollomon. It is evident that the cooperative nature of the martensitic reaction results in a significant stimulating or autocatalytic effect on the isothermal reaction rate. Experimental Procedure The chemical compositions of the alloys used in this investigation are listed in Table I. The Fe-Ni-Mn alloys A and B were melted in an induction furnace, cast into ingots 2 in. diam by 4 in. long, and forged into % in. diam rods. The manganese steel (alloy C) was melted in an arc furnace and cast into ceramic molds 1/4 in. diam by 5 in. long. The rods were sealed in evacuated Vycor tubes and homogenized at 1175" to 1200°C for 50 hr. The long homogenization resulted in some manganese loss from the surface, producing a thin layer of transformed material. This surface layer was removed by grinding and the specimens were then swaged to 0.050 in. diam wire. Measurements of electrical resistance were made with a Kelvin double bridge to follow the course of the martensitic transformation. A small permanent magnet was also useful in scanning an entire specimen for small localized quantities of martensite. This test is almost as sensitive as the electrical resistance method in detecting the presence of martensite (which is ferromagnetic in these alloys) and it was especially useful in deciding whether a specimen was completely free of martensite. The wire specimens (0.050 in. diam by 2.5 in. long) were sealed in evacuated tubes and austenitized for 5 min at 1150°C. The specimens were quenched into water and, unless otherwise stated, stress-relieved for 1 hr at 650 °C in order to induce greater uniformity in the subsequent martensitic transformation. As dem-

Jan 1, 1956

By D. H. Shaffer, W. F. Harris, W. M. Hickam, M. H. Loeffler

Experiments have been performed on the quantitative addition to niobium of enriched isotopes 018 and 017 at the 0.1 - 40 micro-gram level and their subsequent recovery. A measured quantity of molecular oxygen of known isotopic concentration is added to niobium metal by oxidation. Recovery of the enriched isotopes as carbon monoxide is by the vacuum fusion technique. Quantitative determinations of the enriched isotopes are made in standard volumes at constant temperature using accurately calibrated micromanometers and the mass spectrometer as pressure measuring instruments. THE presence of low concentrations of nonmetallic impurities in metals can often adversely affect the physical properties of the metal. The increase in hardness and the embrittlement of refractory metals due to oxygen is well known. In metallurgical studies dealing with the diffusion rates or the effect of oxygen on the physical properties of refractory metals, it is often necessary to add small quantities of oxygen to the metal and later recover the total quantity present. It is desirable, therefore, to establish the accuracy with which microgram quantities of oxygen can be added to niobium and recovered by vacuum fusion. The successful addition of microgram quantities of oxygen to metals by the usual manometric techniques and the subsequent recovery by vacuum fusion is difficult because of the uncertainty in the accurate determination of the quantity of oxygen originally present in the metal and because of the chance of contamination by atmospheric oxygen. In order to minimize these uncertainties earlier workers have added quantities of O16 at levels much higher than the oxygen concentrations that are of interest.'-3 In order to eliminate the uncertainty associated with the O16 additions to metals at low microgram levels, experiments have been performed on the quantitative addition of oxygen highly enriched in O17 and O18 at the 0.1 to 40 pg level to niobium and the subsequent quantitative recovery of the isotopes by vacuum fusion. Since the natural abundance of O17 is 0.04 pct and of 0" is 0.2 pct this enriched oxygen provides a uniqueness from interference not achieved in earlier work.'-= A measured quantity of molecular oxygen of known isotopic concentration is diffused into the metal. Recovery of the isotopes in the form of carbon monoxide is by vacuum fusion. The total quantity of gas is determined in standard volumes at constant tempera- ture using accurately calibrated Consolidated Electrodynamics micromanometers and the mass spectrometer for pressure measurements. The molecular and isotopic composition is determined mass spectrometrically. APPARATUS A schematic of the oxygen addition apparatus is shown in Fig. 1. Take-offs are provided for the attachment of the isotope container and for sample bulbs which are used to transfer samples to the mass spectrometer. Metal valves are used throughout the system including the sample bulbs in order to achieve a vacuum of 10"6 mm Hg. Evacuation is accomplished with a 3-stage oil-diffusion pump backed by a mechanical pump. A liquid nitrogen trap is used to remove condensables and to prevent oil vapor from entering the system. A micromano-meter is used for pressure measurements. The furnace assembly is shown in Fig. 2. It consists of a quartz tube joined to the apparatus through a 40/W joint with Apiezon W low-pressure wax. The furnace cap, also a 40/W pyrex joint, is provided with a pyrex hook. The sample is suspended from this hook with a platinum wire. The total volume of the furnace section is 435 ml. All volumes were determined by expanding a known volume of gas at a known pressure into the evacuated system and re-measuring the pressure. Both the micromanometer used on the oxygen addition system and the micromanometer used on the mass spectrometer were compared to a precision

Jan 1, 1961

By Oren C. Baptist, Eliot J. White

Samples of four reservoir sands having different degrees of water sensitivity were subjected to several laboratory tests to determine differences in capillary behavior attributable to clay-mineral effects. The degree of water sensitivity was estimated by the difference between gas and water permeability. Unsaturated pore volumes determined with mercury injection were comparable to irreducible water saturations determined with the semipermeable bar-rier method only for the non-sensitive sands that contained small amounts of non-swelling clay minerals. Irreducible saturations were independent of salinity of the water, which suggests that most residual water is adsorbed 0.7 a film over solid surfaces and that internal retention by clay minerals is relatively insignificant. The water-sensitive sands imbibed water to higher saturations than did non-sensitive sands, and this result is believed to be a combination of the effects of clay minerals and preferential wettability; however, the relative importance of each of these effects is riot determinable. Thus it is concluded that the semipermeable barrier method is the best of the laborafory methods used for estimating formntion water .saturations in the sands studied. INTRODUCTION This investigation is a continuation of studies of the role of clay minerals in petroleum production in the Rocky Mountain area. Previous work has shown large differences in gas and water permeability in numerous reservoir sands; these water-sensitivity effects observed in the laboratory have been correlated with well behavior in the field, and the degree of water sensitivity imparted to reservoirs by the various clay minerals has been determined.'.' The effect of interstitial clay minerals on formation water3 saturations is not so well known. It has been reported that formation water saturations probably are higher in clayey than clean sands,' but this effect has not been evaluated in the laboratory, and the relative effect of the various types of clay minerals on formation water saturation has not been determined. The clay-mineral groups of most importance to this study and to petroleum production in general are kaolinite, illite, and montmorillonite. The minute layers of montmorillonite are loosely bound to one another so that water enters between them, causing great expansion of the particles. Kaolinite and illite do not exhibit interlayer hydration, but they do immobilize considerable amounts of water owing to their large surface areas, which are of the order of 15 to 97 m2/gm of clay.5 The four Wyoming sands used in this study were selected to represent a wide range of water sensitivities. These sands, with the number of wells and fields from which the samples were obtained, are: Second Frontier, five wells in two fields; Newcastle, six wells in one field; Tensleep, two wells in two fields; and Lower Muddy, five wells in one field. EXPERIMENTAL METHODS AND PROCEDURES Water-displacement data were obtained by the semipermeable barrier method," using both fresh water and brines having either 16,500 ppm sodium chloride or calcium chloride. A displacement pressure of 35 psi was found to be sufficient to obtain the practical irreducible water or brine saturation (IWS, IBS) in most samples. Mercury-injection data were ob-tained with equipment and pro-cedures similar to those described by Purcell.7 Exceedingly high pressures are required to attain complete mercury saturation by this method; however, since saturations in most samples change very little with large pressure increases above 1,000 psia, the maximum pressure used was 1,400 psia. To facilitate comparison of mercury-injection and water-displacement results, it is convenient to express mercury-injection data in terms of unsaturated pore volume. The abbreviation, (100 - SHg)min, is used to denote the pore volume unsaturated by mercury at 1,400 psia injection pressure. Gas permeabilities, ki, were deter-mined by the method proposed by Klinkenberg.8 Methods of determining types and amounts of clay minerals by X-ray diffraction analyses, as well as methods of determining water permeability, have been described previously.' The imbibition characteristics of

Jan 1, 1958

By W. H. Holman, J. B. Wagstaff

IN spite of considerable interest among blast furnace operators on the question of the penetration of air into the furnace, there is still uncertainty as to how far the blast does, in fact, penetrate. Moreover, it is not always clear just what is meant by the word penetration in this sense. In 1952, Elliott et al.1 showed that at the end of each tuyere of a blast furnace there is more or less of a void. In this region, coke particles are blown around by the force of the air. This explained the well-known observation reported by Sweetser2 hat if a bar is pushed into a furnace through a tuyere it will go easily into the furnace a distance of some

Jan 1, 1958

By W. Chubb

FOR the past several years there has been considerable interest in the development of zirconium and zirconium alloys for application in nuclear reactors. In a portion of the development work being conducted, attention has been given to the development of high-strength zirconium alloys. One of the most outstanding alloys developed in the course of this work is Zr-4 wt pct Sn-1.6 wt pct Mo.' Fabrication and Test Methods Over 50 ingots of zirconium containing either tin and molybdenum or both have been evaluated in the process of selection of an optimum composition. Most of these were prepared as 20-g are-melted buttons; a few were prepared by induction melting. All ingots were prepared by the me of Foote Mineral

Jan 1, 1958

By Donald Cummings

MEASURES appropriate for the control of the silicosis hazard in mining cannot be formulated precisely, but sufficient knowledge1-19 has accumu-lated during the past quarter century to permit the suggestion of useful, though partly empirical, rules for its alleviation. The industrial hygienist today recognizes that the peril incurred by the inhalation of harmful dust is a function of two variable factors-the degree of harmful exposure and the specific susceptibility of the exposed individual to pulmonary injury. Con-trol of the danger arising out of prolonged contact with pernicious air-borne particulate matter is consequently best exercised by influencing both of these recognized variables. Obviously the problem has two broad aspects-one, medical; the other within the province of the engineer.

Jan 1, 1938

By S. J. Noesen, J. R. Hughes

Several four-inch-diameter tungsten ingots were arc melted in vacuum or in hydrogen atmospheres. Melting pressures, melt-off rates, effect of atmospheres, and other pertinent factors were examined. Two of these ingots were extruded at 1650°C. Subsequently, forging and rolling were carried out at lower temperatures. For a 60 per cent area reduction by rolling, a one-hour recrystallization temperature of 1250°C was obtained. This temperature is considerably lower than those reported in previously published work, and can probably be attributed to the extreme purity of the as-cast ingots (N, H, 0 all less than 1 ppm). EVER since W. D. Coolidge, in 1909, described his process for producing tungsten metal of high density and good workability via the powder metallurgy tech-

Jan 1, 1961

By R. S. Archibald

THE Blueberry mine is about 10 miles west of Ishpeming, Marquette County, Michigan. The property consists of about 2000 acres in sets. 3, 4 and 5, T. 47, N.R. 28W. and sets. 32, 33 and 34, T. 48, N.R. 28W., and, excepting one intervening 80-acre tract, contains the iron formation for a length of about 2 1/4 miles. The property is traversed by State Highway M-28 and is served by three railways, the Chicago & Northwestern, the Duluth, South Shore & Atlantic, and the Lake Superior & Ishpeming. The Northwestern transports the ore to a dock at Escanaba; the other railways, to Mar¬quette. Ore for Chicago goes via Escanaba and that for Lower Lake ports, as Detroit, Cleveland, and Buffalo, via Marquette.

Jan 1, 1935

By W. L. Zeigler

THE gravity concentrator of the Hecla Mining Co. was originally constructed in 1888 by the Milwaukee Mining Co., which was operating the Gem of the Mountains mine. It was purchased by the Hecla Mining Co. in 1900, and placed in operation 2 years later. At that time FIG. 1.-HECLA MINING CO. GEM CONCENTRATOR, GEM, IDAHO. the capacity was only about 200 tons a day, but many additions and changes in equipment have been made so that the present capacity is about 800 tons. One of the outstanding improvements made was the substitution of Callow flotation cells for vanners, which occurred in 1915. The recent building of a flotation plant for treating jig tailings, and the construction of a modern surface plant at the mine, following the

Jan 1, 1927

By Frederic Benard

RECOVERY of selenium and tellurium at Copper Cliff by the Ontario Refining Co. has been previously described by the writer.1 During 1935 a new building was erected to house this operation and description of the new plant and process form the subject of this paper. The building, of modern steel and tile construction, covers an area of 5900 sq. ft. with a volume of approximately 165,000 cu. ft. The large monitored center bay is flanked by two smaller outside bays, one of which is devoted to the tellurium section. All equipment, ceilings and upper walls, are treated with aluminum paint, giving good illumination and facilitating good housekeeping, essential from a health standpoint in handling material of this nature.

Jan 1, 1938

By F. H. Willcox

THE CHAIRMAN (HENRY D. HIBBARD, Plainfield, N. J.).-This paper is timely because of the changed conditions due to the great war, but apparently its scope is limited to oxidation process steels. Referring to the four numbered observations on page 199: No. 1 seems to ignore Johnson's discoveries about oxygen in cast iron. No. 2 ignores crucible steel. No. 3 ignores red short steel containing enough gas solvents to make it solid, while No. 4 assumes that a deoxidizer is necessarily a gas decomposer or solvent and vice versa, which it not always is. From these observations it is deduced. that the only hole-forming gas in steel is an oxide of carbon (CO presumably is meant), which is not true.

Jan 4, 1917

WM. A. COWAN, Brooklyn, N. Y. (written discussion*). -This is evidently an excellent continuation of the work described in the article "An Investigation of Fusible Tin Boiler Plugs" by Messrs. Burgess and Merica.1 The present paper gives information of much value in con-nection with the manufacture and inspection of fusible boiler plugs, and the investigation of the cooling curves of tin with various other metals close to the tin side of the diagram is very interesting. These curves corroborate in all cases, except that of antimony, the diagrams given by other investigators. However, only the liquidus curves of the thermal equilibrium diagrams are given, except for copper-tin alloys where one branch only of the solidus (representing the freezing, of the eutectic)

Jan 11, 1919

By Charles R. Wilson, Thomas W. Doe, Jane C. S Long, Howard K. Endo

An approach to treating flow through fractured rocks is presented which involves (1) determining statistical distributions for fracture area, density, orientation, and aperture from field data, (2) computer generation of fracture systems from the statistical distributions, and (3) analysis of the permeability and porosity of the fracture systems. The fracture density and orientation data my come from core logging or mapping. The hydraulically appropriate apertures and areas of the fractures come from transient flow analyses of single fracture well tests. These tests my also yield information on fracture deformability. Analysis of flow through computer generated fracture systems shows that an equivalent porous medium permeability can be defined for some fracture systems if a large number of fractures is taken into account.

Jan 1, 1982