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Airborne measurements of cloud condensation nuclei (CCN), total particle counts, the size distribution of particles, and the microstructure of warm clouds have been made in the vicinity of a large Kraft pulp and paper mill. The plume of CCN and total particles from the mill is well-defined at distances up to 40 km downwind and the concentrations of these particles reach values which exceed those in the ambient air by a factor of about 4. A large peak in the concentrations of CCN was measured in the plume at a distance downwind of the mill corresponding to a travel time of about 4 hr. The total particle count in the plume peaked after about 2 hr of travel time downwind. The particles in the plume were measured over the size range 0.3 to 8 μm; their concentrations were much higher than in the ambient air, particularly those with diameters

We have investigated the role of polymerization degree on the surface microstructure of insulating paper for power cable by means of the electronmicroscope.When the pulp of _??_ 1, 650_??_445 is beaten to SR 40°, in the case of _??_ 1, 650, the surface is covered with S1 wall layer and internal fibrillation of S2 wall layer is incomplete. In _??_ 1, 270, it is clarified that most part of the S1 wall layer is separated, and fine internal fibrillation parallel to the fiber axis is found. In such a microstructure, the values of the mechanical and electrical properties are found higher.Under the _??_ 1, 000, fiber was partially cut and broken during beating, and then mechanical strength of paper was lowered. Moreover, it appears that the fibrillation of S1 and S2 wall layer is disproportionate. But most of the S2 wall layer is internally less fibrillated, and the microstructure on the surface disordered.

There exist two kinds of methods for pulp refining ; that is, the low consistency refining and the high consistency refining. The low consistency refining method (LCR) has been conventionally used, but it has proved to damages and shortens the fibres. On the other hand, the high consistency refining (HCR) loosens the fibre structure and makes it flexible with a minimum of fibre damages, despite of the fact that HCR method requires more power in order to produce papers of maximum strength. This paper presents comparisons between these two methods from the following points of view. (1) Comparison of paper formation measured by the Bata-Radiograph method. (2) Comparison of the microstructure of the fibre by the scanning electron micrographs. (3) Comparison of dry paper physical properties. Our experiments have demonstrated the following. (1) The scanning electron micrographs of paper produced by each different rifining method show different shapes of fibre : In LCR method the outer layer of the fibre is removed in the lumpy shape, while external fibrillation of the HCR fibre is seen extensively and the fibre surface becomes fuzzy. (2) The paper formation by LCR method becomes poorer with high beaten pulp and the paper formation by HCR method grows better with high beaten pulp on the contrary to our expectation. (3) Uniform refining is a most necessary to obtain paper of good formation.

In the first section of this paper it is pointed out that one and the same metal may cause a great variety of different colours, just as the colour of gold vapour differs from the colour of the light reflected from gold as well as from the colour of the light transmitted by gold leaf. While the ultimate cause of the colour of a metalliferous medium is to be found in the structure of the metal molecule itself, the arrangement of these mole­cules, according to any fixed law, causes them to affect one another’s free periods in a definite manner, and thus gives rise to corresponding optical properties. The object of this paper is to discover, by means of these optical properties, the molecular arrangement (microstructure) of various metal glasses, of colloidal solutions of metal and of metallic films. Expressions giving the refractive index and the absorption coefficient (the optical constants) of a compound medium consisting of metal (1) in small spheres (granular), and (2) in discrete molecules (amorphous), diffused through an isotropic non-dispersive transparent medium (the solvent), are next investigated in terms of the corresponding optical constants of the normal metal.

When strained, with or without subsequent heating, many metals produce twinned markings. It is customary to call the former mechanical twins and the latter annealing twins. According to Dana “ twin crystals are those in which one or more parts regularly arranged are in reverse position with reference to the other part or parts.” This must be held to apply not merely to the external symmetry of crystals which possess plane faces, but also to the internal symmetry of such substances as metals and alloys. which do not possess plane faces. Metallic crystals may result in one of several ways. They are formed, e. g., by solidification from the liquid state, a process which is known as primary crystallisation, and results in the formation of crystallites, or they are produced by rearrangement of the atoms in primary crystals giving rise to what may be termed secondary crystals. This term includes such phenomena as crystal growth, recrystallisation, polymorphic transformation, etc. Primary crystals which have solidified in such a way that they are unstrained do not contain twin crystals. The phenomenon is confined to the various types of secondary crystals just mentioned, and, therefore, appears to be related to what may be called atomic rearrangement. The present paper describes observations made on annealing twins, mainly those of copper and its alloys. It has arisen as a result of what the authors have found and described in another paper, viz., that it has proved impossible to prepare large copper crystals by the method of critical straining and annealing without at the same time producing twin crystals. Experiments . The copper used was commercially pure “ high conductivity ” metal in the form of cold rolled strip. The distorted crystals contained numerous twins which had been produced by repeated annealings and rollings during manufacture. When the strip was heated in an atmosphere of nitrogen at a temperature of 800° C. for six hours, complete recrystallisation occurred with the production of equiaxed crystals. Subsequently the strip was deformed to a very slight extent and again heated at 800° C. for six hours, after which the small equiaxed crystals were completely converted by crystal growth into a few large crystals. Representative microstructures of the strip as received, after crystallisation and crystal growth, are shown in photographs Nos. 1, 2 and 3, at a magnification of 80 diameters. It will be noticed that the crystal size increases markedly under the above treatments, and, in fact, No. 3 represents only a portion of one copper crystal which, however, contains twin crystals oriented in three directions. It will be noticed that all three photographs show the presence of twins. They may either appear light on a dark crystal or dark on a light crystal; they may extend right across a given crystal or over only a part of it. Further, they vary very considerably in thickness. These photographs show that the twinned crystals in copper which are present in the originally cold worked metal are neither removed by recrystallisation nor by subsequent crystal growth, although during the former process all the old crystals are replaced by new ones, and during the latter a large number of crystals are absorbed into a few large ones. Photograph No. 4 represents an area, part of which has undergone recrystallisation (small crystals), and the remainder crystal growth in addition. The multiple twinning shown in the large crystals is very striking.

In the previous papers, the authors investigated the change in residual stress and microstructure in relation to the change in half-value breadth of annealed carbon steel in fatigue process, adopting (310) diffraction line. Based on the results of the experiments, the following conclusions were derived. Slip traces appear as regularly arranged line in the special slip planes of certain crystal grains in the early stage of alternating stressing, and they grow longer and wider with the increase of the number of cycles. In this period, both half-value breadth and compressive residual stress increase rapidly. It was considered that the broadening of half-value breadth comes from the accumlation of dislocations that occurs predominantly on the slip plane {110} by cross slip mechanism. In other words, it may be assumed that the extrusion and intrusion phenomena occur and the fatigue damage proceeds mainly by Cottrell and Hulls mechanism, and this also causes compressive residual stress to generate. In the second stage of fatigue, the half-value breadth increases gradually, while compressive residual stress decreases steeply and thereafter no change cccurs till fracture. Micro-structure shows distinctly that slip bands spread in the limited zone in certain grains. We may assume that micro-cracks initiate in these active slip bands and they promote the development of the visible cracks.However, there are two sorts of ploblems regarding the above investigation made by the authors. The first is that; in order to obtain an experimental proof to support the previous discussion, direct observations of the micro crack, extrusion, intrusion and cross slip phenomena are to be made in fatigue processs for present material. The second is that; according to the extrusion and intrusion mechanism, it is expected that the X-ray diffraction plane dependency of the change in half-value breadth and that of the changes in residual stress are present. In these connections, the authors attempted to investigate the relation between changes in half-value breadth diffracted from several atomic planes (310), (211), (220), (200) and (110), and changes in residual stress obtained from different lines of (310), (211) and (220) atomic planes. Specimens used in these series of experiments are annealed and electro-polished 0.07% carbon steel plate. A reversed bending fatigue testing machine was used for the fatigue test, and the speed of repetitions was 1700 cycles per minute. Residual stress was measured from (310), (211) and (220) diffraction lines, using CoKα1 and CrKα1 radiations, adopting the well known two exposure method at vorious numbers of stress cycles. The CoKα radiation was used to measure the change in half-value breadth of (310), (220), (211), (200) and (110) diffraction lines due to stress repetitions by normal X-ray diffractometer arrangement.Obtained conclusions are as follows;(1) Cross slip traces, extrusion and intrusion phenomena appeared extinctly in the first stage of fatigue stressing in the certain grains, and intensified gradually with increasing number of stress repetitions.(2) Micro cracks initiate in active bands zone, namely, it is observed obviously by electronmicroscope at the bottom of the intrusion slip at the stage of transition point from first stage to second. This micro cracks developed into visible cracks which lead to fracture during the second stage of fatigue.(3) The changes in half-value breadth of (220) and (211) diffraction lines during stress repetitions are quite similar to that of the (310) diffraction line which has been pointed out in previous papers. However, (200) diffraction line width changes greatly and that of (110) is a little in fatigue process.

Few researches have been published on variation of properties of Al-Mg alloy with lapse of time of aging at 50-70°C. Otto Dahl and Klaus Detert recently published a very interesting paper relating to the problem.In this paper, it is found that any marked variation of mechanical and physical properties such as hardness, electrical resistance, lattice constants, etc. could not be seen, when aged at at room temperature or thereabout. As the cause of these phenomena, the contiguity of atomic number of aluminium and magnesium are suggested (13 and 12 respectively).The authors also treated this problem:Alloy specimen were prepared by alloying four nine aluminum with magnesium and mischmetal, the composition of the first series being 2.5, 3.5, 5, 7, 10 and 12% of Mg, and of the second series 5, 7, 10 and 12% Mg with 0.3 and 0.5% of mischmetal. The small specimen of sheets, 1.2mm thick, were solution treated at 400°C, for 2 hours, then quenched in the water (1°C) and then aged at 50, 80 and 100°C for about 3, 000 hours.During aging, hardness, microstructure, electrical resistance and corrosion resistance were intermittently tested. The corrosion resistance was tested by Mylius method; the specimen was immersed in 10% HCl water solution and the amounts of evolved hydrogen were measured.As the results of the study, a marked variation of corrosion resistance was found. When corrosion resistance is represented by “Reaction Number” (RN), or quantity of hydrogen evolved per unit area and per unit time, its variation is shown in Fig. 6 and 7.In other words, RN is smallest at as quenched condition, then rapidly increasses with the lapse of aging time and after passing through the maximum, it decreases on the contrary.Corresponding to the variation of RN the hardness curve has also its inflexion point near the aging time of the maximum RN.These changes probably suggest a formation of some special arrangement of magnesium atoms among aluminium space lattice or of an arrangement similar to Guinier-Preston Zone.

Although the microstructure of carbon black has been under investigation for more than fifty years, there are still many aspects which are controversial and some which are virtually unexplored. The inherently low degree of crystallinity and the finely-divided state of carbon blacks have greatly hindered efforts to understand them. The purpose of this article is to cite the principal contributors to our understanding of carbon black microstructure, to discuss the significance of their contribution, to present a clear picture of the present state of our knowledge, and to note areas where controversy exists and where our knowledge is incomplete. The scope of this article is necessarily limited to a reasonably complete treatment of the several aspects of carbon black microstructure; that is, the arrangement of carbon atoms to form graphite layer planes, the arrangement of layer planes to form crystallites, and the arrangement of crystallites to form the more familiar carbon black “particles” or aggregates. Particular attention is paid to more recent articles and those which have shaped our thinking on carbon black microstructure. This article also includes a fairly complete review of various studies on the changes in microstructure which are brought about by heat treatment or oxidation. In general, the rather large number of studies reporting on the microstructure of other forms of carbon have not been reviewed (except for the work of Franklin whose contribution to our understanding of carbon-black microstructure is so immense that it must be included). Although gross, morphological features such as particle size, primary aggregate size and shape are studied briefly in order to relate them to microstructure, no effort was made to review comprehensively the body of literature pertinent to this subject. Also porosity and surface characteristics per se (as measured by gas adsorption techniques) are not treated in detail here. Rather than review a dreary list of papers which have only the slightest bearing on carbon black, the author has taken the liberty of dividing the articles reviewed into two categories. The first category, which is reviewed in some detail, includes those publications in which an important contribution was made to the understanding of carbon-black microstructure. The second category includes all those articles which are discussed only briefly or not at all because the authors have reported superficial or routine studies or they (probably unknown to them) have essentially duplicated the work of an earlier worker, or have reported uncorrected results which are thus so inaccurate as to be without real value to this article; or because they comprise work which is only peripherally related to carbon black microstructure. Also, references taken from other papers, but not reviewed here, are included in the latter category. Articles by Warren, Hofmann and Wilm, Steward and Cook and Walker contain bibliographies which will be helpful to those interested in the earlier work or in the microstructure of carbons other than carbon black. For the reader whose time is limited, an adequate picture of current understanding of carbon black microstructure can be gained by reading Sections II, IV, and V which are relatively short. Finally, a word about the spirit in which the review was written. At the request of the late Dr. Craig, a critical review was prepared in which every effort was made to point out shortcomings as well as classic contributions contained in the pertinent literature. Where the experts have disagreed, the reviewer, often with skill unequal to the task, has attempted to decide which one was the more correct in the light of current knowledge. It is with deep humility and great respect for those who have gone before that this review is submitted.

Abstract As fractures are propagated through rocks, energy is absorbed near the extending crack tip. Apparent surface energies for several rocks have been measured by cleavage under dynamic conditions. At nominal crack velocities from 0.5 to 500 in./min. measurements showed that fractures propagated in discrete jumps. Calculated surface energies and moduli were relatively insensitive to nominal rate of cleavage. In another set of experiments, rocks were cleaved under high confining stresses. The rocks were submerged in low leak-off fluids which formed a filter cake on the freshly cleaved surfaces (similar to the hydraulic fracturing process). Apparent surface energies were increased substantially as the surrounding fluid pressure was increased. Moduli in bending increased significantly upon application of the first 1,000 psi but were insensitive to stress level at greater pressures. INTRODUCTION For almost 20 years, hydraulic fracturing processes have been utilized effectively to stimulate oil and gas wells. During this period, some process improvements have resulted from studies of fracture orientation, mechanics of fracturing, areas generated, conductivities of cracks, etc. Yet many questions remain concerning the conditions and pressures needed during fracture propagation. In this paper we will report additional studies of the mechanics of fracture extension. It was shown previously3 that large rock samples could be cleaved under controlled conditions so as to measure the apparent surface energy (that amount of energy absorbed per unit area of new surface created). In this paper we consider the effects of two additional factors on surface energies, viz.:effect of cleavage rate andeffect of confining stress level. THEORY Cleavage experiments were conducted on rock samples similar to that illustrated in Fig. 1. Blocks of rock several inches wide, 2- to 3-in. thick, and up to 3 ft in length were grooved longitudinally with shallow guide slots. A crack was initiated and allowed to extend along the web as the top of the rock specimen was pulled (or pushed) apart. Auxiliary equipment permits the measurement offorce applied at the top,separation at the top andcrack length. (Further experimental details will be given in the next section.) The rock beams created by the crack are considered to' be cantilever beams. The deflection (or separation of the rock beams) at any point is calculated4,5 by the beam Eq. 1.

The Research Institute For Iron, Steel and Other Metals. Tohoku University. Effects of the roughness of graphite substrate on the properties of pyrolytic graphite have been examined. Pyrolytic graphite is obtained by pyrolysis of commercial propane gas at the deposition temperature of 2025°C, the pressure of 10mm Hg and the flow rate of 640cc/min by direct heat method. The three kinds of roughness of the substrates are obtained using of abrassive papers (05, 280). The effects are not remarkable as compared with that of the deposition temperature and gas pressure, but can not be ignored. In the case of the smooth surface (abrassive paper 05), the surface of the deposit is smooth and the microstructure is fine, in which the crack does not appear. Furthermore, the formation rate is large, the ordering is good and the preferred orientation is remarkable. But in the case of the rough surface, the above mentioned phenomena tend to appear in the reverse side. Especially, the electrical resistivity of c-axis in the smooth case is about 10per cent higher than that of the rough surface. However, there are inconsiderable difference in the lattice constant and density between the smooth and rough surfaces.

The attempt to apply the potentiostatic method in study of anodic dissolution of copper and its alloys for metallographic purposes is presented. The results of copper and Cu−0.5% Be, Cu−1% Zr, and Cu−0.3% Be−2% Ni alloys examination in 85% phosphoric acid are published in the previous paper [A. Mance, Metallography4, 287–296 (1971)]. It has been found that only Cu−1% Zr alloy has a polarization curve with passivation step. For good polishing of all three alloys, potentials more than −250 mV (SSE) are recommended. This paper gives the results of examination of mentioned three alloys in 50% citric acid. Optimal conditions for revealing microstructure have been determined It has been found that selective anodic dissolution in citric acid occurs in a wide potential range from about −300 mV to +1000 mV.

In a recent paper (McConnell 1965) an account was presented of the mechanism of the polymorphic inversion in KAlSi3O8. This was based on the electron optical study of the microstructure of a natural material, adularia, which showed evidence of partial inversion. The present paper deals with the application of similar techniques to the study of the earliest stages in the processes of exsolution and inversion in a member of the binary series NaAlSi3O8-KAlSi3O8. Single crystal x-ray photographs of this material showed a monoclinic array of Bragg maxima with associated intense streaks of intensity normal to b. Electron diffraction photographs indicated that these strong streaks were aligned close to a and had maximum intensity in the a direction in reciprocal space. Associated intense electron diffraction contrast effects were observed and interpreted in terms of incipient exsolution into fine scale, lenticular regions enriched in sodium or potassium. An additional suite of streaks with much lower in...

In the previous paper (J. Ceram. Assoc. Japan, 68 [10] 223 (1960)) the authors reported that some glasses of low lithium content (4%) in the system Li2O-MgO-Al2O3-SiO2 could be converted, by the heat treatment, into a polycrystalline material without showing any appreciable deformation even if no special nucleating agent, such as platinum, was added. The present paper contains the results of experiments designed to determine the optimum conditions of heat treatment of the glass of this type for producing a polycrystalline material of high mechanical strength.(1) Chemical composition of the glass studied The glasses of the composition, MgO x, Al2O3 y, SiO2 z, Li2O 4, where x+y+z=100 by weight, were melted and formed into a specimen of the size 2.5×5×50mm. They were heated from room temperature to 1200°C with the rate of 5°C/min. and then held there for two hours. Among the polycrystalline materials, the one produced from a glass of the composition of Li2O 4, MgO 15, Al2O323, SiO262 showed the highest modulus of rupture (1, 550kg/cm2).(2) Process of cristallization of the glass during heat treatment Thermal differential and X-ray analysis made with the glass specimen of above composition showed that, during its heat treatment, β-eucryptite was first precipitated at about 850°C and then β-spodumene at about 1000°C (Fig. 9). Microscopic examination showed that β-spodumene, after its precipitation, decreased its grain size by fission, by still unknown reason, with increasing temperature (Fig. 10, b, c, d). Above 1000°C the marked increase in specific density of the specimen with increasing temperature was also observed (Fig. 12).(3) Effects of heat treatments on strength The conditions of heat treatment such as the heating rate and the maximum holding temperature were varied and their effects on the modulus of rupture of the resultant polycrystalline materials were determined. The slow heating with the rate at least below 5°C/min. in the temperature interval of 800 to 900°C, in which β-eucryptite was first precipitated in the specimen, was found to be necessary increasing the strength (Fig. 6). The specimen which missed this heat treatment had poor strength (Fig. 5). The strength was also found to increase with increasing the maximum holding temperature (Fig. 7). This change was attributed to the decrease in grain size of β-spodumene and also to the compacting of microstructure.

This paper is divided into two major sections. The first of these describes the types of defects which may arise in crystalline materials. These may be classified as point, line, sheet and volume defects, examples of the four groups being vacancies, dislocations, grain boundaries and precipitates. The basic defects of crystal structures are first described, particular attention being paid to dislocation lines and the way in which a perfect dislocation may dissociate into two partial dislocations and a ribbon of stacking fault. The motion of defects, including glide, climb and cross-slip is discussed. This section ends with a summary of the ways in which basic defects may interact and combine, and be used to describe such microstructural features as deformation twins and precipitate boundaries. These defects form the basis of the mechanisms, given in the second part of the paper, which have been used to explain the various phenomena of hardening and fracture. No attempt has been made to give detailed theories of these mechanical properties. The treatment is intended for the nonspecialist, interested in obtaining an understanding of how a knowledge of the microstructure of materials may be applied to specific problems.

In this study, various chemical and electrographical methods were tested so that to determine porosity in the coatings on aluminium. Filter paper or desilvered photographic paper was used as the printing medium. Certain sensitive indicating reagent was dissolved in alcohol which contains, as electrolyte, a small quantity of NaCl dissolved in water. When the printing medium was pressed on the surface of a specimen, aluminium was preferentially dissolved. Aluminium ions were transfered through pores in the coating to the printing medium and reacted to form a colored product. It was found that aluminon and eriochromcyanine R were suitable agents for good printing.It was revealed by optical microscopy, that the porosity prints obtained by this method were closely relative to the microstructure of the surfaces. The method was also applied to the determination of porosity in the anodized films. Also was it known by the corrosion test that the corrosion spots found on the specimen printed by the method are relatively in parallel with the printed spots.