Showing papers on "Texture (crystalline) published in 1976"

Synthesis of Continuous Sic Fibers with High Tensile Strength

Abstract: Continuous Sic fibers with a tensile strength of 350 kg/mm2 and a Young's modulus of 30 tons/mm2 were synthesized from an organometallic polymer. Continuous fibers were first obtained by heat-treating a polycarbosilane polymer which had been synthesized from dimethyldichlorosilane. The fiber, which contains ultrafine-grain crystallites of β-Sic, has no fiber texture measurable by X-ray diffraction and high-voltage electron microscopy.

Composition and Morphology of Hydrated Tricalcium Silicate

Abstract: Hardened C3S paste cured for 1 year at 20°C was examined to confirm the composition and the morphology of hydrated tricalcium silicate. A new technique was used in which the samples for scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were etched in 1% HNO3-alcohol or in glycerol-alcohol (4:6 by volume). After the surface was etched in 1% HNO3-alcohol, SEM clearly showed the difference in texture in the outer and inner C-S-H products. The existence of a zonal texture within the inner C-S-H products was shown, in addition to the unreacted core; particles 0.1 to 0.2 μm in diameter were observed. After free CH extraction with glycerol-alcohol, two new types of C-S-H grains could be identified. One type has a smooth surface, which seems to be produced from C3S grains trapped within the growing CH crystals in the early stage of hydration, the C/S mol ratio for these being >3. The other type is covered with many acicular outer C-S-H gel hydration products and has a C/S mol ratio >3.

Cleavage separations in warm-rolled lowcarbon steels

Abstract: Rolling of low-carbon steels at 650°C produces a crystallographic texture in which both {100} and {111}planes are aligned parallel to the rolling plane. This texture gives rise to cleavage separations on Charpy specimens, which become visible after rolling strains of ER∼0·6. They run parallel to the rolling plane and are associated with the presence of the {100} textural component. A mechanism is proposed for their formation. Their occurrence leads to a rising upper shelf on the Charpy energy-absorbed curve and a lowering of the impact transition temperature to below that of the as-hot-rolled stock.

Apparatus for gauging the texture of a conducting surface

Abstract: A capacitance gauging apparatus is described for monitoring the texture or flatness of a conductive surface. Conductive plate members, resiliently supported on a flexible substrate, provide a probe to measure the texture of a surface to be monitored, the surface itself forming the other plate of a capacitor. The capacitance probe is electrically energized and connected to a monitoring circuit. As the insulated probe rests on the conducting surface, the resulting capacitance changes the frequency of the monitoring circuit. The monitoring circuitry counts the pulses within a period, the number of pulses being proportional to the surface texture, i.e., the higher the number, the coarser the surface texture, and conversely. The period of counting is set such that the surface texture may be displayed directly in microinches or micrometers.

Quantitative determination of preferred orientation by energy-dispersive x-ray diffraction

Abstract: The use of energy-dispersive X-ray diffraction for quantitative determination of preferred orientations in polycrystalline specimens is analysed. The method is applied to determinations of rolling texture and fibre texture. The adaptability of the method to in situ studies is demonstrated by observations of texture changes simultaneous with the deformation of a specimen in a tension test.

Growth Texture of Polycrystalline Silicon Prepared by Chemical Vapor Deposition

Abstract: The crystallographic texture of CVD polycrystalline silicon is found to be a very sharp (110) fiber texture, with the (110) direction parallel to the direction of growth, and with no preferred orientation about this axis. The texture does not appear to be influenced by the orientation of the rod from which growth starts. This (110) growth texture has also been found in silicon films grown by similar methods on various substrates. (5 figures)

Texture Dependence of Corrosion of Mild Steel after Cold Rolling

Abstract: The dependence of the corrosion rate of mild steel on the deformation texture produced by cold rolling has been investigated. The individual corrosion rates were determined for surfaces which were either perpendicular to, or parallel to, the rolling plane, and the morphology of the corrosive attack was studied by optical metallography.Corrosion is localised on the transverse faces and uniform on the longitudinal face. The apparent corrosion rate is highest on the short transverse face (where it is localised in the form of grooving) and lowest on the face parallel to the rolling plane. However, the true corrosion rate (per unit true area of exposed surface) is believed to be higher on the longitudinal face. The possible correlation between the corrosion behaviour of the individual faces and the deformation texture as determined by X-ray diffraction is discussed.

Cholesteric Texture and Phase Change Effects

Abstract: This paper describes the more useful ways of using thin layers of cholesteric liquid crystals as display devices. There are two metastable configurations of thin layers of cholesterics, the Grandjean (or planar) texture and the focal conic texture. The transformation between textures by either an electric field or a thermal process forms the basis of the texture change effect. It is also possible by applying an electric field to completely unwind the cholesteric helix to form a pseudo-nematic. This phase change effect has several unusual features which make it attractive for use in displays: the materials can be tailored to operate over a wide range of threshold voltages, the response times are shorter than in the conventional liquid crystal displays, and it is possible to multiplex 100 characters. The dynamics of the phase change are complex, and under certain conditions there are potentially useful hysteresis effects. An important technique for improving the legibility of cholesteric devices is the conversion of the scattering into absorption by using pleochroic dyes. It is possible that the use of dyes in phase change devices will produce displays with equivalent contrast but much higher brightness than twisted nematic devices. All these electrooptic effects are critically compared, where possible also with other liquid crystal devices. The present state of the art and future trends are examined.

Epitaxial growth of al thin films on mica and investigation of film structure

Abstract: The temperature dependence of the structure of the aluminium thin film was studied. Reflection and transmission electron diffraction (RED and TED, respectively) patterns show that the changes of the polar orientation (texture) and the azimuthal orientation (due to epitaxy) arise in the film as the temperature of substrate surface is increased. The simultaneous presence of spot patterns at RED and arc or ring patterns at TED in a certain temperature range is explained by the preferred orientation of the film grains in the azimuthal direction and the nearly perfect orientation in the polar direction. The particular changes of the azimuthal orientation became at the temperature of the largest desorption of water molecules from mica so that we deduce that the presence of water molecules is necessary for the particular degree of the azimuthal orientation at lower temperature. At a higher temperature (≈500°C) of the substrate surface the well-oriented films were prepared with the same diffraction patterns as single crystal with orientation (111)Al// //(001)M and (110)Al//(010)M (double positioning is present in the films).

Texture transformations in optically negative liquid crystals

Abstract: A system for transforming an optically negative liquid crystalline composition from the focal-conic texture state to the Grandjean texture state by means of an applied electrical field which may be a D.C. electrical field or a relatively low frequency A.C. electrical field. Imaging and display systems wherein a member comprising a film of an optically negative liquid crystalline composition is imaged in a desired image configuration by the electrical field induced texture transformation system are also described.

Use of the impulse technique for rapid texture evaluation in commercial tube and plate materials

Abstract: A simple, rapid method for the nondestructive evaluation of texture in metal sheet of arbitrary thickness is presented. The method uses a recently developed technique to generate and receive Rayleigh waves on thick plates or Lamb waves on thin materials. The correlation of Rayleigh wave velocity data with calculated values based on elastic constant measurements and with X-ray pole figures is discussed in detail. The technique is applied to a variety of commercially important materials and geometries by the generation of “ultrasonic pole figures.”

Nucleation of the focal conic texture in lamellar liquid crystals

Abstract: In lamellar liquid crystals, planar layers transform in special cases into curved layers taking the form of Dupin cyclides. In this paper we explain the transformation of the planar texture into the focal conic texture in terms of a buckling of the layers induced by the dilatation stress field existing around the dislocations.

Optical Studies of Electric Field Effects in Nematic Liquid Crystals That Have Some Smectic Ordering

Abstract: A broken Williams Domain or square texture has been observed when low frequency a.c. electric and d.c. magnetic fields are applied to Eastman Dynamic Scattering Mixture II or di-4′,4′-octyloxybenzy...

Plastic Anisotropy of Directionally Solidified Nickel-Base Superalloys with Columnar- Grained and Monocrystal Structures in Conventional and Plane-Strain Compression

Abstract: The plastic anisotropy in transverse compression (i.e., the direction of compression,x-axis is perpendicular to the growth direction,z-axis of the specimen) of a direction-ally-solidified nickel-base superalloy of Hf-modified Mar-M200 composition was studied at 1149°C and 1216°C. The lateral strain ratio d∈zz/d∈yy was found to be in the range of 1.6 to 3.0 and the yield strengths were 5 to 19 pct higher than those of monocrystals yielded along 〈001〉. These data were compared with those predicted from the Hosford-Backofen texture analysis for a model DS structure in which all the columnar grains are parallel to 〈001〉 and randomly rotated about this direction. It was shown that the relatively low plastic anisotropy observed experimentally can be explained, by means of the texture analysis, in terms of the scattering in the growth directions of the columnar grains and the nonrandom rotations of the grains about these directions. The relative yield strengths of monocrystals in plane-strain compression in which the direction of elongation is parallel to 〈001〉 has been analyzed using Bishop-Hill plasticity analysis which shows that the Taylor factorM is equal to √6, independent of orientation of the compression axis. The theoretical result was experimentally verified with low-carbon Mar-M200 monocrystals tested under plane-strain condition at 1093°C. The experimental results are in good agreement with those of the theoretical analysis.

Domain texture and dielectric constant variations observed along ferroelectric loops of a pure triglycine sulphate crystal

Abstract: The modification of domain texture in triglycine sulphate (TGS) is observed during different ferroelectric loops. Nucleation and domain wall motions are easily observed and they generally involve a small number of domains except at high frequencies. The dielectric constant shows important variations along the loop from e = 28 to e = 55 at room temperature and at low frequency (0.005 Hz). The smallest value corresponds to one single domain and a high dc field (2.8 MV/m), the highest one to a polydomain crystal. At higher frequencies the number of domains and the maximum of the dielectric constant are much higher (i.e. e = 260 at 1600 Hz).

Effect of Freezing Process on the Texture of Vegetables

Abstract: 比較的大型の冷凍ニンジン供試片に適したテクスチャー測定法として,インストロン型引張圧縮試験機を用いる定速度貫入測定法を検討した。(1) 測定条件として,厚さ10mmの輪切り試料の断面を垂直に保持し,直径4mm,先端半球状の丸棒を10mm/minで,試料の中心まで貫入する方法を設定した。(2) プランジャーの直径が太い場合には貫入曲線の変化が鈍い。また貫入速度が早いときには貫入抵抗はやや大きいが,設定ひずみが不正確になる。(3) 貫入曲線は横断面上の各組織の位置とよく一致し,ニンジン全体のテクスチャーが測定できる。(4) 加熱処理によってニンジンは著しく軟化し,表面の貫入ひずみが大きく,貫入力は形成層のピークより低下した。凍結解凍後には表面の貫入ひずみはさらに増大し,圧縮破砕の場合と同様に貫入曲線は湾曲した。各処理によるかたさの減少率は圧縮破砕の場合より小さいが,その傾向はほぼ同様であった。

Preferred orientation and elastic anisotropy in sheets of copper–nickel alloys

Abstract: A combination of texture measurements and measurements of the angular variation of the elastic modulus in the plane of the sheet has been used with a range of copper–nickel alloys to derive a description of the preferred orientation in terms of textural components. The deduced distribution of orientations along the orientation distribution tube characteristic of f.c.c. metals is shown to be consistent with a limited texture transition from a “pure-metal” to an “alloy” texture in the copper–nickel system. Die Kombination von Texturmessungen und Messungen der Winkelverteilung der Elastizitatsmoduln in der Schichtebene wurde auf eine Reihe von Kupfer-Nickel-Legie-rungen angewandt, um eine Beschreibung der bevorzugten Orientierung in Abhangigkeit von den Texturkomponenten abzuleiten. Es wird gezeigt, das die abgeleitete Vertei-lung der Orientierungen in Richtung der Orientierungsverteilungskurve, die fur k.f.z.-Metalle charakteristisch ist, konsistent mit einem begrenzten Texturubergang von einer “rein metallischen” zu einer “Legierungs”-Textur im Kupfer–Nickel-System ist.

Effect of Sugars and Sugar-alcohols on the Texture of Pectin Jelly

Abstract: グルコース, フラクトース, シュクロース, サンマルト (マルトース85%, グルコース5～7%, オリゴ糖7～10%) および, ソルピトール, マルピット (マルチトール75%水溶液) キリシトールならびに水あめの8種の糖類と糖アルコール類がペクチンゼリーのテクスチャーに及ぼす影響を検討し, 次のような結果を得, 血清コレステロール低下用食品, 低カロリー食品およびカルシウム給源としてのペクチンぜリーにダイエテイックフードとして大きな期待を持てることを認めた。1. 異なった糖濃度を用いたHMPぜリーでは, 糖の種類によって硬さの最大値が異なり, また, pHの影響も糖の種類と濃度によって異なることを認めた。2. LMPぜリーでは, 一般に糖濃度の増加に従って硬さを増す傾向にあるが, ソルビトールとキシリトールを用いたぜリーは, 濃度を増加しても, 硬さはほとんど変化しなかった。3. 異なった糖類を用いたLMPゼリーの嗜好性に関する官能検査において, 同一甘味度に調製したゼリーでは, 水あめを用いたぜリーのみが有意に好まれないが, その他の塘類には有意差を認めず, 糖アルコール類をペクチソゼリーの糖質源として利用可能なことを認めた。