Control of the compound layer structure in gaseous nitrocarburizing

1992 ◽  
Vol 9 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Lars Sproge ◽  
Jan Slycke
Keyword(s):  
Layer Structure ◽  
Compound Layer

scholarly journals A POSSIBLE MECHANISM FOR THE MORPHOGENESIS OF LAMELLAR SYSTEMS IN PLANT CELLS

1956 ◽  
Vol 2 (5) ◽  
pp. 597-608 ◽  
Author(s):  
A. J. Hodge ◽  
J. D. McLean ◽  
F. V. Mercer
Keyword(s):  
Normal Development ◽  
Layer Structure ◽  
Subsequent Development ◽  
Peripheral Zone ◽  
Compound Layer ◽  
Prolamellar Body ◽  
Membrane Structures ◽  
Prolamellar Bodies ◽  
Precursor Material ◽  
The Individual

A mechanism for the formation of lamellar systems in the plant cell has been proposed as a result of electron microscope observations of young and mature cells of Nitella cristata and the plastids of Zea mays in normal plants, developing plants, and certain mutant types. The results are compatible with the concept that lamellar structures arise by the fusion or coalescence of small vesicular elements, giving rise initially to closed double membrane Structures (cisternae). In the chloroplasts of Zea, the cisternae subsequently undergo structural transformations to give rise to a compound layer structure already described for the individual chloroplast lamellae. During normal development, the minute vesicles in the young chloroplast are aggregated into one or more dense granular bodies (prolamellar bodies) which often appear crystalline. Lamellae grow out from these bodies. In fully etiolated leaves lamellae are absent and the prolamellar bodies become quite large, presumably because of inhibition of the fusion step which appears to require chlorophyll. Lamellae develop rapidly on exposure of the plant to light, and subsequent development closely parallels that seen under normal conditions. The plastids of white and very pale green mutants of Zea similarly lack lamellae and contain only vesicular elements. A specialized peripheral zone immediately below the double limiting membrane in Zea chloroplasts appears to be responsible for the production of vesicles. These may be immediately converted to lamellae under normal conditions, but accumulate to form a prolamellar body if lamellar formation is prevented, as in the case of etiolation and chlorophyll-deficient mutation, or when the rate of lamellar formation is slower than that of the production of precursor material (as appears to be the case in the early stages of normal development).

Fatigue Strength Evaluation for Sn-Zn-Bi Lead-Free Solder Joints

2002 ◽  
Author(s):  
Qiang Yu ◽  
Doseop Kim ◽  
Jaechul Jin ◽  
Yasuhiro Takahashi ◽  
Masaki Shiratori
Keyword(s):  
Fatigue Strength ◽  
Solder Joint ◽  
Solder Joints ◽  
Layer Structure ◽  
Solder Matrix ◽  
High Stress ◽  
Compound Layer ◽  
Intermetallic Compound Layer ◽  
Mechanical Fatigue ◽  
Free Solder

In this paper, the authors have investigated mechanical fatigue strength of Sn-Zn-Bi lead-free solder joints. The use of Sn-Zn-Bi solder is increasing for the advantage of low cost and low melting point. Therefore, it becomes important to ensure the fatigue strength of Sn-Zn-Bi solder joint. However, when the Sn-Zn-Bi solder was used as a solder material, there is serious problem that the fatigue crack is easy to generate at the interface between intermetallic compound layer and the solder matrix, and it makes the fatigue life of solder joint lower. Because the yield strength of Sn-Zn-Bi solder is high, and the difficulty of deformation causes high stress level concentrating at the corner of the interface between solder joint and substrate/package. It seems that the crack become easy to generate at the interface between intermetallic compound layer and solder matrix by this high stress concentration. The authors have found if Sn-Zn-Bi is used with another Pb-free solder material, a kind of composite structure can be built during the reflowing processes. In this study, the mechanical fatigue strength of this kind of Sn-Zn-Bi solder joint was studied. Based upon the results of mechanical shear fatigue test and FEM (Finite Element Method) analysis, it was found that if SnZn-Bi was used as reflow solder with Sn-Ag-Cu ball, the CSP solder joints are as reliable as thc pure Sn-Ag-Cu CSP. This is because Sn-Zn-Bi solder paste and Sn-Ag-Cu solder ball did not melt together completely and formed two-layer structure, and this two-layer structure reduces the stress concentration at the joint corners, and prevents successfully the occurrence of the interface cracks. As a result the fatigue life of Sn-Zn-Bi/Sn-Ag-Cu CSP is equivalent to that of Sn-Ag-Cu joints.

Compound Formation in Pd Metallized Strained Layers of Sige on Si

1991 ◽  
Vol 230 ◽  
Author(s):  
A. Buxbaum ◽  
M. Eizenberg ◽  
A. Raizmann ◽  
F. Schaffler
Keyword(s):  
High Temperature ◽  
Layered Structure ◽  
Ternary Phase ◽  
Annealing Temperature ◽  
Layer Structure ◽  
Strain Relaxation ◽  
Compound Layer ◽  
Compound Formation ◽  
Strained Layers ◽  
Double Layer Structure

AbstractIn this paper we report on the formation of compounds following the interaction of Pd with strained epitaxial layers of Si1−xGex (x=0.18) MBE grown on Si( 100), in the temperature range of 200 to 650°C. Compositional and structural analyses show that the dominant compound formed was an hexagonal ternary phase, Pd2Si1−yGey where the value of y is lower than of x, and varies with the reaction temperature. In addition to the ternary phase, the binary phase PdGe was also detected. The hexagonal compound grew in a textured manner with its c-axis oriented along the [100] direction of the Si1−xGex film. High temperature anneals (T≥550°C) resulted in the formation of a double layered structure, with the silicide/germanide compound layer on the surface, and below it a Ge rich epitaxial Si1−xGex layer. Strain relaxation of the unreacted layer occurred for specimens in which the double layer structure appeared (annealing temperature ≥550°C). A mechanism for the formation of the double layered structure is proposed.

High-temperature interfacial reaction of an Al thin film with single-crystal 6H–SiC

2000 ◽  
Vol 15 (11) ◽  
pp. 2284-2287 ◽  
Author(s):  
Byung-Teak Lee ◽  
Yang-Soo Shin ◽  
Jin Hyeok Kim
Keyword(s):  
Thin Film ◽  
Single Crystal ◽  
Layer Structure ◽  
Compound Layer ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Double Layer Structure ◽  
Transmission Electron ◽  
Al Thin Film

Interfacial reactions between an Al thin film and a single-crystal (001) 6H–SiC substrate were investigated using x-ray diffraction and cross-sectional transmission electron microscopy. Aluminum thin films were prepared by radio-frequency magnetron sputtering method on 6H–SiC substrates at room temperature and then annealed at various temperatures from 500 to 900 °C. A columnar-type polycrystalline Al thin film was formed on a 6H–SiC substrate in the as-deposited sample. No remarkable microstructural change, compared to the as-deposited sample, was observed in the sample annealed at 500 °C for 1 h. However, it was found that the Al layer reacted with the SiC substrate at 700 °C and formed an Al–Si–C ternary compound at the Al/SiC interface. Samples annealed at 900 °C showed a double-layer structure with an Al–Si mixed surface layer and an Al–Si–C compound layer below in contact with the substrate.

Influence of Nitrocarburizing Process Parameters on the Development of Surface Roughness and Layer Formation

2016 ◽  
Vol 674 ◽  
pp. 325-330 ◽  
Author(s):  
Ewald Badisch ◽  
Andreas Trausmuth ◽  
Manel Rodríguez Ripoll ◽  
Alexander Diem ◽  
Wolfgang Kunze ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Layer Structure ◽  
Compound Layer ◽  
Processing Parameters ◽  
Salt Bath ◽  
Layer Formation ◽  
Depth Profiles ◽  
Original Surface ◽  
Modification Procedure ◽  
Hardness Depth

Nitriding of tools and engineering components is a well-established surface modification procedure in many industries to ensure operational efficiency. The focus of this work is laid on understanding the influence of nitriding processing technology on the resulting surface properties which strongly dominate its tribological performance. Therefore, nitriding layers based on salt bath and plasma procedure were realised using 31CrMoV9 substrate. The surface roughness before nitriding was set to a Ra value of ~0.16 μm which corresponds to at technically fine grinded surface. 3D measurements as well as SEM micrographs of the nitrided surfaces were compared to the original surface prior to the nitriding procedure. Additionally, cross-section microscopy and hardness depth profiles were done to describe nitriding layer structure and nitriding hardness depth (NHD). Results show a correlation of nitriding processing parameters with the resulting compound layer formation and nitriding hardening depth (NHD). An increase of surface roughness during nitriding can be correlated with the growth of ɛ-nitrides on top of the surface.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

Generation of 4H and 6H Structures During the Hexagonal-Rhombohedral Transformation in Dy2Co17

1975 ◽  
Vol 33 ◽  
pp. 38-39
Author(s):  
C. W. Allen ◽  
D. L. Kuruzar
Keyword(s):  
Elevated Temperatures ◽  
Layer Structure ◽  
Transition Element ◽  
Temperature Structure ◽  
Allotropic Transformation ◽  
Layer Plane ◽  
Planar Defects ◽  
Topologically Close Packed ◽  
Transformation Mechanisms ◽  
Shear Transformation

The rare earth/transition element intermetallics R2T17 are essentially topologically close packed phases for which layer structure models have already been presented. Many of these compounds are known to undergo allotropic transformation of the type at elevated temperatures. It is not unexpected that shear transformation mechanisms are involved in view of the layering character of the structures. The transformations are evidently quite sluggish, illustrated in furnace cooled Dy2Co17 by the fact that only rarely has the low temperature rhombohedral form been seen. The more usual structures observed so far in furnace cooled alloys include 4H and 6H in Dy2Co17 (Figs. 1 and 2) . In any event it is quite clear that the general microstructure is very complicated as a consequence of the allotropy, illustrated in Fig. 3. Numerous planar defects in the layer plane orientation are evident as are non-layer plane defects inherited from a high temperature structure.

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

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