The erosion and deformation of polyethylene by solid-particle impact

1987 ◽  
Vol 321 (1558) ◽  
pp. 277-303 ◽  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mass Loss ◽  
Solid Particle ◽  
High Speed ◽  
Particle Impact ◽  
High Speed Photography ◽  
Flux Rate ◽  
Steel Sphere ◽  
Scanning Electron

In recent years, polyethylene (PE) has found increasing use in applications involving impact and erosion. This paper describes a detailed study of the properties of PE subjected to solid particle impact. Flat discs of the material were eroded by sieved sand (300-600 pm) accelerated by using an air blast rig in which the important variables of velocity, angle and mass flux rate are accurately controllable and measurable. Scanning electron microscopy of lightly eroded specimens enabled four basic crater types to be identified: smooth, ploughed, cut, and dented. The proportions of each were established over a range of angles. Long time erosion experiments were conducted in which the flux rate for each angle was adjusted to keep the number of impacts per unit time constant. The dimensionless erosion parameter, e (mass lost per unit mass of erodent that has struck) was computed by using the rate of mass loss when steady-state erosion had been established. Most erosion was found to occur at an angle of 20—30°, the mass loss becoming zero at around 80°. An analysis by D. R. Andrews is presented, showing that the flux rates used in these experiments are well below those needed to cause wear by thermal mechanisms, and this was confirmed by changing the flux rate: mass loss increased in proportion. Macroscopic particles were used to model sand grain impacts, spheres for rounded particles and square plates for sharp ones. A range of techniques was used in this study including high-speed photography (framing speed of 5 x 10 4 s -1 ), scanning electron microscopy, and moire methods (both in-plane and out-of-plane). A deformation map was constructed for steel sphere im pacts giving the type of crater to be expected at a given angle and speed. It was observed that sand grains required much lower speeds at a given angle to produce a given crater type. High-speed photography enabled mass-loss mechanisms for single-particle impact to be identified. These were the drawing-out of filaments and the machining-out of chips. Quantitative data on kinetic energy losses were obtained, and these, combined with moire methods that gave the sizes of deformed zones, enabled an estimate of the temperature rise per impact to be made (25 K).

scholarly journals Effects of Jet Path on Electrospun Polystyrene Fibers

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 842 ◽  
Author(s):  
Yuansheng Zheng ◽  
Na Meng ◽  
Binjie Xin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Surface Morphology ◽  
High Speed ◽  
Solution Concentration ◽  
Electrospinning Process ◽  
High Speed Photography ◽  
Fiber Mats ◽  
Jet Length ◽  
Scanning Electron

In this study we investigated the effects of jet path on the morphology and mat size of synthetic polystyrene (PS) fibers during the electrospinning process. In addition, the mechanism of the fiber mats, which were prepared by varying the solution concentration, was evaluated. The straight jet length, envelope cone and whipping frequency of each electrospun jet were studied using images captured by a high-speed photography camera. The results showed that higher solution concentrations led to longer straight jet lengths, smaller envelope cones and lower whipping frequencies. The diameter and surface morphology of the PS fibers were also characterized by scanning electron microscopy (SEM). It was found that fibers spun with higher solution concentrations exhibited larger diameters and diameter distributions because of their jet path features. Furthermore, the electrospun jets with higher concentrations increased elongation and produced smaller fiber mats and higher breaking forces as a result of their different jet paths, which was a consequence of varying the solution concentration.

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

Spin-polarized Scanning Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 768-769
Author(s):  
Kazuyuki Koike ◽  
Hideo Matsuyama
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Speed ◽  
Magnetic Thin Films ◽  
Electron Spin Polarization ◽  
Acquisition Time ◽  
Magnetization Direction ◽  
Spin Polarized ◽  
Conventional Methods ◽  
Scanning Electron

Spin-polarized scanning electron microscopy (spin SEM), where the secondary electron spin polarization is used as the image signal, is a novel technique for magnetic domain observation. Since its first development by Koike and Hayakawa in 1984, several laboratories have extensively studied this technique and have greatly improved its capability for data extraction and its range of applications. This paper reviews the progress over the last few years.Almost all the high expectations initially held for spin SEM have been realized. A spatial resolution of several hundreds angstroms has been attained, which is nearly one order of magnitude higher than that of conventional methods for thick samples. Quantitative analysis of magnetization direction has been performed more easily than with conventional methods. Domain observation of the surface of three-dimensional samples has been confirmed to be possible. One of the drawbacks, a long image acquisition time, has been eased by combining highspeed image-signal processing with high speed scanning, although at the cost of image quality. By using spin SEM, the magnetic structure of a 180 degrees surface Neel wall, magnetic thin films, multilayered films, magnetic discs, etc., have been investigated.

The Fracture Failure Analysis of Precision Centrifuge Spindle

2014 ◽  
Vol 971-973 ◽  
pp. 802-805
Author(s):  
Wei Feng Zhang ◽  
Li Yan ◽  
Fu Xia Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Composition ◽  
Fracture Mechanics ◽  
Failure Analysis ◽  
Fatigue Failure ◽  
High Speed ◽  
Experimental Results ◽  
Fracture Failure ◽  
Scanning Electron

For the problem of high-speed rotating centrifuge spindle fracture failures, relevant analyses are conducted from the perspective of microstructure, chemical composition and fracture mechanics by using scanning electron microscopy and related instruments. Experimental results and analyses indicate that the spindle fracture is fatigue failure, mainly caused by cold cracks generated on the journal surfacing. Based on the analysis results, improvements and measures are suggested to better solve the spindle weld fracture failure problems.

scholarly journals The Bright Future of Digital Imaging in Scanning Electron Microscopy

1994 ◽  
Vol 2 (4) ◽  
pp. 19-20 ◽  
Author(s):  
M.T. Postek ◽  
A.E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 X 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 X 4096 resolution or greater.

Preparation of Molybdenum High Speed Tool Steels with Addition of Niobium Carbide by Powder Metallurgy Techniques

2014 ◽  
Vol 802 ◽  
pp. 102-107 ◽  
Author(s):  
Oscar Olimpio de Araújo Filho ◽  
Rodrigo Tecchio Antonello ◽  
Cezar Henrique Gonzalez ◽  
Severino Leopoldino Urtiga Filho ◽  
Francisco Ambrozio Filho
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Powder Metallurgy ◽  
Liquid Phase ◽  
High Speed ◽  
Niobium Carbide ◽  
High Energy ◽  
Tool Steels ◽  
Vacuum Sintering ◽  
Scanning Electron

High speed steels processed by Powder Metallurgy (PM) techniques present better mechanical properties when compared with similar steels obtained by the conventional process of cast to ingot and hot working. PM techniques produce improved microstructures with smaller and better distribution of carbides. Liquid phase sintering high speed steel seems to be a cheaper processing route in the manufacturing of tool steels if compared to the well-known and expansive hot isostatic pressing high speed steels. The introduction of niobium as alloying element began with the object of replacing elements like vanadium (V) and tungsten (W). Phase liquid sintering consists in a manufacturing technique to process high speed steels by powder metallurgy. The aim of this work of research is to process and obtain AISI M2 and M3:2 with and without the addition of niobium carbide by high energy milling, cold uniaxial compaction and vacuum sintering in the presence of a liquid phase. The powders of the AISI M2 and M3:2 were processed by high energy milling adding a small quantity of niobium carbide (6% in mass), then the powders were characterized by means of X-ray diffraction (XRD) and scanning electron Microscopy (SEM) plus energy dispersion spectroscopy (EDS) in order to evaluate the milling process. The powders of the AISI M2 and M3:2 with the addition of niobium carbide (NbC) were uniaxially cold compacted and then submitted to vacuum sintering. The sintered samples had their microstructure, porosity and carbide distribution observed and evaluated by means of Scanning Electron Microscopy (SEM) and the mechanical property of hardness was investigated by means of Vickers hardness tests. At least five samples of each steel were investigated.

Plastic Deformation and Surface Recrystallization of Cu-4 Mass%Zn Alloy under Instantaneous Extrusion and High Speed Friction

2011 ◽  
Vol 467-469 ◽  
pp. 1280-1284
Author(s):  
Jun Hui Yin ◽  
Jian Zheng ◽  
Chang Zhi Jia ◽  
Ming Hui Ye
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Plastic Deformation ◽  
Surface Layer ◽  
High Speed ◽  
Fibrous Tissue ◽  
Equiaxed Grains ◽  
Rotating Band ◽  
Zn Alloy ◽  
Scanning Electron

As a special hot-work progress, artillery shooting test was put in practice, and rotating band specimen of Cu-4 Mass%Zn alloy was prepared. The mesostructure and microstructure evolution of the alloy under instantaneous extrusion and high speed friction were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Severe plastic deformation (SPD) and dynamic recrystallization phenomena were researched. The analysis results are as follows. At the beginning of SPD, under the instantaneous compression, the surface layer of alloy became fibrous tissue with the phenomena of work-hardening. With the plastic deformation continue, temperature of alloy arising rapidly under the high speed friction. Recrystallization occurs within the outermost part of fibrous tissue due to heating, so subgrains gradually become homogeneous equiaxed grains. In addition, SPD has little effect on the inner tissue, which is full of equiaxed grains still. Between equiaxed grains and fibrous tissue, there are many oblique strip grains which formed by radial extrusion stress , tangential slip stress and axial sliding stress .

scholarly journals Influence of Microbubble on Fine Wolframite Flotation

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1079
Author(s):  
Penggang Wei ◽  
Liuyi Ren ◽  
Yimin Zhang ◽  
Shenxu Bao
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydroxamic Acid ◽  
High Speed ◽  
High Speed Camera ◽  
Single Factor ◽  
Scanning Electron Microscopy Analysis ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Scanning Electron

The recovery of fine wolframite is low when using traditional flotation that does not use a microbubble. In this study, a microbubble was introduced into the fine wolframite flotation system; −20 μm wolframite was used as an experiment sample and octyl hydroxamic acid as the collector. The recovery of microbubble flotation reached 84.07%, which is about 12.04% higher than that of traditional flotation. A single-factor flotation experiment, high-speed camera analysis, and SEM (Scanning Electron Microscopy) analysis were used to study the influence of microbubbles on the flotation of fine wolframite. The results show that fine wolframite will more easily agglomerate under the action of microbubbles. The octyl hydroxamic acid adsorbed on the surface of wolframite treated with microbubbles is denser and more abundant.

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