scholarly journals Failure Analysis of Diode Components of Electronic Relay Packages Via Thorough Microstructural Characterization

2019 ◽  
Vol 4 (3) ◽  
pp. 124-136
Author(s):  
Mrityunjoy Hazra ◽  
Satyapal Singh
Keyword(s):  
Microstructural Characterization ◽  
Electroless Nickel ◽  
Optical Microscope ◽  
Present System ◽  
Weapon System ◽  
Porosity Level ◽  
Eds Analysis ◽  
Electronic Relay ◽  
Thickness Layer

Diode components used in the electronic relay packages of avionics of a weapon system had been found corroded. Two sets of the complete assembly of the damaged diode parts consisting of diode body, plain washer, spring washer and mounting nuts were analysed for finding out the root causes of failures. Detailed metallographic characterization of the failed materials was carried out using optical microscope, scanning electron microscope (SEM), electron dispersive spectroscopy (EDS) analysis within SEM and microhardness study. Inadequate electroless nickel (EN) plating along with significant amount of porosity and presence of MnS type of stringers affected the corrosion resistance of the diode body tremendously for both the sets. Inadequate electroplated Zn layer was observed on spring washer, plain washer and nut, wherein both uniform and pitting corrosion were detected. Important recommendations included: (i) thicker (more than 25 µm) EN coating with as-specified porosity level for diode body, (ii) replacement of electroplated zinc layers with galvanized zinc (of higher thickness) layer on all the fasteners, (iii) precaution in minimizing formation of galvanic couplings observed in the present system, like that between EN-coated diode body and zinc coated fasteners, between mild steel and stainless steel fasteners etc.

scholarly journals Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

2015 ◽  
Vol 60 (2) ◽  
pp. 1331-1334 ◽  
Author(s):  
M.C. Oh ◽  
H. Yeom ◽  
Y. Jeon ◽  
B. Ahn
Keyword(s):  
Fatigue Strength ◽  
Alloy Steel ◽  
Microstructural Evolution ◽  
Fatigue Behavior ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
Heat Treated ◽  
Aisi 4140 ◽  
Ultrasonic Fatigue

Abstract The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

Effect of Post Weld Heat Treatment on Al 5052-SS 316 Explosive Cladding with Copper Interlayer

2018 ◽  
Vol 910 ◽  
pp. 35-40
Author(s):  
Eswaran Elango ◽  
Somasundaram Saravanan ◽  
Krishnamorthy Raghukandan
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Intermetallic Compounds ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
Post Weld Heat Treatment ◽  
Inclination Angles ◽  
Copper Interlayer ◽  
Weld Heat

This study focuses on effect of post weld heat treatment (PWHT) on interfacial and mechanical properties of Al 5052-SS 316 explosive clad with copper interlayer at varied loading ratios and inclination angles. The use of interlayer is proposed for the control of additional kinetic energy dissipation and to alleviate the formation of intermetallic compounds at the interface. The Al-Steel clads are subjected to PWHT at varied temperatures (300°C-450°C) for 30 minutes and the results are presented. The microstructural characterization of as-clad and PWHT samples is observed by an optical microscope and Scanning Electron Microscope (SEM). Maximum hardness is obtained at the interface of the as-clad and PWHT samples. Increase in PWHT temperature enhances the tensile strength of the composite, whereas, the tensile strength decreases at 300°C due to the diffusion of Al and Cu elements and the formation of detrimental intermetallic compounds.

Effect of stitch and biaxial yarn types on the impact properties of biaxial weft knitted textile composites

2013 ◽  
Vol 20 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Ozgur Demircan ◽  
Tatsuya Kosui ◽  
Shinsuke Ashibe ◽  
Yohji Hamada ◽  
Asami Nakai
Keyword(s):  
Microstructural Characterization ◽  
Optical Microscope ◽  
Textile Composites ◽  
Composite Panel ◽  
Weft Yarn ◽  
Plate Bending ◽  
Impact Properties ◽  
Three Point Bending ◽  
The Impact

AbstractWithin the scope of experiments, the effects of stitch yarn type, such as aramid, glass, and nylon, and biaxial, warp, and weft yarn type, such as aramid and glass, on biaxial weft knitted (BWK) composites were investigated. Five different types of composite panel, which include fiber contents, such as glass-glass-glass, glass-glass-nylon, glass-glass-aramid, aramid-glass-aramid, and aramid-aramid-aramid, were fabricated by hand lay-up method. After the production of composite panels, three-point bending impact and plate bending impact tests were conducted on the specimens. Microstructural characterization of the impact-tested materials was performed using an optical microscope. This study shows that composites with BWK preforms consisting of fiber combinations such as glass-glass-aramid had higher plate bending impact and three-point bending impact properties than the other four types of composite structure.

Impurity-controlled contrast in secondary-electron images of reaction-bonded silicon carbide

1990 ◽  
Vol 48 (4) ◽  
pp. 888-889
Author(s):  
R.A. Youngman
Keyword(s):  
Secondary Electron ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
The Past ◽  
Contrast Mechanism ◽  
Backscattered Electron ◽  
In Situ Formation ◽  
Secondary Ion

Reaction-bonded SiC is formed by the high temperature (>2100°C) heat treatment of a mixture of alpha-SiC powder and organic binders in the presence of elemental Si. The bonding occurs by the in-situ formation of beta-SiC from the reaction of the pyrolyzed binder and the Si. Substantial microstructural characterization of these materials has been carried out in the past. A particular feature of these analyses is the so-called trace-impurity-controlled contrast of secondary electron (SE) images of uncoated specimens. This report describes further attempts to elucidate the origin of this contrast mechanism.Samples of reaction-bonded SiC (Hexoloy KT, The Carborundum Co.) were prepared for multiple-technique analysis. This was accomplished by preparing an optical thin section for reflected and transmitted optical microscopy. Regions of interest were diamond-scribed on the optical microscope (Leitz, Orthoplan) and then SE and backscattered electron (BE) microscopy (CamScan, Series IV) of the same areas (both coated and uncoated with evaporated carbon) was conducted. Finally, the same areas were imaged in a secondary ion mass spectrometer (SIMS) (Cameca, IMS3F) to detect trace and major impurity levels.

scholarly journals Advanced microstructural characterization of four East Antarctic firn/ice cores

2011 ◽  
Vol 57 (205) ◽  
pp. 796-810 ◽  
Author(s):  
N.E. Spaulding ◽  
D.A. Meese ◽  
I. Baker
Keyword(s):  
Subgrain Boundary ◽  
Accumulation Rate ◽  
Chemical Characterization ◽  
Ice Cores ◽  
Internal Surface ◽  
Microstructural Characterization ◽  
Eds Analysis ◽  
Ice Sheet Modeling ◽  
The Relationship

AbstractThe microstructures and microchemistry of four US International Trans-Antarctic Scientific Expedition ice cores were examined, at three depths (30, 60, 90 m) each, using scanning electron microscopy, including electron backscattered patterns and energy-dispersive spectroscopy (EDS), in order to assess the relationship between chemical and physical properties. The physical characteristics (grain size, porosity, density, internal surface volume, and crystallographic orientation) at the four sites were inhomogeneous, as expected on the basis of differences in the moisture content of deposited snow and the accumulation rate at their respective locations. Evidence of shallow subgrain boundary formation and trends in internal surface volume, having implications for the study of firn densification and ice-sheet modeling, were also found. Chemical characterization revealed that site-specific variations in particulate concentration and source could accurately be determined using EDS analysis. It was also found that the combination of elements predominant within the sample controls the morphology and microstructural location of the impurities.

scholarly journals Morphological and Mechanical Characterization of Al-4032/SiC/GMP Hybrid Composites

2021 ◽  
Author(s):  
Deepak Kumar ◽  
Pardeep Saini ◽  
Pradeep K. Singh
Keyword(s):  
Hybrid Composite ◽  
Hybrid Composites ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
Reinforcement Particle ◽  
Unreinforced Alloy ◽  
Equal Proportion ◽  
Hybrid Particles ◽  
Composite Samples

Abstract The pattern of metal matrix composites can be enhanced by integrating the concept of hybrid composite to produce newer engineering materials. The morphological and mechanical characteristics of Al-4032/SiC/GMP hybrid composites have been investigated. The aluminium alloy (Al-4032) based hybrid composites have been fabricated through the bottom pouring stir casting set up, by reinforcing the silicon carbide (SiC) and granite marble powder ceramic particles as the reinforcement material at various fraction level i.e. 0, 3, 6, 9 weight% in equal proportion. The reinforcement particle size is up to 54 µm. The microstructural characterization of the hybrid composite samples has been carried out using optical microscope, SEM and XRD. The study reveals that the reinforcement hybrid particles (SiC + GMP) are almost uniformly distributed throughout the matrix phase. The mechanical properties (tensile strength, impact strength and microhardness) of the composite samples have been obtained and found to be better than the unreinforced alloy.

Microstructural characterization of a microwave-sintered silicon nitride based ceramic

1995 ◽  
Vol 10 (6) ◽  
pp. 1387-1396 ◽  
Author(s):  
Kevin P. Plucknett ◽  
David S. Wilkinson
Keyword(s):  
Silicon Nitride ◽  
Heat Dissipation ◽  
Microstructural Characterization ◽  
Grain Structure ◽  
Boundary Phase ◽  
Sintered Ceramic ◽  
Porosity Level ◽  
Glass Viscosity ◽  
Sintered Silicon

The microstructure of a microwave-densified silicon nitride based ceramic has been assessed in the as-sintered, post-sinter hot-isostatically pressed (HIPed) and annealed conditions. The grain size of the as-sintered material, which is a low substitution β′-Sialon, was significantly finer than observed in conventionally processed materials of similar composition. The as-sintered ceramic exhibits a reverse porosity gradient (with the highest porosity level at the surface) due to heat dissipation to the cooler surroundings during microwave processing. This also results in a higher β′ aspect ratio close to the surface arising from an increased glass viscosity (due to heat loss) and compositional change in this region during sintering. HIPing results in removal of all porosity from the sample core; however, a reduced porosity surface layer is retained. Significant β′-Sialon grain growth is also apparent after HIPing. A fine β′ grain structure was retained after annealing, with partial devitrification of the glassy grain boundary phase to β-Y2Si2O7.

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

1991 ◽  
Vol 49 ◽  
pp. 762-763
Author(s):  
M.A. Parker ◽  
K.E. Johnson ◽  
C. Hwang ◽  
A. Bermea
Keyword(s):  
Magnetic Recording ◽  
Electron Probe ◽  
Microstructural Characterization ◽  
Crystallographic Structure ◽  
Recording Media ◽  
Layer By Layer ◽  
Cross Sectional ◽  
New Techniques ◽  
Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

1987 ◽  
Vol 45 ◽  
pp. 326-327
Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Microstructural Characterization ◽  
Almost Everywhere ◽  
Spacer Layer ◽  
Good Contact ◽  
The Relationship ◽  
Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

A correlation of CL emissions from Penrith sandstone with elemental distributions obtained by simultaneous SEM-CL and EDS analysis

1995 ◽  
Vol 53 ◽  
pp. 392-393
Author(s):  
Paul J. Wright
Keyword(s):  
Optical Microscope ◽  
Electron Gun ◽  
High Electron ◽  
Collection System ◽  
Electron Hole ◽  
Depositional Processes ◽  
Eds Analysis ◽  
Distribution Mapping ◽  
Backscattered Electron ◽  
Electron Imaging

Most industrial and academic geologists are familiar with the beautiful red and orange cathodoluminescence colours produced by carbonate minerals in an optical microscope with a cold cathode electron gun attached. The cement stratigraphies interpreted from colour photographs have been widely used to determine the post depositional processes which have modified sedimentary rock textures.However to study quartzose materials high electron densities and kV's are necessary to stimulate sufficient emission. A scanning electron microscope with an optical collection system and monochromator provides an adequate tool and gives the advantage of providing secondary and backscattered electron imaging as well as elemental analysis and distribution mapping via standard EDS/WDS facilities.It has been known that the incorporation of many elements modify the characteristics of the CL emissions from geological materials. They do this by taking up positions between the valence and conduction band thus providing sites to assist in the recombination of electron hole pairs.

Sign in / Sign up

Export Citation Format

Share Document