A Materials Investigation of Nickel Based Contacts to n-SiC Subjected to Operational Thermal Stresses Characteristic of High Power Switching

ABSTRACTThis study developed and performed Laboratory experiments which mimic the acute cyclic thermal loading characteristic of pulsed power device switching operation. Ni contacts to n-SiC were the device components selected for cyclic thermal testing. Modifications of the contact- SIC materials properties in response to cyclic thermal fatigue were quantitatively assessed via Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM), atomic force microscopy (AFM), surface profilometry, transmission electron microscopy (TEM), nanoindentation testing and current-voltage measurements. Decreases in nanohardness and elastic modulus were observed in response to thermal fatigue. No compositional modifications were observed at the metal-semiconductor interface. Our results demonstrated that the majority of the material changes were initiated after the first thermal pulse and that the effects of subsequent thermal cycling (up to 10 pulses) were negligible. The stability of the metalsemiconductor interface after exposure to repeated pulsed thermal cycling lends support for the utilization of Ni as a contact metallization for pulsed power switching applications.

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The Materials Properties of a Nickel Based Composite Contact to n-Sic for Pulsed Power Switching

MRS Proceedings ◽

10.1557/proc-622-t8.2.1 ◽

2000 ◽

Vol 622 ◽

Cited By ~ 1

Author(s):

M. W. Cole ◽

P. C. Joshi ◽

F. Ren ◽

C. W. Hubbard ◽

M. C. Wood ◽

...

Keyword(s):

Ohmic Contacts ◽

Pulsed Power ◽

Power Switching ◽

Semiconductor Interface ◽

Carbide Phases ◽

Annealing Temperatures ◽

Ohmic Behavior ◽

Reaction Region ◽

Composite Contact ◽

Surface Morphologies

ABSTRACTNovel Ni/WSi/Ti/Pt composite Ohmic contacts to n-SiC were investigated as a function of annealing temperatures up to 1000°C. The onset of Ohmic behavior occurred at annealing temperatures of 900°C. Annealing at temperatures between 950°and 1000°C yielded excellent Ohmic behavior. At these temperatures the contact-SiC interface was smooth, defect free and characterized by a narrow Ni2Si reaction region. The annealed contacts possessed atomically smooth surface morphologies and exhibited minimal contact expansion. The residual carbon, resultant from SiC decomposition, was constrained by reaction with the WSi and Ti metallization layers forming carbide phases of W and Ti. The locations of the carbide phases were spatially distant from the metal semiconductor interface. Our results demonstrate that the Ni/WSi/Ti/Pt composite Ohmic contact maintains the desirable electrical properties associated with Ni contacts and possess excellent interfacial, compositional and surface properties which are required for reliable high power and high temperature device operation.

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An Empirical Relationship to Predict Damages in Carbon Fiber Reinforced Composites under Extreme Thermal Cycling Conditions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.531-532.153 ◽

2012 ◽

Vol 531-532 ◽

pp. 153-158

Author(s):

Fateeha Nisar Siddiqui ◽

Nada Saleh ◽

Ayesha Rahat ◽

Asif Israr ◽

Atiq Ur Rehman

Keyword(s):

Carbon Fiber ◽

Thermal Cycling ◽

Thermal Loading ◽

Thermal Stresses ◽

Fiber Reinforced Composites ◽

Space Environment ◽

Reinforced Composites ◽

Fiber Reinforced ◽

Carbon Fiber Reinforced Composites ◽

Carbon Fiber Reinforced

Carbon Fiber Reinforced Composites are presently used in satellites structure for better performance during extreme thermal cycling space environment. These materials display unexpected failure because the satellite periodically goes into and out of the earth shadow region on orbit, leading to a change in its surface temperature. As the coefficient of thermal expansion of carbon fibers is an order of magnitude lower than that of the polymer matrix, repeated thermal stresses are generated in the composites under the alternative temperature field, resulting in damage to the materials and a decrease in mechanical properties. The main objective of this study is to develop an analytical model to predict the damage produce in the composites subjected to extreme thermal loading. These thermal loading also causes the material to release strain energy. The results are presented in terms of strain produced during thermal cycling and also in the process of delamination.

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Thermal Fatigue of Composites: Ultrasonic and SEM Evaluations

Journal of Engineering Materials and Technology ◽

10.1115/1.2904246 ◽

1994 ◽

Vol 116 (1) ◽

pp. 113-120 ◽

Cited By ~ 13

Author(s):

D. S. Forsyth ◽

S. O. Kasap ◽

I. Wacker ◽

S. Yannacopoulos

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Thermal Cycling ◽

Thermal Fatigue ◽

Ultrasonic Attenuation ◽

Aramid Fibers ◽

Fiber Reinforced Polymer Composites ◽

Ultrasonic Techniques ◽

Primary Damage ◽

Scanning Electron

Results are presented on the evaluation of thermal fatigue in three fiber reinforced polymer composites, using ultrasonic techniques and scanning electron microscopy. The composites examined were (a) continuous carbon fibers in a vinylester matrix (b) continuous aramid fibers in a vinylester matrix and (c) randomly oriented aramid fibers in a polyphenylene matrix. Specimens of these composites were subjected to thermal fatigue by thermal cycling from −25°C to 75°C. Changes in ultrasonic attenuation and velocity were monitored during thermal cycling, and scanning electron microscopy was used to qualitatively evaluate any damage. It was observed that ultrasonic attenuation is sensitive to thermal fatigue, increasing with increasing number of thermal cycles. SEM evaluations showed that the primary damage due to thermal fatigue is due to fiber-matrix debonding.

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The behaviour of aluminium matrix composites under thermal stresses

Science and Engineering of Composite Materials ◽

10.1515/secm-2013-0185 ◽

2016 ◽

Vol 23 (1) ◽

pp. 1-20 ◽

Cited By ~ 11

Author(s):

Khushbu Dash ◽

Suvin Sukumaran ◽

Bankim C. Ray

Keyword(s):

Thermal Conductivity ◽

Thermal Cycling ◽

Thermal Fatigue ◽

Thermal Stresses ◽

Volume Fraction ◽

Coefficient Of Thermal Expansion ◽

Interparticle Spacing ◽

Aluminium Matrix ◽

Matrix Composites ◽

Aluminium Matrix Composites

AbstractThe present review work elaborates the behaviour of aluminium matrix composites (AMCs) under various kinds of thermal stresses. AMCs find a number of applications such as automobile brake systems, cryostats, microprocessor lids, space structures, rocket turbine housing, and fan exit guide vanes in gas turbine engines. These applications require operation at varying temperature conditions ranging from high to cryogenic temperatures. The main objective of this paper was to understand the behaviour of AMCs during thermal cycling, under induced thermal stresses and thermal fatigue. It also focuses on the various thermal properties of AMCs such as thermal conductivity and coefficient of thermal expansion (CTE). CTE mismatch between the reinforcement phase and the aluminium matrix results in the generation of residual thermal stress by virtue of fabrication. These thermal stresses increase with increasing volume fraction of the reinforcement and decrease with increasing interparticle spacing. Thermal cycling enhances plasticity at the interface, resulting in deformation at stresses much lower than their yield stress. Low and stable CTE can be achieved by increasing the volume fraction of the reinforcement. The thermal fatigue resistance of AMC can be increased by increasing the reinforcement volume fraction and decreasing the particle size. The thermal conductivity of AMCs decreases with increase in reinforcement volume fraction and porosity.

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Thermal Fatigue in Teeth

Journal of Dental Research ◽

10.1177/00220345720510023601 ◽

1972 ◽

Vol 51 (2) ◽

pp. 461-467 ◽

Cited By ~ 86

Author(s):

W.S. Brown ◽

H.R. Jacobs ◽

R.E. Thompson

Keyword(s):

Thermal Cycling ◽

Thermal Fatigue ◽

Thermal Stresses ◽

Conclusive Evidence ◽

Temperature Cycling ◽

Thermal Fracture ◽

Thermal Cycles

This paper presents the results of experiments conducted with extracted human and bovine teeth. The teeth were subjected to thermal cycling at temperatures between 140 and 90 F. The results offer conclusive evidence that thermal fracture may be induced by the thermal stresses caused by the temperature cycling. Less than 3,000 thermal cycles cause severe cracking or the propagation of cracks previously existing in the teeth, or both.

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Study of SiC Device for Pulsed Power Switching Circuit

IEEJ Transactions on Fundamentals and Materials ◽

10.1541/ieejfms.139.345 ◽

2019 ◽

Vol 139 (8) ◽

pp. 345-350

Author(s):

Toru Tagawa ◽

Tomohiko Yamashita ◽

Takashi Sakugawa ◽

Sunao Katsuki ◽

Kenzi Hukuda ◽

...

Keyword(s):

Pulsed Power ◽

Switching Circuit ◽

Power Switching

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Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals

MRS Proceedings ◽

10.1557/proc-536-499 ◽

1998 ◽

Vol 536 ◽

Author(s):

V. P. Popov ◽

A. K. Gutakovsky ◽

I. V. Antonova ◽

K. S. Zhuravlev ◽

E. V. Spesivtsev ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Rutherford Backscattering Spectrometry ◽

Nanocrystalline Structure ◽

Structural Defects ◽

High Dose ◽

Silicon Crystals ◽

Strong Energy ◽

Transmission Electron ◽

Hydrogen Implantation

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.

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Concentrator photovoltaic (CPV) modules. Thermal cycling test to differentiate increased thermal fatigue durability

10.3403/30313721 ◽

2017 ◽

Keyword(s):

Thermal Cycling ◽

Thermal Fatigue ◽

Thermal Cycling Test ◽

Cycling Test ◽

Fatigue Durability

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An Experimental and Numerical Methodology to Investigate Crack Growth in a 304L Austenitic Stainless Steel Pipe Under Thermal Fatigue

ASME 2010 Pressure Vessels and Piping Conference: Volume 3 ◽

10.1115/pvp2010-25386 ◽

2010 ◽

Cited By ~ 1

Author(s):

Pauline Bouin ◽

Antoine Fissolo ◽

Ce´dric Gourdin

Keyword(s):

Finite Element ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Crack Growth ◽

Thermal Fatigue ◽

Thermal Loading ◽

Steel Pipe ◽

Design Stage ◽

Inner Surface ◽

Stainless Steel Pipe

This paper covers work carried out by the French Atomic Energy Commission (CEA) to investigate on mechanisms leading to cracking of piping as a result of thermal loading existing in flow mixing zones. The main purpose of this work is to analyse, with a new experiment and its numerical interpretation, and to understand the mechanism of propagation of cracks in such components. To address this issue, a new specimen has been developed on the basis of the Fat3D experiment. This thermal fatigue test consists in heating a 304L steel pre-cracked tube while cyclically injecting ambient water onto its inner surface. The tube is regularly removed from the furnace for a crack characterisation. Finally, the crack growth is evaluated from the crack length differences between two stops. In parallel, a finite element analysis is developed using the finite element Cast3M code. A pipe with a semi-elliptical crack on its inner surface is modelled. A cyclic thermal loading is imposed on the tube. This loading is in agreement with experimental data. The crack propagates through the thickness. A prediction of the velocity of the crack is finally assessed using a Paris’ law type criteria. Finally, this combined experimental and numerical work on 304L austenitic stainless steel pipes will enable to improve existing methods to accurately predict the crack growth under cyclic thermal loadings in austenitic stainless steel pipe at the design stage.

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