The Effect of Film Stress on Indentation Modulus/Hardness for Silicon Oxide Films

1999 ◽  
Vol 563 ◽  
Author(s):  
Brad Sun ◽  
Jin Lee ◽  
Patrick Kofron ◽  
Qing Ma
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Elevated Temperatures ◽  
Silicon Oxide ◽  
Oxide Films ◽  
Sio2 Film ◽  
Indentation Modulus ◽  
Rf Power ◽  
Appreciable Change ◽  
Steel Substrates

AbstractA controlled experiment was performed to determine whether residual stresses in silicon oxide films affect the apparent modulus and hardness of the films measured using microindentation. A set of wafers, each with a SiO2 film of different residual stress, were produced by PECVD deposition using different RF power settings. Residual stresses, determined by curvature measurement, were shown to become more compressive with the increase of the RF power. Correlation between indentation modulus/hardness and residual stress was established because the modulus was also observed to be trending with the RF power. To determine whether the residual stress change is the cause for the change of indentation modulus/hardness, one of the wafers was cut to pieces and bonded to steel substrates of different thickness at elevated temperatures. Because of the thermal mismatch between silicon and steel, the silicon pieces were stressed by the steel substrates and therefore provided additional stresses to the SiO2 film on the top surface. The applied stresses were determined using Raman piezospectroscopy. Micro-indentation tests performed on these samples showed no appreciable change of modulus/hardness due to additional stresses. It was concluded that the material change, such as density, was behind the correlation between indentation modulus and residual stress.

Nanohardness of DC Magnetron Sputtered W – C Coatings as a Function of Composition and Residual Stresses

2015 ◽  
Vol 662 ◽  
pp. 107-110 ◽  
Author(s):  
Michal Novák ◽  
František Lofaj ◽  
Petra Hviščová ◽  
Rudolf Podoba ◽  
Marián Haršáni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Magnetron Sputtering ◽  
Linear Increase ◽  
Indentation Modulus ◽  
Dc Magnetron Sputtering ◽  
Glass Substrates ◽  
Compressive Stresses ◽  
Deposition Parameters

The effects of residual stresses in thin W-C based coatings were investigated with the aim to find their influence on nanohardness and indentation modulus. Ten samples of W-C based coatings were deposited on microslide glass substrates using DC magnetron sputtering at the identical deposition parameters. Their thickness was in the range from 500 to 600 nm. The residual stresses in the coatings varied from 1.5 GPa up to 4.4 GPa. Increase of residual stress caused linear increase of HITfrom 16 to 19.5 GPa. This increase was only the result of the compressive stresses. EITof the studied coatings was not sensitive to residual stresses and corresponded to 185 GPa ± 15 GPa.

Residual Stress in Sputtered Silicon Oxycarbide Thin Films

2011 ◽  
Vol 1299 ◽  
Author(s):  
Ping Du ◽  
I-Kuan Lin ◽  
Yunfei Yan ◽  
Xin Zhang
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Elevated Temperatures ◽  
Silicon Oxide ◽  
Composite Films ◽  
Deposition Process ◽  
Silicon Oxycarbide ◽  
X Ray ◽  
Curvature Measurement ◽  
Film Substrate

ABSTRACTSilicon carbide (SiC) has received increasing attention on the integration of microelectro-mechanical system (MEMS) due to its excellent mechanical and chemical stability at elevated temperatures. However, the deposition process of SiC thin films tends to induce relative large residual stress. In this work, the relative low stress material silicon oxide was added into SiC by RF magnetron co-sputtering to form silicon oxycarbide (SiOC) composite films. The composition of the films was characterized by Energy dispersive X-ray (EDX) analysis. The Young’s modulus and hardness of the films were measured by nanoindentation technique. The influence of oxygen/carbon ratio and rapid thermal annealing (RTA) temperature on the residual stress of the composite films was investigated by film-substrate curvature measurement using the Stoney’s equation. By choosing the appropriate composition and post processing, a film with relative low residual stress could be obtained.

Experimental and Computational Residual Stress Evaluation of a Weld Clad Plate and Machined Test Specimens

1988 ◽  
Vol 110 (4) ◽  
pp. 297-304 ◽  
Author(s):  
E. F. Rybicki ◽  
J. R. Shadley ◽  
A. S. Sandhu ◽  
R. B. Stonesifer
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Computational Model ◽  
Stress Analysis ◽  
Elevated Temperatures ◽  
Stress Distributions ◽  
Heat Treated ◽  
Residual Stress Analysis ◽  
The Difference ◽  
Set Up

Residual stresses in a heat treated weld clad plate and test specimens obtained from the plate are determined using a combination of experimental residual stress analysis and a finite element computational model. The plate is 102 mm thick and made of A 533-B Class 2 steel with 308 stainless steel cladding. The plate is heated to 538 C and allowed to cool uniformly. Upon cooling, residual stresses are set up in the clad plate because of the difference between the coefficients of thermal expansion of the plate and the cladding. Residual stress in the clad plate is determined using both a previously verified experimental residual stress analysis technique and a computational model. Removing test specimens from the clad plate can relax the stresses in the cladding. Thus, residual stress distributions were also determined for two types of clad test specimens that were removed from the plate. These test specimens were designed to examine the effect of cladding thickness on residual stresses. Good agreement was found between the experimentally obtained residual stress values and the residual stresses calculated from the computational model. Because of the interest in tests conducted at elevated temperatures and the inherent difficulty in doing experimental residual stress analysis at elevated temperatures, the computational model was applied to examine the effect of elevated temperature on the residual stresses in the test specimens. Peak stresses in the heat treated clad plate were found to approach the yield stress of the cladding material. It was also found that removing a 32 mm clad specimen with cladding on one side reduced the residual stresses in the cladding. However, the residual stresses in the cladding were found to increase when one-half of the cladding thickness was machined away to form the second test specimen geometry. Residual stresses parallel and perpendicular to the weld direction were very similar in magnitude for all cases considered. The effect that heating the test specimens to 204 C has on residual stress distributions was to reduce the residual stress in the cladding and the plate.

Residual Stress Analysis in Both As-Deposited and Annealed CrN Coatings

2005 ◽  
Vol 490-491 ◽  
pp. 643-648 ◽  
Author(s):  
Ru Lin Peng ◽  
Yan Dong Wang ◽  
Magnus Odén ◽  
Jonathan Almer
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Orientation Distribution ◽  
High Energy ◽  
Linear Distribution ◽  
Residual Stress Analysis ◽  
Steel Substrates ◽  
Thick Coatings ◽  
Crn Coatings

In this paper, we report on residual stress analysis in physical vapour deposited (PVD) CrN coatings. Two 9 µm thick coatings were grown on tool steel substrates with bias voltages of - 50 V and -300 V, respectively. High-energy (E=80 keV) synchrotron radiation measurements have been performed to investigate residual stresses in both as-deposited and annealed CrN coatings. To understand the origins of non-linear distribution of lattice strain versus sin2ψ for certain (hkl) planes in both coatings, a stress orientation distribution function (SODF) analysis has been carried out, which yields grain-orientation-dependent residual stresses. The results are compared to previous analyses using Reuss and Vook-Witt models on the as-deposited coatings.

Numerical Simulation of Residual Stresses Induced in Compact Tension Specimens Using Electron Beam Welding

2012 ◽  
Author(s):  
P. Kapadia ◽  
C. M. Davies ◽  
D. W. Dean ◽  
K. M. Nikbin
Keyword(s):  
Residual Stress ◽  
Electron Beam ◽  
Residual Stresses ◽  
Mechanical Model ◽  
Elevated Temperatures ◽  
Electron Beam Welding ◽  
Creep Crack Growth ◽  
Crack Tip ◽  
Compact Tension ◽  
Eb Welding

In welded components residual stresses on the order of yield magnitude can exist, allowing creep damage and cracking to occur under secondary stresses at elevated temperatures. A method of inducing residual stresses in compact tension, C(T), specimens is proposed using Electron Beam (EB) welding, which is simulated using a sequential thermal-mechanical model. The thermal model has been verified by comparison to thermocouple measurements obtained from instrumented EB welding experiments on blocks made of ex-service Type 316H stainless steel. Residual stress measurements, obtained by the neutron diffraction technique, have also been used to verify the mechanical model. It has been found that in the proposed EB welding method plasticity is localised and limited to just a few millimetres away from the notch whilst at the same time exhibiting a near yield level residual stress at the crack tip. Thus this technique may allow the effects of residual stresses on creep crack growth to be investigated by the EB welding technique without material property changes due to crack tip plasticity influencing the results.

On the Stress Development in SA508 Autogenous Weld

2014 ◽  
Vol 783-786 ◽  
pp. 2123-2128 ◽  
Author(s):  
Hamidreza Abdolvand ◽  
Mike Keavey ◽  
H. Dai ◽  
Alison Mark ◽  
N. O’Meara ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Phase Transformations ◽  
High Speed ◽  
Elevated Temperatures ◽  
Kinematic Hardening ◽  
Stress Development ◽  
Wide Range ◽  
Martensitic Phase Transformations ◽  
Welding Processes

Considering the significant role that residual stresses play in determining the lifetime-service of materials, it is mandatory to have a good understanding of and a means of predicting those that develop during welding processes. For this purpose, a User MATerial subroutine (UMAT) is developed to study the effects of various parameters that influence solid state phase transformations and residual stress evolution during welding of SA508 ferritic steel. The temperature dependent elastic and kinematic hardening parameters for each of the individual phases that can potentially develop during cooling from elevated temperatures are measured and are used for calculating stress development during low (75 mm/min) and high (300 mm/min) speed gas-tungsten arc welding (GTAW) on SA508 grade 3. These two speeds are selected to cover a wide range of cooling rates in the heat affected zone so that different phase proportions would be present. The results of the numerical simulations for residual stresses are compared against those measured by neutron diffraction. It is shown here that a low speed weld results in bainite formation whereas a high speed weld results in bainitic as well as subsequent martensitic phase transformations where each welding rate results in different residual stress development.

Residual Stress Characteristics of Plasma Sprayed CoNiCrAlY Coatings by X-Ray Diffraction

2007 ◽  
Vol 353-358 ◽  
pp. 495-498 ◽  
Author(s):  
Hiroyuki Waki ◽  
Akira Kobayashi
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plasma Spraying ◽  
Expansion Coefficient ◽  
Bending Test ◽  
Powder Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sprayed ◽  
Steel Substrates

Plasma sprayed CoNiCrAlY coating can prevent oxidation and corrosion of turbine blades in a gas turbine plant. Cracking and delamination of coatings are affected by the residual stresses in the coatings. In this study, the arising mechanism of residual stress in the plasma sprayed coating was discussed. The residual stresses in CoNiCrAlY coatings were measured by X-ray diffraction method. The coatings were deposited by either low pressure plasma spraying (LPPS) or atmospheric plasma spraying (APS). Each elastic constant which was used for determining the X-ray stress constant was mechanically measured by a bending test. Two kinds of substrates were prepared for each coating in order to examine the effect of thermal expansion coefficient of a substrate. Results were as follows. The residual stresses of the coatings on steel substrates were tensile. On the other hand, the residual stresses on stainless substrates were lower than those on steel substrates. Arising mechanism of the residual stresses can be explained by both the linear expansion coefficient and the range of changing temperature. It was also found that the absolute residual stresses were affected by the spraying powder size and increased with a decrease of the spraying powder size. It was principally caused by the difference in the elastic constants.

scholarly journals Influence of Abrasive Water Jet parameters on the surface integrity of Inconel 718

2021 ◽  
Author(s):  
Lorena Cano Salinas ◽  
Kamel Moussaoui ◽  
Akshay Hejjaji ◽  
Mehdi Salem ◽  
Anis Hor ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Residual Stresses ◽  
Inconel 718 ◽  
Surface Characterization ◽  
Elevated Temperatures ◽  
High Surface ◽  
Water Jet ◽  
Depth Of Cut ◽  
Abrasive Water Jet

Abstract Inconel 718 (IN718) is a precipitation hardened nickel-base super-alloy exhibiting high strength and good corrosion resistance at elevated temperatures and on the downside it is characterized by poor machinability. Abrasive Water Jet (AWJ) process, offers a potential method to machining difficult-to-cut materials such as IN718. The present work investigates the influence of Abrasive Water Jet parameters on surface roughness, topography, depth of cut and residual stress when milling IN718. Surface characterization was conducted through 3D optical microscopy and SEM techniques. Residual stresses were measured in longitudinal and transverse directions with respect to the machining path using X-ray diffraction (XRD) technique. The obtained results showed that milled surfaces have a homogeneous texture with embedded abrasive particles and high surface roughness. AWJ process introduced high compressive residual stresses with similar order of level in both directions (X and Y). In addition, it was observed that jet pressure is the most influencing parameter on roughness and depth of cut, whilst traverse speed and step-over distance had a significant effect on the residual stress. Based on the experimental analysis, an empirical model to predict the depth of cut was proposed. The validation of the proposed model, has shown around 5% error in the predicted and actual pocket depth.

Analysis of Sputtered Zinc Oxide Films

1980 ◽  
Vol 38 ◽  
pp. 416-417
Author(s):  
T. A. Emma ◽  
M. P. Singh
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Piezoelectric Materials ◽  
Oxide Films ◽  
Optical Quality ◽  
Zno Films ◽  
Rf Power ◽  
X Ray Diffraction ◽  
Sputtered Films ◽  
Zinc Oxide Films

Optical quality zinc oxide films have been characterized using reflection electron diffraction (RED), replication electron microscopy (REM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Significant microstructural differences were observed between rf sputtered films and planar magnetron rf sputtered films. Piezoelectric materials have been attractive for applications to integrated optics since they provide an active medium for signal processing. Among the desirable physical characteristics of sputtered ZnO films used for this and related applications are a highly preferred crystallographic texture and relatively smooth surfaces. It has been found that these characteristics are very sensitive to the type and condition of the substrate and to the several sputtering parameters: target, rf power, gas composition and substrate temperature.

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