Cracking and Adhesion of Ceramic Films

1991 ◽  
Vol 239 ◽  
Author(s):  
Alan Atkinson ◽  
Richard M. Guppy
Keyword(s):  
Critical Thickness ◽  
Scratch Testing ◽  
Buckling Instability ◽  
Interfacial Delamination ◽  
Ceramic Films ◽  
Tension And Compression ◽  
Observed Behaviour ◽  
Film Cracking ◽  
Steel Substrates ◽  
The Relationship

ABSTRACTBrittle films of ceramics on metal substrates become mechanically unstable when a critical thickness is exceeded. Experiments have been carried out to investigate this instability for films under tension and compression. Films of cerium oxide gel under tension were prepared by spin-coating a ceria sol onto stainless steel substrates. Films exceeding a critical thickness failed by through-film cracking. The relationship between crack spacing and film thickness was consistent with partial interfacial delamination accompanying film cracking. Films of nickel oxide under compression were prepared by the oxidation of nickel and NiAl and NiCr alloys. The adhesion of the films to the substrates was measured in a double bending beam configuration and by scratch testing. A critical thickness was observed at which adhesion became very low and which depended on the composition of the metal substrate. The observed behaviour is consistent with a buckling instability in the film. In both types of film the conditions for crack propagation appear to determine instability, but the nature of the failure-initiating defects remains obscure.

scholarly journals The Effect of Multilayer Architecture and Ta Alloying on the Mechanical Performance of Ti-Al-N Coatings under Scratching and Uniaxial Tension

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1307
Author(s):  
Artur Rubinovich Shugurov ◽  
Evgenii Dmitrievich Kuzminov
Keyword(s):  
Uniaxial Tension ◽  
Mechanical Performance ◽  
Multilayer Coating ◽  
High Hardness ◽  
Scratch Testing ◽  
Normal Contact ◽  
Multilayer Architecture ◽  
Normal Contact Pressure ◽  
Steel Substrates ◽  
Metal Layers

The present work is focused on a comparative study of the effect of Ti-Al interlayers and Ta alloying on the mechanical behavior of Ti1−xAlxN coatings under normal contact pressure and in-plane straining. The contact loading of the samples was carried out by scratch testing, while the in-plane tensile straining was performed by uniaxial tension of the coated steel substrates. The Ti0.45Al0.55N and Ti0.43Al0.45Ta0.12N monolithic coatings as well as the Ti0.45Al0.55N/Ti0.45Al0.55 multilayer coatings with different number and thickness of the layers were deposited by DC magnetron sputtering. It was found that the introduction of the ductile Ti0.45Al0.55 layers into the Ti0.45Al0.55N coating and alloying with Ta led to their significant toughening. The improved toughness of the Ti0.43Al0.45Ta0.12N coating coupled with high residual compressive stress and high hardness resulted in its strongest resistance to cracking under scratching and tensile straining among the coatings studied. The multilayer coating with the thickest metal layers exhibited the improved resistance to delamination under in-plane straining.

Development of Metal-Ceramic-Lubricant Composite Coatings Obtained by Cold Spray for Tribological Applications in the Automotive Industry

2021 ◽  
Author(s):  
G. Garcin ◽  
F. Delloro ◽  
M. Jeandin ◽  
J-F. Hochepied ◽  
C. Grente ◽  
...  
Keyword(s):  
Automotive Industry ◽  
Composite Coatings ◽  
Solid Lubricants ◽  
Friction Reduction ◽  
Hard Particles ◽  
Wide Range ◽  
Metal Ceramic ◽  
Coating Microstructure ◽  
Steel Substrates ◽  
The Relationship

Abstract One of the main levers to reduce CO2 emissions in cars and trucks is mass and friction reduction, which is often achieved through the use of special coatings. The aim of the present work was to develop metal-ceramic-lubricant composite coatings with the best combination of wear, seizure, fatigue, and thermal resistance. Metal-based coatings incorporating hard particles and solid lubricants were cold sprayed onto steel substrates and the relationship between coating microstructure and tribology was studied. To meet the demanding tribological requirements of heavily loaded engines, the interfaces between the different components were optimized by selecting appropriate feedstock powders and assessing a wide range of process parameters. Alumina-reinforced bronze composite coatings were made from powders with different morphologies. Aggregated ceramic powders were found to be more beneficial in terms of wear than massive powders, and graphite was found to be effective for reducing seizure.

The Effect of Surface Finish on Zinc Whisker Growth

2012 ◽  
Vol 472-475 ◽  
pp. 2756-2759
Author(s):  
Wen Cui ◽  
Shao Jun Qi
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Finish ◽  
Whisker Growth ◽  
Experimental Conditions ◽  
Steel Substrates ◽  
The Relationship ◽  
Rough Surface Finish ◽  
Scanning Electron ◽  
Effect Of Surface

To understand the relationship between surface finish and zinc whisker growth, this study investigated the growth of whiskers on two mild steel substrates of different surface finish by Field Emission Gun Scanning Electron Microscope (FEG SEM). Results show that, under the same experimental conditions, deposits on substrates with a mirror finish grew less whiskers and nodules than substrates with a rough surface finish.

Specimen Current Imaging of Delamination in Ceramic Films on Metal Substrates in the SEM

1999 ◽  
Vol 589 ◽  
Author(s):  
S. Rangarajan ◽  
A.H. King
Keyword(s):  
Quantitative Measure ◽  
Stress Relief ◽  
Stabilized Zirconia ◽  
Quick Method ◽  
Insulating Films ◽  
Ceramic Films ◽  
The Right ◽  
Edge Delamination ◽  
Rapidly Solidified ◽  
Steel Substrates

AbstractPlasma spraying of yttria-stabilized zirconia on stainless steel substrates generates rapidly solidified thin film discs called splats. Constraint due to adhesion at their interface generates sufficient stresses during cooling from the splat melting to generate extensive cracking. Stress relief by cracking always accompanied by delamination of the thin films at the edges of cracked segments. It is shown here that images obtained in the SEM through amplification of the specimen current signal generate the right contrast for delineating regions of edge delamination in the cracked segments of a splat. Image analysis using this contrast provides a quantitative measure of the extent of delamination at the interface. Greater delamination in the splats formed on cooler substrates. Correlation also indicates complimentary nature of stress relief by delamination and cracking. A detailed analysis including data from solidification and cooling and cracking statistics will give a measure of the adhesion strength at the interface. This technique is a quick method for measuring delamination of microscopic degree in thin insulating films on conducting substrates.

Needle Pain Severity in Children: Does the Relationship Between Self-Report and Observed Behaviour Vary As a Function of Age?

1998 ◽  
Vol 50 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Belinda Goodenough ◽  
G. David Champion ◽  
Liliane Laubreaux ◽  
Liane Tabah ◽  
Laura Kampel
Keyword(s):  
Self Report ◽  
Pain Severity ◽  
Observed Behaviour ◽  
The Relationship

Stages of Plastic Deformation in Metallic Nanocrystals

2011 ◽  
Vol 683 ◽  
pp. 183-187 ◽  
Author(s):  
Nina Koneva ◽  
Eduard Kozlov
Keyword(s):  
Plastic Deformation ◽  
Work Hardening ◽  
Pure Copper ◽  
Paper Analysis ◽  
Deformation Localization ◽  
Tension And Compression ◽  
Average Size ◽  
20 Nm ◽  
First Time ◽  
The Relationship

In this paper, analysis of work hardening laws for grains with sizes on nano- and microlevel is carried out. The work is based on experimental data of deformation behavior of mainly pure copper at room temperature (RT). A special attention is given to the interval of grains with the average size between 20 nm and 230 nm. Work hardening stages of active plastic deformation during tension and compression are characterized. The dependence of work hardening coefficients on the average grains size at the nanoscale in the II, IV and VI stages is revealed for the first time. Mechanisms of deformation in the range of grains sizes between 10 nm and 1000 nm are categorized. The relationship between work hardening stages and deformation mechanisms is discussed. The stage of deformation where deformation localization takes place is determined.

INFLUENCE OF SURFACE FREE ENERGY ON ADHESION OF CrN THIN FILM DEPOSITED BY AIP METHOD

2012 ◽  
Vol 06 ◽  
pp. 509-514 ◽  
Author(s):  
HIKARU NOUDA ◽  
HIROATSU ODA ◽  
DAISUKE YONEKURA ◽  
RI-ICHI MURAKAMI
Keyword(s):  
Thin Film ◽  
Free Energy ◽  
Surface Free Energy ◽  
High Speed ◽  
Gas Flow ◽  
Sessile Drop ◽  
Ion Bombardment ◽  
Polar Component ◽  
Scratch Testing ◽  
The Relationship

The purpose of this study is to examine the relationship between adhesion of CrN thin film and the surface free energy of substrate. CrN film was deposited on JIS SKH2 high speed tool steel by arc ion plating (AIP) method. The surface free energy of the substrate was measured with/without ion bombardment process using nitrogen and argon gas under various gas flow rate before CrN deposition. The surface free energy was measured by the sessile drop method using distilled water and methylene iodide. The adhesion was evaluated by scratch testing and the relationship between a critical load and the surface free energy in each ion bombardment condition was discussed. As a result, it was found that the adhesion increased with decreasing the surface free energy, in particular the polar component strongly affects the adhesion.

scholarly journals Are Rate and Selectivity Correlated in Iridium-Catalysed Hydrogen Isotope Exchange Reactions?

2021 ◽  
Author(s):  
Daria Timofeeva ◽  
David Lindsay ◽  
William Kerr ◽  
David Nelson
Keyword(s):  
Functional Groups ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Reaction Rate ◽  
Lewis Base ◽  
Exchange Reactions ◽  
Different Types ◽  
Observed Behaviour ◽  
Directing Group ◽  
The Relationship

Herein we examine the relationship between reaction rate and reaction selectivity in iridium-catalysed hydrogen isotope<br>exchange (HIE) reactions directed by Lewis basic functional groups. We have recently develped a directing group scale that allows semi-quantitative predictions of Lewis base directed selectivity in HIE, formally ranking ‘relative rates’ determined from a structured set of competition experiments. Here, we show that selectivity and rate are in fact not correlated, but that different types of behaviour emerge in competition experiments and that the observed behaviour can be predicted from our established selectivity scale.

scholarly journals A Review of Current Development of Graphene Mechanics

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 357 ◽  
Author(s):  
Qiang Cao ◽  
Xiao Geng ◽  
Huaipeng Wang ◽  
Pengjie Wang ◽  
Aaron Liu ◽  
...  
Keyword(s):  
Essential Role ◽  
Compression Fracture ◽  
Short Review ◽  
Single Atom ◽  
Two Dimensional ◽  
Future Prospects ◽  
Current Development ◽  
Graphene Derivatives ◽  
Tension And Compression ◽  
The Relationship

Graphene, a two-dimensional carbon in honeycomb crystal with single-atom thickness, possesses extraordinary properties and fascinating applications. Graphene mechanics is very important, as it relates to the integrity and various nanomechanical behaviors including flexing, moving, rotating, vibrating, and even twisting of graphene. The relationship between the strain and stress plays an essential role in graphene mechanics. Strain can dramatically influence the electronic and optical properties, and could be utilized to engineering those properties. Furthermore, graphene with specific kinds of defects exhibit mechanical enhancements and thus the electronic enhancements. In this short review, we focus on the current development of graphene mechanics, including tension and compression, fracture, shearing, bending, friction, and dynamics properties of graphene from both experiments and numerical simulations. We also touch graphene derivatives, including graphane, graphone, graphyne, fluorographene, and graphene oxide, which carve some fancy mechanical properties out from graphene. Our review summarizes the current achievements of graphene mechanics, and then shows the future prospects.

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