Fracture Behavior of CVD Diamond

1991 ◽  
Vol 239 ◽  
Author(s):  
M. D. Drory ◽  
J. F. Gardinier ◽  
J. M. Pinneo
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Slow Crack Growth ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Testing Conditions ◽  
Plasma Enhanced Cvd ◽  
Low Load ◽  
Length Measurements ◽  
Corrosion Susceptibility

ABSTRACTThe fracture behavior of CVD diamond is examined by indentation experiments in which slow crack growth has been observed. Diamond films of 400μm thickness were prepared by plasma-enhanced CVD on a silicon substrate, subsequently removed from the substrate, and polished for indentation testing. A microhardness tester was used to produce Vickers indentations under low load. Crack length measurements over time revealed susceptibility to slow crack growth in ambient testing conditions. The stress-corrosion susceptibility coefficient, N, was measured as 9.3.

Slow crack growth of CVD diamond

1992 ◽  
Vol 7 (4) ◽  
pp. 781-783 ◽  
Author(s):  
M.D. Drory ◽  
C.F. Gardinier
Keyword(s):  
Crack Growth ◽  
Slow Crack Growth ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Testing Conditions ◽  
Plasma Enhanced Cvd ◽  
Low Load ◽  
Length Measurements ◽  
Corrosion Susceptibility ◽  
Over Time

Slow crack growth in CVD diamond has been observed from indentation experiments. Diamond films of 400 μm thickness were prepared by plasma-enhanced CVD on a silicon substrate, subsequently removed from the substrate, and polished for indentation testing. A microhardness tester was used to produce Vickers indentations under low load. Crack length measurements over time revealed susceptibility to slow crack growth in ambient testing conditions. The stress-corrosion susceptibility coefficient, N, was measured as 9.3.

Measuring the Adhesion of Diamond Thin Films to Substrates Using the Blister Test

1995 ◽  
Vol 383 ◽  
Author(s):  
Jim Sizemore ◽  
R. J. Hohlfelder ◽  
J. J. Vlassak ◽  
W. D. Nix
Keyword(s):  
Thin Films ◽  
Test Data ◽  
Diamond Films ◽  
Cvd Diamond ◽  
Simple Equation ◽  
Testing Technique ◽  
Blister Test ◽  
Plasma Enhanced Cvd ◽  
Si Substrates ◽  
Diamond Thin Films

ABSTRACTIt is shown that the blister testing technique can be used to measure the adhesion of thin films to their substrates. A brief discussion of blister test mechanics is presented here, leading to a simple equation relating adhesion to the height of the blister and the pressure causing it to grow. Blister test data for plasma-enhanced CVD diamond films on Si substrates have been analyzed using this relation. The tests show adhesion energies of 1.8– 2.6 J/m2.

Dependence of fracture stress on applied stress rate in a Yb2O3–SiO2-doped hot-pressed silicon nitride ceramic

2001 ◽  
Vol 16 (11) ◽  
pp. 3254-3261 ◽  
Author(s):  
Shuqi Guo ◽  
Naoto Hirosaki ◽  
Yoshinobu Yamamoto ◽  
Toshiyuki Nishimura ◽  
Mamoru Mitomo
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Crack Growth ◽  
Applied Stress ◽  
Fracture Stress ◽  
Fracture Behavior ◽  
Slow Crack Growth ◽  
Silicon Nitride Ceramic ◽  
Temperature Fracture ◽  
Stressing Rate

High-temperature fracture behavior of a Yb2O3–SiO2–doped hot-pressed silicon nitride (Si3N4) ceramic was investigated in four-point flexure between 1000 and 1500 °C at five crosshead speeds, using the specimens precracked with three indentation loads. Above 1000 °C, a temperature and stressing rate dependence of fracture stress was seen. At 1200 °C the fracture stress of the precracked specimens increased with decreasing stressing rates due to a toughening effect, the absence of slow crack growth (SCG). However, at 1400 and 1500 °C the fracture stress decreased with decreasing stressing rate. In particular, this dependence was stronger at 1500 °C than at 1400 °C. The SCG was observed only in the specimens precracked with indentation loads of 98 and 196 N. This crack extended with increasing test temperature and/or decreasing stressing rate. The dependence of fracture stress on stressing rate was attributed to a SCG behavior at higher temperatures.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

scholarly journals Unique Slow Crack Growth Behavior of Isotactic Polypropylene: The Role of Shear Layer-Spherulites Layer Alternated Structure

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2746
Author(s):  
Mingjin Liu ◽  
Jiaxu Luo ◽  
Jin Chen ◽  
Xueqin Gao ◽  
Qiang Fu ◽  
...  
Keyword(s):  
Shear Layer ◽  
Crack Growth ◽  
Isotactic Polypropylene ◽  
Slow Crack Growth ◽  
Crack Growth Behavior ◽  
Polymer Science ◽  
The Past ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

With the development of polymer science, more attention is being paid to the longevity of polymer products. Slow crack growth (SCG), one of the most important factors that reveal the service life of the products, has been investigated widely in the past decades. Here, we manufactured an isotactic polypropylene (iPP) sample with a novel shear layer–spherulites layer alternated structure using multiflow vibration injection molding (MFVIM). However, the effect of the alternated structure on the SCG behavior has never been reported before. Surprisingly, the results showed that the resistivity of polymer to SCG can be enhanced remarkably due to the special alternated structure. Moreover, this sample shows unique slow crack propagation behavior in contrast to the sample with the same thickness of shear layer, presenting multiple microcracks in the spherulites layer, which can explain the reason of the resistivity improvement of polymer to SCG.

Investigation of the Slow Crack Growth Behavior of Static and Cyclic Loaded Specimens of Polyethylene by 2D and 3D Optical Fracture Surface Analysis

2012 ◽  
Vol 311 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Andreas Frank ◽  
Katharina Bruckmoser ◽  
Anita Redhead ◽  
Dieter P. Gruber ◽  
Gerald Pinter
Keyword(s):  
Fracture Surface ◽  
Crack Growth ◽  
Surface Analysis ◽  
Slow Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fracture Surface Analysis ◽  
2D And 3D

Slow crack growth in polyethylene - a review

1991 ◽  
Vol 41 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Norman Brown ◽  
Xici Lu ◽  
Yan-Ling Huang ◽  
Ruzheng Qian
Keyword(s):  
Crack Growth ◽  
Slow Crack Growth

The Fracture Toughness of Hardened Tool Steels

1987 ◽  
Vol 109 (4) ◽  
pp. 314-318 ◽  
Author(s):  
D. F. Watt ◽  
Pamela Nadin ◽  
S. B. Biner
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Crack Opening ◽  
Compact Tension ◽  
Testing Procedure ◽  
Tool Steels ◽  
Opening Displacement ◽  
Tempering Temperature ◽  
Toughness Testing

This report details the development of a three-stage fracture toughness testing procedure used to study the effect of tempering temperature on toughness in 01 tool steel. Modified compact tension specimens were used in which the fatigue precracking stage in the ASTM E-399 Procedure was replaced by stable precracking, followed by a slow crack growth. The specimen geometry has been designed to provide a region where slow crack growth can be achieved in brittle materials. Three parameters, load, crack opening displacement, and time have been monitored during the testing procedure and a combination of heat tinting and a compliance equation have been used to identify the position of the crack front. Significant KIC results have been obtained using a modified ASTM fracture toughness equation. An inverse relationship between KIC and hardness has been measured.

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