The Experts below are selected from a list of 2979 Experts worldwide ranked by ideXlab platform
Y Gotoh - One of the best experts on this subject based on the ideXlab platform.
-
effect of wc size on Interface Fracture toughness of wc co hvof sprayed coatings
Surface & Coatings Technology, 2006Co-Authors: Makoto Watanabe, A Owada, S Kuroda, Y GotohAbstract:Abstract The Interface Fracture toughness of high velocity oxygen fuel (HVOF) sprayed coatings on carbon steel made of various types of WC–12 wt.% Co powders with different WC particle sizes of 0.2 to 7.0 μm was evaluated by the pre-notched four-point bending test to clarify the size effect of WC particles and to explore the superior adhesion mechanisms of this coating system. The correlation between the splat microstructure and the toughness variation was investigated by observing a cross-section of WC–Co splats around the Interface using the focused-ion-beam (FIB) technique. The Interface Fracture toughness of WC–12 wt.% Co coating/carbon steel under a mixed Mode I/Mode II loading condition increases from 600 to 1800 J/m2 as the WC particle size increases. Compaction of the underlying microstructure, the intrusion of WC particles into the substrate, and the volume fraction of the metallic binder phase in the coating are key factors in achieving excellent adhesion of this coating system.
A Owada - One of the best experts on this subject based on the ideXlab platform.
-
effect of wc size on Interface Fracture toughness of wc co hvof sprayed coatings
Surface & Coatings Technology, 2006Co-Authors: Makoto Watanabe, A Owada, S Kuroda, Y GotohAbstract:Abstract The Interface Fracture toughness of high velocity oxygen fuel (HVOF) sprayed coatings on carbon steel made of various types of WC–12 wt.% Co powders with different WC particle sizes of 0.2 to 7.0 μm was evaluated by the pre-notched four-point bending test to clarify the size effect of WC particles and to explore the superior adhesion mechanisms of this coating system. The correlation between the splat microstructure and the toughness variation was investigated by observing a cross-section of WC–Co splats around the Interface using the focused-ion-beam (FIB) technique. The Interface Fracture toughness of WC–12 wt.% Co coating/carbon steel under a mixed Mode I/Mode II loading condition increases from 600 to 1800 J/m2 as the WC particle size increases. Compaction of the underlying microstructure, the intrusion of WC particles into the substrate, and the volume fraction of the metallic binder phase in the coating are key factors in achieving excellent adhesion of this coating system.
Alan Atkinson - One of the best experts on this subject based on the ideXlab platform.
-
Interface Fracture toughness in thermal barrier coatings by cross sectional indentation
Acta Materialia, 2012Co-Authors: Xin Wang, Changjiang Wang, Alan AtkinsonAbstract:The Interface Fracture toughness of thermal barrier coatings (TBCs) on high-pressure turbine blades manufactured by electron beam physical vapour deposition was measured by a cross-sectional indentation (CSI) method. Scanning electron microscopy and luminescence mapping were employed to reveal that coating delamination induced by CSI was predominantly along the thermally grown oxide–bond coat Interface and the shape of the delaminated area was approximately semicircular. The critical energy release rate (Gc)for delamination was calculated based on a clamped circular plate model. Analysis of the stored energy release revealed that the residual stresses in the coating do not contribute to the total energy release rate provided that the delaminated area of the coating does not buckle. Therefore, for this method, detailed information of residual stresses is not necessary for the determination of Interface Fracture toughness. However, intercolumnar microFracture and shear displacement in the YSZ top coat can lead to significant overestimation of the Interface Fracture toughness in some situations. A method of specimen preparation is described to inhibit these effects. The Interface Fracture resistance of the TBCs was found to be 29 ± 9 J/m−2 after between 35 and 100 thermal cycles (from room temperature to 1150 °C with 1 h duration.
Mohd Nasir Tamin - One of the best experts on this subject based on the ideXlab platform.
-
Damage Mechanics Model for Solder/Intermetallics Interface Fracture Process in Solder Joints
Key Engineering Materials, 2011Co-Authors: N.m. Shaffiar, Mohd Nasir TaminAbstract:The relatively brittle solder/IMC Interface Fracture process in reflowed solder joints is examined using finite element (FE) method. The Interface decohesion is described using a traction-separation quadratic failure criterion along with a mixed-mode displacement formulation for the Interface Fracture event. Reflowed Sn-4Ag-0.5Cu (SAC405) solder ball on OSP copper pad and orthotropic FR4 substrate under ball shear push test condition at 3000 mm/sec is simulated. Unified inelastic strain constitutive model describes the strain rate-response of the SAC405 solder. Comparable simulated and measured load-displacement values during solder ball shear push test serve as validation of the damage-based FE model. Results indicate a nonlinear damage evolution at each material point of the solder/IMC Interface during the ball shear push test. The normal-to-shear traction ratio at the onset of the Interface Fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid Interface crack propagation is predicted following crack initiation event with the average crack speed up to 24.6 times the applied shear tool speed. The high stress concentration along the edge of the solder/IMC Interface facilitates local crack initiation and dictates the shape of the predicted dynamic crack front.
-
Damage mechanics of solder/IMC Interface Fracture in Pb-free solder interconnects
2009 11th Electronics Packaging Technology Conference, 2009Co-Authors: Lai Zheng Bo, Loh Wei Keat, Mohd Nasir TaminAbstract:This study addresses the mechanics of the relatively brittle solder/intermetallic (IMC) Interface Fracture process using damage mechanics concept. The damage state, ¿ of a material point in the solder/IMC Interface, is expressed in terms of orthogonal traction components in a quadratic failure criterion of a cohesive zone model. The model is then employed in a finite element analysis of a solder ball shear push test. The simulated test specimen consists of reflowed SAC405 solder-on-OSP copper pad and orthotropic FR4 substrate. Unified inelastic strain constitutive model with optimized material parameters describes the strain rate-response of the SAC405 solder. The cohesive zone model parameter values are compiled from published experimental data on SAC405 solder ball pull tests and shear push tests. The predicted shear tool force-displacement curve compared well with published experimental data. The normal-to-shear traction ratio at the onset of Interface Fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid Interface crack propagation is predicted following the initiation of crack with the average crack speed up to 24.6 times the applied shear tool speed at 3000 mm/sec. The progressive boundary between damaged (¿
-
Damage Mechanics Model for Interface Fracture Process in Solder Interconnects
2008 10th Electronics Packaging Technology Conference, 2008Co-Authors: Loh Wei Keat, Nazri Kamsah, Mohd Nasir TaminAbstract:In this study, cohesive damage zone model is evaluated and employed to model solder/intermetallics (IMC) Interface crack initiation and propagation in solder interconnects. Interface materials damage is quantified in terms of stress-to-strength ratios of orthogonal components in a quadratic failure criterion along with a mixed-mode displacement formulation for crack initiation event. Subsequent crack propagation is predicted based on Fracture energy considerations. The mechanics of solder/IMC Interface decohesion is examined through finite element modeling of a typical solder ball shear test. The 3D model consists of Sn40Pb solder, Ni3Sn4 intermetallics and Ni layers, copper substrate and a rigid shear tool. Unified inelastic strain theory describes the strain rate- and temperature-dependent response of the solder. The strength and work of Fracture of the bi-material Interface are derived from load-displacement data of solder ball pull tests and ball shear tests. The quasi-static solder ball shear test of reflowed solder sample is simulated at 30°C with a prescribed displacement rate of 0.01 mm/sec. Results show that complex stresses developed on the Interface plane due to applied shear and induced bending effects by the shear tool clearance. A nonlinear damage evolution is predicted at each Interface material point during the test. Stresses in the "Fractured" material points diminish as the crack front progresses. The progression of damage indicates a straight crack front for the brittle solder/IMC Interface Fracture, as observed experimentally. The corresponding fractographic analysis on the sheared Interface indicates that the crack initiated and propagated along the bi-material solder/IMC Interface.
Makoto Watanabe - One of the best experts on this subject based on the ideXlab platform.
-
effect of wc size on Interface Fracture toughness of wc co hvof sprayed coatings
Surface & Coatings Technology, 2006Co-Authors: Makoto Watanabe, A Owada, S Kuroda, Y GotohAbstract:Abstract The Interface Fracture toughness of high velocity oxygen fuel (HVOF) sprayed coatings on carbon steel made of various types of WC–12 wt.% Co powders with different WC particle sizes of 0.2 to 7.0 μm was evaluated by the pre-notched four-point bending test to clarify the size effect of WC particles and to explore the superior adhesion mechanisms of this coating system. The correlation between the splat microstructure and the toughness variation was investigated by observing a cross-section of WC–Co splats around the Interface using the focused-ion-beam (FIB) technique. The Interface Fracture toughness of WC–12 wt.% Co coating/carbon steel under a mixed Mode I/Mode II loading condition increases from 600 to 1800 J/m2 as the WC particle size increases. Compaction of the underlying microstructure, the intrusion of WC particles into the substrate, and the volume fraction of the metallic binder phase in the coating are key factors in achieving excellent adhesion of this coating system.