Diffusion of water into oxides during microhardness indentation

1987 ◽  
Vol 6 (7) ◽  
pp. 867-868 ◽  
Author(s):  
M. Tomozawa ◽  
K. Hirao
Keyword(s):  
Microhardness Indentation

General Microhardness Indentation Theory for Multilayer Contacts

1997 ◽  
Vol 119 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Peter A. Engel ◽  
Qian Yang
Keyword(s):  
Iterative Procedure ◽  
Microhardness Measurement ◽  
Computational Method ◽  
Experimental Investigations ◽  
Load Range ◽  
Composite Action ◽  
Refined Method ◽  
General Rules ◽  
Microhardness Indentation ◽  
Multilayer Materials

A refined method for interpreting the Vickers composite microhardness measurement for multilayer materials having layers of arbitrary plating thickness is first presented. The position of an “effective substrate” is found using the concept of the “plastic boundary,” and the depth-wise deformation of each layer is considered in a double-iterative procedure which converges fast. This computational method is then extended from pyramidal indenters to conical and spherical indenters (e.g., Meyer’s). For its confirmation, experimental investigations are carried out for two configurations of Cu/Ni/Au sandwiches, using different diameter spherical indenters and spherical tipped cones, through and well above the microhardness load range. The general rules for composite action are established.

scholarly journals Crack-Resistance Behavior of an Encapsulated, Healing Agent Embedded Buffer Layer on Self-Healing Thermal Barrier Coatings

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 358
Author(s):  
Dowon Song ◽  
Taeseup Song ◽  
Ungyu Paik ◽  
Guanlin Lyu ◽  
Yeon-Gil Jung ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Thermal Fatigue ◽  
Thermal Barrier ◽  
Self Healing ◽  
Crack Healing ◽  
Indentation Method ◽  
Jet Engine ◽  
Barrier Coating ◽  
Healing Agent ◽  
Microhardness Indentation

In this work, a novel thermal barrier coating (TBC) system is proposed that embeds silicon particles in coating as a crack-healing agent. The healing agent is encapsulated to avoid unintended reactions and premature oxidation. Thermal durability of the developed TBCs is evaluated through cyclic thermal fatigue and jet engine thermal shock tests. Moreover, artificial cracks are introduced into the buffer layer’s cross section using a microhardness indentation method. Then, the indented TBC specimens are subject to heat treatment to investigate their crack-resisting behavior in detail. The TBC specimens with the embedded healing agents exhibit a relatively better thermal fatigue resistance than the conventional TBCs. The encapsulated healing agent protects rapid large crack openings under thermal shock conditions. Different crack-resisting behaviors and mechanisms are proposed depending on the embedding healing agents.

Experimental and Simulation Study of Microhardness Indentation of Solid Oxide Fuel Cell Using Progressive Damage Material Model

2013 ◽  
Vol 538 ◽  
pp. 89-92
Author(s):  
Jing Zhang ◽  
Jia Yang Liu
Keyword(s):  
Material Model ◽  
Element Model ◽  
Progressive Damage ◽  
Electrolyte Layer ◽  
Half Cell ◽  
Cell Structures ◽  
Interface Delamination ◽  
Indentation Tests ◽  
Microhardness Indentation ◽  
Potential Failure

A finite element model with progressive damage material properties is proposed to study the mechanical behavior of Ni-8YSZ/8YSZ half-cell structures under Vickers indentation tests. The simulation results show that the simulated hardnesses of the as-received anode (NiO-8YSZ with 12% porosity) and the reduced anode (NiO-8YSZ with 36.68% porosity) samples were 2.54 GPa and 0.66 GPa, respectively, which are fairly in agreement with the experimental data. The interface delamination between the anode layer and the electrolyte layer was investigated by varying the mechanical properties of the interface between the two layers. The parametric study shows that a weak interfacial layer (with a low Young’s modulus) may cause potential failure due to delamination.

Changing the Indentation Behaviour of MgO by Ion Implantation

1983 ◽  
Vol 27 ◽  
Author(s):  
P.J. Burnett ◽  
T.F. Page
Keyword(s):  
Ion Implantation ◽  
Single Crystal ◽  
Surface Hardening ◽  
Fracture Behaviour ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Indentation Tests ◽  
Microhardness Indentation ◽  
Higher Doses ◽  
Post Implantation

ABSTRACTCleaved {100} MgO single crystal surfaces have been implanted with 300keV Ti+and Cr+ ions to doses in the range 10 16 −1018 ions cm−2. Localised plasticity and fracture behaviour has been investigated using microhardness indentation tests at loads of between 10gf and 500gf.Significant surface hardening has been observed at lower doses with amorphisation related softening occurring at higher doses. Post-implantation heat treatments produce precipitation reactions with associated hardness changes.

Surface Modification of Ceramics Using Microwave Energy

1992 ◽  
Vol 269 ◽  
Author(s):  
Z. Fathi ◽  
D.E. Clark ◽  
R. Hutcheon
Keyword(s):  
Microwave Field ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Glass Composition ◽  
Silicate Glasses ◽  
Potassium Ions ◽  
Constant Concentration ◽  
Alkali Ions ◽  
Microhardness Indentation ◽  
Alumino Silicate

ABSTRACTSodium alumino-silicate glasses having a constant concentration of alkali ions (15mol%) were prepared. The interdiffusion of potassium ions, K+, for sodium ions, Na+, in the glass composition having AI/Na= 1 was investigated in the presence and absence of a microwave field. Characterization consisted of dielectric loss measurements, electron microprobe analysis (EMP), and microhardness indentation.

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