Indentation

About: Indentation is a research topic. Over the lifetime, 13002 publications have been published within this topic receiving 340476 citations.

Influence of the electric field on vickers indentation crack growth in BaTiO3

Abstract: In this study, the Vickers indentation method was used to determine the crack growth of ferroelectric barium titanate (BaTiO3) ceramic under the influence of electric fields. It was verified that an applied electric field induces distinct anisotropic crack growth parallel and perpendicular to the poling direction which is mainly interpreted as an anisotropy in fracture toughness. The curve of the measured crack lengths as a function of the applied electric field shows similarity with the strain hysteresis. Curves of cracks parallel and perpendicular to the electric field direction are symmetric to each other. Stress-induced ferroelastic domain switching is used to explain the observed crack lengths anisotropy and change in fracture toughness.

Evaluation of modulus of elasticity, nano-hardness and fracture toughness of TiB2–TiC–Al2O3 composite coating developed by SHS and laser cladding

Abstract: Modulus of elasticity (E) and nano-hardness (H) of the composite TiB2–TiC–Al2O3 coating deposited on AISI 1020 steel by combined self-propagating high-temperature synthesis (SHS) and laser cladding process have been measured from load–displacement curves, resulting from nano-indentation testing. Fracture toughness (KIC) of the coatings has been evaluated from the indentation method. A qualitative evaluation of interfacial strength between coating and substrate material was also performed by indentation method. Results indicated elastic modulus and fracture toughness of the composite coatings are in the range of 230–280 GPa and 5.46–6.12 MPa m1/2 those are respectively lower and higher than those of the individual constituent ceramics. Nano-hardness of the coating microstructure obtained was in the range of 16–22 GPa and was found to vary depending on the laser-processing parameter adopted. Indentation taken with high load at the coating–substrate interface indicated a strong interfacial bond between coating and steel substrate. An attempt has been made to co-relate the wear rate of the coating with H/E ratio.

Investigation of the radial compression of carbon nanotubes with a scanning probe microscope

Abstract: Efforts have been made to characterize the mechanical properties of carbon nanotubes. Previous work has concentrated on the tubes' longitudinal properties, and studies of their radial properties have lagged behind. We have used a scanning probe microscope with an indentation/scratch function to investigate the radial compression of multiwalled carbon nanotubes under an asymmetric stress. In particular, we have determined the radial compressive elastic modulus at different compression levels and have estimated the compressive strength to be well beyond 5.3 GPa.

Engineered Interfaces for Adherent Diamond Coatings on Large Thermal-Expansion Coefficient Mismatched Substrates

Abstract: Adhesion of thin or thick films on substrates is a critical issue in systems where the thermal-expansion coefficients of the coating and bulk material are significantly different from each other. The large mismatch of the expansion coefficients results in the generation of very high stresses in the coating that may lead to delamination, cracking, or other deleterious effects. A method to increase the adherence of diamond coatings on tungsten-carbide and stainless steel substrates is reported based on a substrate-modification process that creates a three-dimensional thermally and compositionally graded interface. Scratch and indentation tests on diamond-coated steel and tungsten-carbide samples did not exhibit film fracture at the interface and concomitant catastrophic propagation of interfacial cracks.