Indentation

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

Relationships Between Initial Unloading Slope, Contact Depth, and Mechanical Properties for Conical Indentation in Linear Viscoelastic Solids

Abstract: Using analytical and finite element modeling, we examine the relationships between initial unloading slope, contact depth, and mechanical properties for spherical indentation in viscoelastic solids with either displacement or load as the independent variable. We then investigate whether the Oliver-Pharr method for determining the contact depth and contact radius, originally proposed for indentation in elastic and elastic-plastic solids, is applicable to spherical indentation in viscoelastic solids. Finally, the analytical and numerical results are used to answer questions raised in recent literature about measuring viscoelastic properties from instrumented spherical indentation experiments.

Mechanical characterization of a polysiloxane-derived SiOC glass

Abstract: Silicon oxycarbide glass with the composition Si1.0O1.6C0.8 was synthesized from a commercial polysiloxane by polymer pyrolysis. Dense SiOC samples were obtained by cross linking of the polysiloxane followed by warm pressing to form cylindrical samples and subsequent pyrolysis of the shaped polymer at 1100 °C in Ar. Hardness (H), Young's modulus (E) and Poisson's ratio (ν) of the as-prepared SiOC glass were evaluated from indentation studies and from acoustic microscopy. Indentation studies showed that E depends on the applied load and amounts to 90 GPa for low load and to 180 GPa for high load. Average values of 6.4 and 101 GPa were obtained for H and E, respectively, by the Vickers indentation method. Acoustic microscopy analysis yielded values of 96 GPa and 0.11 for E and ν, respectively. Compared to vitreous silica, the Young's modulus of the SiOC glass is about 1.3–1.5 times higher. To the knowledge of the present authors, the measured Poisson's ratio (ν = 0.11) is the lowest reported so far for glasses and polycrystalline ceramics.

The mechanical behavior of silicon during small-scale indentation

Abstract: The mechanical behavior of crystalline silicon during small-scale indentation has been studied using a Nanoindenter Tests were performed on bothp-type andn-type materials in the (100), (110), and (111) orientations at peak loads ranging from 05 to 120 mN The indentation load-displacement curves exhibit two features which appear to be unique to silicon First, at large peak loads, a sharp discontinuity in displacement is observed as the indenter is unloaded Second, at small peak loads, a large, non-degenerative hysteresis is exhibited Possible mechanistic origins for the discontinuity and hysteresis are discussed

Microstructure and properties of carbon nanotube/zirconia composite

Abstract: Sintering and hot pressing have been used for preparation of monolithic ZrO2 and zirconia–carbon nanotube (CNT) composite. The effect of the processing route and the CNT's addition on the microstructure, fracture/mechanical and electrical properties of the zirconia has been investigated at room temperature. The microstructure of the sintered and hot-pressed monolithic ZrO2 consists of a submicron-sized grains. The matrix of the ZrO2–CNT composite consists of a grains with even smaller size (approximately 140 nm) with relatively well dispersed carbon nanotubes. The hardness and the indentation toughness of the sintered monolithic zirconia are 1297 kg/mm2 and 8.01 MPa m0.5 and of the hot-pressed monolithic zirconia 1397 kg/mm2 and 6.24 MPa m0.5, respectively. The addition of the CNT's decreased the hardness and indentation toughness to 830 kg/mm2 and 5.6 MPa m0.5 however the electrical resistivity decreased significantly in comparison to the monolithic zirconia to the value of 0.1 Ω cm.