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Showing papers on "Indentation published in 1997"


Journal ArticleDOI
TL;DR: The hardness and brittleness of ceramic materials are interrelated as mentioned in this paper, and a new index of britteness is proposed by means of extensive Vickers hardness testing, which examines the interrelationship between hardness and fracture processes.
Abstract: The hardness and brittleness of ceramic materials are interrelated. Hard materials are more apt to fracture in the vicinity of an indentation during a hardness test, while softer materials tend to plastically deform to the indenter shape without fracturing. Measured hardness, in turn, is affected by both specimen deformation and fracture processes. This interrelationship is examined by means of extensive Vickers hardness testing. A new index of brittleness is proposed.

423 citations


Journal ArticleDOI
TL;DR: In this paper, the authors combine hardness indentation tests and micro-Raman spectroscopy to show that metallic Si-II is produced near the interface of a diamond indenter and silicon to a depth of about 0.5 μm.
Abstract: Combining hardness indentation tests and micro-Raman spectroscopy it is shown that metallic Si-II is produced near the interface of a diamond indenter and silicon to a depth of about 0.5 μm, where the highest stresses (hydrostatic and deviatoric) exist. At fast unloading rates Si-II transforms to the amorphous state, whereas a mixture of the r8 high pressure polymorph Si-XII and the bc8 phase Si-III forms upon a slow load release. The region of Si-III+Si-XII is surrounded by the wurtzite structured Si-IV, where the stresses during the indentation had not been high enough to cause the transition to the metallic state. Thus, because of shear deformation a direct transformation to Si-IV takes place. Outside the phase-transformed regions the classical aspects of indentation-induced deformation by dislocation glide, twinning and crack formation are observed. Annealing of the high pressure phases leads to the formation of Si-IV at moderate temperatures and to the reversal to the original diamond structure (Si-I...

346 citations


Journal ArticleDOI
TL;DR: It is found that the factor kappa increases almost proportionally to the increase of the indentation depth, especially obvious with a larger Poisson's ratio v and a larger aspect ratio a/h.

281 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented analytical and computational results for the evolution of stresses and deformation fields due to indentation from a rigid axisymmetric indentor on an elastic substrate.

250 citations


Journal ArticleDOI
TL;DR: In this article, an extensive study of indentation creep on the nanometre scale has been made on single-crystal indium, tungsten and gallium arsenide.
Abstract: An extensive study of indentation creep on the nanometre scale has been made on single-crystal indium, tungsten and gallium arsenide. We use the force modulation technique which gives a direct measure of contact stiffness and, being insensitive to thermal drift, allows the accurate observation of creep in small indents to be carried out over long time periods: We show that strain rate indices similar to those for macroscopic creep can be obtained for indium. Stress relaxation negative creep is also observed in a manner similar to macroscopic tests. Indentation of tungsten and gallium arsenide shows a distinct pop-in at a critical load, before which the deformation is essentially elastic and after which it is elastoplastic with significant dislocation multiplication. The creep behaviour is quite different before and after pop-in, clearly demonstrating the role of mobile dislocations in creep, even in nanometre-sized volumes of materials.

204 citations


Journal ArticleDOI
TL;DR: In this article, the authors used finite element simulations to check the analytical theory of Giannakopoulos and Suresh, and to gain further insights into the effects of the variation in Poisson ratio, v, with depth.

177 citations


Journal ArticleDOI
TL;DR: In this article, the Vickers indentation technique was used to detect cracks in a piezoelectric lead-zirconium-titanate (PZT) material under simultaneous mechanical loading and applied electric fields.
Abstract: Crack propagation in a piezoelectric lead–zirconium–titanate (PZT) material under simultaneous mechanical loading and applied electric fields is studied using the Vickers indentation technique. It is demonstrated experimentally that electric fields can inhibit or enhance crack propagation in piezoelectric materials. Cracks introduced by indentation are observed to propagate less under a positive applied electric field (the polarity of the field was the same as that for poling), whereas under a negative applied electric field, crack propagation is enhanced. Such an effect is observed to be more profound with increasing electric-field strength and decreasing mechanical loading. Attempts are made to compare these experimental observations with the results of various theoretical analyses. A mechanism for the change in crack propagation behavior of the piezoelectric PZT material under applied electric fields is presented.

163 citations


Journal ArticleDOI
TL;DR: In this paper, the use of the atomic force microscope (AFM) to measure surface forces has been developed to optimize its operation as a surface imaging tool, which can potentially be extended to evaluate nanoscale material response to indentation and would be ideal for the evaluation of multi-component polymer systems, such as adhesives and composites.
Abstract: The use of the atomic force microscope (AFM) to measure surface forces has been developed to optimize its operation as a surface imaging tool. This capability can potentially be extended to evaluate nanoscale material response to indentation and would be ideal for the evaluation of multi-component polymer systems, such as adhesives and composites. In this paper, previous work related to the development of the AFM as a nanoindentation device is reviewed, and a technique is proposed which allows the AFM to be used to probe local stiffness changes in polymer systems. Cantilever probes with spring constants ranging from 0.4–150 N m were used to investigate a number of polymer systems, including an elastomer, several polyurethane systems, thermally cured epoxies, a thermoplastic polymer-thermosetting polymer adhesive system, and a thermoplastic matrix composite.

159 citations



Journal ArticleDOI
TL;DR: In this paper, a parametric analysis of Vickers and Berkovich indentations using the finite element method was performed and the pressure sensitivity of the materials was modeled according to the classic Drucker-Prager plastic potential.

107 citations


Journal ArticleDOI
TL;DR: In this paper, the authors presented the elastic solution of a layered half space with perfect interfacial bonding under an axisymmetrical compressive loading on the plane surface, which is intended to model the nano-indentation of thin-film coating/substrate systems.

Journal ArticleDOI
TL;DR: In this paper, the shape of the unloading portion of indentation curves is used to calculate the area of contact between the indenter and the material, and the results obtained in fused silica and nickel, including Young's modulus and hardness values, are presented to illustrate the validity of the approach.
Abstract: The information provided by the shape of the unloading portion of indentation curves is used to calculate the area of contact between the indenter and the material. Results obtained in fused silica and nickel, including Young’s modulus and hardness values, are presented to illustrate the validity of the approach. It is shown that errors of only a few percent are introduced when fitting unloading curves with power laws. The present method is especially useful when direct specimen stiffness measurements can be performed.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that the indentation response is determined by the interaction between the evolving plastic zone and the mechanical properties of the specimen material, in particular, the ratio of the elastic modulus to the yield stress.
Abstract: Certain ceramic materials display an indentation response similar to that observed for ductile metals when loaded with a spherical indenter. This unusual behaviour, for what are nominally brittle materials, influences the mode of contact damage in applications such as machining, wear, impact damage and hardness testing. The shape of the plastic zone beneath the indenter is typically fully contained within the circle of contact on the specimen surface and thus conventional hardness theories, such as the popular expanding cavity model, provide an inadequate account of indentation response of the material. The present work demonstrates, by experiment, finite element modelling and theoretical considerations, that the indentation response is determined by the interaction between the evolving plastic zone and the mechanical properties of the specimen material, in particular, the ratio of the elastic modulus to the yield stress.

Journal ArticleDOI
TL;DR: In this paper, a simple relationship between the initial unloading slope, the contact area, and the elastic modulus is derived for indentation in elastic-plastic solids by an indenter with an arbitrary axisymmetric smooth profile.
Abstract: A simple relationship between the initial unloading slope, the contact area, and the elastic modulus is derived for indentation in elastic-plastic solids by an indenter with an arbitrary axisymmetric smooth profile Although the same expression was known to hold for elastic solids, the new derivation shows that it is also true for elastic-plastic solids with or without work hardening and residual stress These results should provide a sound basis for the use of the relationship for mechanical property determination using indentation techniques

Journal ArticleDOI
TL;DR: In this paper, the top skin is modeled as a linear elastic beam and the core as an elastic-plastic foundation, which is used successfully to predict the loads at which the core yields and the skin fails.

Journal ArticleDOI
01 Mar 1997-Wear
TL;DR: In this article, a series of coatings with different average splat size were sprayed from pure alumina powders of different particle size under conditions optimized to obtain the best microstructures.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method to improve the quality of the data collected by the data collection system of the Internet.Abstracts are not published in this journal. But
Abstract: Abstracts are not published in this journal

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the mechanical and tribological properties of amorphous diamond-like carbon (DLC) coatings deposited on Si(100) by a pulsed bias deposition technique.

Journal ArticleDOI
TL;DR: In this article, the authors identify and map differences in the stiffness or elasticity of these ultrathin films at the very near surface (up to a few nm) by using the force modulation technique.
Abstract: Magnetic recording, microelectro mechanical systems, and other microelectronics industries use ultrathin continuous films as well as composite films. The motivation of this research was to identify and map differences in the stiffness or elasticity of these ultrathin films at the very near surface (up to a few nm) by using the force modulation technique. We have shown that this technique amplitudes on samples can yield quantitative elasticity data on samples with an elastic modulus up to a few tens of GPa. This technique provides an alternative to current elasticity measurements that require forces higher than 1 μN, and which can only make single point measurements. With this technique it is possible to make quantitative measurements with loads as low as a few tenths of a μN. By choosing tips that match the stiffness of the sample, the depth of the indentation during the elasticity measurement is kept small, thus eliminating significant plastic deformation of samples of any hardness and any stiffness. The...

Journal ArticleDOI
TL;DR: In this article, the residual stress field and the different structural states induced by loading were studied by mapping the indented zones by their micro-Raman response, and a Raman signature of amorphous silicon is found in the center of the impression.
Abstract: Vickers microindentations obtained with loads between 0.05 N and 2 N were performed on crystalline (100) silicon. The residual stress field and the different structural states induced by loading were studied by mapping the indented zones by their micro-Raman response. A Raman signature of amorphous silicon is found in the center of the impression. The energy of the Γ25 zone center phonon is found to vary from 522 cm−1 when probing the silicon at a distance of 80 μm from the center of the indentation up to 527 cm−1 when probing the pileup region of the impression. When probing cracked zones in the vicinity of the pileup region, wave numbers as high as 536 cm−1 are measured. The stress components induced by a point indentation (1 N) have been calculated from analytical expressions given in the literature. For an average conversion factor of 3.2 cm−1/GPa, the residual local stresses after unloading are found of the same order of magnitude or even larger than the calculated stresses that are generated during loading. A tentative explanation is proposed. Finally a systematic laser-induced thermal treatment of the central area and of the pileup region of indentations was performed. It is shown that the amorphous silicon in the center can partly recrystallize but that the residual stress state in the pileup region cannot be completely relaxed by local laser heating.

Patent
15 Apr 1997
TL;DR: An indentation measurement apparatus is retrofittable onto any of a variety of load-applying frames and includes a mount for mounting an indenter of any geometry (for example blunt or sharp) The arrangement is very stiff and mechanical values including Young's modulus, strain hardening exponent, yield strength and hardness can be obtained from a single load/unload versus displacement test as discussed by the authors.
Abstract: An indentation measurement apparatus is retrofittable onto any of a variety of load-applying frames and includes a mount for mounting an indenter of any geometry (for example blunt or sharp) The arrangement is very stiff and mechanical values including Young's modulus, strain hardening exponent, yield strength, and hardness can be obtained from a single load/unload versus displacement test A wide variety of materials can be tested using the apparatus An optical probe can measure displacement of the indenter head relative to a sample A method of calculating an area of contact between the indenter and the sample directly from the load/displacement measurements is presented, as is a method of calculating the strain hardening exponent

Journal ArticleDOI
TL;DR: In this article, the authors measured the through-the-thickness variations of mechanical properties in SA508 Gr.3 pressure vessel steels using the automated ball indentation (ABI) test technique.

Journal ArticleDOI
V.D. Blank1, M. Popov1, N. Lvova1, K. Gogolinsky, V. Reshetov 
TL;DR: In this paper, a new procedure for the hardness measurements of superhard materials including diamond using the scanning force microscope with the ultra-hard fullerite C60 tip was developed, and the hardness values measured are 137 ± 6 and 167 ± 5 GPa for the diamond faces (100) and (111), respectively.
Abstract: The new procedure for the hardness measurements of superhard materials including diamond using the scanning force microscope with the ultrahard fullerite C60 tip was developed. It is shown that diamond is plastically deformed under the indentation by the ultrahard fullerite indenter at room temperature. Now the correct measurements of diamond hardness have become possible. The hardness values measured are 137 ± 6 and 167 ± 5 GPa for the diamond faces (100) and (111), respectively.

Journal ArticleDOI
TL;DR: In this article, the surface properties of alumina/silicon carbide nanocomposites containing 5 vol.% SiC particles of 4 different size distributions with mean particle size from 12 to 115 nm were examined.

Journal ArticleDOI
TL;DR: In this paper, a finite element simulation of the indentation of rigid indenter into an elastic-plastic half space has been conducted in order to evaluate the influence of material properties on the unloading response.

Journal ArticleDOI
TL;DR: A review of recent work in this area is presented along with results obtained using SFM-based nanoindentation techniques on surfaces and thin coatings in this paper, and some prospects for the future are outlined.

Journal ArticleDOI
TL;DR: In this article, the authors used a 20 μm-thick chromium nitrided chromium film for diamond deposition on iron-based alloys and measured the adhesion of the diamond film to the substrate using an indentation test.

Journal ArticleDOI
TL;DR: In this paper, the effect of reducing Ti layer thickness (λTi) on the mechanical and tribological properties of the laminates was investigated. But the results of the experiments were limited to two types of composites: multi-layered Ti/TiN and Ti/Cu films.
Abstract: Multilayered Ti/TiN and Ti/Cu films of 12–15 μm thickness were produced using an r.f. triode-magnetron sputtering technique. The thickness of Ti layers in both types of composites varied between 150 and 1000 nm. TiN and Cu layers were thinner, and their thicknesses varied within a narrower range of 20–120 nm. The volume fractions of the constituents in the composites were kept constant in order to study the effect of reducing Ti layer thickness (λTi) on the mechanical and tribological properties of the laminates. Nanoindentation tests were performed to determine hardnesses and elastic moduli of the composites and to analyze the energy expenditure during the indentation process. The elastic modulus and hardness of the Ti/TiN films were both higher when tested in a direction parallel to the plane of the layers compared to a direction normal to their planes. The strength of Ti/TiN also increased with (λTi) and showed a good agreement with the strength levels calculated by considering the difference in the elastic moduli of the constituents on the basis of the Koehler strengthening mechanism. Thin Cu layers in Ti/Cu were not effective as barriers to dislocation motion, and Ti/Cu interfaces were susceptible to delamination during indentation tests and sliding wear tests. A linear relationship was observed between the wear rates of Ti/TiN and (λTi)−0.5 which suggests that the wear resistance of the laminated composites can be improved by reducing the distance between the TiN layers.

Patent
14 Nov 1997
TL;DR: In this article, a diffusion plate or microlens array which is free from unevenness of the individual indentation positions to be formed in spite of the random arrangements formed by machining and has good diffusivity is provided.
Abstract: PROBLEM TO BE SOLVED: To provide a diffusion plate or microlens array which is free from unevenness of the individual indentation positions to be formed in spite of the random arrangements formed by machining and has good diffusivity without specifically controlling a machine tool and a process for producing the same. SOLUTION: The formation of the indentations of the same size adjacent to each other is averted in the process for producing the diffusion plate produced by forming the indentations on a workpiece by an indentation using (n) kinds of pressers varying in sizes or the microlens array produced by forming the indentations on a metal mold base material by the indentation method and using such metal mold. COPYRIGHT: (C)1999,JPO

Patent
04 Feb 1997
TL;DR: In this paper, a pointed tip on the end of a bendable cantilever is used to measure the mechanical properties of a surface by pushing the tip into the surface using the bending of the cantilevers as the measure of the constant force.
Abstract: The mechanical properties of a surface are measured by using a pointed tip on the end of a bendable cantilever such that with force on the other end of the cantilever the tip can be pushed into the surface using the bending of the cantilever as the measure of the constant force The indentation, scratch, or wear created by the application of forces between the tip and sample is then measured with the same tip and cantilever by raising the cantilever off the surface and putting it into oscillation The tip is then scanned over the area where the indentation was made with the tip tapping on the surface in order to image the surface