Procedure of the multiple indentations for determination of the hardness parameters of structurally heterogeneous materials

Abstract

A procedure of multiple indentations has been proposed as a promising method of studying surface properties of structurally heterogeneous bodies. It has been shown that this procedure is applicable to a wide spectrum of multiphase (including superhard) materials, ceramics, and metals and makes it pos sible to assess mean properties of separate phases and a composite as a whole as well as a degree of the sam ple hardness inhomogeneity at various scale levels. Such information is important in prediction of the wear and machinability of structurally heterogeneous materials. Experimental and model results that verify the efficiency of the procedure have been presented.

Printable, castable, nanocrystalline cellulose-epoxy composites exhibiting hierarchical nacre-like toughening

“…At this point, we can draw an analogy between the microstructure and mechanics of CNC-epoxy composites and those of biological composites such as bone and nacre, which are largely composed of brittle constituents, and yet display ductile mechanical behavior at larger scales [12]. Here, statistical results from nanoindentation can connect the nanoscale mechanical behavior to the micro-mechanical properties of the CNC-epoxy composites, by relating the indentation depth to the intrinsic length scale of the microstructure of the material [47]. Indentation at shallow depth allows individual phases in the sample microstructure to be resolved, while deep indents provide averaged values representative of the macroscopic mechanical properties.…”

Intensive electro sintering of diamond composites with multicomponent Ni-Sn based binder

“…It has been found that adding Cr increases the contact thermal conductivity of diamond-binder interface tenfold, from 2.1·10 6 to 2.3·10 7 W/(m 2 •K) [14] being typical value for chemical bonding case [15]. [16], which consists in conducting a series of tests ( fig. 9) followed by statistical processing of the obtained indentation curves ( fig.…”

Young’s modulus and hardness of multiphase CaZrO3-MgO ceramics by micro and nanoindentation

“…In the same way, heterogeneous anisotropic composites such as layered or coated materials present a similar problem, being the thin films a clear example of this behaviour [15]. Moreover, even for phases whose properties can be determined in bulk specimens, their characteristics when included in a composite are often somewhat different from material characteristics in bulk pieces [16][17][18]. Thus, in many cases the mechanical characterization of the constituent phases, in order to deduce their contribution to the overall behaviour of the composite, obviates conventional mechanical testing of large representative specimens.…”

“…the slope of the initial portion of the unloading curve, employing the Oliver-Pharr method [19]. Extensive work has been dedicated to extract the local mechanical characteristics of ceramics from the loading-unloading curves [13][14][15][16][17][18][20][21][22][23][24][25][26][27].…”

“…In order to characterize multiphase bulk materials, the grid indentation statistical analysis was proposed by Ulm et al [20] and has successfully been applied to assess mean properties of separate phases in different ceramic materials [13][14][15][16][17]21,22]. The method involves the analysis of a large number of indentations performed blindly on the surface assuming that the frequency of results is determined by the volume fraction of the phases.…”