Nanoindentation tests

The modulus from a nanoindentation test is often reported in terms of a reduced elastic modulus, Er, to take into account the fact that at this size scale, the elastic response of the probe tip, E(, as well as the modulus of the test material, E, must be considered ... 

Page, T.F. 1996. Nanoindentation testing. In Solid-Solid Interactions (M.J. Adams, B.K. Biswas, B.J. Briscoe, eds.), pp. 93-116, Imperial College Press, London. 

Nanoindentation testing by CDR does not give values of absolute microhardness directly. This is because microhardness is usually defined as load divided by indent area projected onto the plane of the surface, and this area is not explicitly measured in nanoindentation testing. However, the data can be processed on the basis of well established assumptions (Loubet et al, 1984) to yield relatively direct information that is of value in quality control. 

Figure 2.15. Types of information obtained from nanoindentation testing by CDR. (From Pollock, 1992.)...

In practice, several investigators have found the advantages of CDR to be overriding. Pollock (1992) offered a very valuable review dealing primarily with nanoindentation testing using CDR. 

The hardening and embrittlement of polyimides by ion implantation has been also studied (Pivin, 1994). Nanoindentation tests performed using a sharp diamond pyramid of apical angle 35° provided very quantitative depth profiles of microhardness in polyimides implanted with C, N, O, Ne or Si ions. In all cases the microhardness increased steeply when the amount of deposited energy reached the order of 20 eV atom". For energies of 200 eV atom" the polymer is transformed into an amorphous hydrocarbon and the microhardening factor saturates at a value of 13-20. However, the carbonized layer is poorly adherent, as is evidenced by reproducible discontinuities in the depth vs load curves, when the indenter tip reached the interface. 

Pellicle and tea-immersed pellicle were analyzed using nanoDMA (dynamic mechanical analysis) to see if the tannins had an effect on the viscoelasticity of the pellicle. NanoDMA is a technique used to study and characterize mechanical properties in viscoelastic materials. The method is an extension of nanoindentation testing [58, 59], An analysis of the nanoindentation load-depth curve gives the hardness (H) and reduced elastic modulus (E ), provided the area of contact, A, between the indenter tip and the sample is known [ 13]. By... 

A significant improvement in nanoindentation testing is continuous stiffness measurement (CSM). ... 

Fig. 12.29. Snapshot from the deformation history for a nanoindentation test simnlated nsing molecular dynamics (adapted from Kelchner et at. (1998)). The atoms shown in the figure are those with energy above a certain threshhold and reveal the passage of dislocations.

Fig. 12.32. Size dependence of hardness as revealed nsing a nanoindentation test (adapted from Nix and Gao (1998)).

Nanoindentation tests of the samples show that hardness of (Ti,Zr)N films (Fig. 3) increases in comparison with TiN and ZrN films approaching to the hardness of boron carbide B4C (40GPa). The effect of increased hardness is probably due to a solid-solution strengthening mechanism. 

In Figure 6.8, the histogram is adduced, which shows elasticity modulus E change, obtained in nanoindentation tests, as a function of load on indenter P or nanoindentation depth /r. If the dependences E P) or EQi) are identical qualitatively for all the three considered nanocomposites, then the dependence E h) for nanocomposite BSR/TC was chosen, which reflects the indicated scale effect quantitative aspect in the most clearest way. 

Two parameters are often of most interest in nanoindentation testing ... 

Load (P) versus depth of penetration (h) curves, also called compliance curves, are the output from a nanoindentation test. The curves are obtained as load is applied to the indenter tip up to some maximum value and then back to zero. 

The scratch tests are very similar to the nanoindentation tests and can be considered side by side. In both teclmiques, a prime tip is used for the adhesion measurements by dragging across the measuring surface under an increasing load, which results in an indentation. Scratch and indentation tests are suitable for the analyses of the coatings and thin films [100]. Sharp diamond indenters are usually used for the adhesion and scratch resistance determination between the substrate and coating. These techniques can fail for the analyses of hard coatings on soft substrates due to no detectable failures as a result of small critical loads. Therefore,... 

According to the Eq. (34) v =0.20 and calculation according to the Eq. (33) gives the value 0.283, that is close enough to the value v=0.216 according to the Eq. (32) estimation. The obtained by the indicated methods values V and comparison demonstrates, that in the dependence E h ) h j<0.5 mcm) the first part in nanoindentation tests only rubber-like polymer matrix (v=v 0.475) is included and in this dependence the second part-the entire nanocomposite as homogeneous system [51] - v=v =0.22. 

In this study, nanoindentation tests were used to examine the load-displacement behavior of different constituents of C/C composites, to obtain information on their hardness, elasticity, plasticity, and recovery... 

The elastic moduli of the as-sintered porous LSCF cathode film samples were measured using a NanoTest nanoindentation platform (Micromaterials, UK) with a spherical diamond indenter tip of 50pm diameter. Compared with sharp indenters like Berkovich tips, benefits of using spherical tips include less sensitivity to surface condition. At least 20 measurements were conducted in different locations for each sample in order to measure the variability of the mechanical response of the sample. Prior to nanoindentation tests, the NanoTest platform was precisely calibrated using a standard sihca sample to establish the system frame compliance. 

In nanoindentation tests of thin films, one of the key difficulties is to avoid errors in measuring film properties caused by influence of the substrate. To do so, an appropriate indentation depth (hmax) and/or an indent load (Pmax) are desired by taking into account the test film s thickness and the nature of the substrate (whether it has higher or lower elastic modulus than the film). Indenting to a depth less than 10% of the thickness of a film (namely hmax/tf < 0.1) has been empirically considered as a safe condition to avoid effects from substrate and extract intrinsic film properties in routine nanoindentation tests " . However, it can be found in our case that the effect from substrate was much less significant for indentation depth up to 0.2tf, as shown in Figure 3. Moreover, the influence of the substrate was not as marked for films sintered at 1100 and 1200 °C, as the plots stabilised as plateaus after indentation depth increased beyond 0.2tf. This was most probably because the stiffness of these films was closer to that of the substrate. 

Rico, A., Garrido, M. A., Otero, E. Rodriguez, J. Roughness Effect on the Mechanical Properties of Ceramic Materials Measured from Nanoindentation Tests. Key Engineering Materials 333, 247-250 (2007). 

Nanoindentation is regarded as a good method to evaluate hardness in materials. In the nanoindentation test, a diamond indenter is forced into... 

Nanoindentation tests were used by Dhaka and collaborators to study the effect of various organoclay concentrations on the nanomechanical properties of UP nanocomposites [10]. A strong correlation was found between the mechanical properties and interlayer d-spacing of clay particles in the nanocomposite system. Cured UP resins with incorporated 1%, 3%, and 5 wt% organoclay exhibited hardness increased by 29%, 24%, and 14%, respectively. Also the elastic modulus was increased by 23% with the introduction of 5 wt% organoclay. 

During nanoindentation testing, a set load in the miUinewton range is applied to the indenter in contact with the specimen (Fig. 6.2). The penetration depth in the... 

Figure 6.2 Schematic diagram of a nanoindentation test (a) and commonly used indenter type (b) Vickers indenter (c) elongated diamond-shaped indent formed on the sample by Knoop indenter (d) spherical indenter and (e) Berkovich indenter.

Haj-Ali, R., Kim, H.K., Koh, S.W., Saxena, A., Tummala, R., 2008. Nonlinear constitutive models from nanoindentation tests using artificial neural networks. Int. J. Plast. 24, 371-396. 

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