Application of Nanoindentation in the Characterization of a Porous Material with a Clastic Texture

Abstract

In materials science and engineering, a significant amount of research has been carried out using indentation techniques in order to characterize the mechanical properties and microstructure of a broad range of natural and engineered materials. However, there are many unresearched or partly researched areas, such as, for example, the investigation of the shape of the indentation load–displacement curve, the associated mechanism in porous materials with clastic texture, and the influence of the texture on the constitutive behavior of the materials. In the present study, nanoindentation is employed in the analysis of the mechanical behavior of a benchmark material composed of plaster of Paris, which represents a brand of highly porous-clastic materials with a complex structure; such materials may find many applications in medicine, production industry, and energy sectors. The focus of the study is directed at the examination of the influence of the porous structure on the load–displacement response in loading and unloading phases based on nanoindentation experiments, as well as the variation with repeating the indentation in already indented locations. Events such as pop-in in the loading phase and bowing out and elbowing in the unloading phase of a given nanoindentation test are studied. Modulus, hardness, and the elastic stiffness values were additionally examined. The repeated indentation tests provided validations of various mechanisms in the loading and unloading phases of the indentation tests. The results from this study provide some fundamental insights into the interpretation of the nanoindentation behavior and the viscoelastic nature of porous-clastic materials. Some insights on the influence of indentation spacing to depth ratio were also obtained, providing scope for further studies.

Encouraging tribomechanical and biological responses of hydroxyapatite coatings reinforced by various levels of niobium pentoxide particles

“…While the pop-in events measured less than 10 nm and 100 nm in length fall under the micron and moderate classes, respectively, those with a length >100 nm are labeled extreme. 56 In general, the observed pop-ins in this work are micron and moderate. For instance, there is a moderate pop-in with a length of 25 nm in the load–displacement curve of the S2 sample, shown by an arrow.…”

Micromechanical Contrast of Ordos Basin Sandstone‐Mudstone Interbedded Layered Rocks

“…During the unloading stage of the load‐displacement curves of minerals, a sudden or gradual change in the unloading slope, known as the “elbow” event, is commonly observed. This phenomenon is associated with the material's relaxation upon the indenter's removal under a specific unloading rate (Kasyap & Senetakis, 2021). On the whole, the features of load‐displacement curves described above can be served as probes to identify mineral types.…”

Multiscale Mechanical Performance of Wood: From Nano- to Macro-Scale across Structure Hierarchy and Size Effects

“…The specific internal and external SEs have been studied not only in void-free poreless materials (metals, alloys, rocks, composites, etc. ), but also in such porous materials as ceramics, solidified foams [ 141 , 142 , 143 , 144 ], and organic gels [ 145 ].…”

“…Due to a discrete character of damage accumulation in porous materials under load, the loading diagrams obtained in NI and in microsample deformation contain deformation jumps. They carry information about elementary events, their rate and statistics as a function of size of the area under load, deformation rate and other experiment conditions [ 143 ].…”