Use Of Nanoindentation Technique Research Articles

Characterization of Mechanical Properties and Creep Behavior of Woven Glass/Epoxy Substrates by Nanoindentation

Reliability is of a concern when designing new products. Extensive set of reliability tests are performed before a product is ready to be shipped for use. Drop testing, thermal cycling, power cycling, etc. are some of the tests used to assess the reliability of new electronic products. However, performing experimental study of every new design is costly and time consuming. Computational tools (such as finite element analysis software) are often employed to perform the required reliability analysis in a shorter time period and save valuable resources. One of the challenges of performing computational analysis is obtaining accurate material property data to be used for building accurate models. Extensive set of material characterization work needs to be carried out before an accurate model can be developed. For example, for a new printed circuit board (PCB), the bulk properties are often characterized by equipment such as thermomechanical analyzer and tensile testing machines to obtain the bulk properties that can be used for the computational study. However, if a detailed layer-by-layer model is required for the study, it is often difficult to obtain location-dependent mechanical properties for a given woven glass/epoxy substrate. In this article, the use of nanoindentation technique to measure the modulus and creep behavior for a specific layer in the PCB stack-up is investigated. Using measurements at room temperature, the effect of surface roughness, hold time, and maximum load on measurement values is examined.

Durability of crystalline phase in concrete microstructure modified by the mineral powders: evaluation by nanoindentation tests

Abstract This paper presents the nanoindentation investigation of the evolution of concrete microstructure modified by the Internal Crystallization Technology mineral powders. The samples under study were retrieved from a fragment of a circular concrete lining of the vertical mine shaft at a depth of approximately 1,000 m. Due to the aggressive environment and exposure to contaminated water, the internal surface of the structure was deteriorated, decreasing its strength significantly. The mineral powders were applied directly on the surface lining. The specimens were investigated one month, three months and one year after the application of the aforementioned substance in order to verify the time dependence of the strengthening processes and durability of the crystalline phase. The microstructural changes of concrete were assessed with the use of nanoindentation technique. The testing procedure involved including the previously cut specimens in the epoxy resin and grinding and polishing in order to reduce the surface roughness. As a result of the nanoindentation tests the hardness as well as Young’s modulus of the material were evaluated. The results were then compared and statistically analyzed. As a consequence, the disintegration time of the crystalline network in the pores of concrete was identified.

Comparative adhesion analysis at glue joints in European beech and Norway spruce wood by means of nanoindentation

To gain a better insight into the delamination behaviour of glue joints in hardwood, the adhesion at the cell wall level was investigated. By the use of nanoindentation techniques, the adhesion, hardness and Young's modulus of adhesively bonded European beech wood (Fagus silvatica L.) was analysed. To highlight differences between soft- and hardwood adherends, Norway spruce wood (Picea abies KARST.) was also investigated. One-component polyurethane (PUR) and phenol resorcinol formaldehyde resin (PRF) were used for bonding. Untreated and aged samples (artificially and naturally weathered) were analysed and compared to silylated samples as reference, assuming the silylation reduces the adhesion to a minimum. From the gathered results it can be concluded that artificial ageing has the same effect as natural weathering on, both, adhesion and the properties of the single components of a bond. In beech wood, weathering increases the adhesion of PUR significantly. For PUR in spruce wood, the adhesion is not affected by any treatment. Tensile shear tests signified a reduced adhesion in all silylated samples. Additionally, the stiffness and hardness of both adhesives were found to be reduced by approximately 10%. As a consequence, the applied silylation is not considered as adequate treatment for reference samples.

Reduction of Elastic Modulus of Titanium Alloy Ti-6Al-4V by Quenching

The use of nanoindentation techniques enhances the capabilities of qualitative analysis of elasto-plastic characteristics, especially, estimating mechanical properties of relatively small specimens in their surface layers. The results are in agreement with macromethods, which gather the information over the higher volume of the material. It was confirmed, that hardening of double phase Ti-6Al-4V alloy by quenching from beta temperatures (above beta-transus), reduces the elastic modulus by about 8 % due to increased ratio of low-modulus beta phase from 8 to 34 %.

Use of nanoindentation technique for a better understanding of the fracture toughness of Strombus gigas conch shell

In this work the nanochemical properties of the composite organomineral biomaterial constituting Strombus gigas conch shell are studied by means of dynamic mechanical analyses associated to nanoidentation technique. The measurements are performed on shell samples presenting different surface orientations relative to the growth axis of the conch shell. The influence of the organic component of the biomaterial on its nanomechanical properties is also investigated by studying fresh and dried S. gigas conch shells. Monocrystalline aragonite is used as a reference. For the understanding of nanochemical behaviour, special attention is paid to the pop in events observed on the load/displacement curves which results from nanofractures' initiation and propagation occuring during the load process. In order to better understand the mechanical properties systematic studies of the structure and morphology are performed using scanning electron microscopy, atomic force microscopy and X-ray diffractometry. The hardness and Young's modulus values measured on bio aragonite samples are close to those of the aragonite mineral standard. This surprising result shows that, H and E values are not related to the bio composition and lamellar structure of the bio aragonite. However, it was found that the organic layer and the micro architecture strongly influence the nanofracture initiation and propagation processes in the samples. Statistic study of the pop-in events can help to predict the macroscopic mechanical behaviour of the material.

Material characterization of blanked parts in the vicinity of the cut edge using nanoindentation technique and inverse analysis

Sheet metal blanking is widely used in various industrial applications such as automotive and electrical rotating machines. When this process is used, the designer can be faced with several problems introduced by the change of the material state in the vicinity of the cut edge. In general, blanking operations severely affect mechanical and physical properties of blanked parts. To take into account these modifications during the part design, it is important to assess the influence of the process parameters on the resulting material properties. Previous experimental and numerical investigations of blanking process have been carried out, leading to the development and the validation of a finite element model that predicts the shape of the cut edge and state of the material. The study presented in this paper makes use of nanoindentation technique to improve the validation of the previously cited model. To this end, nanoindentation tests were combined with inverse identification technique to approach some of the characteristics of material state like work hardening near its cut edges. Indentation tests were carried out in the vicinity of several parts of cut edges. Based on the corresponding load versus penetration curves, the evolution of the yielding stress resulting from the material work hardening was estimated and compared to the predictions obtained from the numerical simulation of blanking process. These comparisons show good agreement between the measurements and the predictions from finite element model.

Nanoindentation stress–strain curves of plasma-enhanced chemical vapor deposited silicon oxide thin films

Plasma-enhanced chemical vapor deposited (PECVD) silicon oxide (SiO x ) thin films have been widely used in Micro/Nano Electro Mechanical Systems to form electrical and mechanical components. In this paper, we explore the use of nanoindentation techniques as a method of measuring equivalent stress–strain curves of the PECVD SiO x thin films. Four indenter tips with different geometries were adopted in our experiments, enabling us to probe the elastic, elasto-plastic, and fully plastic deformation regimes of the PECVD SiO x thin films. The initial yielding point ( σ I) and stationary yielding point ( σ II ) are separately identified for the as-deposited and annealed PECVD SiO x thin films, as well as a standard fused quartz sample. Based on the experimental results, a shear transformation zone based amorphous plasticity theory is applied to depict the plastic deformation mechanism in the PECVD SiO x .

Novel routes to nanocrystalline mechanical characterization

The use of nanoindentation techniques to measure nanoscale mechanical behavior is a new path of interest to researchers today. Load drops and displacement excursions can be utilized to measure activation volumes for dislocation events in single crystals, thin films, and nanoposts. Through the introduction of a new length-scale parameter, the dislocation wall spacing, a mechanism describing staircase yielding, is presented. The dislocation wall spacing can also be used to estimate activation volumes. Molecular dynamics simulations of nickel film indentation have been used to validate the origin of staircase yielding and also show consistent dislocation wall spacings. Additionally, stress relaxation experiments have been used to estimate activation volumes.

Measurement of Stress-strain Curves of PECVD Silicon Oxide Thin Films by Means of Nanoindentation

AbstractIn this paper, we explore the use of nanoindentation techniques as a method of measuring equivalent stress-strain curves of the PECVD SiOx thin films. Three indenter tips with different geometries were adopted in our experiments, enabling us to probe different regimes of plastic deformation in the PECVD SiOx thin films. A shear transformation zone (STZ) based amorphous plasticity theory is applied to depict the underlying plastic deformation mechanism.

Substrate Effects on Hardness and Polishing of SiO2 Thin Films

The hardness of films grown or deposited on silicon was measured by use of nanoindentation techniques to determine the effect of the substrate on the film hardness. These experiments were compared with polishing experiments of films. Our results indicate that the substrate had no influence on the polish rate, although it strongly influenced the hardness. The observations suggest that the depth of deformation of films by abrasives during polishing is much shallower than that by the diamond indenter. A greater influence on polishing rate is expected for films on softer substrates, such as aluminum, where greater deformation of the film by abrasives would take place.

Nanoindentation Studies in a Liquid Environment

Surface and chemomechanical effects are of considerable importance in tribology, wear, and friction. Recently there has been substantial interest in the use of nanoindentation techniques to investigate these phenomena for asperity size indentations. In this paper we report a new type of nanoindentation experiment where tip and sample are immersed. We show that with due care the difficulties due to surface tension when testing in liquid can be overcome, and well-controlled nanoindentation experiments can be conducted for even the shallowest indentation depths. This type of testing, under model environmental conditions, has potential utility in the examination of several key mechanisms involved in tribology. This is demonstrated by experimental results for GaAs in distilled water and single-crystal tungsten in aqueous HCl and distilled water. When GaAs is indented in conditions of high atmospheric humidity, the area around the indentation exhibits substantial bulging, reminiscent of lateral cracking. Testing of the same sample under distilled water does not give this result. The implication is that capillary condensation present in atmospheric ambient has a quite different effect to complete immersion in water. This is probably due to the modified forces acting when water has condensed at the tip-sample interface. Nanoindentation curves for electropolished, single-crystal tungsten are almost perfectly elastic for shallow indentations. We have assessed the effects of the passivating, surface oxide film on the elastic behavior by nanoindentation tests in air and under aqueous HCl and distilled water. The results for HCl, which is known to remove the oxide film, indicate that the elastic behavior in BCC metals is modified by the passivating layer, but is not wholly dependent on it.