Damage Precursors in Individual Microfibers

Structural health monitoring of composite materials is limited by the lack of fundamental understanding of early stage damage at the local material level. This includes damage precursor formation on fiber surfaces, within the matrix, and at the fiber-matrix interface/interphase. In this effort, we present a micro-/nano-scale technique for characterizing damage precursor formation on individual carbon fibers exposed to cyclic tensile loads. Nanoindentation and atomic force microscopy (AFM) were used to study the local properties of the individual microfibers before and after global loading events. An AFM image analysis was used to track evolution of topography on the fiber surfaces. The work is a first step toward understanding damage precursor formation in individual microfibers; the work is expected to enable multiscale composites modeling efforts as well as enable the development of future self-sensing materials.

Download Full-text

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100166798 ◽

1996 ◽

Vol 54 ◽

pp. 866-867

Author(s):

H. Kinney ◽

M.L. Occelli ◽

S.A.C. Gould

Keyword(s):

Surface Roughness ◽

Zeolite Y ◽

Atomic Level ◽

Microporous Structure ◽

Contact Mode ◽

Force Microscopy ◽

Atomic Force ◽

Before And After ◽

Roughness Measurements ◽

Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

Download Full-text

An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope

Materials ◽

10.3390/ma14164384 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4384

Author(s):

Mohd Aidy Faizal Johari ◽

Asmawan Mohd Sarman ◽

Saiful Amri Mazlan ◽

Ubaidillah U ◽

Nur Azmah Nordin ◽

...

Keyword(s):

Stress Relaxation ◽

Shear Band ◽

Shear Bands ◽

Test Duration ◽

Phase Imaging ◽

Force Microscopy ◽

Atomic Force ◽

The Matrix ◽

Relaxation Stress ◽

Band Deformation

Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

Download Full-text

The Physicochemical and Antibacterial Properties of Chitosan-Based Materials Modified with Phenolic Acids Irradiated by UVC Light

International Journal of Molecular Sciences ◽

10.3390/ijms22126472 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6472

Author(s):

Beata Kaczmarek-Szczepańska ◽

Marcin Wekwejt ◽

Olha Mazur ◽

Lidia Zasada ◽

Anna Pałubicka ◽

...

Keyword(s):

Thin Films ◽

Antimicrobial Activity ◽

Ferulic Acid ◽

Phenolic Acid ◽

Food Packaging ◽

Antibacterial Properties ◽

Force Microscopy ◽

Atomic Force ◽

Before And After

This paper concerns the physicochemical properties of chitosan/phenolic acid thin films irradiated by ultraviolet radiation with wavelengths between 200 and 290 nm (UVC) light. We investigated the preparation and characterization of thin films based on chitosan (CTS) with tannic (TA), caffeic (CA) and ferulic acid (FA) addition as potential food-packaging materials. Such materials were then exposed to the UVC light (254 nm) for 1 and 2 h to perform the sterilization process. Different properties of thin films before and after irradiation were determined by various methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimeter (DSC), mechanical properties and by the surface free energy determination. Moreover, the antimicrobial activity of the films and their potential to reduce the risk of contamination was assessed. The results showed that the phenolic acid improving properties of chitosan-based films, short UVC radiation may be used as sterilization method for those films, and also that the addition of ferulic acid obtains effective antimicrobial activity, which have great benefit for food packing applications.

Download Full-text

The Combined Effect of Chemical and Structural Factors on Pitting Corrosion Induced by MnS-(Cr, Mn, Al)O Duplex Inclusions

CORROSION ◽

10.5006/2581 ◽

2017 ◽

Vol 74 (3) ◽

pp. 312-325 ◽

Cited By ~ 8

Author(s):

Cheng Man ◽

Chaofang Dong ◽

Kui Xiao ◽

Qiang Yu ◽

Xiaogang Li

Keyword(s):

Pitting Corrosion ◽

Selective Dissolution ◽

Dissolution Mechanism ◽

Structural Factors ◽

Metal Interface ◽

Kelvin Probe ◽

Force Microscopy ◽

Atomic Force ◽

The Individual

In situ atomic force microscopy, scanning Kelvin probe force microscopy, and potential pulse technology were used to study the pitting behavior induced by inclusions in AM355 martensitic stainless steel. The MnS-(Cr, Mn, Al)O duplex inclusion exhibited the highest sensitivity to the pitting corrosion with respect to the individual MnS and (Cr, Mn, Al)O inclusions. When exposed to a solution containing Cl−, the selective dissolution occurred on the sulfide segment of the duplex inclusion, leading to trenching along the oxide part. The dissolution mechanism of MnS segment in the duplex inclusion is similar to the individual MnS inclusion. The Cr depletion in the boundary layer at the inclusion/metal interface promoted the transition from metastable to stable pitting corrosion in the duplex inclusion.

Download Full-text

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

Powder Diffraction ◽

10.1017/s0885715613000109 ◽

2013 ◽

Vol 28 (2) ◽

pp. 68-71 ◽

Cited By ~ 40

Author(s):

Thomas N. Blanton ◽

Debasis Majumdar

Keyword(s):

Atomic Force Microscopy ◽

Graphene Oxide ◽

Photoelectron Spectroscopy ◽

High Energy ◽

X Ray Diffraction ◽

Carbon Phase ◽

X Ray ◽

Force Microscopy ◽

Atomic Force ◽

Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

Download Full-text

Фотофизические свойства тонких пленок перилена, модифицированного функциональными группами диангидрида и диимида тетракарбоновой кислоты

Физика твердого тела ◽

10.21883/ftt.2021.09.51281.091 ◽

2021 ◽

Vol 63 (9) ◽

pp. 1437

Author(s):

А.С. Комолов ◽

Э.Ф. Лазнева ◽

Е.В. Жижин ◽

Э.К. Алиджанов ◽

Ю.Д. Лантух ◽

...

Keyword(s):

Charge Carrier ◽

Band Gap ◽

Charge Carrier Mobility ◽

Dark Conductivity ◽

Localized States ◽

Semiconductor Films ◽

Force Microscopy ◽

Atomic Force ◽

Before And After ◽

Carrier Traps

The morphology of organic semiconductor films of perylenetetracarboxylic acid dianhydride (PTCDA) and perylenetetracarboxylic acid dibenzyl-diimide (N, N`-DBPTCDI) formed by thermal vacuum deposition was studied by atomic force microscopy. It was shown that annealing of films at 420 K leads to rearrangement of their structure and crystallization. The optical absorption spectra of the films under study were used to estimate the optical band gap. The temperature dependence of the dark conductivity of PTCDA and N, N-DBPTCDI films before and after annealing (Т = 420 K) was established. The values of the activation energy of charge carrier traps are determined. The computer simulation of the density of localized states in the band gap of the films studied was carried out using the photoconductivity spectra in the constant photocurrent mode. Model photovoltaic cells based on PTCDA / СuPc and N, N-DBPTCDI / СuPc structures were formed. The kinetics of decay of the interfacial photo-voltage of the cells prepared was measured using pulsed light as an excitation source. On the basis of the performed measurements, the charge carrier mobility values in the investigated semiconductor materials were estimated.

Download Full-text

Early-Stage Growth Mechanism and Synthesis Conditions-Dependent Morphology of Nanocrystalline Bi Films Electrodeposited from Perchlorate Electrolyte

Nanomaterials ◽

10.3390/nano10061245 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1245 ◽

Cited By ~ 2

Author(s):

Daria Tishkevich ◽

Sergey Grabchikov ◽

Tatiana Zubar ◽

Denis Vasin ◽

Sergei Trukhanov ◽

...

Keyword(s):

Growth Mechanism ◽

Early Stage ◽

Abnormal Behavior ◽

Morphological Properties ◽

Synthesis Conditions ◽

Force Microscopy ◽

Atomic Force ◽

Galvanostatic Regime ◽

Current Densities ◽

Deposition Duration

Bi nanocrystalline films were formed from perchlorate electrolyte (PE) on Cu substrate via electrochemical deposition with different duration and current densities. The microstructural, morphological properties, and elemental composition were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray microanalysis (EDX). The optimal range of current densities for Bi electrodeposition in PE using polarization measurements was demonstrated. For the first time, it was shown and explained why, with a deposition duration of 1 s, co-deposition of Pb and Bi occurs. The correlation between synthesis conditions and chemical composition and microstructure for Bi films was discussed. The analysis of the microstructure evolution revealed the changing mechanism of the films’ growth from pillar-like (for Pb-rich phase) to layered granular form (for Bi) with deposition duration rising. This abnormal behavior is explained by the appearance of a strong Bi growth texture and coalescence effects. The investigations of porosity showed that Bi films have a closely-packed microstructure. The main stages and the growth mechanism of Bi films in the galvanostatic regime in PE with a deposition duration of 1–30 s are proposed.

Download Full-text

THE INFLUENCE OF OXYGEN-CONTAINING FUNCTIONAL GROUPS ON THE SURFACE BEHAVIOR AND ROUGHNESS CHARACTERISTICS OF GRAPHENE OXIDE

NANO ◽

10.1142/s1793292013500458 ◽

2013 ◽

Vol 08 (04) ◽

pp. 1350045 ◽

Cited By ~ 27

Author(s):

AHMAD ALLAHBAKHSH ◽

FARHAD SHARIF ◽

SAEEDEH MAZINANI

Keyword(s):

Graphene Oxide ◽

Functional Groups ◽

Three Dimensional ◽

Diffraction Method ◽

Force Microscopy ◽

Atomic Force ◽

Wire Frame ◽

Stick Model ◽

The Individual ◽

Graphene Oxide Sheets

The effects of oxygen-containing functional groups on the surface roughness of graphene oxide are thoroughly studied using three-dimensional atomic force microscopy images, ball-and-stick model and wire-frame view results. Moreover, X-ray diffraction method and Fourier transform infrared spectroscopy are employed for characterizing the structural and chemical behavior of graphene oxide, respectively. Graphene oxide sheets show a clear concavity on one side when the aggregation of functional groups increased on the other side. This behavior could be the main reason for the surface fluctuation of graphene oxide sheets that is observed in microscopic images. In addition, the individual graphene oxide sheet presents greater values of mean roughness compared to multilayered sheets.

Download Full-text

Comparative abrasive wear resistance and surface analysis of dental resin-based materials

European Journal of Dentistry ◽

10.4103/ejd.ejd_380_17 ◽

2018 ◽

Vol 12 (01) ◽

pp. 057-066 ◽

Cited By ~ 10

Author(s):

Maleeha Nayyer ◽

Shahreen Zahid ◽

Syed Hammad Hassan ◽

Salman Aziz Mian ◽

Sana Mehmood ◽

...

Keyword(s):

Wear Resistance ◽

Structural Changes ◽

Wear Testing ◽

Dental Resin ◽

Force Microscopy ◽

Atomic Force ◽

Custom Made ◽

Significant Difference ◽

Before And After ◽

Roughness Analysis

ABSTRACT Objective: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared. Materials and Methods: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques. Results: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant. Conclusions: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis.

Download Full-text