Papers by Keyword: Nanomechanical Properties

Abstract: Investigating how two different ceramic additives affect the microstructure and nanomechanical characteristics of the Ti6Al4V matrix forms the goal of this work. Under 50 MPa pressure, 10 min dwell time, and 100 °C/min sintering rate at 950 °C, a pulsed electric current sintering process, or PECS, was used. An XRD spectrometer was used to examine the phases, and SEM-EDS was used to examine the bulk morphology of the starting powders and sintered composites. The fabricated Cs1, Cs2, and Cs3 composites attained theoretical densities of 99.74, 98.90, and 96.7%, respectively, above 96.22% of unreinforced Ti-alloy. The SEM analysis showed an even dispersion of the ceramic reinforcements in the matrix of Ti6Al4V, with the characteristics of porous craters in all the samples. Of the three composite samples, Cs1 showed the highest elastic modulus, micro, and nanohardness absolute values of 173 GPa, 796 MPa, and 8942 MPa, respectively, as compared to the unreinforced titanium alloy of 114 GPa, 589 MPa, and 6466 MPa. It was thought that the improved mechanical properties of the sintered composites were due to the production of intermediate phases of Ti₂N and SiO₂ during the sintering process. The materials improvement stands at approximately 30% of the unreinforced Ti-alloy.

Abstract: We studied the microstructure and nanomechanical properties of cast samples of the alloy Mg61Cu28Gd11, obtained by the original method. The alloy Mg61Cu28Cd11 is distinguished by a particularly high glass transition property. In this study samples with a diameter of 16 mm were obtained an inert atmosphere with a cooling rate of 1K/s. Liquid alloy Mg61Cu28Gd11 before crystallization was heated to 780 °C. It was previously installed that, with such heating, irreversible structural changes occur in the melt, which increase the tendency of the metal to glass transition. A metallographic study of the microstructure was performed using a scanning electron microscope and EDS-analysis. Nanohardness HV and Young's modulus E Mg₂CuCd and Mg₂Cu were measured using the nanoindentation method.The microstructure of the Mg61Cu28Cd11 alloy in the cast state consists mainly of Mg₂Cu dendrites; the interdendritic space is represented by the Mg₂CuCd phase. The presence of exogenous nonmetallic inclusions of a complex composition CdO + CuO + MgO was also established by the method of micro X-ray spectral analysis.Analysis of the measurement data of HV(GPa), E (GPa) gave a conclusion about the same degree of homogeneity of the mechanical properties of dendrites and interdendritic space.

Abstract: nanomechanical testing system in this paper has been applied to get elastic modulus and hardness of dragonfly wing, and showing their gradient changes along the wing, and also analyzing the mechanical properties in nanodimension. It is significant to make a further research for specific biological functions of dragonfly wing.

Abstract: Epoxy resin (EP) nanocomposites reinforced with different contents of core-shell structured Ni@NiO nanoparticles (NPs) were fabricated by using a surface wetting method. The nanoindentation and nanoscratch properties of Ni@NiO/EP nanocomposites were comparatively studied based on nanoindentation technique. Results revealed that 5 wt.% content of Ni@NiO NPs was the optimal concentration for Ni@NiO/EP composites to obtain the best improvement of nanomechanical properties. In comparison with pristine EP, the highest enhancements of hardness and elastic modulus of 5 wt.% Ni@NiO/EP nanocomposites were increased by 37.8% and 16.3%, respectively.

Abstract: Carbon based materials have attracted much for its unique surface microstructure and nanomechanical properties among researchers. In this study, the influence of microstructure on the nanomechanical properties of thin carbon based films was studied in detail. For which amorphous Carbon nitride (a-CN) and Titanium incorporated amorphous Carbon nitride (Ti/a-CN) thin films were prepared with a thickness of less than 100 nm using hybrid ion beam deposition technique. The incorporation of Ti into the a-CN matrix greatly modified the sp³/sp² hybridized bonding ratio and it is reflected in the mechanical hardness of Ti/a-CN thin film. Most of the incorporated Ti reacts with carbon and nitrogen to form TiN and TiCN phases respectively. On the other hand, owing to the usage of energetic ion bombardment and the presence of TiN/TiCN phases in the carbon nitride matrix, the Ti/a-CN nanocomposite film shows improved adhesion strength compared to that of pure a-CN film. Overall the presence of hard metallic phase in the amorphous carbon network alters the microstructure and improves the adhesion strength of a-CN films suitable for protective coating applications.

Abstract: According to insect biometric friction sound parts, the nanomechanical measurements were carried out on the cricket wings, the nanomechanical characterization testing analysis results with the sound parts of the friction were obtained and the sound signal extraction eigenvalues correlation with its nanomechanical properties were analyzed. The results show that the nanomechanical properties of biological materials have a relevance with the sound characteristics, the average correlation coefficient between the nanohardness and the sound feature value vector is 0.8875, and the nanohardness is significantly better than elastic modulus parameters, the biological material nanomechanical properties has strong correlation with its sound friction characteristic, and a new method for the relationship between the nanomechanical properties and the insects sound signal friction mechanism are provided.

Abstract: The paper proposed a nanomechanical measurements method according to insect parts biometric friction sound, the nanomechanical measurements were carried out on the cricket and grasshoppers wings, meanwhile, two common insects song signal were collected and the sound quality evaluation parameter vectors were constructed from it. The correlation analysis calculations were made between the nanomechanical properties parameters and the sound quality evaluation parameter vectors. The results show that the nanomechanical properties of biological materials have relevance with the sound quality characteristics, and the average correlation coefficient of the cricket is better, the crickets elastic modulus correlation coefficient with loudness were with the highest average correlation coefficient.

Abstract: Polycarbonate has been widely used in optical and aeronautic areas due to its low weight, transparency and high impact strength. The deposition of hard, transparent and scratch-resistant coatings on polycarbonate can significantly improve the surface mechanical behavior while capitalizing on their desirable bulk characteristics. In this work, nanomechanical properties of transparent scratch-resistant coating on polycarbonate, including nanoindentation and nanoscratch behaviors, were detailed investigated. The significant enhancement of nanomechanical response, containing hardness elastic modulus and friction-resistance, could be obtained after the deposition of the scratch-resistant coating. The results of the systematic investigation of indentation and scratch performance at the nanoscale reveal their significant differences between the surface region and bulk of coatings. Furthermore, the aging properties of scratch-resistant coatings under hygrothermal environment (65°C water for different time) can be followed-up and quantitatively detected in terms of hardness and maximum loading depth changing by nanoindentation technique, which prove to be a new and available method to study aging behavior of thin coatings.

Abstract: The adhesion and mechanical stability of thin film coatings on substrates is increasingly becoming a key issue in device reliability as magnetic and storage technology driven products demand smaller, thinner and more complex functional coatings. In the present study, chemical vapor deposited Co and Co₃O₄ thin films on SiO₂ and Si substrates are produced, respectively. Chemical vapor deposition is the most widely used deposition technique which produces thin films well adherent to the substrate. Co and Co₃O₄ thin films can be used in innovative applications such as magnetic sensors, data storage devices and protective layers. The produced thin films are characterized using nanoindentation technique and their nanomechanical properties (hardness and elastic modulus) are obtained. Finally, an evaluation of the reliability of each thin film (wear analysis) is performed using the hardness to elastic modulus ratio in correlation to the ratio of irreversible work to total work for a complete loading-unloading procedure.