Cavitation Erosion Behavior of HPDL-Treated TWAS-Coated Ti6Al4V Alloy and Its Similarity with Water Droplet Erosion

Twin wire arc-sprayed (TWAS) coating of commercially available SHS 7170-cored wire was obtained on Ti6AL4V alloy, and to improve its properties, it was further surface treated with high-power diode laser (HPDL). The cavitation erosion (CE) resistance of TWAS-coated samples was evaluated as per ASTM G-32-2003 and it was compared with laser-treated and untreated Ti6Al4V alloys. The CE resistance of TWAS-coated SHS 7170 samples after HPDL treatment has improved significantly. The main reasons for its improvement are elimination of pores, increased fracture toughness, reduced hardness, and brittleness. The CE resistance of HPDL-treated TWAS coating is compared with water droplet erosion resistance. It is observed that there is a similarity in the both the phenomenon.     

Development and Characterization of a Diaphragm-Shaped Force Transducer for Static Force Measurement

There are different types of force transducers, used over the years, comprising of different principles and have different grades of uncertainty. Force transducers may be analog or digital and may be strain gauged, tuning fork type, piezoresistive type, Hall Effect based etc. Though different types of force transducers have been developed in last few decades, still strain gauged force transducers are used over the larger scale due to practical viability and reliability for force measurement. The paper describes low-cost indigenous development of a force transducer, which has been developed for a nominal capacity of 5 kN with ease of design and manufacturing. It has strain gauges applied at suitable locations to form a Wheatstone bridge. The force transducer has been calibrated according to the standard calibration procedures based on ISO 376 and IS 4169 standards. Measurement results and an uncertainty analysis have been presented. The uncertainty of measurement of the force transducer is found up to 0.06%. The paper also discusses the implications of applying multiple strain gauges at a single location in series to enhance the sensitivity of the force transducer. Two strain gauges are arranged in series for the given location and the sensitivity of the force transducer is enhanced. It also indicates that the uncertainty of measurement of the force transducer in such case is enhanced up to 0.05% or better to make force transducer suitable for most of metrological and industrial applications.     

Low temperature UV/ozone oxidation formation of HfSiON gate dielectric

Physical and electrical properties of hafnium silicon oxynitride (HfSi_xO_yN_z) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSi_xO_yN_z are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10⁻⁵ A/cm² at V_fb+1 V. The films have a breakdown field strength >10 MV/cm.     

Biodosimetry using chromosome aberrations in human lymphocytes

In vitro dose-response calibration curves for (60)Co gamma rays have been established for unstable chromosome aberrations in human peripheral blood lymphocytes. The observed dose-response data were fitted to a linear quadratic model. The calibration curve parameters were used to estimate the equivalent whole-body dose and dose to the irradiated region in partial body irradiation of cancer patients. The derived partial body doses and fractions of lymphocytes irradiated were in agreement with those estimated from the radiotherapy regimes.     

Cross-national assessment of specialization patterns in chemistry

In this study, the specialization profiles of eleven countries are compared along two interconnected but distinct dimensions of research, viz. publication output and citation impact in nine subfields of chemistry. The data for comparative analysis were taken from Scientometric Datafiles.¹Since raw counts of publications and citations are confounded by the size of the countries and the size of subject fields, cross-national comparison is made, using relative indicators—activity index and attractivity index. The subfields of relative strength and weakness for these countries are identified from the values of these indicators. The similarity structure of specialization profiles of the eleven countries is mapped, using hierarchical cluster analysis and multidimensional scaling. This mapping leads to the representation of chemistry as it is structured by the dynamics of national science policies of these countries.     

Theory and Practice of γ + α2 Ti Aluminide: A Review

Among the high temperature materials γ + α₂ Ti aluminide is the most promising material, which has unique characteristics of low density coupled with high temperature properties. However, the low room temperature ductility of the alloy has limited its commercial application. Many studies have been carried out on this alloy to understand the phase transformation and role of alloying elements. Several processing methodologies have been attempted and advantages of various routes have been explored. However, poor ductility at room temperature is still a concern. In the present paper a thorough review of relevant studies has been carried out and viable route for industrial processing has been suggested. This paper includes theoretical concepts behind limited ductility of alloy at room temperature and its processing difficulty through the conventional methods. Modification in binary Ti aluminide alloy through alloying addition, selection of suitable processing route and heat treatment are noted as important areas which can provide a practical solution for this alloy to bring it to industrial processing and application.     

Spark Plasma Sintering of Cryomilled Nanocrystalline Al Alloy - Part II: Influence of Processing Conditions on Densification and Properties

In this study, nanostructured Al 5083 powders, which were prepared via cryomilling, were consolidated using spark plasma sintering (SPS). The influence of processing conditions, e.g., the loading mode, starting microstructure (i.e., atomized vs cryomilled powders), sintering pressure, sintering temperature, and powder particle size on the consolidation response and associated mechanical properties were studied. Additionally, the mechanisms that govern densification during SPS were discussed also. The results reported herein suggest that the morphology and microstructure of the cryomilled powder resulted in an enhanced densification rate compared with that of atomized powder. The pressure-loading mode had a significant effect on the mechanical properties of the samples consolidated by SPS. The consolidated compact revealed differences in mechanical response when tested along the SPS loading axis and radial directions. Higher sintering pressures improved both the strength and ductility of the samples. The influence of grain size on diffusion was considered on the basis of available diffusion equations, and the results show that densification was attributed primarily to a plastic flow mechanism during the loading pressure period. Once the final pressure was applied, power law creep became the dominant densification mechanism. Higher sintering temperature improved the ductility of the consolidated compact at the expense of strength, whereas samples sintered at lower temperature exhibited brittle behavior. Finally, densification rate was found to be inversely proportional to the particle size.     

An enrichment based new criterion for the simulation of multiple interacting cracks using element free Galerkin method

This paper presents a new intrinsic enriched element free Galerkin method (EFGM) criterion for the simulation of multiple interacting crack problems. The principle attraction of the proposed criterion lies in its ability to handle multiple cracks of equal/unequal lengths. According to this proposed criterion, few modifications are made in standard intrinsic enriched EFGM criterion to solve multiple interacting cracks lying on the same as well as on the opposite face under plane stress conditions. The values of mode-I and mode-II stress intensity factors have been evaluated using domain based interaction integral approach. The modeling capabilities and accuracy of the proposed criterion has been demonstrated by comparing the results with those obtained by FEM. The proposed enrichment criterion has been found quite capable in analyzing crack growth as well as equal or unequal size multiple cracks.