Stress-corrosion cracking of Zircaloy-2 in methanol-iodine solutions

Annealed Zircaloy-2 cracks intergranularly when uniaxially stressed in boiling methanol-iodine solutions containing 0.002 to 20.0 g $\text{I}{}_2\text{1}$. The time to failure decreases with increasing iodine concentration. Stressing to 75% of the 0.2% proof-stress increases the dissolution rate by about 20 times. Both the corrosion rate and the time to failure under stress are independent of impressed electrochemical potential. The activation energy for dissolution, 8350 cals/mole for the unstressed condition, is reduced to 3360 cals/ mole under applied stress. This activation energy probably corresponds to the adsorption of I₂ on the Zircaloy surface. The mechanism of the stress-corrosion cracking seems to be one of stress—assisted dissolution controlled by the adsorption of I₂.     

Drying and energy aspects of tapioca sago processing-an experimental field study

Journal of Mechanical Science and Technology - The drying characteristics of tapioca sago were studied using four different drying methods—Open sun drying (OSD), Conveyor belt drying (CBD),...     

Sustainable thermal energy storage technologies for buildings: A review

Energy management in buildings is indispensable which would control the energy use as well as the cost involved while maintaining comfort conditions and requirements in indoor environments. Energy management is intensely coupled with energy efficiency and increasing of which would provide a cost-effective pathway for reducing greenhouse gas emissions. In recent years, the magnitude of energy consumption in buildings seems to crest from the normal demand and that has to be carefully addressed through implementing energy conservative and energy management techniques. In the class of having several energy efficient schemes, thermal energy storage (TES) technologies for buildings are increasingly attractive among architects and engineers. In the scenario of growing energy demand worldwide, the possibility of improving the energy efficiency of TES systems can be achieved from break-through research efforts. The prime intention of this paper is to review the potential research studies pertaining to a variety of latent heat energy storage (LHES) and cool thermal energy storage (CTES) systems solely dedicated for building heating, cooling and air conditioning (A/C) applications. Technical revelations regarding the integration and performance evaluation of heat storage materials in building fabric elements as well as using separate heat storage facility to satisfy the space thermal load demand have been gleaned from numerous research contributions and presented. Emphasis is also given on advanced heat storage materials produced using micro and nanoparticles to realize their improved heat transfer characteristics which would eventually enhance the overall performance of these TES systems. Furthermore, the sustainable aspects of these TES systems to gain the Leadership in Energy and Environmental Design (LEED) credentials for low carbon/high performance buildings are signified.     

Input advanced control of semi active half car heave model

This paper deals with an input-based half car vehicle model moving with constant velocity over a terrain surface, where MR damper is fixed in both the wheels. The half car model fixed in a rolling dynamometer is operated with various input frequencies corresponding to various speeds. To design and develop control algorithms that will give optimum benefits of the unique features of the MR damper, models have been developed which adequately characterize the damper’s genuine, natural nonlinear behavior. The controller controls both the dampers according to variations in parameters of road surface, speed and load etc., with an advanced time with a particular time bound, through input (pre-programmed) based skyhook on/off control system. Comparison of experimental results of input based and ordinary skyhook on/off results indicates that the model is more functional and rewarding for vibration suppression over a wide range of operating conditions and is passable for control design and analysis.     

Chromium-induced passivity of a Zr-Cr alloy in a chloride solution

An attemp has been made to explain the occurrence of a well defined hump in the cathodic polarisation curve about a potential of −0·550 V sce in a Zr −0·83% Cr alloy as found in an earlier study of stress corrosion cracking of this alloy. By controlled potential weight loss studies it was found that this hump is due to the formation of an active passive transition occuring at this potential in the Zr-Cr alloy but which does not in pure zirconium.     

Passivity and pitting of corrosion resistant pure metals Ta,Nb, Ti,Zr, Cr and A1 in chloride solutions

The relative passivity and pitting resistance of pure metals Ta, Nb, Ti, Zr, Cr and A1 in chloride solutions were studied through quasi-stationary potentiokinetic anodic polarization technique. Studies were conducted in both non-aqueous methanolic and aqueous chloride solutions containing 0.4% HC1 with either hydrogen or oxygen saturation, in order to determine the role of water and oxygen in the passivity of these metals. Ta and Nb are passive in all the solutions, Zr and Cr require sufficient water to become passive, Ti needs both water and oxygen for stable passivity while A1 dissolves actively in all the solutions. The pitting resistance of the above metals decreases in the order Ta > Nb > Ti > Cr > Zr > Al. These passive metals are prone to pitting in chloride solutions in the absence of sufficient water which is the essential passivating agent.     

Experimental investigation of the effect of different cooling methods on drill‐induced damage in pultruded composites

Pultruded (nonlaminated) composites find application in construction of bridges, prefabricated walkways and platforms, ballistic applications, and so forth. However, literature on the drilling of nonlaminated composites is scarce. In addition, many researchers have also proposed that standard twist drill is not suitable for making quality holes in composites under dry conditions. Hence, this study is to analyze the influence of external and internal cooling methods on drill‐induced damage factor while drilling glass fiber‐reinforced epoxy pultruded composites and thereby to find the suitability of widely available twist drill. The drilling experiments using TiN/TiAlN‐coated tungsten carbide twist drills of diameter of 10 mm were conducted using response surface methodology. From this investigation, it is evident that the internal cooling method is significant for obtaining high hole quality followed by external cooling method, and thereby suitability of twist drill has been proved. POLYM. COMPOS., 37:2855–2859, 2016. © 2015 Society of Plastics Engineers     

Novel polyvinyl alcohol polymer based nanostructure with ferrites co‐doped with nickel and cobalt ions for magneto‐sensor application

Uniform nanosheet‐like structures were synthesized by the polymer based co‐precipitation route. Different concentrations of polyvinyl alcohol (pure (0 g), 0.2 g and 0.5 g) were added to nickel (Ni) and cobalt (Co) ion co‐doped ferrite magnetic nanoparticles. X‐ray diffraction confirmed a spinel structure phase of the Ni ? Co ferrites. Enhanced average crystallite size (6.7%) of the Ni ? Co ferrites was found on polymer incorporation. The molecular functional group of polyvinyl alcohol and Ni ? Co ferrites was confirmed by infrared and Raman spectroscopy techniques. On adding polymer, the spherical morphology of the Ni ? Co ferrites was tailored to nanosheets (200 nm × 300 nm). Therefore, the polymer based co‐precipitation technique is an inexpensive, simple and effective route to engineer the morphology of the magnetic nanostructure and could be useful for gas sensor and magnetic sensors. © 2016 Society of Chemical Industry     

Prediction of tensile properties of hybrid-natural fiber composites

The tensile strength and modulus of short, randomly oriented hybrid-natural fiber composite was found out experimentally and also predicted using Rule of Hybrid Mixture (RoHM). Hybrid composites were prepared using banana/sisal fibers of 40:0, 30:10, 20:20, 10:30, and 0:40 ratios, while overall fiber volume fraction was fixed as 0.4V_f. The comparison between experimental and RoHM showed that they are in good agreement.