Reliability of ferrocement slabs under cyclic thermal-shock loading

The reliability of ferrocement slabs subjected to cyclic thermal-shock loading induced by raindrops during service is investigated. The data are obtained experimentally by subjecting specimens to heating and wetting cycles and monitoring the residual first-crack strength at different periods. The imposed thermal-shock loads simulate actual service conditions and are estimated by monitoring the temperature of typical roofing slabs just before the commencement of rain over a period of time. The mean deterioration in strength obtained after correcting for curing effects due to ageing and temperature, as well as the uncertainty present, are used to assess the reliability of slabs having residual first-crack strengths above some prescribed values at different periods. The results indicate that ferrocement slabs posses good flexural resistance with respect to the cyclic loadings studied and are suitable for use as roofing elements.     

Preparation of a functional nanofibrous polymer membrane incorporated with poly(2-aminothio phenol) stabilized gold nanoparticles

Functional nanofibrous polymer membranes were prepared by incorporating poly(2-aminothio phenol) (P2AT) stabilized Au NPs onto electrospun polyvinylidene fluoride (PVdF) nanofibers (designated as P2AT-Au NPs@PVdF-NFM). The preparation of P2AT-Au NPs@PVdF-NFM involves two steps: loading of 2AT (monomer) into electrospun PVdF nanofibrous membrane and polymerization of 2AT by gold chloride. P2AT and Au NPs were simultaneously formed into the electrospun PVdF-NFM. Transmission electron microscope image of P2AT-Au NPs@PVdF-NFM informs the presence of Au NPs (with sizes ~10 nm) onto PVdF-NFM.     

Electrochemical synthesis and characterization of poly(aniline-co-1-amino-9,10-anthraquinone), a nanosized conducting copolymer

The electrochemical copolymerization of aniline (ANI) with 1-amino-9,10-anthraquinone (1-AAQ) was carried out in 4 M sulfuric acid by potential cycling in the potential range of −0.1 V to 1.3 V vs. SCE. Copolymer films were grown from different feed ratios of ANI and 1-AAQ (0.2:0.8, 0.4:0.6, 0.5:0.5, 0.6:0.4, 0.8:0.2) on a glassy carbon electrode (GCE). Studies on the effect of scan rate on the conductivity of the copolymer film confirmed the formation of a stable conducting copolymer film. The FTIR spectrum recorded for the copolymer film provides concrete evidence of copolymer formation, since it indicates the presence of quinone units in the copolymer backbone. XRD data (particle size: 47 nm) and SEM (grain size: 100 nm) micrographs provide a clear picture of the nano-sized polymeric particles formed. It is envisaged that the newly reported copolymer could be a useful material for performing the catalytic reduction of oxygen in an acidic medium—a useful process for fuel cell applications.     

Thermal stress and probability of failure analyses of functionally graded solid oxide fuel cells

Thermal stresses and probability of failure of a functionally graded solid oxide fuel cell (SOFC) are investigated using graded finite elements. Two types of anode-supported SOFCs with different cathode materials are considered: NiO-YSZ/YSZ/LSM and NiO-YSZ/YSZ/GDC-LSCF. Thermal stresses are significantly reduced in a functionally graded SOFC as compared with a conventional layered SOFC when they are subject to spatially uniform and non-uniform temperature loads. Stress discontinuities are observed across the interfaces between the electrodes and the electrolyte for the layered SOFC due to material discontinuity. The total probability of failure is also computed using the Weibull analysis. For the regions of graded electrodes, we considered the gradation of mechanical properties (such as Young’s modulus, the Poisson’s ratio, the thermal expansion coefficient) and Weibull parameters (such as the characteristic strength and the Weibull modulus). A functionally graded SOFC showed the least probability of failure based on the continuum mechanics approach used herein.