A numerical analysis program, based on slab analysis, was developed to calculate the stresses and strains that occur in the component layers of a composite sheet in the roll bite during the fabrication of clad metal (e.g. silver clad phosphor bronze) by roll bonding. Results calculated using the perfect plastic and strain hardening models were compared with experimental results: the results obtained using the strain hardening model were found to be in better agreement with values of rolling force and thickness of component layers measured after roll bonding. The program requires input data such as roll radius, initial thickness of the specimen, initial cladding thickness fraction, reduction ratio, coefficients offriction between rolls and material and between component layers, and front and back tensions. The coefficients offriction were evaluated indirectly by comparison of the measured rolling force with that calculated using slab analysis. Measured coefficients of friction varied with reduction ratio and initial thickness, but were independent of rolling speed.MST/1334 List of symbolsh thickness of monolithic or composite sheet after rolling, mm hA, hB thickness of soft and hard layers, respectively, mm H initial thickness of monolithic or composite sheet, mm HA, HB initial thickness of soft and hard layers, respectively, mm k A , k B shear yield stress of soft and hard layers, respectively, MN m-2 k A mean shear yield stress of Ag, MN m -2 P vertical pressure, MN m -2 PA, PB rolling pressure on soft and hard layers, respectively, MN m-2 PAB pressure on soft/hard layer interface, MN m-2Pc, Pe calculated and experimental rolling force, respectively q soft/hard layer thickness ratio r reduction ratio RA, RB radius of roll in contact with soft and hard layers, respectively, mm v rolling speed, m s -1

This paper introduces a strategy for improving the sensitivity of a gas sensor to NO2 gas. The gas sensor was fabricated using urchin-like ZnO nanostructures grown on MgO particles via vapor-phase growth and decorated with MgZnO nanoparticles via a sol-gel process. The urchin-like ZnO gas sensor decorated with MgZnO showed higher sensitivity to NO2 gas than a pristine urchin-like ZnO gas sensor. When ZnO and MgZnO form a heterojunction, a two-dimensional electron gas is generated. This improves the performance of the fabricated gas sensor. The growth morphology, atomic composition, and phase structure were confirmed through field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

A strategy for improving the sensitivity of a sensor for detecting CO and NH3 gases is presented herein. The gas sensor was fabricated from ZnO metal oxide semiconductor nanostructures grown via a vapor–liquid–solid process and decorated with α-Fe2O3 nanoparticles via a sol–gel process. The response was enhanced by the formation of an α-Fe2O3/ZnO n–n heterojunction and the growth of thinner wires. ZnO nanowires were grown on indium–tin–oxide glass electrodes using Sn as a catalyst for growth instead of Au. The structure and elemental composition were investigated using field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The gas sensing results indicate that the response value to 100 ppm CO was 18.8 at the optimum operating temperature of 300 °C.

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