Search

An attempt has been made to determine the influence of oxygen diffusion hardening (ODH) treatment on the microstructure, microhardness and wear behaviour of TC4 alloy. In order to study the effect of ODH treatment, specimens were laser surface melted under ambient atmosphere by different laser input power and scan speed. Characteristic features of the ODH surface were revealed by scanning electron microscope (SEM). The composition of the ODH scales were measured by energy dispersive X-ray analysis (EDX). The microhardness of the ODH scales and the TC4 substrate were identified by microhardness tester. The load was 100 g with a holding time 15 seconds. The wear performance was also evaluated. The surface layer comprises an oxidised rutile TiO2 layer and an underlying oxygen diffusion hardening zone. And it has been found that the surface oxidised layer was adherent to the substrate. The oxygen concentration was gradually decreased from the outmost surface to the substrate. The microhardness was found to be as high as 927 HV, while the substrate had a microhardness of about 340 HV. The laser ODH treated TC4 titanium alloy exhibited significantly improved abrasive wear resistance. [ABSTRACT FROM AUTHOR]

In the present work a self-fluxing NiCrBSi+WC powder was laser clad onto a H13 hot worked tool steel. The purpose of the experiment was to enhance the wear resistance of the H13 steel. The results show that up to 0.9 mm thick, fully dense and crack-free NiCrBSi+WC laser clad layers could be formed on the H13 steel substrates. The microstructure of the clad coating was analysed by scanning electron microscope (SEM) with attached energy dispersive X-ray analysis (EDX). The microhardness of the clad layers was measured using a Vickers microhardness tester. Wear behaviour was determined by using block-on-ring sliding linear contact at 133.5 N loads and sliding speeds 0.65 m/s. It was found that no pores and crack-free clad layers could be obtained, with measured hardness ranging from 732 to 874 Hv. Higher concentration of precipitates were observed in the overlapped clad tracks. The clad layer wear resistance was a factor of 2 to 3 times higher than that of the unclad H13 tool steel. The wear mechanisms are discussed. [ABSTRACT FROM AUTHOR]

SUMMARYEchinacea purpureahas been introduced in to Taiwan and grown successfully. However, information regarding the effects of the growing climate on its active constituents (e.g. caffeoyl derivatives) and biomass production is very limited. In this study the biomass of field-grown E. purpureaplants harvested during three different crop seasons was compared. The content of caffeoyl phenols and the production of aerial plant parts were also assayed. The results indicated that both morphological and agronomic traits were affected by crop season, with spring-grown plants producing more stems and flowers but fewer leaves than autumn-grown plants. Autumn-grown plants produced more caffeoyl phenols, particularly cichoric acid and caftaric acid, in leaf and flower tissues than spring grown plants. Thus, transplanting E. purpureaseedlings in the autumn and harvesting the aerial parts at the beginning of winter first, and then harvesting the rhizome-regenerated plants again in the following summer are technically feasible. This farming system would give commercial cultivation of E. purpureain Taiwan a great competitive advantage over other growing regions, provided that an environmentally suitable population is selected and established in Taiwan. [ABSTRACT FROM AUTHOR]

Lithiated Nafion 112 ionomer was characterized by FT-IR spectroscopy, AC impedance, and cyclic voltammetry. The ionomer swollen with mixed solvents of propylene carbonate (PC) and ethylene carbonate shows ionic conductivity of 8.18×10-5Scm-1 at 25°C and good electrochemical stability to allow operation in Li/ionomer/LiCoO2 cells. The discharge capacity of the first cycle is 126mAhg-1. Significant capacity loss occurs during cycling due to the presence of PC. AC impedance shows that the passive layer formed at the Li/ionomer interface dominates the cycling performance of the cell. [ABSTRACT FROM AUTHOR]

Examines the fabrication of lead magnesium niobate (PMN) ceramics by reactive sintering of metal oxide mixtures. Transformation of the precursor powder to perovskite PMN-lead titanate (PT); Production of PMN-PT crystals by solid-state conversion; Use of PMN as a ferroelectric material for capacitors.