Effect of Yttrium on Toughness of Weld Metal Deposited by TiO_2－CaO Type Electrode

Effect of yttrium on low temperature toughness of weld metal deposited by TiO2-CaO type electrode has been investigated by transfering yttrium from welding pool to weld with fluxcored wire.The results show that the decrease in surface tension of liquid iron in welding pool and the variation in density of inclusion in weld are main causes for toughness improvement effect on weld by yttrium.

Machine-vision-based electrode wear analysis for closed loop wire EDM process control

The purpose of this study was to develop a closed-loop machine vision system for wire electrical discharge machining(EDM)process control.Excessive wire wear leading to wire breakage is the primary cause of wire EDM process failures.Such process interruptions are undesirable because they affect cost efficiency,surface quality,and process sustainability.The developed system monitors wire wear using an image-processing algorithm and suggests parametric changes according to the severity of the wire wear.Microscopic images of the wire electrode coming out from the machining zone are fed to the system as raw images.In the proposed method,the images are preprocessed and enhanced to obtain a binary image that is used to compute the wire wear ratio(WWR).The input parameters that are adjusted to recover from the unstable conditions that cause excessive wire wear are pulse off time,servo voltage,and wire feed rate.The algorithm successfully predicted wire breakage events.In addition,the alternative parametric settings proposed by the control algorithm were successful in reducing the wire wear to safe limits,thereby preventing wire breakage interruptions.

Development of new potentiometric sensors for the determination of proguanil hydrochloride in serum and urine

Potentiometric electrodes were developed for the rapid determination of proguanil hydrochloride in pure samples, pharmaceutical preparations and spiked serum and urine samples using PVC membrane,screen printed（SPE）, coated wired（CWE）, carbon paste（CPE） and modified carbon paste（MCPE）electrodes based on the ion-exchanger of proguanil with phosphotungestic acid（Pr-PT） as a chemical modifier. The prepared electrodes showed Nernestian slopes of 59.7, 58.1, 58.5, 58.5 and 57.0 for the PVC,SPE, CWE, CPE and MCPE for the proguanil ions in a wide concentration range of 1.0 ＊ 10^-5–1.0 ＊ 10^-2mol L^-1 at 25°C with detection limits of 7.94 ＊ 10^-6, 1.0 ＊ 10^-5, 1.0 ＊ 10^-6, 7.07 ＊ 10^-6 and 2.5 ＊ 10^-6 mol L^-1, respectively. The prepared electrodes exhibited high proguanil selectivity in relation to several inorganic ions and sugars and they could be successfully utilized for its determination in pure solutions, pharmaceutical preparations and serum and urine samples using the direct potentiometry and standard addition methods with very good recovery values.

On the localised corrosion of carbon steel induced by the in-situ local damage of porous corrosion products

The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.