Effect of Rare Earth Upon As-Cast Microstructure and High Temperature Performance of ZA40 Alloy
In testing comparison, this study is made on the modification effect of 0.05 wt.% La-rich rare earth (RE) upon as-cast microstructure, mechanical properties of materials at high temperatures (100, 150, 200°C) and wear resistance under different temperatures (100and 200°C) of ZA40 alloy containing Si. The addition of RE shows that it can not only effectively refine Al-rich and Cu-rich phase, but also reduce the amount of needle-like eutectic silicon, and then make the size of massive primary silicon phase smaller. Thus, there are the improvement of strength, ductility and wear resistance of materials at high temperature. The analyses are also conducted on the mechanism of underlying RE elements.
Research on the wear characteristics of hypereutectoid steel
Abstract In this research, the wear behavior of hyper-eutectoid steel was examined at ambient temperature ranging from room temperature to a high temperature of 400 °C. A common asymmetric test rig was used, where a pin specimen of hyper-eutectoid steel is pressed against a disk of carbon steel for machine structure use. Two types of pin specimen were prepared: an as-received specimen and a quenched specimen.. As a result, the following was clarified. The protective surface film of iron oxide is not a main factor in determining the wear behavior of the hyper-eutectoid steel of as-received pin specimens. The wear behavior is closely related to the separation of the oxide film from bulk material when the sliding conditions are severe. The wear behavior of a quenched pin specimen is strongly influenced by a microstructural transition and a reduction in hardness of the pin specimen at elevated temperature.
AN ANALYSIS OF POLYMERIC THICK-FILM RESISTORS AS PRESSURE SENSORS
Abstract The strain-sensing characteristics of thick-film polymer-based resistors printed and cured on 96% alumina are presented. Two layout configurations have been analysed: planar and sandwich. Various strain-gauge characteristics have been studied, including the mechanical and temperature-dependent properties of the polymeric films. It has been shown that the planar polymer resistors exhibit low sensitivity, comparable to that of metal-foil gauges, whereas the MRM (metal-resistor-metal) configurations exhibit similar characteristics to those of cermet thick-film MRM gauges. It has also been observed that the mechanical properties of the polymeric films are significantly poorer than those of cermet-based gauges. This degradation in performance is attributed to the epoxy/pseudo-plastic structure of the polymeric thick-film resistor layer.