A review on the rotary ultrasonic machining of advanced ceramics

Advanced ceramics are likely candidates for many industrial applications due to their superior properties. However, their high machining costs lead to limited applications. Rotary ultrasonic machining (RUM) is one of the cost-effective machining processes available for drilling holes in advanced ceramics. This paper reports on investigations in the last few years on RUM process of advanced ceramics. Emphasis is given on the effect of RUM process parameters (such as applied static load, rotational speed, ultrasonic power and vibration amplitude, abrasive grit size and coolant) on machinability parameters (such as material removal rate, tool wear and surface roughness). Results on tool wear and edge chipping are also reported

Phase transformation and microstructure behaviour of Cu-Al-Ni shape memory alloys incorporated with cobalt addition

The effect of Co addition on phase transformation temperatures and microstructures of Cu-Al-Ni SMA were investigated via differential scanning calorimetry, field emission scanning electron microscopy corresponding with energy dispersive spectroscopy and x-ray diffraction. The results revealed that the β1’ and γ1’ phases’ morphology and orientation were varied after the addition of Co along with the presence of intermetallic compounds known as γ2. This phase was indicated using the EDS and XRD is related to the intermetallic compound of Al75Co22Ni3. In addition, the phase transformation temperatures tend to increase with the addition of Co and this enhancement is mainly attributed to the variation of phase morphology and the existence of γ2 precipitates

The role of bismuth on the microstructure and corrosion behavior of ternary Mg-1.2Ca-xBi alloys for biomedical applications

In this study the influence of various Bi additions on the microstructure and corrosion behavior of the Mg-1.2Ca-xBi alloys (x = 0.5, 1.5, 3, 5, 12 wt.%) were evaluated by using optical and scanning electron microscopy, immersion and electrochemical tests. Microstructural observations showed that the refinement efficiency became more pronounced with increased Bi amount. Microstructural results of Mg-1.2Ca-xBi (x = 0.5, 1.5, and 3) indicated that the formation of three distinct phases - namely a-Mg, Mg2Ca and Mg3Bi2. However, further addition of Bi to 5 and 12 wt.% leads to evolution of a-Mg, Mg3Bi2, and Mg2Bi2Ca phases. The addition of Bi up to 0.5 wt.% enhanced corrosion resistance while further addition from 1.5 to 12 wt.% accelerated the degradation rate because of the emergence of more galvanic coupling between the a-Mg phases and secondary phases. The analyses showed that the Mg-1.2Ca-0.5Bi alloy gives the best corrosion resistance behavior, which makes it ideal for biodegradable medical applications