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ZnO varistors with submicrometre and nanoscaled microstructures and enhanced electrical properties were prepared by spark plasma sintering (SPS). The densification, grain size and switch field of the varistors were compared with those of hot pressed material. The switching field increased with decreasing grain size, and very rapidly below 500 nm. Switching fields up to 180 kV cm 21 were obtained for ceramics with submicrometre grain sizes (380 nm). This is nearly two orders of magnitude higher than those currently reported for commercial ZnO varistors. A nano powder, prepared by high energy milling, was sintered to a high density at much lower temperatures compared with the submicron powders and had a nanoscale grain size (45 nm). The nanoceramic broke down dielectrically under very high fields (.260 kV cm 21 ) before a varistive response was apparent.

The basis of this research was an exploration of the fundamental phenomena that determine the response of silicon carbide-reinforced aluminium composite material to thermal cycling between cryogenic and ambient temperatures. This analysis began with a phenomenological approach that investigated the role of the production, processing, and machining of composite materials, and led to study of their mechanical behavior at cryogenic temperatures. Electric discharge machining was done on the composite specimens and mathematical models were developed for predicting the machining parameters such as metal removal rate, tool wear rate, and surface roughness. A five-level factorial design was chosen for experimentation and mathematical models were developed using the software DOE-PC IV. An analysis of variance technique was used to calculate the regression coefficients and to check the significance of the models developed. This approach provided an understanding of how temperature and vol.% of SiC influence composite machining behavior. The hardness, wear resistance, and tensile property are high for cryo-treated specimens and these properties reduce with increase in temperature. The properties also increase with increasing % of SiC reinforcements. The microstructures of the wear specimens show worn-out layers and grooves formed in the debris. The cryo-treated and the higher reinforced specimens exhibit less material removal and tool wear rate and this increases with increase in temperature. There is a relatively higher surface roughness when there is greater material removal.

Manufacturing of composite material has been an extensive area of research as they have high strength-to-weight ratio that are equivalent or superior to many metallic materials. This paper describes the preparation of E-Glass (woven fabric) Fiber Reinforced Polymer Composite (GFRP) with different fiber mat material, orientation and resin. The purpose of this paper is to investigate the influence of the process parameters on the mechanical properties of GFRP composite using Taguchi experimental design in combination with Grey Relational Analysis (GRA). The conclusion revealed that fiber orientation and resin were the most influential factor on the mechanical properties, respectively. It is observed that the optimum properties were obtained at 400 fabric mat, polyester resin, 45°/–45°orientation.

Many of the machines and systems having rotating components are designed for operation at high speeds, and hence, it is obvious that only these elements are damaged initially and becomes the root cause of a defect in any machine. Using on line, continuous monitoring techniques, any defect in a rotating part can be detected at its initial stage itself and the user could be alerted before it leads to a catastrophic failure. In this experimental work of the acoustical failure diagnosis, three domestic mixers, the first one in healthy condition, the next mixer about to fail and the last with completely damaged bush were analyzed, with a Type-1 and Delta ohm HD2010 Model sound level meter (SLM). The acoustical readings of the three mixers were measured and tabulated in decibel, using Delta Ohm Noise Studio software. Graphs were drawn for different sets of readings and by analyzing the graphs of the three mixers, the threshold value of the initiation of the defect was found to be 80 decibel, at which failure starts.