Densification and Deformation Behavior of Sintered P/M Zinc-Zinc Oxide Composite during Cold Upsetting
Studies were carried out to evaluate the initially preformed density and initial aspect ratio on the densification behavior of sintered Zinc and Zinc Oxide composite. The preform possessed 0.85 is the initial density. Aspect ratio for three different oxidizing temperatures (at 150°C, 200°C and 250°C) varied from 0.4 to 0.85. Properties of Zinc-Zinc Oxide composites with respect to linear strain, lateral strain and true stress were evaluated and plotted. Studies revealed that higher stress and higher strain values are obtained in composite when compared to the Zinc dust. The composite of Zinc-Zinc Oxide obtained at 150 o C possessed the highest stress and strain when compared to the composites obtained at others two temperatures (200 o C and 250 o C).
Application of Aluminium Matrix Composites in Inertial Navigation Instruments
Metal matrix composites (MMCs) is wellsuited for inertial navigation instruments (INS) with its good performance and low cost.With the development of main application technologies such as balanced reinforcement,molding,machining and heat treatment,three major processes become maturity.This paper analyzes the random vibration and damping feature of MMCs of which a key part of a typical fixed INS is made and concludes that such material will be helpful to improve inertial navigation system in coherent frequency,damping factor and accuracy stability.This material will be available for INS in about two years.
Processing and properties of Al2O3 nanocomposites reinforced with sub-micron Ni and NiAl2O4
Abstract A new process has been developed to produce sintered α-Al2O3 reinforced with sub-micron Ni particles. The process is based on the infiltration of ceramic preforms with liquid salts, which are reduced during pressureless sintering to form metal particles. The reduction occurs within the open pores of the ceramic preform, after evaporation of the metal salts into the gas phase. By controlling the partial pressure of oxygen during the sintering process, a reaction between the Ni particles and the alumina matrix can be invoked to form Ni-spinel (NiAl2O4) particles. Three-point bending experiments show an increase in strength for the nickel-reinforced alumina and a significant increase for the spinel-reinforced alumina.