Experimental analyses defining mechanical characteristics of obtained W-Cu-Ni composite applied as a radiation shielding material

Abstract

This work aims to obtain a new composite material of system W-Cu-Ni using the powder metallurgy usable as material for strongly shielding of the gamma radiation as an environmental friendly alternative to lead. Tungsten (W) is the main shielding element in this composite. The main reason to use CuNi in this compound is the miscibility of both metals and their low fusion temperature, allowing liquid phase sintering. The tungsten has high density (19.25 gcm-3), high melting point (3,422 °C) and is presented as matrix of the composite. In order to meet the need for sintering with low temperatures, the liquid phase sintering technique has been used. For sintering temperature optimization, the particles of the metal powders have been homogenized in shape and size. In order to reduce the average particles size, a ball mill has been used for 48 hours. After grinding, the particle size analysis has showed that the mean particle size in WCuNi composition has been 8.6 μm. The powder mixture has been compacted in isostatic press at 200 MPa pressure. The samples have been sintered between 1,100 °C and 1,400 °C at 1100 mbar pressure with a flow of protective atmosphere (Ar2) for 180 min for each temperature. The formation of the isomorphic system CuNi is responsible for giving the mechanical characteristic of solid to the composite WCuNi. The result of micro hardness test shows a maximum of 331 HV and average of 276 HV. Optical and electronic microscopy (SEM) with EDS have been undertaken in order to characterize the samples. The classical scientific method of experimentations with gamma radiation of the cobalt-60 source by attenuation of the energies has been employed to study these effects on the samples. The results shows that composite has more shielding efficient than lead and is safety for life and environment when compared with lead toxity.