Porosity Analysis in Porous Brass Using Dual Approaches

Abstract

The goal of this research is to produce porous samples for various applications such as heat exchangers, filters and radiation shields. The level of porosity is an important objective yet the level of confidence in two main methods (hand calculations and microscopic analysis) is not high. This work will compare porosity values obtained from traditional hand calculations against analysis from microscopic imaging. Brass powder was mixed with sodium chloride (NaCl) and Polyvinyl Alcohol (PVA) to create porous brass to examine the different levels of porosity in the porous brass. Porous brass was fabricated by powder metallurgy using the dissolution sintering technique by mixing brass with NaCl to obtain the volume ratios of 1:0.5, 1:1, 1:1.5 and 1:2 brass to sodium chloride. The expected porosities are as follows: 1:0.5-33, 1:1-50, 1:1.5-60 and 1:2-67%. In order to create a mixture of the desired volume ratios the respective density of each component must be factored into an equation to determine the measured mass for mixing. The NaCl was leached away for 2 hours in 90°C water after sintering. Scanning Electron Microscopy (SEM) was used to confirm the morphology of the porous brass. It was also used to observe the particle size while viewing the particle’s shape and surface appearance. SEM imaging showed a hierarchical bimodal structure existing of macropores and micropores throughout all samples. The porous samples were polished and their micro pore morphology was captured at three different levels.