A novel technique for automatic quantification of porosities in spray formed warm rolled Al-Si-graphite composite

Microstructural features mainly porosities affect the mechanical and tribological properties significantly in spray deposited composite materials. These make undesirable microstructural features to develop the components for automobile and aerospace. Secondary processes like rolling, extrusion and forging generally minimize these porosities results improve the mechanical and tribological properties. The proper analysis of the porosities in the spray deposited composites is difficult. It requires material researchers or scientist who identifies and measures the porosity manually, but this process takes the more time, labor and exhibits poor repeatability. Additionally, some image processing tools are also available to analyze the porosities in which ImageJ exhibits great importance. But, it does not distinguish between the inclusions and porosities. This paper overcomes the challenges of actual porosity by proposing a new program made in MATLAB. The image processing algorithm is developed to isolate the inclusions and porosities in the microstructural features. MATLAB plays a crucial role in scanning both the scanning elonton microscope (SEM) and backscattered electrons (BSE) images and subtracts the area of inclusion phases from the total detected dark phase and thus produced another fresh image with only the actual porosity. With this method, the porosity of spray formed warm rolled Al-Si-Gr composite is investigated under different rolling reduction (20, 40, 60 and 80%) and verified experimentally by Archimedes principle (ASTM G99-95a). The proposed technique used to measure the porosities may improve the speed and repeatability of the results.