Surface layer structure of Al2O3-Ni graded composites depending on gypsum mold porosity
Justyna Zygmuntowicz, Aleksandra Miazga, Katarzyna Konopka, Waldemar Kaszuwara
Quarterly No. 1, 2017 pages 37-40
DOI:
keywords: centrifugal slip casting, Al2O3-Ni, gypsum mold, microstructure
abstract The paper presents the influence of gypsum mold porosity as one of the process parameters allowing change in the gradient microstructure of composites obtained by centrifugal slip casting (CSC). This method combines the effects of slip casting and centrifugation. Composites made by centrifugal slip casting have the shape of hollow cylinders. Three types of gypsum molds with different porosity were used in the experiment. Alumina matrix graded composites with nickel particles were investigated. Slurries with a 45 vol.% solid content were consolidated using centrifugation at 1700 rpm. The composite properties were characterized using X-ray diffraction and scanning electron microscopy. Selected physical properties of the sintered specimens were measured by the Archimedes method. Applying a reductive atmosphere (H2/N2) during sintering averted the formation of NiAl2O4. The research showed that the use of different gypsum molds has an influence on the microstructure of Al2O3-Ni composites. The presented results revealed that with an increase in gypsum mold porosity, the width of the zone with nickel particles in the composites increases. It was found that the maximum width of the zone with the metal particles was obtained by the composites produced using the gypsum mold with the highest porosity.