Application of slip casting method in fabrication of ceramic-metal composites with graded concentration of metallic particles
Mikołaj Szafran, Ewa Bobryk, Magdalena Gizowska, Grzegorz Rosłoniec, Katarzyna Konopka 1-3 Politechnika Warszawska, Wydział Chemiczny, ul. Noakowskiego 3, 00-664 Warszawa, Poland 4, 5 Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa, Poland
Quarterly No. 3, 2007 pages 126-129
DOI:
keywords: ceramic-metal composites, gradient materials, slip casting
abstract The main advantage of ceramic-metal composites is an increase of the fracture toughness of the brittle ceramic matrix. Functionally graded materials (FGM) in the mentioned system provides possibility to obtain material which properties such as fracture toughness, thermal, electrical conductivity etc. change as a function of distance from the surface of material. In the paper the method of ceramic-metal composites with gradient concentration of metal particles is presented. Slip casting was chosen as a composite forming method. The gradient was obtained by means of iron particles sedimentation under gravitation force. In the samples produced from more concentrated slurries magnetic field had to be used in order to obtain a FGM. The slurry consisted of a mixture of iron and alumina powders, liquidizers, surface-active agents and binders and water as a solvent. The composites Al2O3-Fe were fabricated from the slip casting slurry containing 39.5, 42.6, 50% (by volume) solid state. Obtaining FGM by the sedimentation in the gravity force field is possible only when the distance between the dispersed particles/agglomerates is bigger then the diameter of metal particle. Otherwise magnetic field applying is indispensable. Using magnetic field leads to graded character of iron particles distribution in samples produced from more concentrated slurries. Moreover metal particles agglomerates are situated along the magnetic field lines. A fluctuation of iron particles surface in a sample produced from slurry with high solid state concentration of 50% by volume, which is desirable in ceramic technological processes, proving graded distribution of iron along the axis of the composite sample.