Ceramic-metal composites obtained by slip casting method
Magdalena Gizowska, Mikołaj Szafran, Ewa Bobryk, Łukasz Wasilewski, 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. 1, 2008 pages 53-58
DOI:
keywords: ceramic-metal composites, gradient materials, slip casting
abstract In the study the results of researches considering the use of slip casting method in fabrication ceramic-metallic composites are presented. Slurry consisted of ceramic (-Al2O3) and metallic powder suspended in water with addition of a liquidizers’ composition (citric acid and diammonium citrate), surface-active agents and binders. Nickel (of average particle diameter 2.13 m and density of 8.9 g/cm3) and iron (of average particle diameter 4 m and density of 7.81 g/cm3) powders were used as a metallic phase. Both were added in amount of 3% by volume (in reference with total solid state amount). In the proposed environment (e.i. water as liquid medium, deflocculants) it is possible to control the distribution of iron particles in alumina matrix by means of solid state content in slurry, the forces causing the metal particles movement etc. Ceramic-metallic composites Al2O3-Fe with graded concentration of Fe particles were obtained by gravity sedimentation of heavier iron particles and by additional forcing the movement of iron particles in magnetic field. In the latter case higher concentration of solid state in the slurry could be used. The double layer surrounding the suspended iron and alumina particles has in both cases positive charge and there is so electrostatic attraction between them. The gradient of metallic particles concentration can be obtained when distance between the suspended particles in the slurry is bigger then the average metal particle diameter. Nickel particles in water show very low pH value of isoelectric point and in the produced slurry heterofloculation was observed. This effect can guarantee homogeneous distribution in Al2O3-Ni composites obtained via slip casting method.