Abstract: An improved method and system are provided for centrifugally separating a suspended colloidal phase. The method in accordance with a preferred embodiment of the invention involves filling a spinning centrifuge bowl with a fluid medium distinct from the suspension, so that a static zone of liquid forms in the bowl, and then introducing the suspension into the bowl in a feed location concentrically inside of the static zone.

Abstract: A solution containing polymerizable monomers and volatile solvents can be used to disperse ceramic particles along with ceramic whiskers and remain pourable even with high solids. Using this dispersion, a high solids ceramic article can be molded, polymerized in situ and fired with a good binder burnout.

Abstract: Whisker reinforced composites having improved strength and toughness are prepared by a process including densification by essentially pressureless sintering. There is no need to hot press or hot isostatic press to achieve a density of 99+% of theoretical for 10 vol. % whiskers and 93+% for 20 vol. % whiskers. The composites are derived from the desired volume fraction of whiskers, a sintering aid preferably submicron in average size range, and a major portion of a pressureless sinterable matrix material having an average particle size of not more than about 0.5 micron. Yttria-alumina composites are sintered at less than about 1800.degree. C. and for less than about two hours to avoid surface degradation.

Abstract: Slurries or suspensions for forming sintered ceramic or metallic articles are described as having a high volume fraction of sinterable particles, at least 55% by volume. while the slurries maintain a pourable viscosity, such as not more that 2000 cPs at 100 s.sup.-1 ; the slurries can be dilatant and/or pseudoplastic. The slurries are prepared by using specific families of dispersants; namely acrylic acid-based polymeric polyelectrolytes, polyethylene imine-based polyelectrolytes, and coupling agents from the subfamilies of oxy-silane esters and phosphate esters. Fabrication of the compositions includes milling under high energy and the addition of at least a portion of the particles in a step-wise manner.

Abstract: A highly loaded, uniform ceramic composite can be made by first preparing a highly loaded suspension. Due to the particle-particle interactions of a highly concentrated system, virtually any dopant can be added, including other suspensions, fibers, and whiskers. The process is particularly useful for making composites of materials which coagulate when mixed at low concentration.

Abstract: Removal of classified particles from the classifier apparatus is simplified by the addition of a polymeric dispersant in the slurry, added in an amount substantially in excess of that needed to disperse the particles.

Abstract: Commercial wide size distribution powders are size classified into precise size fractions by means of a controlled, semi-continuous, multi-stage centrifugal classification system. The system has utility for a wide range of colloidal materials. The throughput of the semi-continuous process is higher than that of batch processes, and the semi-continuous process produces narrow size ranges and optimum yields.