Nonagglomerated powders

Most food-processing companies use spray dryers to produce powdered products. Spray drying has the ability to handle heat-sensitive foods with maximum retention of their nutritive content. The flexibility of spray-dryer design enables powders to be produced in the various forms required by consumer and industry. This includes agglomerated and nonagglomerated powders having precise particles size distribution, residual moisture content, and bulk density. As examples, spray drying of milk, tomato juice, tea extracts, and coffee is discussed. 

Highly reactive nonagglomerated powders can be sintered to high density at low temperatures, without the need for additives. Fully dense ceramics with grain sizes between 0.15 and 0.75 pm were prepared via a pressureless sintering of Sm-doped nanopowders (14nm) at 1000 °C [289]. 

Tai TW and Lessing PA. Modified resin-intermediate of perovskite powders. Part II. Processing for fine, nonagglomerated strontium-doped lanthanum chromite powders. J. Mater. Res. 1992 7 511-519. 

Morphological characteristics. Iron powders obtained by the two-steps procedure described earlier are formed of polyhedral, and even often cubic, nonagglomerated particles with a rather narrow size distribution and a mean size in the... 

In commercial applications of submicron powdered materials as additives, fillens, and pigments, nonagglomerated or weakly agglomerated primary particles are usually desired. Quantitative, predictive methods for describing neck formation and the nature of the bonds between particles are not available. In the ab,sence of proven methods, we di.scu.ss some guidelines that may serve as a starting point for future research. 

A method for producing submicrometer (0.1 im), low-oxygen-content nonagglomerated TiC powders involved the carbothermal reduction of carbon-coated titanium diboride (TiOa) (27), where carbothermal synthesis proceeded via the purification of titanium oxycarbide toward pure titanium carbide. The carbon coating process provided a high contact area of the reactants to produce a TiC powder with uniform shape by synthesis at 1550 C for 4 h. 

In the continuing effort to improve the quality of ceramic powders, preferred characteristics include small and uniform particle size (<1.0 pm) and a nonagglomerated state of dispersion. Several attempts have been reported involving chemical techniques that produce ceramic powders with nanosize particles (1-7). These chemical techniques have been shown to be advantageous by eliminating the need for high temperature calcination reactions and milling procedures to achieve fine particle sizes. Processes that produce the final powder at low temperature and fast reaction time result in a more cost effective material. 

---