Abstract: A coated particle for synthesizing diamond includes: a single crystal of a fine diamond particle coated with at least one layer which contains at least one kind of solvent metal powder for synthesizing diamond and/or at least one kind of solvent metal powder with organic bonding material. Diamond abrasive particles for sawing are produced by a process which includes the steps of: coating fine diamond particles with at least one layer which contains at least one kind of solvent metal powder for synthesizing diamond and/or at least one kind of solvent metal powder with organic bonding material, filling a molding with the coated fine diamond particles, compacting, arranging a compact in a synthesizing vessel, heating the compact to a temperature above a solvent metal-graphite melting point under a pressure condition in which diamond is thermodynamically stable, and recovering the diamond abrasive particles.

Abstract: An improved method and apparatus for preparing low-concentration polyaluminosilicate microgels from a water soluble silicate and an alkali metal aluminate in which the silicate and the aluminate are mixed at a rate to produce a Reynolds number of at least 4000, the mixture is aged and then diluted to a silica concentration of not more than 1.0 wt. %. The method achieves reduced silica deposition during the preparation of the microgels.