Improved alumina-coated inorganic pigments having a first coating of boehmite alumina, a second coating of amorphous alumina, and a third coating of boehmite alumina which exhibit good durability, dispersibility, and optical properties in plastic compositions are disclosed. Also disclosed is a process whereby an aqueous slurry of an alumina-containing inorganic pigment is milled to achieve a particular particle size distribution, a first coating of boehmite alumina is precipitated onto the pigment material within a first pH range, a second amount of an alumina coating agent is added to the aqueous slurry within a second pH range to obtain a second coating of amorphous alumina over the first boehmite alumina coating, and then the pH of the slurry is adjusted to a third pH range thus forming a third boehmite alumina coating over the second amorphous alumina coating.

A water stabilizer polymeric composition incorporating a hydrated alumina filler, which is characterized by the presence of an effective amount of an antimony V compound. The compositions have a reduced tendency to absorb water and specific compositions find applicaiton as electrical insulation and in the production of dimensionally recoverable article.

The present invention concerns finely divided particles of compounds that provide flame retardancy and/or smoke suppressant properties to fibers, textiles, polymeric articles, paper, paint, coating and insulation. More particularly, the present invention concerns colloidal-sized particles of hydrated salts, organic phosphates, metal borates, polyamides, solid halogenated flame retardants with a melting point greater than 250.degree. C., molybdenum compounds, metallocenes, antimony compounds, zinc compounds, bismuth compounds and other solid chemicals which act as flame retardants or smoke suppressants. The present invention also concerns various milling processes to reduce these materials to colloidal sizes and to disperse them in water, organic liquids and meltable solids.

A process for passivating contaminating metal on a hydrocarbon cracking catalyst is provided. The catalyst is contacted within a hydrocarbon catalytic cracking unit with a stabilized dispersion. The dispersion comprises a fluid vehicle, a dispersion agent, and finely milled particles of one or more metals or metal compounds for passivation of metal-contaminated cracking catalysts. The dispersion is preferably produced by a process wherein an agitated media mill is loaded with comminuting media, fluid vehicle, dispersion agent and particles of a metal or metal compound for passivation of metal-contaminated cracking catalysts. The comminuting media, fluid vehicle, and particles are then agitated until the particles are reduced in size by at least 10% and have a volumetric average particle size of less than 0.5 microns.