Abstract: A method of forming a partial protective coating on phosphor particles to improve initial power output and maintenance of fluorescent lamps made with the phosphor. The phosphor particles are fluidized in a bed and at least partially enveloped by a coating precursor material. Residence time of the phosphor particles in the fluidized bed is short so that the phosphor particles are only partially coated with the coating precursor material. The coating precursor material is reacted to form a protective coating over at least a portion of the surface of the phosphor particles. The partially-coated phosphor particles are then annealed to cause the protective coating to selectively cover at least a portion of certain sites on the surface of the phosphor particles.

Abstract: A process is disclosed for applying a lubricant to a powdered material to control the fluidity of the powdered material. In the process one first obtains at least x number of samples of the powdered material without lubricant. Thereafter, increasing amounts of lubricant are applied to x-1 number of the samples. The bulk and tap densities of the samples are then measured and the Hausner ratio from the densities is calculated. The Hausner ratio versus the concentration of the lubricant in the powder samples is plotted and the concentrations of the minima lubricant in the powder samples at the point of the plot obtained in step e are determined. The concentration of lubricant determined in step f is applied to the remainder of the powdered material whereby an operational level of fluidity of the powder is achieved.