Preparation and Characteristic of β-Al_2O_3 Powdered Material as Electrolytic Coating for Cathode Protection in Atmosphere

β-Al_2O_3 powdered material could be prepared from the mixtures of Li_2CO_3, Na_2CO_3 and AL_2O_3, which were obtained by dry mixing, wet mix-screening or spray-drying process, by stepped calculating without grinding. The effect of preparation condition on the properties of the powdered material was showed. The powder composed of β/β-Al_2O_3 in principle, f(β~)70%, could be fabricated into solid electrolytic coating for metal pipeline in atmosphere, with some binders and solvents. The powder in the coating wus stable chemically and electrochemically to metal, binders and moistur. The polarization behavior of cathode for Beta-coating showed that there was a flat at the polarization curve, which could be evajuated for the cathode protection of metal in atmosphere.