1176 results about "Tungstic acid" patented technology

A method for preparing a rare-earth oxide dispersion strengthened fine-grained tungsten material, comprising: according to a condition that a mass percentage of rare-earth oxide is 0.1-2%, and the remaining composition is W, weighing soluble rare-earth salt and tungstic acid salt, and respectively preparing 50-100 g / L of rare-earth saline solution and 150-300 g / L of tungstic acid saline solution; adding a minor amount of alkali into the rare-earth salt to control the pH to be 7-8, adding an organic dispersing agent, and stirring to enable the rare-earth salt to form uniformly suspending R(OH)3 colloidal particles (R represents a rare-earth element); adding the tungstic acid saline solution into the R(OH)3 colloidal particles, adding a minor amount of acid to control the pH to be 6-7, adding the organic dispersing agent, stirring to enable the tungstic acid salt to form tungstic acid micro-particles, precipitating and coating the R(OH)3 colloidal particles with the R(OH)3 colloidal particles as a core, and forming coprecipitated coated colloidal particles; conducting spray drying on the coprecipitated coated colloidal particles to obtain a composite precursor powder of tungsten and rare-earth oxide; calcining, conducting thermal reduction via hydrogen, and preparing superfine nanometer tungsten powder having a particle size of 50-500 nm; and conducting normal high-temperature sintering after a general pressing forming. The high-performance fine-grained tungsten material dispersed and strengthened by a minor amount of rare-earth oxide prepared by the above method has a density approximate to full density (>=98.5%), and uniform and small tungsten grains having an average size of 5-10 [mu]m; in addition, rare-earth oxide particles having a particle size of 100 nm - 500 nm are uniformly distributed in a tungsten crystal or a crystal boundary.