Research On Densification Technology Of 99.5wt% Sub-Micron Alumina Powder By Dry Pressing

The densification technology of 99.5wt% sub-micron alumina powder is conducted in this thesis, which includes preparation of non-reunion sub-micron slurry, selection of drying parameters, optimization of dry pressing parameters, optimization of sintering process parameters. The preparation of dense alumina ceramics is conducted in normal atmosphere. The last alumina ceramics we got in this thesis has excellent microstructure and mechanical properties.Ordinary mechanical milling is used in the preparation of sub-micron alumina slurry, which includes determine of dosage and addition method of dispersant PAANH4, selection of pH value of slurry, optimization of solid content. The study results show that the preparation of alumina slurry with the excellent performance of no reunion, low viscosity, high solid content and good dispersed is conducted when dispersant dosage is 1.5wt% and repeatedly average addition, pH value is 9, solid content is 71.4wt%. It is sub-micron alumina slurry we got that we can produce density alumina ceramics.In this thesis, centrifugal spray dry is used in the preparation of granulation powder. Because the course of droplet's dry is speedy, we can get non-reunion granulation powder when inlet temperature is 340℃and rotation speed is 40 r/s. The results can provide others important reference to preparation of density alumina ceramics.Two-way synchronization dry pressing technology has been used in this thesis, which includes optimization of experimental parameters of forming. Alumina green body with excellent performance of granulation powder particles completely broken, uniform microstructure, body density relatively higher has been got.Through the analysis on normal atmosphere sintering process parameters and experiment on the sintering process, the results show that relatively uniform microstructure and density alumina ceramics can be got at the temperature of 1600℃. The mean density of alumina ceramics can reach 3.9247g/cm3, the mean three-point bending strength is 433.6MPa, the mean Vickers hardness is 15.66GPa, the mean ceramics grain is 2-3μm.