Advanced preparation of ceramic powders
A process is described for the preparation of sinterable metal oxide ceramic powders, comprising the steps of: (a) forming a first solution of an ammonia donor in a water-miscible organic liquid and a second solution of salts of all the metals whose oxides are present in the metal oxide ceramic powders, the second solution also containing sufficient water to produce by reaction with the ammonia donor in the first solution a sufficient amount of ammonia to precipitate at least part of the cations of the metal salts in the second solution when such ammonia is released into the second solution; (b) mixing the first solution and the second solution while maintaining a temperature of at least 60/sup 0/C in the reaction vessel, so as to form a solid precipitate containing at least part of the ceramic metal content originally in the second solution; (c) treating the solid precipitate with alkali for a sufficient time to prevent discoloration of the precipitate upon subsequent heating to 400/sup 0/C; (d) neutralizing the alkali remaining after the treating of part (c) to produce a pH of 7.0 +. 0.2 in the liquid phase in contact with the solid precipitate; (e) separating the solid phase remaining after part (d) from the bulk of the liquid phase present therewith after part (d); (f) washing the solid phase remaining after part (e) with sufficient aqueous ammonia to remove substantially all the soluble inorganic matter and the last traces of organic matter from the solid phase, (g) drying and calcining the solid phase remaining after part (f) by heating it for a sufficient time at a temperature sufficient to yield a stable crystal phase and degree of hydration if any for sintering but not so high as to cause appreciable sintering or coarsening of particle size in the solid phase.
- Assignee:
- Norton Co., Worcester, MA
- Patent Number(s):
- US 4605631
- OSTI ID:
- 5348623
- Country of Publication:
- United States
- Language:
- English
Similar Records
Process for the extraction of arsenic from aqueous solutions containing alkali metal carbonate, sulfate and hydroxide or hydrogen carbonate and at least one metal including vanadium uranium and molybdenum
Molten salt extraction process for the recovery of valued transition metals from land-based and deep-sea minerals
Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
AMMONIA
AQUEOUS SOLUTIONS
CALCINATION
CERAMICS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CLEANING
DECOMPOSITION
DISPERSIONS
DRYING
ELEMENTS
FABRICATION
HEATING
HIGH TEMPERATURE
HYDRATION
HYDRIDES
HYDROGEN COMPOUNDS
MATERIALS
MEDIUM TEMPERATURE
METALS
MIXING
MIXTURES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PH VALUE
POWDERS
PYROLYSIS
SINTERED MATERIALS
SINTERING
SIZE
SOLUBILITY
SOLUTIONS
SOLVATION
SYNTHESIS
THERMOCHEMICAL PROCESSES
WASHING
WATER
YIELDS