Finely divided metal oxides and sintered objects therefrom

A process for the preparation of submicron barium titanate powders which process comprises the steps of:

• a. contacting a water soluble carbohydrate with an aqueous acidic solution of a tetraalkyl titanate and an aqueous solution of barium alkanoate, to form an intimate mixture thereof, said mixture being essentially free of chloride ions,
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but insufficient to substantially sinter said barium titanate compound;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material and produce easily disrupted agglomerates of sub-micron size barium titanate particles,
• d. disrupting said agglomerates without substantially reducing the size of the individual particles which comprised said agglomerates to produce finely divided barium titanate powder having a mean particle size below one micron.

A process for producing a sintered article comprised of a metal oxide which is sinterable to essentially its theoretical density at low temperatures, sid article having a compressive strength of at least 5,000 pounds per square inch, which process comprises:

• a. contacting a carbohydrate material with a compound of a metal to form an intimate mixture thereof;
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but insufficient to substantially sinter said metal compound;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material and produce easily disrupted agglomerates of metal oxide particles of sub-micron size,
• d. disrupting sid agglomerates without substantially reducing the size of the individual particles which comprised said agglomerates to produce finely divided metal oxide powder having a mean particle size of less than 0.1 micron,
• e. shaping and compacting said powder into the form of said article, and
• f. sintering said shaped article at a temperature and for a period of time sufficient to form said article.

A process for producing a sintered article comprised of zirconia essentially at its theoretical density, said article having a compressive strength of at least 5,000 pounds per square inch, which process comprises:

• a. contacting a carbohydrate material with a compound of zirconium to form an intimate mixture thereof;
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but insufficient to substantially sinter said zirconium compound;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material and produce easily disrupted agglomerates of zirconia particles of sub-micron size,
• d. disrupting said agglomerates without substantially reducing the size of the individual particles which comprised the agglomerates to produce finely divided zirconia powder having a mean particle size of less than 0.1 micron,
• e. shaping and compacting said powder into the form of said article, and
• f. sintering said shaped article, at a temperature and for a period of time sufficient to form said article.

A process for producing a sintered article comprised of thoria essentially at its theoretical density, said article having a compressive strength of at least 5,000 pounds per square inch, which process comprises:

• a. contacting a carbohydrate material with a compound of thorium to form an intimate mixture thereof;
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but sufficient to substantially sinter said thorium compound;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material and produce easily disrupted agglomerates of thoria particles of sub-micron size,
• d. disrupting said agglomerates without substantially reducing the size of the individual particles which comprised the agglomerates to produce finely divided thoria powder having a mean particle size of less than 0.1 micron,
• e. shaping and compacting said powder into the form of said article, and
• f. sintering said shaped article, at a temperature and for a period of time sufficient to form said article.

A process for producing a sintered article comprised of erbia essentially at its theoretical density, said article having a compressive strength of at least 5,000 pounds per square inch, which process comprises:

• a. contacting a carbohydrate material with a compound of erbium to form an intimate mixture thereof;
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but insufficient to substantially sinter said erbium compound;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material to produce easily disrupted agglomerates of erbia particles of sub-micron size,
• d. disrupting said agglomerates without substantially reducing the size of the individual particles which comprised the agglomerates to produce finely divided erbia powder having a mean particle size of less than 0.1 micron,
• e. shaping and compacting said powder into the form of said article, and
• f. sintering said shaped article, at a temperature and for a period of time sufficient to form said article.

A process for producing a sintered article comprised of two or more metal oxides, said article having a surface area which is at least 10 square meters per gram, and a compressive strength of at least 5,000 pounds per square inch, which process comprises:

• a. contacting a carbohydrate material with two or more compounds of a metal to form an intimate mixture thereof;
• b. introducing said mixture into a heating zone having a temperature sufficient to ignite said mixture but insufficient to substantially sinter said metal compounds;
• c. igniting said mixture in said heating zone for a time period sufficient to decompose and remove said carbohydrate material and produce easily disrupted agglomerates of metal oxide particles of sub-micron size, at least some of which metal oxide particles are sinterable;
• d. disrupting said agglomerates without substantially reducing the size of the individual particles which comprised said agglomerates to produce finely divided metal oxide powder having a mean particle size of less than 0.1 micron,
• e. shaping and compacting said powder into the form of said article, and
• f. sintering said shaped article, at a temperature and for a period of time sufficient to form said article.