摘要:
A process for producing dry substantially crack-free shaped bodies, such as grinding wheels, from a sol-gel alumina hydrate composition is disclosed. The shaped bodies are formed by either a one or a two step forming process and avoid having to pre-prepare alpha alumina grits. The addition of specific crack-avoiding drying control additives, e.g. whiskers, chopped fibers, agarose gels, and formamide, to the sol-gel alumina hydrate prior to water removal therefrom substantially prevents crack-formation during the water removal operation.
摘要:
A method of casting a siliconized silicon carbide part. The method includes providing a pre-casting mix comprised of a silicon carbide powder having a maximum particle size within a range of about 1000 to 2000 microns, and water having a percentage by weight of no more than about 9.5% of the mix. A slurry is formed from the mix and poured into a mold. The water is then removed from the mold within a predetermined period of time to form a solid porous green part. The green part is surrounded with silicon metal, and heated to a predetermined temperature above the melting point of the silicon metal. The silicon metal then siliconizes the green part to form a siliconized silicon carbide part.
摘要:
A silicon nitride ceramic comprising:a) inclusions no greater than 25 microns in length,b) agglomerates no greater than 20 microns in diameter, andc) a surface finish of less than about 8 microinches, said ceramic having a four-point flexural strength of at least about 900 MPa.