초록 ▼

A sintered polycrystalline compact of cubic boron nitride is made by forming a mixture of about 45 to 65 percent by weight cubic boron nitride (cBN), from about 30 to 45 percent by weight hexagonal boron nitride (hBN), and from about 2 to 7 percent by weight an aluminum containing material, preferab

A sintered polycrystalline compact of cubic boron nitride is made by forming a mixture of about 45 to 65 percent by weight cubic boron nitride (cBN), from about 30 to 45 percent by weight hexagonal boron nitride (hBN), and from about 2 to 7 percent by weight an aluminum containing material, preferably aluminum nitride, and cobalt aluminide having a melting temperature lower than the melting temperature of cobalt phase. The mixture of cBN crystals, hBN and adjuvant materials is compacted into preforms and subjected to heat treatment in a non-oxidizing atmosphere. The preforms are placed onto a cemented tungsten carbide substrate containing cobalt and subjected to elevated pressure and temperature conditions at which the boron nitride is thermodynamically stable. The elevated pressure and temperature conditions are maintained for a time sufficient to permit the infiltration of a cobalt phase into the cBN matrix and sinter the compact. Typically, the cobalt phase is infiltrated from a tungsten carbide substrate cemented with cobalt phase. The compact is characterized by substantial intercrystalline cBN to cBN bonding, and has superior abrasive wear resistance, chemical resistance, impact resistance, thermal conductivity and stability. Further, the technique produces a sintered cBN compact that can be machined more efficiently by EDM.

대표청구항 ▼

A method for forming a sintered polycrystalline cubic boron nitride compact comprising the steps of: mixing cubic boron nitride crystals, hexagonal boron nitride, cobalt aluminide having a melting point lower than the melting temperature of cobalt, and an aluminum bearing material selected from the

A method for forming a sintered polycrystalline cubic boron nitride compact comprising the steps of: mixing cubic boron nitride crystals, hexagonal boron nitride, cobalt aluminide having a melting point lower than the melting temperature of cobalt, and an aluminum bearing material selected from the group consisting of aluminum nitride, aluminum and aluminum diboride, the mixture comprising at least 30 percent by weight hexagonal boron nitride to facilitate compressing the mixture into a solid preform; and subjecting the mixture in the presence of a cobalt phase to elevated temperature and pressure conditions where cubic boron nitride is thermodynamically stable.