Production capability and powder processing methods for nanostructured WC-Co powder

Industrial scale production of nanostructured WC-Co powders (NANOCARB(R) Powder) with WC grains of <50 nm uniformly dispersed in the metallic Co binder phase has been established with the spray conversion process. The patented production technology has demonstrated process capability to average Cpk levels >1.5 for critical parameters, such as: grain size, carbon balance, impurities and composition. Conditions have been established for milling and sintering to yield flaw-free products with porosity rating of <AO1 B00 C00. Use of VC and Cr3C2 grain growth inhibitors results in mean sintered grain sizes of <0.25 mu and down to 0.15 mu in specialized sintering conditions. The hierarchical structure of millions of nanometer WC grains uniformly mixed with the metallic binder results in enhanced stability via reduced reactivity on exposure to air. The friable particle structure is milled to particle fragment sizes of <1 mu for consolidation. Oxygen pick-up during milling is selectively removed via a hydrogen reduction step in order to eliminate residual porosity. (C) 1997 Elsevier Science Limited.