Characterization and processing of sintered products from Nano-crystalline powders generated by the RTDS method

摘要

Large quantities of nano-crystalline zirconium oxide/oxyhydroxide and nickel-chromium oxide/oxyhydroxide particles agglomerated and sieved into +320/(minus)200 mesh powders have been produced using the rapid thermal decomposition of solutes (RTDS) method. Green compacts (approximately 40% theoretical density) prepared by cold-pressing the RTDS powders at pressures of 140-280-MPa were heated to form dense (86--91% theoretical density) ZrO(sub 2) or Ni(sub 50)Cr(sub 50)components. Dimensional changes in the compacts during heating were used to extract information about the sintering kinetics in these systems. At 800C, grain-boundary diffusion coupled with some surface diffusion are the dominant mechanisms contributing toward the observed densification in the ZrO(sub 2) system. The mechanism-independent activation energy for densification was determined to be 81-kJ/mol for the ZrO(sub 2) system and 56-kj/mol for the NiCr system.