9704237 Lesher This award provides support to acquire equipment for the fabrication of large volume parts of materials with nanocrystalline microstructure for mechanical testing and thermodynamic studies. The backbone of this new fabrication system will be the cubic-anvil apparatus. The multianvil payload isdriven by a 1000-ton uniaxial hydraulic press equipped with automated pressure and temperature control for tailored processing. This equipment is unique in combining ultrahigh pressure (up to 5 Gpa) and large sample capacity (5-10 cc) of the payload with resistance and pulsing direct current heating adapted from current plasma activated sintering systems. The recovery of large nanocrystalline samples using this apparatus offers new research opportunities to examine sintering behavior, to determine mechanical properties, and to characterize thermodynamic properties of a wide range of nanocrystalline ceramic and metallic materials. %%% This project reflects a multidisciplinary collaboration on the UC Davis campus involving faculty, researchers and students in materials science, chemistry, and geology. This new facility will greatly enhance research programs currently supported by NSF to characterize nanocrystalline ceramics (Al2O3, AlN, Si3N4, SiC) and metals (W, Fe, Ni), and various nanocomposites (Al2O3-Sic, Al2O3-ZrO2, Al2O3-diamond, Si3N4-SiC, Ni-Al2O3). New investigations requiring the large sample volume capabilities of the cubic-anvil apparatus will include tensile strength and fracture toughness measurements, and enthalpy determinations by solution and high temperature calorimetry. We anticipate the results of these studies will contribute fundamentally to our understanding of nanocrystalline structures, mechanical and thermodynamic properties, as well as processing parameters essential to the eventual development of large-scale fabrication of durable ceramic composites and monoliths for technological applications ***
