NET SHAPE FORMING OF NANOPHASE CERAMICS FOR MECHANICAL APPLICATIONS

THE OBJECTIVE OF THIS WORK IS TO DEMONSTRATE NET SHAPE FORMING OF VARIOUS NANOPHASE CERAMICS AND TO IMPROVE THEIR PROPERTIES WITH RESPECT TO FORMABILITY. IN PHASE I OF THIS PROJECT, NANOPHASE METAL OXIDES SUCH AS TITANIA AND YTTRIA ARE BEING PRODUCED USING A GAS PHASE CONDENSATION PROCESS. THE RESULTING CLUSTERS ARE CONSOLIDATED INTO SIMPLE SHAPES AT DIFFERENT TEMPERATURES AND PRESSING PARAMETERS. EXTENSIVE PLASTIC DEFORMATION IS BEING DEMONSTRATED AT VARIOUS TEMPERATURES (LESS THAN HALF THE MELTING POINT) AND STRAIN RATES. THE RESULTING SHAPES ARE BEING CHARACTERIZED FOR HARDNESSS, FRACTURE TOUGHNESS, POROSITY, AND MECHANICAL STRENGTH. A NUMBER OF TECHNIQUES ARE BEING EMPLOYED TO MAKETHESE MEASUREMENTS, INCLUDING MICROHARDNESS INDENTERS, GAS PYCNOMETRY, HIGH RESOLUTION SCANNING ELECTRON MICROSCOPY, AND OPTICAL MICROSCOPY. FURTHER, THE CERAMIC POWDERS ARE BEING REFORMULATED WITH AGENTS TO INHIBIT GRAIN GROWTH. COMPUTER CODES ARE BEING DEVELOPED TO MODEL THE DENSIFICATION AND DEFORMATION BEHAVIOR OF NANOPHASE CERAMICS.