Fabrication of whisker-toughened alumina tubes. Final report.

摘要

A process has been developed to fabricate whisker toughened alumina composites by slip casting dense colloidal suspensions of Al(sub 2)O(sub 3)-15% SiC(sub w). Optimum processing parameters for slip casting we developed with slip viscosity of 60--70 centipoise and solids content 78--79 wt %. Slip-cast parts with green densities 65 to 68% theoretical were achieved. Composite parts were pressureless sintered to 96--97% theoretical density with <1% open porosity. The composites exhibited strengths of 500 MPa, toughness of 6.5 MPa m(sup 1/2), and hardness of 17.26 GPa (1765 kg/mm(sup 2)). High temperature strength retention was maintained up to 1200C. Good thermal shock resistance with (Delta)T(sub cr) = 500C was also achieved. The process technology was transferred into pilot scale for producing prototype heat exchanger tubing up to 4 inches in diameter at the facilities of Vesuvius/McDanel.