| The requirement for materials which will withstand elevated temperatures and provide an enhanced level of both wear and corrosion resistance has extended beyond traditional refractory applications to include ceramic/non-metallic coatings on various metallic substrates. This marriage of ceramics and metals serves both to improve the unpredictable reliability of purely ceramic materials and to enhance the thermal limitations of metals and alloys. This study explores the process of combustion synthesis to produce these materials. Specifically, a graded {dollar}rm Nisb3Al/Alsb2Osb3+TiBsb2{dollar} composite has been developed using combustion synthesis to provide a thermal barrier system for nickel-based alloys. Experiments were conducted in an induction furnace to determine the conditions necessary for combustion. Further experiments with applied pressure during combustion were performed in a Gleeble 1500 thermo-mechanical test unit, modified to accept the samples of interest. Characterization of the combustion products by means of X-ray diffraction, scanning electron microscopy, mercury densitometry, Vicker's microhardness, electron probe microanalysis, thermal cycling and finite element analysis is presented. (Abstract shortened by UMI.)... |
