This chapter contains sections titled: Introduction Procedure Homogeneous Stress State Inhomogeneous Stress State Determination of Weibull's Normalized Integral Discussion
This chapter contains sections titled: Introduction Experimental Procedure Results Conclusions
This chapter contains sections titled: Introduction Experimental Result and Discussion Conclusions
This chapter contains sections titled: Introduction Experimental Details Mathematical Model Results and Discussion Conclusion
This chapter contains sections titled: Introduction Experimental Procedure Results Discussion Conclusions
This chapter contains sections titled: Introduction Experimental Results and Discusion Conclusion
This chapter contains sections titled: Introduction Experimental Procedures Results Conclusion
This chapter contains sections titled: Introduction Experimental Procedures Results Discussion
Extensive creep testing of a hot-pressed silicon nitride (NC 132) was performed at 1300 C in air using five different specimen-loading configurations: (1) pure tension, (2) pure compression, (3) four-point uniaxial flexure, (4) ball-on-ring biaxial flexure, and (5) ring-on-ring biaxial flexure. This paper reports experimental results as well as test techniques developed in this work. Nominal creep strain and its rate for a given nominal applied stress were greatest in tension, least in compression, and intermediate in uniaxial and biaxial flexure. Except for the case of compression loading, nominal creep strain generally decreased with time, resulting in a less-defined steady-state condition. Of the four creep formulations-power-law, hyperbolic sine, step, and redistribution--the conventional power-law formulation still provides the most convenient and reasonable estimation of the creep parameters of the NC 132 material. The data base to be obtained will be used to validate the NASA Glenn-developed design code CARES/Creep (ceramics analysis and reliability evaluation of structures and creep).
This chapter contains sections titled: Introduction Experimental Details Results and Discussion Conclusion
This chapter contains sections titled: Introduction Design of the Heat Exchanger Unit Material Alternatives and Characterisation Processing and Joining Alternatives Computer Aided Design Test RIG Operation Status Conclusions and Outlook Acknowledgements References
An indentation-quench method based on Vickers cracks for measuring thermal-shock properties has been applied to beta-sialon materials. The thermal-shock properties have been correlated with the morphology of the beta-sialon grains, the z value in the beta-sialon solid solution Si6-zAlzOzN8-z and the amount of residual intergranular glass phase. z Values in the range 0.6-3.0 were tested, and the amount of residual yttrium-containing glass phase was varied between 0 and 20 vol.%. The best thermal-shock resistance was found at low z values, and was further improved by adding an intergranular glass phase. The poorest resistance to thermal shock was found for the highest z value where the presence of glass had no measurable influence. One composition (z = 1.5, 10 vol.% glass) was selected for studying the influence of the microstructure on the thermal-shock properties. The microstructure was varied by applying different sintering conditions. An improvement of the thermal-shock properties and the fracture toughness was found in samples containing elongated beta-sialon grains formed in situ. In general, in-situ reinforced beta-sialon materials with low z valued and containing an intergranular glass phase exhibited the best thermal-shock resistance and improved fracture toughness (K-1c > 4 MPa m1/2). (C) 2002 Elsevier Science Ltd. All rights reserved.
This chapter contains sections titled: Introduction Experimental Results and Discussion Conclusions
This chapter contains sections titled: Introduction Laser-Assisted Turning of Silicon-Nitride Ceramic Machining Demo-Parts Surface Quality And Sub-Surface Characteristics Development of Machine Prototype
