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Design principles and manufacturing approaches in carbide-carbon hetero-modulus ceramics
|Igor L. Shabalin 1, Anna Biedunkiewicz 2, Urszula R. Gabriel 2|
1. Salford University, Physics Department, Salford M5 4WT, United Kingdom
By means of the inclusion of sp2-structured carbon phases with low Young’s modulus, the properties of refractory/hard carbide ceramic matrix with high Young’s modulus can be improved significantly. The application of those hetero-modulus ceramic composites is extremely effective at high temperatures. The behaviour and properties of the transition-metal carbide – carbon ceramics are mainly defined by the interface of the high-modulus matrix with covalent-bonded planes of graphite phase. The great difference in the coefficients of thermal expansion between the matrix and its anisotropic reinforcement leads to the formation of specific microstructure. The thermal shock resistance of the carbide-carbon ceramics is greatly improved in comparison with those for the single-phase carbides. This effect is observed due to the Cook – Gordon stopping crack mechanism, which is realized in carbide-carbon systems on the weak interface boundaries. The experience of recently discovered, novel temperature-pressure-dependent phenomenon, 'ridge effect' allows preparing of protective self-sintering scales on the surface of carbide-carbon ceramics to inhibit high-temperature corrosion/erosion of the material. The proposed design principles consist in searching the compositional ranges, which are met the requirements to both crack initiation and crack propagation thermal-shock-resistance criteria in particular case of exploitation of ceramics parts. The subsequent procedure resolves itself into selection of the better Pilling – Bedworth ratio for the composite to form effective coatings by means of pre-oxidizing technique. The optimization procedures can be realized only in the frame of corresponding concept of the manufacture. The previously developed methods for fabrication of carbide-carbon composite can be essentially improved due to the nanotechnological approach, in particular, advanced synthesis of carbides and application of different polymer and metallorganic precursors.
Presentation: Oral at E-MRS Fall Meeting 2008, Symposium I, by Igor L. Shabalin
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-11 14:45 Revised: 2009-06-07 00:48