Chapter 20. Room- and High-Temperature Tensile Fracture of Directionally Solidified Chromia-Doped Sapphire Fibers

  1. Waltraud M. Kriven and
  2. Hua-Tay Lin
  1. J. J. Quispe Cancapa1,
  2. A. R. De Arellano López1 and
  3. A. Sayir2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294826.ch20

27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4

27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4

How to Cite

Cancapa, J. J. Q., De Arellano López, A. R. and Sayir, A. (2003) Room- and High-Temperature Tensile Fracture of Directionally Solidified Chromia-Doped Sapphire Fibers, in 27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4 (eds W. M. Kriven and H.-T. Lin), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294826.ch20

Author Information

  1. 1

    Dpto. Física de la Materia Condensada Universidad de Sevilla, Spain

  2. 2

    NASA Glenn Research Center and Case-Western Reserve University Cleveland, OH, USA

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2003

ISBN Information

Print ISBN: 9780470375846

Online ISBN: 9780470294826

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Keywords:

  • crystal ruby fibers;
  • sapphire fibers;
  • slow-crack growth;
  • ceramic;
  • alumina

Summary

Delayed failure of single crystal ruby fibers along »0001« direction (containing 300 ppm and 10% of a nominal amount of Cr2O3) has been studied in tension both at room temperature (RT) and at 1400°C. Commercial sapphire c-axis fibers have been also studied to establish a comparison between the mechanical properties of doped and undoped Al2O3. True tensile stressing rates in the range 0.37 to 1353 MPa. s−1 were applied. Average rupture stress is higher at RT, 1.67 - 3.19 GPa, than at high temperature (HT), 397 - 675 MPa, and increase in each range with the stressing rate. Both at RT and at HT 300 ppm Cr3+ -doped fibers are stronger than sapphire fibers, and both are stronger than 10% Cr2O3-doped fibers. Solution hardening is considered to be responsible for the observed increase of tensile strength in the 300 ppm fibers, and an increased density of internal defects is considered responsible of the reduction of tensile strength in the 10% fibers. At RT, typical slow-crack growth (SCG) exponents are higher than 40. At 1400°C, SCG exponents are smaller than 20, i. e., N=12–19.