Investigation Of Hardness Anisotropy In Tourmaline
- 1 Department of Metallurgical and Materials Engineering,Obafemi Awolowo University,Ile-Ife.Nigeria
- 2 Engineering Materials Development Institute, Akure, Nigeria
Abstract
Tourmaline is a ring silicate material with a hexagonal crystal structure. Tourmaline crystal is made use of as an electronic component, e.g, as a transducer, mainly because of the anisotropy it exhibits in its properties. Microindentation technique was employed in the research reported in this paper, using a Knoop indenter, to investigate the anisotropy in the hardness of the tourmaline crystal on its two major crystallographic planes: (0001) and {10 1 0}. The material was found to exhibit hardness anisotropy in conformity with its rotary symmetry elements. The material was identified and analysed using various x-ray techniques, and was found to contain some impurities as expected of natural crystals. Tourmaline was found to have a Si/Al ratio of 1.4. The orientations of the crystal samples were determined by obtaining and indexing the Laue x-ray back-reflection patterns of the crystal samples.
- Adewoye O. O. Anisotropy flow and fracture in beryl [Be 3 Al 2 (SiO 3 ) 6 ]. J. Mater. Sci. 21, 1161. 1986
- Adewoye O. O. and Page T. F. The anisotropy behaviour of etched hardness indentation in SiC. J. Mater. Sci. 11, 981.1976
- Henry D. J. and Guidotti C. V. Tourmaline as a petrogenetic indicator mineral: An example from the straurolite-grade metapelite of NW Maine. Am. Mineralogist 70, 1.1985
- Deer W. A., Howie R. A. and Zussman J. “Rock-Forming Minerals.” Vol. 1B:Disilicates and Ring Silicates. 2nd edition. London, Longman Group Ltd. 1986
- Deer W. A., Howie R. A. and Zussman J. “An Introduction to the Rock-Forming Minerals.” England, Longman Scientific and Technical. 1992
- Phillips F. C. “An Introduction to Crystallography.” Fourth edition. English Language Book Society and Longman Group Limited. 1971
- Klein C. and Hurlburt jr. C. S. “Manual of Mineralogy.” New York, John Wiley and Sons, Inc. 1993
- Cullity B. D. “Elements of X-Ray Diffraction.” 2nd edition. Addison-Wesley Publishing Company, Inc.. 1978
- Kelly A. and Groves G. W. “Crystallography and Crystal Defects.” London, Longman Group Limited. 1970
- International Union of Crystallography “International Tables for X-ray Crystallography” Vol. I: Symmetry Groups. Henry N. F. M. and Lonsdale K. (eds.) Birmingham, England, Kynoch Press. pp.15 - 21. 1969
- Katz R. N. “Proceedings of the Third International Conference on Mechanical Behaviour of Materials.” Volume I. Miller K. J. and Smith R. F. (eds.) 20th August, 1979. Pergamon Press. 1980
- Sargent P. M. Ph. D. Thesis: Factors Affecting The Microhardness of Solids. University of Cambridge, England. 1979
- Longhurst R. S. “Geometrical and Physical Optics.” London, Longman Groups Limited. 1973
- Adeoye M. O. Ph.D. Thesis: Flow And Fracture in Tourmaline and Beryl Using Indentation Techniques. Obafemi Awolowo University, Ile-Ife, Nigeria. 1998