Frictional anisotropy of the basal plane of natural fluorapatite single crystals was observed ; the coefficient of friction (β) in the [2110] direction (β = 0.217) was approximately 12% higher than that in the [0110] direction (β = 0.193). The load at which the ductile-to-brittle transition occurred (Ω) was significantly higher in the [2110] direction (Ω = 77 gm) than in the [0110] direction (Ω = 15 gm). A mechanism is proposed involving the maximum normal stress and probable cleavage planes.
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References
1.
Powers, J.M., and Craig, R.G.: Wear of Fluorapatite Single Crystals: I. A Method for Quantitative Evaluation of Wear, J Dent Res51: 168-176, 1972.
2.
Powers, J.M. , and Craig, R.G.: Wear of Fluorapatite Single Crystals: II. Frictional Behavior, J Dent Res51 : 605-610, 1972.
3.
Powers, J.M. , and Craig, R.G.: Wear of Fluorapatite Single Crystals: III. Classification of Surface Failure, J Dent Res51: 611-618, 1972.
4.
Buckley, D.H. : The Influence of the Atomic Nature of Crystalline Materials on Friction, Am Soc Lubrication Engineers Trans11: 89-100, 1968.
5.
Steijn, R.P. : On the Wear of Sapphire, J Appl Phys32: 1951-1958, 1961.
6.
Bowden, F.P. ; Brookes, C.A.; and Hanwell, A.E.: Anisotropy of Friction in Crystals, Nature (Lond) 203: 27-29, 1964.
7.
Bowden, F.P. , and Brookes, C.A.: Frictional Anisotropy in Non-Metallic Crystals , Proc Roy Soc LondA295: 244-258, 1966.
8.
Time Series Analysis, Ann Arbor, Mich: Statistical Research Laboratory, University of Michigan, 1971.
9.
Hertz, H.R.: On the Contact of Elastic Solids, J Reine Angew Math92: 156-171, 1881.
10.
Katz, J.L., and Ukraincik, K.: On the Anisotropic Elastic Properties of HydroxyapatiteJ Biomechanics4: 221-227, 1971.
11.
Huber, M.T.: Zur Theoric der Beruhrung fester elastischer Korper, Ann Phys (Lpz) 14: 153-163, 1904.
12.
Timoshenko, S.P., and Goodier, J.N.: Theory of Elasticity, 3rd ed, New York: McGraw-Hill, 1970.
13.
Mindlin, R.D. : Compliance of Elastic Bodies in Contact, J Appl Mech16: 259-268, 1949.
14.
Duncan, D.B. : Multiple Range and Multiple F-Test, Biometrics11:1-42, 1955.
15.
Dana, E.S.: A Textbook of Mineralogy, New York: John Wiley and Sons, Inc., 1963, p 704.
16.
Hopkins, R.H. , and Kramer, W.E.: The Origin of Secondary Phases in Melt-Grown Fluorapatite Crystals, J Electrochem Soc116: 638-640, 1969.
17.
Mcmanus, G.M. ; Hopkins, R.H.; and Takei, W.J.: Dislocation Arrangements in Fluoraapatite , J Appl Phys40: 180-183, 1969.
18.
Hopkins, R.H. : The Origin of Decorated Dislocation Arrays in Fluorapatite, J Crystal Growth6: 91-96, 1969.
19.
Powers, J.M.: The Influence of Crystallographic Direction and Environment on the Ductile to Brittle Transition of Fluorapatite Single Crystals under Sliding, dissertation . Ann Arbor, University of Michigan , 1972.
