Crystallographic changes in calcium phosphates during plasma-spraying.

L G Ellies; D G Nelson; J D Featherstone

doi:10.1016/0142-9612(92)90055-s

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Crystallographic changes in calcium phosphates during plasma-spraying.

L G Ellies·D G Nelson·J D Featherstone

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Abstract

Coating hydroxyapatite (HA) onto metal implant surfaces using the plasma-spraying technique has been investigated in several laboratories as a means of improving the mechanical properties of the bulk ceramic. This study describes crystallographic changes which can occur during the plasma-spraying of calcium phosphate powders. A precipitated calcium-deficient apatite and a high temperature near-stoichiometric HA were each sprayed onto metal substrate in an argon plasma using several hydrogen gas flow conditions at various temperatures. The surfaces were examined by X-ray diffraction and scanning electron microscopy. The plasma-sprayed products were identified as a mixture of calcium phosphates including HA, beta-tricalcium phosphate (beta-TCP) and calcium oxide. Stoichiometric HA when plasma-sprayed showed the least (5%) degradation. Since beta-TCP is more resorbable than HA in vivo, varying the HA/beta-TCP ratio on the plasma-sprayed surface may provide a method to control surface dissolution of the coating.

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Biocompatible Materials Bone and Bones Calcium Phosphates Durapatite Humans Hydroxyapatites Materials Testing Metals Microscopy, Electron, Scanning Prostheses and Implants Surface Properties X-Ray Diffraction Journal Article Research Support, U.S. Gov't, P.H.S.

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L G Ellies, D G Nelson, J D Featherstone. 1992. Crystallographic changes in calcium phosphates during plasma-spraying.. https://doi.org/10.1016/0142-9612(92)90055-s

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