SEDL / STP / STP1196-EB / STP25180S

A Calibrated Method for Crystallinity Determination of Hydroxylapatite Coatings

Flach, JS
Research Scientist, CAM Implants B.V., Leiden,

Shimp, LA
President, CAM Implants Inc., Arvada, Colorado

van Blitterswijk, CA
Associate Professor, Laboratory Otobiology and Biocompatibility, Biomaterials Research Group, Leiden,

de Groot, K
Professor, Biomaterials Research Group, Leiden,

Pages: 8    Published: Jan 1994

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Abstract

A quick and inexpensive method was developed to determine the crystallinity of hydroxylapatite coatings using X-ray diffraction for the purpose of production control.

Crystalline hydroxylapatite powder, when sprayed onto a substrate with thermal spraying, forms a mostly two phase material consisting of crystalline hydroxylapatite and amorphous material and very likely some trace impurities. The term crystallinity of a thermal sprayed hydroxylapatite coating is defined as the weight percentage of crystalline hydroxylapatite material to the total amount of material in the coating. With X-ray diffraction of the coating, the integrated crystalline hydroxylapatite peak intensity between 25° and 40° (2⊖) is measured and divided by the same integrated intensity of a 100% crystalline hydroxylapatite standard. The ratio between both is called the crystallinity of the hydroxylapatite coating. The method is calibrated using crystallinity standards which have been made by mixing 100% crystalline hydroxylapatite powder with 100% amorphous powder in different ratios.