Sintering process for producing thin films of calcium phosphate entities

Abstract

An improved process for producing a thin film of calcium phosphate entities to support bone cell activity thereon. The material to be sintered is prepared by combining a solution of ammonium phosphate with a solution of calcium nitrate to form a sol-gel containing hydroxyapatite. A film of the sol gel is applied to at least one side of the substrate and the film coated on the substrate is sintered to form a solid film of calcium phosphate entities. The improvement in the process comprising sintering the film at temperatures selected from a range of temperatures which optimize a composition of calcium phosphate entities in the film. The sintering step converts hydroxyapatite to .alpha.-tricalcium phosphate where extent of such conversion is temperature dependent. The optimized composition comprises a ratio of hydroxyapatite to .alpha.-tricalcium phosphate in the range of 50:50 to 20:80. A sintering temperature is selected to provide these ratios. The sintering temperature is selected from a range of 920.degree. C. up to 1100.degree. C. where the higher the select temperature, the greater the amount of .alpha.-tricalcium phosphate in the ratio.

Dependencies are inferred from the claim text.