APATITES FORMATION ON ELECTRODEPOSITED CALCIUM PHOSPHATES IN THE Ca(NO3)2 / NH4H2PO4 AND CаCO3 / Ca(H2PO4)2 SYSTEMS

Abstract

Calcium phosphate coatings on titanium plates were obtained by electrochemical deposition at room temperature in a two-electrode cell at a constant current density of 30 mA/sm^2 and a deposition time of 10 min, and brushite coatings from Ca(NO3)2 / NH4H2PO4 system at pH=4, and composite (brushite/calcite/apatite) coatings from the CаCO3 / Ca(H2PO4)2 system at pH=5. The apatite-forming ability (bioactivity) was determined by soaking both types of calcium phosphate coatings in a model SBF solution during month. The newly formed amorphized apatite layer after heat treatment at 800°С crystallized into β–tricalcium phosphate/hydroxyapatite on brushite coatings and hydroxyapatite on composite coatings due to the presence of calcite, whose carbonate ions initiate formation of hydroxyapatite, as well as apatite nanoparticles in the initial coating. The obtained calcium phosphate coatings are promising as biocoatings capable to increase osseointegration of metal implants.

Keywords

• calcium phosphate coatings
• brushite
• calcite
• sbf model solution
• apatite
• hydroxyapatite