Структурные изменения плазменных покрытий гидроксиапатита в зависимости от мощности плазмы

Abstract

The structure of hydroxyapatite (HA) plasma coatings obtained by changing the power of the plasma torch (P) from 20 to 26 kW was studied by X-ray diffraction analysis. All coatings contained the decomposition products of hydroxyapatite in the plasma flow, phases of tetracalcium phosphate (TTCP) and CaO. Their number, which increases with increasing P and plasma temperature (Tp), is determined by the partial loss of phosphorus by the initial HA powder in plasma and the shift in the chemical composition of the coating to higher calcium contents. An increase in P and Tp is accompanied by an increase in the intensity of the HA basic texture. In the range of 24 < P < 26 kW, the intensity ratio of X-ray reflections HA δ = I(200)/I(211) exceeds 3.0 in its value, while at P = 20 kW δ <1.5. The presence of orientation relationships between the predominant crystallographic orientations of HA and TTCP crystals in coatings is associated with the similarity of their structures, the proximity of lattice periods, and the presence of identical fragments in their structures. The possibility of the formation of mixed-layer structures involving these compounds is discussed. The following factors are considered as the factors that have the greatest influence on the nature of the dependences obtained: the substrate temperature, the particle size in the initial HA powder, and the composition of the plasma gases.