Preparation method for hydroxylapatite coating

Abstract

The invention relates to a preparation method for a hydroxylapatite coating. A liquid material which is a calcium salt solution precursor or hydroxylapatite suspension liquid serves as the feedstock. Plasma spraying or hypersonic flame spraying or common flame spraying thermal spraying flame flow serves as the heating means to heat liquid drops. The liquid material is injected into the flame flow through a pressure pump or a peristaltic pump, and after entering the flame flow, the liquid drops are subjected to all or a part of the processes of decomposition, evaporation, nucleation, growth, melting and acceleration and are deposited on a metallic matrix to form the coating. According to the preparation method for the hydroxylapatite coating, the defects that a hydroxylapatite coating in the plasma spraying process is prone to being decomposed, low in crystallinity, large in residual stress and the like are overcome; the flame flow is surrounded by water vapor which beneficially improves the crystallinity of the hydroxylapatite, accordingly, compared with a conventional coating method, reducing of the residual stress in the coating is facilitated through liquid material spraying, and the crystallinity of the hydroxylapatite coating is very high.

Description

technical field [0001] The invention relates to engineering and material science, in particular to a method for preparing a hydroxyapatite coating. Background technique [0002] Hydroxyapatite is the main inorganic component of human hard bone tissue. The chemical composition and crystal structure of artificially synthesized hydroxyapatite are basically the same as the main inorganic mineral components of human bone tissue. Ash has broad application prospects in bone repair substitute materials. [0003] However, with the deepening of research and clinical application, it is found that in the process of preparing coatings by traditional plasma spraying, due to the high temperature of plasma flame, hydroxyapatite decomposes to form impurity phases such as tricalcium phosphate, tetracalcium phosphate, and calcium oxide, while the particles The solidification and cooling stage on the surface of the substrate is another chilling process. There are a lot of amorphous in the coat...

AI Technical Summary

Problems solved by technology

[0003] However, with the deepening of research and clinical application, it is found that in the process of preparing coatings by traditional plasma spraying, due to the high temperature of plasma flame, hydroxyapatite decomposes to form impurity phases such as tricalcium phosphate, tetracalcium phosphate, and calcium oxide, while the particles The solidification and cooling stage on the surface of the substrate is another chilling process. There are a lot of amorphous in the coating, and the rapid heating-cooling process leads to insufficient crystallinity of the coating and excessive residual stress. These problems still restrict the hydroxyapatite material system. Applications

[0004] Before the present invention was made, the hydroxyapatite coating in the existing traditional plasma spraying process had problems such as easy decomposition, low crystallinity, and large residual stress, especially the consequences of insufficient crystallinity were the most serious

Hydroxyapatite with insufficient crystallinity will be rapidly dissolved by body fluids after implantation, resulting in poor biological stability

The ISO13779-2 standard stipulates that the crystallinity of the hydroxyapatite coating must be greater than 45%, but the crystallinity of the traditional plasma sprayed hydroxyapatite coating is difficult to meet this requirement, and post-treatment steps such as heat treatment are required to improve the crystallization of the coating. However, this will lead to problems such as grain growth or decrease in coating bonding strength, and the process is complicated and the molding cost is increased.

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