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首页> 外文期刊>Acta biomaterialia >Kinetics of hydrothermal crystallization under saturated steam pressure and the self-healing effect by nanocrystallite for hydroxyapatite coatings.
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Kinetics of hydrothermal crystallization under saturated steam pressure and the self-healing effect by nanocrystallite for hydroxyapatite coatings.

机译：饱和蒸汽压下水热结晶的动力学及羟基磷灰石涂料的纳米微晶自愈作用。

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摘要

Hydroxyapatite coatings (HACs) with a low crystalline state were prepared using the plasma spraying process followed by hermetic autoclaving hydrothermal treatment at 100, 150 and 200 degrees C. Experimental evidence confirmed that the HACs became significantly crystallized and the content of amorphous calcium phosphate decreased by performing the autoclaving hydrothermal treatment in an ambient saturated steam pressure system. The obvious chemisorbed hydroxy groups (OH) peak in the X-ray photoelectron spectra detected from the hydrothermally crystallized HAC specimens means that the hydroxyl-deficient state of plasma-sprayed HACs is significantly improved by the abundant replenished OH groups. The HA nanocrystallite observed from scanning electron microscopy and transmission electron microscopy images within hydrothermally treated HACs is the result of nucleation and grain growth through the replenishment of OH groups into the hydroxyl-deficient HA crystal structure. The microstructural self-healing effect is a result of reduction in defects (pores, microcracks and lamellar boundaries) due to new-growth HA nanocrystallite. According to the systematic derivation of the Arrhenius equation, the HA crystallization is a second-order Arrhenius reaction kinetics. Besides the effects of heating temperature and an atmosphere with abundant water molecules, the saturated steam pressure is a crucial factor which significantly improves the crystallization rate constant and further reduces the activation energy for the hydrothermal HA crystallization.
机译：使用等离子喷涂工艺，然后在100、150和200℃下进行密闭高压灭菌水热处理，制备出低结晶态的羟基磷灰石涂层（HAC）。实验证据证实，HAC显着结晶，非晶态磷酸钙的含量降低了。在环境饱和蒸汽压力系统中进行高压灭菌水热处理。在从水热结晶的HAC样品中检测到的X射线光电子光谱中，明显的化学吸附羟基（OH）峰意味着通过大量补充的OH基可以显着改善等离子喷涂HAC的羟基不足状态。从经过水热处理的HAC中的扫描电子显微镜和透射电子显微镜图像观察到的HA纳米晶体是通过将OH基团补充到缺乏羟基的HA晶体结构中而形核和晶粒长大的结果。微观结构的自我修复效果是由于新生长的HA纳米微晶减少了缺陷（孔，微裂纹和层状边界）的结果。根据Arrhenius方程的系统推导，HA结晶是二级Arrhenius反应动力学。除了加热温度和水分子丰富的气氛的影响外，饱和蒸汽压是至关重要的因素，它可以显着提高结晶速率常数，并进一步降低水热HA结晶的活化能。

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