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首页> 外文期刊>Journal of biomedical materials research. Part B, Applied biomaterials. >Electrochemically assisted deposition of thin calcium phosphate coatings at near-physiological pH and temperature
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Electrochemically assisted deposition of thin calcium phosphate coatings at near-physiological pH and temperature

机译：在接近生理pH和温度的情况下电化学辅助沉积磷酸钙薄涂层

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摘要

An electrochemical method for the deposition of calcium phosphate phases on titanium surfaces using the galvanostatic mode is presented. Deposition was performed in a (Ca~(2+)/H_xPO_4~(3-x)-)~containing electrolyte near physiological conditions with regard to pH (6.4) and temperature (36 deg C). Cathodic alkalization leads first to the formation of a thin homogeneous layer that shows a nanoscale surface topography of alternating wall-like elevations and channels. It is thought that these channels in the calcium phosphate prelayer are formed as pathways for hydroxyl ions and hydrogen. Upon this layer, spheres of amorphous calcium phosphate (ACP) are formed as indicated by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy. According to transmission electron microscopy images, these spheres consist of small clusters of calcium phosphate (approx 30 nm) and can grow up to 300 nm in diameter. Characteristic for this ACP is a high water content as seen by FTIR. As a function of current density, the ACP is then transformed into crystalline hydroxyapatite (HAP), which was identified using FTIR and X-ray diffraction. The morphology of the HAP crystals can be described as needles with dimensions of <500-nm length and <60-nm width. By choice of different electrochemical parameters, a homogeneous coating of either ACP, HAP, or the intermediate phase can be achieved, as shown in a kinetic phase diagram, thus allowing the formation of coatings with different properties in solubility and morphology.
机译：提出了一种用恒电流模式在钛表面沉积磷酸钙相的电化学方法。关于pH（6.4）和温度（36℃），在接近生理条件的含（Ca 2+）/ H_xPO 4-（3-x）-的电解质中进行沉积。阴极碱化首先导致形成均匀的薄层，该薄层显示出交替的壁状凸起和通道的纳米级表面形貌。认为磷酸钙预层中的这些通道形成为氢氧根离子和氢的通道。如傅立叶变换红外光谱（FTIR）和透射电子显微镜所示，在该层上形成了无定形磷酸钙（ACP）球。根据透射电子显微镜图像，这些球体由小的磷酸钙簇（约30 nm）组成，直径可以增长到300 nm。如FTIR所见，该ACP的特点是水含量高。然后，作为电流密度的函数，将ACP转变为结晶羟基磷灰石（HAP），可使用FTIR和X射线衍射对其进行鉴定。 HAP晶体的形貌可以描述为长度小于500 nm，宽度小于60 nm的针。通过选择不同的电化学参数，可以实现ACP，HAP或中间相的均相涂层，如动力学相图所示，从而可以形成具有不同溶解度和形态特性的涂层。

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