【作者】 张驰；

【导师】 丁明惠；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2014， 硕士

【摘要】 本文采用射频磁控溅射技术在316L不锈钢表面制备了 ZrC涂层。采用X射线衍射分析、透射电子显微观察、扫描电子显微镜观察、原子力显微镜观察、纳米压痕实验、划痕实验、电化学实验、血小板粘附实验研究了 ZrC涂层的相组成、微观结构、力学性能、抗腐蚀性以及血液相容性,重点考察了磁控溅射工艺参数中衬底温度的变化对其性能的影响。XRD结果表明:316L不锈钢基体和25℃、200℃和400℃下制备的的ZrC涂层均为面心立方结构。随着沉积温度的升高,ZrC涂层的衍射峰的强度升高,半峰宽变窄。这说明高的基体温度使沉积到316L不锈钢基体上的C原子和Zr原子获得了更多的能量能充分地发生扩散反应形成大尺寸的晶粒。当沉积温度升高到400℃时ZrC涂层的(111)取向变得十分明显。TEM观察结果表明:ZrC涂层是由形状规则的直径约为5nm左右的球状晶粒组成,其中(111)晶面(晶面间距为d(111)=0.273nm)和(200)晶面(晶面间距为d(200)=0.238nm)更多的出现在纳米球晶中,这与XRD的结果是一致的,傅里叶变换图谱中可以标记出(111)晶面和(200)晶面,选区电子衍射图谱显示400℃下制备的ZrC涂层为多晶结构,根据相应的相机常数值并结合衍射环半径值可标记出ZrC涂层为面心立方结构。SEM的分析结果表明:ZrC涂层表面平整、结构致密、厚度和形貌均匀,ZrC涂层和基体间结合很好,无明显的孔洞出现,在不同基体温度下制备的ZrC涂层的厚度均为1μmn左右。AFM分析结果表明:25℃、200℃和400℃下制备的ZrC涂层的表面粗糙度变化的趋势为先降低然后微升。这是由于在较低的基体温度下沉积在基体上的Zr原子和C原子的获得的能量不足,导致相互间扩散不充分,而随着基体温度的升高Zr原子和C原子获得更多的能量,高的扩散速度和充分的扩散程度导致ZrC涂层表面粗糙度下降,但当温度升高到400℃时Zr原子和C原子的扩散加剧,促使ZrC纳米晶的快速长大,纳米晶的长大和团聚使ZrC涂层的表面粗糙度稍微升高。纳米压痕实验结果表明:ZrC涂层的塑性变形程度比基体316L不锈钢小,加载时的压入深度和卸载后的残余压入深度都低于316L不锈钢基体,对于ZrC涂层而言,随着基体温度的升高加载时压入的最大深度和卸载后的残余深度均变小。这表明ZrC涂层的纳米硬度和弹性模量都随温度的升高而提高,这是由于高的基体温度下溅射到316L不锈钢基体上的Zr和C原子获得更高的能量,加剧了扩散速度,形成了更致密均匀的ZrC涂层。划痕实验测试表明:当基体温度升高到200℃以上时ZrC涂层与基体有很好的结合。这表明在较高的基体温度下沉积到316L不锈钢基体上的Zr和C原子获得高的能量与基体产生了牢固的结合,导致形成的涂层和基体之间有更高的结合力。电化学实验结果表明:在PBS模拟体液中基体温度为200℃和400℃下制备的ZrC涂层比25℃制备的ZrC涂层有更好的耐腐蚀性能。这是由于随着基体温度的升高涂层和基体间结合力加大且涂层粗糙度下降,从而减少了涂层与腐蚀介质接触,提高了涂层的耐腐蚀性能。血小板粘附实验结果表明:ZrC涂层的血液相容性优于316L不锈钢。随着基体温度的升高,ZrC涂层粘附的血小板数量减少并且血小板激活程度减轻。这说明血液相容性跟基体温度密切相关。一方面基体温度升高涂层的表面粗糙度下降。另一方面润湿实验结果显示随着基体温度的升高,ZrC涂层的表面张力减小,而极性色散比也显著降低。这两方面结果导致ZrC涂层的血液相容性随基体温度升高而变好。更多还原

【Abstract】 ZrC coatings were fabricated on 316L stainless steel (316L SS) by radio-frequency (RF)magnetron sputtering at different substrate temperatures (Ts). The phase constitution,microstructures,mechanical properties, corrosion resistance and hemocompatibility of ZrC coatings were systematically investigated by X-ray diffraction (XRD), transmission electron microscope (TEN),scanning electron microscope (SEM),atomic force microscopy (AFM),nanoindentation techniques, scratch test, electrochemical measurments and platelet adhension test. The influence of substrate temperature (Ts) on the properties of ZrC coatings was inspected specially.The XRD results showed that 316L stainless steel and the ZrC coatings (Ts =25℃,200℃ and 400℃) are FCC lattice structure. When substrate temperature (Ts) increases, the diffraction peak intensity of ZrC coatings increases and half peak width of diffraction peak turns to be narrower. It indicated that ZrC grains grow bigger with the increase of substrate temperature (Ts) which gives the Zr and C atoms more energy to diffuse fully. The ZrC phase with (111) preferred orientation was formed when Ts was 400 ℃. The TEM results showed that the ZrC coatings exhibited in the form of particulates with the crystallite sizes of about 5 nm. Moreover, (111) lattice fringes with d =0.273 run and (2 0 0) lattice fringes with d=0.238 nm were most frequently observed. The same region of fast Fourier transform (FFT)pattern was indexed into diffraction spots, indicating the single crystalline nature of the nanoparticles. Selected area electron diffraction (SAED) image reveals the polycrystalline nature of the ZrC coating, which is also confirmed by X-ray diffraction (XRD). According to the camera constant value and diffraction ring radius value, ZrC coating is FCC structure. The SEM results showed that a thin ZrC coating of about 1.0 μm is clearly observed (outermost layer) over the 316L SS substrate. The coating reveals an extremely smooth, dense,homogeneous and featureless morphology. The AFM results showed that the total varying trend of the root-mean-square (Sq) values of ZrC coatings was gradually decreasing, and then increased slightly with the increasing of substrate temperature, which is due to the improving of diffusion rate with the increasing of Ts which can decrease the surface roughness of ZrC coatings. However, when Ts increased to 400℃, the diffusion of Zr and C atoms became sufficient,which promoted the rapid growth of ZrC nanocrystalline. The growth and agglomeration of nanocrystals increased surface roughness of the ZrC coating slightly.The results of nano-indentation tests indicated that the degree of plastic deformation and residual indentation depth were lower than that of 316L stainless steel, which decreased with the increasing of Ts for the ZrC coatings. The above results indicated that the higher Ts gived Zr and C atoms more energy which contributed to the increasing of diffusion rate and form a more dense and homogeneous ZrC coating.The scratch test results demonstrated that ZrC coatings deposited above 200 ℃ exhibited good adhesion performance. It is obvious that the higher Ts bright more energy to Zr and C atoms, which contributed to improve the the critical load (Lc) between 316L SS and ZrC coatings.The potentiodynamic polarization test results showed that the ZrC coatings deposited at Ts of 200 ℃ and 400 ℃ possessed better corrosion resistance than those deposited at Ts of 25℃,which was due to high adhension and low the root-mean-square (Sq) values which favor the isolation of coating and PBS in order to improve the corrosion resistance.The platelet adhesion test results showed that the blood compatibility of ZrC coating is better than that of 316L stainless steel. When Ts increased, the number and activated pattern of the platelets adherent to the ZrC coatings were in less. It is obvious that the hemocompatibility of ZrC coating was affected by Ts. Firstly,the root-mean-square (Sq)values decreased with the increasing of Ts. Secondly, wetting experimental results also showed that surface tension and polar dispersion ratio of the ZrC coating all decreases with the increasing of Ts. Both will lead to better blood compatibility of ZrC coatings with the increasing of Ts.更多还原