钛合金表面激光制备生物陶瓷梯度涂层研究

Laser Cladding Biological Ceramic Gradient Coating on Surface of Titanium Alloy

利用激光熔覆制备技术,通过涂层成分设计与梯度制备方法,在Ti-6Al-4V钛合金基体上制备界面冶金结合的生物陶瓷梯度涂层。主要利用金相显微、扫描电镜、硬度计和X-射线衍射等分析手段,对制备梯度涂层的熔覆工艺、组织结构、相组成及其形成机理进行了研究。实验结果表明:梯度涂层的成分组成分别为第一层Ti粉80%、CaCO3和CaHPO4为19%、Y2O3为1%;第二层Ti粉40%、CaCO3和CaHPO4为59%、Y2O3为1%;第三层Ti粉为0%、CaCO3和CaHPO4为99%、Y2O3为1%。在优化激光制备工艺参数条件下,成功在钛合金表面制备出了界面冶金结合、无裂纹缺陷的类生物骨组织结构的梯度涂层。涂层中的主要生物陶瓷相是CaTiO3、CaP及Ca3(PO4)2相。由于采用了钛成分含量的梯度变换设计,避免了基体和涂层及层与层之间材料因热膨胀系数、弹性模量差异过大而造成结合界面的孔洞、裂纹现象,同时保证了钛合金基体与生物骨涂层之间形成了牢固的冶金结合。

A biological ceramic gradient coating with interface metallurgical bonding on Ti-6Al-4V alloy substrate was prepared using laser cladding through the method of the composition design and the gradient preparation. The preparation of gradient coating cladding, microstructure, phase composition and its formation mechanism of the samples were analyzed using means of metallographic microscope, scanning electron microscope, hardness tester and X- ray diffraction. The experimental results show that the composite powder of the first gradient coating is 80wt.% Ti, 19%wt.% mixed powder of CaCO3 and CaHPO4, and 1wt.% Y2O3; the second gradient coating powder composite is 40 wt.% Ti, 59wt.% mixed powder of CaCO3 and CaHPO4, and 1wt.% Y2O3; the third gradient coating powder composite is 0wt.%Ti, 99wt.% mixed powder of CaCO3 and CaHPO4, and 1wt.%Y2O3. The biological ceramic gradient coating with interface metallurgical bonding and without cracks were prepared successfully under the optimized laser cladding parameters. The main biological ceramic phases in gradient coating are CaTiO3, CaP and Ca3 （PO4） 2. Due to the adoption of the titanium content gradient transform design, some pores and cracks were avoided to form in interface of the substrate and the coating and between layers due to the great difference of thermal expansion coefficient and elastic modulus of the materials, while ensuring that a firm metallurgical bonding is formed between the titanium alloy substrate and biological bone coating.