冷喷纳米双结构生物陶瓷金属梯度复合涂层形成机制与性能

The structure and composition portability of solid particles at a lower temperature made it potential to fabricate structure thermal sensitive materials by cold spray processes. Focused on the adjusting the plastic deformation and deposition efficiency, the single tetracalcium phosphate/hydroxyapatite/titanium composite particles with different composition, ceramic particle size and porosity was deposited on substrate with different hardness, the deformation and interfacial bonding of adhered splats was examined. The effect of the particle features on its impact velocity and deposition critical velocity in different spray conditions was researched. The transition of structure and composition during cold deposition and the formation of the nano dual-structure gradient composite coatings were researched based on controlling the plastic deformation and depositing efficiency through regulating powder features and spray conditions. The evolution of the composition and microstructure and interfacial bonding of the coating with the spray processes and powder features was researched, and the practicable deposition condition was explored. In addition, the effect of microstructure, composition and phase constitution of the coating on its mechanical performance and biological property was studied through in vitro bioactivity experiment in a simulated body fluid and by mechanical property test, repectively. Based on this research it is expected to have some useful theoretical instructions for fabrication the dual structural nano tetracalcium phosphate/hydroxyapatite/titanium gradient composite coatings with compatible bioactivity, stability and mechanical property.

冷喷涂颗粒低温结构移植特性对制备结构热敏感材料涂层具有应用价值。本项目用微纳米磷酸四钙、羟基磷灰石及其与钛复合的粉末，围绕调控低韧性颗粒冷喷塑性变形和沉积率两个制约粒子可控沉积的关键问题，进行不同硬度基体单个粒子沉积，研究不同尺度、成分和结构粒子冷喷塑性变形行为及界面结合特征，探讨不同喷涂工艺条件下粒子特性对其沉积临界速度和碰撞速度的影响。基于粒子特性和喷涂工艺条件调控粒子塑性变形及沉积率，研究冷喷复合粒子成分、组织结构移植和双结构梯度涂层形成机制，探讨涂层成分、组织结构及界面结合随粉末成分结构和喷涂工艺的变化，探讨适合制备双结构纳米磷酸四钙/羟基磷灰石/钛梯度复合生物涂层的可控参量。在此基础上，通过模拟体液浸泡等实验，研究涂层成分、组织结构对其生物和力学的性能影响及在模拟体液中的演化，为制备表面高生物活性、内部高生物稳定性和力学性能匹配的纳米双结构生物陶瓷金属梯度复合涂层提供理论依据。

本项目围绕冷喷涂生物陶瓷及其与金属(Ti)复合粒子沉积行为和涂层形成机制，采用团聚烧结制备的羟基磷灰石(HA)、羟基磷灰石/钛(HA/Ti)、磷酸三钙(TCP)和磷酸四钙(TTCP)粉末及不同喷涂工艺条件，通过在不锈钢、Ti6Al4V、HA /Ti 及HA基体上进行单粒子沉积和在不锈钢、Ti6Al4V基体上粒子累积沉积实验，研究了不同尺度、成分和结构粒子碰撞变形及界面结合特征，探讨了单粒子沉积和粒子累积沉积过程中显微组织结构、相结构及化学结构的变化。研究发现，球形HA粉末粒子在不同基体上均可发生一定的（塑性或准塑性）变形-扁平化，表面形态由原来完整的球状演化为帽子状扁平粒子，出现了中心凸起、周边变薄和径向条纹的现象。截面形状由原来的对称的圆形演化为非対称上下表面的椭球状。粒子中的空隙由原来随机分布演化为沿碰撞方向靠近界面的递减，且大空隙有所减小。首次发现冷喷HA粒子变形呈现为扁平粒子的径向铺展和在粒子碰撞方向的夯实或致密化。其变形机制为破碎粒子或碎化微团非连续移动。研究表明，冷喷纳米羟基磷灰石及羟基磷灰石/钛复合粒子也发生了类似的变形行为。冷喷粒子变形程度随加速气体温度和碰撞基体硬度增加而增加，嵌入基体程度随基体硬度增加而降低。微米HA冷喷沉积的临界速速为400-600 m/s，纳米HA沉积的临界速度为548m/s，H3T7复合粒子沉积临界速度约为450-650 m/s。H7T3复合粒子沉积临界速度约为420-590 m/s。在单粒子沉积及累积沉积过程中未发生HA及TCP、TTCP粒子成分和化学结构变化。HA /Ti复合粒子冷喷累积沉积过程中钛组分的沉积率低于HA组分。温喷HA、HA/Ti、磷酸三钙(TCP)-HA-HA/Ti涂层，磷酸四钙(TTCP)-HA-HA/Ti，纳米羟基磷灰石(nHA)-HA-HA/Ti均具有结合良好的致密涂层结构，可实现涂层制备过程中生物陶瓷组织结构、化学结构及相结构的移植。研究还发现超音速火焰悬浮液喷涂可实现nHA-nHA/Ti、nHA-nHA/TiO-TiO梯度生物涂层nHA无分解制备。冷喷微米HA涂层的显微硬度、结合强度及两体磨粒磨损失重量（载荷为2N）分别为HV0.1：59.0 ± 5.6 kg/mm2, 10.9 ± 1.1 MPa 和1.3 ± 0.2×10−1 mg/(m•N)。冷喷纳米HA涂层的显微硬度、结合强度及（载荷为