两相流场中舰船冲蚀和腐蚀耦合效应的摩擦学行为研究

With the development of the exploration and exploitation of the resources from offshore to the pelagic, two poles and other waters, the rotating parts of the hull in marine two-phase flows will form erosion by eroding of solid particles, and there exists seawater corrosion at the same time. The cavitation and corrosion coupling wear has become a key scientific issue restricting the improvement of running speed of the ship. This project uses the hull of ship in two-phase flow field as research objects, adopting the combining methods of cavitation wear test, electrochemical test and surface analysis test to systematically study the tribological behavior of the specimens and the cavitation and corrosion coupling wear mechanism in simulating working conditions (material properties, solid particles parameters, the corrosive medium, the low temperature, flow field parameters and other factors). Based on the theory of fluid dynamics, the change laws of the flow field parameters (pressure, velocity, temperature, bubble, etc.) are numerically analyzed. Using material science, tribology, thermodynamics, corrosion and protection theory, the micro-structural feature of the wear scar, the corrosion pit morphology and the micro-crack propagation are analyzed on the basis of the experimental study, and so the tribological behavior, the wear mechanism and the characterization methods of micro-cracks and crack groups of the hull are obtained under the cavitation and corrosion coupling effect in marine two-phrase flows.

随着资源的勘探和开采由近海向远海、两极等海域发展，运行在海洋两相流场中的舰船船体将受到固体颗粒的冲刷形成冲蚀，同时海水对船体还存在腐蚀作用。冲蚀和腐蚀耦合磨损已成为制约提高舰船运行速度的关键科学问题。本项目以海洋两相流场舰船船体为研究对象，采用冲蚀磨损测试、电化学测试及表面分析测试相结合的方法，系统地研究模拟工况（材料性质、固体颗粒参数、腐蚀介质、流场参数等因素）下，试件的摩擦学行为以及冲蚀和腐蚀耦合效应的磨损机理。同时基于流体动力学理论，数值分析流场参数（压力、速度、温度、颗粒等）的变化规律；在试验研究的基础上，应用材料学、摩擦学、热力学、腐蚀与防护等理论，分析磨痕的微结构特征、腐蚀坑形貌、微裂纹扩展，从而得出海洋两相流场中舰船船体在冲蚀和腐蚀耦合效应下的摩擦学行为、磨损机理、微裂纹及裂纹群的表征方法。

江河、海洋中舰船等运输装备在行驶过程中，其表面将受到含沙水的冲蚀，由于海水对金属材料有腐蚀作用，因此冲蚀和腐蚀复合作用将对运输装备表面材料产生严重破坏，这将大大威胁这些运输装备的运行安全，降低这些运输装备的寿命。本项目研究研制出一套模拟海洋舰船运行工况的多相流冲蚀和腐蚀耦合磨损试验系统，实现了实时监测试件表面动力学参数和电化学参数的变化，且测试数据具有良好的重复性和置信度。系统地实验研究了材料特性（材料种类）、固体颗粒性质（粒子浓度及尺寸）、流体动力学因素（水流速度）、试验时间等因素对材料流失规律、冲蚀磨损和腐蚀电化学参数变化规律的影响。得到：冲蚀和腐蚀耦合磨损程度强于冲蚀或腐蚀磨损，在较低的沙粒浓度和较低的含盐浓度范围内，耦合磨损量与工作时间、沙粒浓度、沙粒尺寸、含盐浓度、冲蚀速度和塑性材料的强度均呈正比关系。金属塑性材料的冲蚀空蚀和腐蚀的磨损机理：材料表面磨损是冲蚀泥沟，空蚀针孔和腐蚀孔的联合作用。低强度的塑性材料受到冲蚀和空蚀的交互作用时，表面材料较易流失，腐蚀破坏作用不那么明显；而高强度的塑性材料受到的腐蚀破坏作用严重，加之冲蚀和空蚀的联合作用，材料流失量更大。低强度低硬度的塑性材料，材料破坏形式以冲蚀和空蚀为主，高强度高硬度的塑性材料，材料破坏的主因是腐蚀。本项目研究的海洋两相流中冲蚀和腐蚀耦合效应和摩擦学特性为海洋环境下舰船及工程机械等主要部件的选材及结构抗磨设计提供了理论依据。