Development of Multi-functional Coatings for Heat Transfer and Wear Protection

涂层广泛应用于为机械零件提供保护，使其免受表面退化过程的不利影响。由于对不只是提供被动保护的涂层的需求，已经开发了各种涂层。申请人已经确认，具有多功能功能的新型先进涂层的开发将超越被动表面保护，将涂层的用途独特地扩展到行业和政府已经建立的新领域。在风力涡轮机的叶片上，运行过程中结冰会导致边界层破坏，增加阻力，并影响气动和结构稳定性。拟议研究计划的目标之一是开发和模拟涂层的传热性能，这些涂层将被用作阻性加热元件，以缓解或避免在暴露在低温环境中的叶片上积冰或除冰。模拟的重点是使用热传导原理来确定各向异性多孔介质中的能量产生，以及在非傅立叶热传导过程中确定涂层内的局部温度分布，这是由于涂层被高速冷水滴快速强烈冷却。*预计暴露在环境中的涂层也将暴露在可能导致涂层磨损的腐蚀剂颗粒中。因此，除了作为热能来源外，涂层还将被开发成耐磨的。申请人开发了耐磨金属基复合材料(MMC)涂层，该涂层具有更高的硬度、增强效果和降低磨损率等更好的材料和机械性能。这些复合材料是可取的，因为它们提供了由于基质和增强材料的性能的结合和协同而产生的增强的性能，例如重量轻、强度、硬度、耐磨性、抗蠕变以及改善的导电性和导热性；然而，对于导致MMC涂层材料体系的增强效应和降低磨损率的机理还缺乏完整的了解。因此，拟议的研究计划将通过进行各种磨损试验和模拟涂层的断裂行为来研究MMC涂层的微观结构和磨损性能，以解释观察到的涂层磨损。还可以预期，在MMC涂层的金属基质的微结构中加入固体增强颗粒将增加涂层的有效电阻率或电子流过涂层的阻力，从而增加涂层中的能量产生及其作为加热元件的有效性。

Coatings are used in a plenitude of applications to provide protection to machine parts from the adverse effects of surface degradation processes. Variations of coatings have been developed due to a desire for coatings that do more than provide passive protection. The applicant has identified that the development of new advanced coatings with multi-functional capabilities that extend beyond passive surface protection will offer a unique expansion of the utility of coatings into novel areas that have been established by industry and government. On the blades of wind turbines, ice formation during operation causes the disruption of boundary layers, increases drag, and affects aerodynamic and structural stability. One of the objectives of the proposed research program is to develop and model the heat transfer performance of coatings that will be utilized as resistive heating elements to allow for the mitigation or avoidance of ice accumulation or removal of ice on the blades that are exposed to low-temperature ambient environments. The modelling will focus on the use of heat conduction principles to determine energy generation in an anisotropic porous medium and the determination of the local temperature distribution within the coating during non-Fourier heat conduction due to rapid intense cooling of the coating by high-speed cold water droplets.***It is expected that coatings that are exposed to the ambient environment will also be exposed to erodant particles that may cause wear damage of the coating. Thus, in addition to serving as a source of heat energy, the coatings will be developed to be wear resistant. The applicant has developed wear-resistant metal matrix composite (MMC) coatings that possess improved material and mechanical properties such as higher hardness, increased “strengthening effect”, and decreased wear rates. These composite materials are desirable because they offer enhanced properties resulting from the combination and synergies of the properties of both the matrix and the reinforcing materials, such as light weight, strength, stiffness, wear resistance, creep resistance, and improved electrical and thermal conductivity; however, a complete understanding of the mechanisms that result in the increased “strengthening effect” and decreased wear rates of the MMC coating material systems is lacking. The proposed research program will therefore study the microstructure and wear performance of the MMC coatings by conducting a variety of wear tests and modelling the fracture behavior of the coatings to explain the observed wear of the coatings. It is also expected that the inclusion of solid reinforcing particles into the microstructure of the metal matrix of the MMC coatings will increase the effective resistivity or the resistance to electron flow through the coating, thus increasing energy generation in the coating and its effectiveness as a heating element.**************