Efficient Production of Novel Fe-based Coatings for Large-area Applications by Means of AC-HVAF Spraying

由于压缩空气的流量非常高，与传统的HVOF喷涂相比，最近开发的AC-HVAF喷涂工艺提供了更高的颗粒速度和更低的颗粒温度。该工艺适用于喷涂较细的喷雾粉末。由于其高喷涂率，该工艺在高效生产大面积涂料方面是有利的。用于大面积应用的新型铁基原料的AC-HVAF喷涂在文献中未见记载。本方案的目的是对AC-HVAF喷涂新型铁基原料进行基础性研究，以便在造纸机滚筒干燥器等大面积应用中高效地生产磨损和腐蚀防护涂层。AC-HVAF的特殊工艺特性将与新型铁基材料的高耐磨性和耐腐蚀性相结合，与目前用于造纸机的现有电弧喷涂铁基涂层相比，将实现经济和生态优势。这些优势归功于涂层厚度的减少、喷涂时间的缩短、原料消耗的减少、精加工工作量的减少和导热性能的改善。为了实现这一目的，必须开发一种合适的工艺。因此，在工艺开发过程中，将研究颗粒速度和温度与工艺参数和粉末比例的关系。研究了它们对涂层形成、原料氧化和涂层组织的影响。通过测定涂层的机械性能和热物性，以及与现有的电弧喷涂涂层相比，涂层的磨损和腐蚀行为将显示出预期的优势。

The recently developed AC-HVAF spray process provides higher particle velocities and lower particle temperatures compared to conventional HVOF spraying due to very high flow rates of compressed air. This process is suitable for spraying finer spray powders. This process is advantageous in terms of efficient production of large-area coatings because of its high spray rates. AC-HVAF spraying of novel Fe-based feedstock materials for large-area applications is not documented in literature. The purpose of this proposal is the fundamental investigation of AC-HVAF spraying of novel Fe-based feedstock materials for efficient production of wear and corrosion protective coatings in terms of large-area applications such as cylinder dryers of paper machines. The special process characteristics of the AC-HVAF will be combined with the high wear and corrosion resistance of novel Fe-based materials to achieve economic and ecologic advantages compared to established arc-sprayed Fe-based coatings as used in paper machines today. These advantages are attributed to reduced coating thickness, shorter spray time, less consumption of feedstock materials, reduced finishing work and improved thermal conductive behavior. A suitable process must be developed in order to achieve this purpose. Therefore, particle velocities and temperatures depending on process parameters and powder fractions will be investigated in the process development. Their influences on coating formation, oxidation of feedstock materials and coating microstructure will be studied. The expected advantages will be demonstrated by determination of mechanical and thermos-physical properties of the coatings and their wear and corrosion behavior in comparison with established arc-sprayed coating.