Geometrically defined surface structuring for the form-locked bonding of thermal sprayed coatings

热喷涂涂层基材的预处理通常是通过使用刚玉的磨料喷砂工艺来完成的。该步骤的特点是处理时间长。此外，还需要一台额外的机器来实现这种预处理。因此，有必要评估替代工艺，以产生适合最终涂层工艺的表面结构。因此，本研究项目将研究通过滚花铣削和深滚加工的结合来产生可重复的基材表面拓扑结构的可能性。这种组合可以在表面形成凹痕，从而提高喷涂涂层在基材上的附着力。这种创新的预处理工艺的潜力可以通过初步的调查来指出。由于凹痕，涂层的粘结抗拉强度比滚花表面显著增加。通过对喷涂涂层进行后处理，使胶粘剂的抗拉强度接近喷砂涂层的强度。此外，通过轧制工艺还实现了涂层表面的光滑和压实。调查指出，层压板的破坏发生在以光滑表面为特征的凹口之间的区域。在此基础上，将在项目中减小滚花间距尺寸，以影响凹口之间光滑表面的尺寸，并使涂层的粘合抗拉强度增加。总之，新的工艺链可以提高热喷涂的生产效率，扩大热喷涂涂料的应用领域。有可能开发出用于发动机的创新磨损保护涂层。此外，光滑和压实的涂层可以用作功能表面。

The pre-treatment of substrates for thermal sprayed coatings is conventionally done by abrasive blasting processes using corundum. This step is characterized by a long process time. Moreover, an additional machine is required to realize this kind of pre-treatment. Because of this, it is necessary to evaluate alternative processes to generate a suitable surface structure for the final coating process. Thus, this research project will investigate the possibility to generate a reproducible surface topology of substrates by the combination of the processes knurl milling and deep rolling. This combination leads to undercuts at the surface that enable an improved adhesion of sprayed coatings onto the substrate. The potential of this innovative pre-treatment process could be pointed out by preliminary investigations. Due to the undercuts the adhesive tensile strength of the coating was significantly increased in comparison to knurled surfaces. By using an additional deep rolling process as post-treatment of the sprayed coating, the adhesive tensile strength can nearly reach the amount of abrasive blasted and coated substrates. Furthermore, a smooth surface and a compaction of the coating is also realized by the rolling process. Investigations pointed out, that the failure of the laminate occurs in the areas between the undercuts which are characterized by a smoothed surface. Based on this, the knurl pitch size will be reduced in the project to affect the dimension of the smoothed surfaces between the undercuts and enable an increased adhesive tensile strength of the coating. All in all, the new process chain can increase the productivity of thermal spraying and enlarge the application area of thermal sprayed coatings. It could be possible to develop innovative wear protection coatings for the usage in engines. Moreover, the smoothed and compacted coatings can be used as functional surfaces.