Polished diamond coatings for dry tapering of aluminum

润滑剂用于成形工艺，以降低摩擦和防止粘着磨损。润滑剂的使用和后续加工所需的对工件的化学净化相结合，导致了显著的环境影响。初步研究表明，在以铝球为对应体的干式振动球-板摩擦试验机上，抛光金刚石涂层的摩擦系数很低。无论是在金刚石涂层上还是在氧化铝球上都没有检测到附着力。在5.5小时的试验时间后，金刚石涂层没有任何磨损。氧化铝球在接触区域的氧化物量增加，这可能是由于温度的升高造成的。本项目的目标是利用金刚石涂层刀具实现铝的无润滑锥化。这一假设得到了摩擦试验机测试的支持，即足够好的抛光金刚石涂层能够实现铝合金的干法成形。在降低模具上生产抛光的多晶CVD金刚石涂层以经济的价格是一个障碍。解决方案是利用偏置时存在的CVD工艺进行涂层沉积。金刚石涂层的抛光应通过两步法实现，成本较低。首先用皮秒激光烧蚀粗糙度峰，然后通过委托机械抛光获得最终的表面粗糙度。在项目范围内，碳化钨的压延模具将被涂上多晶CVD金刚石涂层。目的是在模具内壁上获得均匀的涂层厚度。此外，还将研究使用皮秒激光可以获得哪些表面粗糙度。激光烧蚀的过程必须转移到压下模具的几何形状上。在整个项目期间，将对铝合金锥度的成形试验进行干燥和润滑检查。

Lubricants are used in forming technologies to lower friction and prevent adhesive wear. The use of lubricants combined with the chemical purification of the work pieces, which is necessary for subsequent processing, leads to a significant environmental impact.Preliminary investigations showed a low coefficient of friction of a polished diamond coating in a dry oscillating ball-on-plate tribometer test with an aluminum ball as counter body. Neither on the diamond coating nor on the alumina ball adhesion could be detected. The diamond coating did not show any wear after a test duration of 5.5 hours. The alumina ball showed an increase of the amount of oxide in the contact area, which might be explained by the occurring rise in temperature.The aim of the project is the realization of lubricant free tapering of aluminum with diamond coated tools. The hypothesis, which is supported by the tribometer tests, is, that sufficiently well polished diamond coatings enable dry forming of aluminum alloys. The production of polished polycrystalline CVD diamond coatings on reduction dies for economic prices represents a hurdle. The solution approach is that the coating deposition will be carried out with the CVD process which exists at BIAS. The polishing of the diamond coating should be realized for low costs in a two-stage process. Initially the roughness peaks are ablated using a picosecond laser and afterwards the final surface roughness will be achieved by commissioned mechanical polishing.Within the scope of the project reduction dies out of tungsten carbide will be coated with polycrystalline CVD diamond coatings. The aim is to achieve a homogenous coating thickness on the inner wall of the die. Furthermore it will be examined which surface roughness can be obtained by the use of a picosecond laser. The procedure of laser ablation has to be transferred onto the geometry of the reduction die. Throughout the project duration forming tests of the tapering of aluminum alloys will be examined dry as well as lubricated.