Polished diamond coatings for dry tapering of aluminum

在成型工艺中使用润滑剂来降低摩擦和防止粘合剂磨损。润滑油的使用与后续加工所必需的工件的化学净化相结合，导致对环境的重大影响。初步研究表明，在以铝球为对抗体的干式振荡球-板摩擦计试验中，抛光金刚石涂层具有较低的摩擦系数。在金刚石涂层和氧化铝球上均未检测到附着力。经过5.5小时的测试，金刚石涂层没有显示出任何磨损。氧化铝球在接触区显示出氧化量的增加，这可能是由于温度的升高造成的。本项目的目的是利用金刚石涂层刀具实现铝的无润滑剂锥化。该假设得到了摩擦计试验的支持，即抛光得足够好的金刚石涂层能够使铝合金干燥成形。在经济价格的还原模上生产抛光多晶CVD金刚石涂层是一个障碍。解决的方法是利用存在于BIAS的CVD工艺进行涂层沉积。金刚石涂层的抛光应在低成本的两阶段过程中实现。最初使用皮秒激光消融粗糙度峰，然后通过委托机械抛光实现最终表面粗糙度。在项目范围内，减少模具的碳化钨将涂覆多晶CVD金刚石涂层。目的是在模具内壁上实现均匀的涂层厚度。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还原模的几何形状上。在整个项目期间，将对铝合金锥形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.