Silva Eduardo L, Pratas Sérgio, Neto Miguel A, Fernandes Cristina M, Figueiredo Daniel, Silva Rui F
Department of Materials and Ceramics Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
Palbit S.A., P.O. Box 4, Branca, 3854-908 Albergaria-a-Velha, Portugal.
Materials (Basel). 2021 Jun 16;14(12):3333. doi: 10.3390/ma14123333.
Cobalt-cemented carbide micro-end mills were coated with diamond grown by chemical vapor deposition (CVD), with the purpose of micro-machining cemented carbides. The diamond coatings were designed with a multilayer architecture, alternating between sub-microcrystalline and nanocrystalline diamond layers. The structure of the coatings was studied by transmission electron microscopy. High adhesion to the chemically pre-treated WC-7Co tool substrates was observed by Rockwell C indentation, with the diamond coatings withstanding a critical load of 1250 N. The coated tools were tested for micro-end-milling of WC-15Co under air-cooling conditions, being able to cut more than 6500 m over a period of 120 min, after which a flank wear of 47.8 μm was attained. The machining performance and wear behavior of the micro-cutters was studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystallographic analysis through cross-sectional selected area electron diffraction patterns, along with characterization in dark-field and HRTEM modes, provided a possible correlation between interfacial stress relaxation and wear properties of the coatings. Overall, this work demonstrates that high adhesion of diamond coatings can be achieved by proper combination of chemical attack and coating architecture. By preventing catastrophic delamination, multilayer CVD diamond coatings are central towards the enhancement of the wear properties and mechanical robustness of carbide tools used for micro-machining of ultra-hard materials.
采用化学气相沉积（CVD）法在钴基硬质合金微立铣刀上生长金刚石涂层，用于微加工硬质合金。金刚石涂层设计为多层结构，由亚微晶金刚石层和纳米晶金刚石层交替组成。通过透射电子显微镜研究涂层的结构。通过洛氏C硬度压痕观察到，化学预处理的WC-7Co刀具基体与金刚石涂层具有高附着力，金刚石涂层能够承受1250 N的临界载荷。对涂层刀具在空气冷却条件下进行WC-15Co微立铣削测试，在120分钟内能够切削超过6500米，之后后刀面磨损达到47.8μm。通过扫描电子显微镜和能量色散X射线光谱研究了微铣刀的加工性能和磨损行为。通过横截面选区电子衍射图进行晶体学分析，以及在暗场和高分辨率透射电子显微镜模式下的表征，揭示了涂层界面应力松弛与磨损性能之间的可能关联。总体而言，这项工作表明，通过化学侵蚀和涂层结构的适当组合，可以实现金刚石涂层的高附着力。通过防止灾难性分层，多层CVD金刚石涂层对于提高用于超硬材料微加工的硬质合金刀具的磨损性能和机械强度至关重要。
