The development of niobium carbide-based cutting tools and investigation of their behavior during use in the cutting process

• Applicants: Professor Dr. Jens Günster, Ph.D., since 7/2023; Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274971066

Niobium carbide (NbC) is a promising alternative to conventional cutting materials such as tungsten carbide (WC) in machining due to its advantageous tribological properties. In this context, the significantly higher melting temperature suggests advantages in high-speed machining. Until now, in this research project the production of cobalt- (Co-) and nickel- (Ni-) -bonded cutting materials based on NbC by means of spark plasma sintering (SPS) and liquid phase sintering (LPS) were addressed. Based on these results, exclusively Ni-bonded NbC cutting materials were investigated. These were produced by different powder metallurgical processes using LPS. The focus of the current research period is on the reduction of grain size during the sintering process and the analysis of the performance behavior of nickel-molybdenum (NiMo)-based NbC in machining. In contrast to previous manufacturing processes, mechanical milling is used to reduce the particle and grain size of the powder for the first time. In addition, rate-controlled LPS sintering is used to achieve a NbC grain size dK ≤ 1 µm. In-depth investigations of the microstructure should provide insights into the interface connection, diffusion processes and the crystal structure of individual phases within the NbC-Ni-hard metals. In addition to the characterization of the microstructure and the mechanical properties, the tribological properties are deployed to identify the most suitable sintering process parameters to produce NbC cutting tools. Subsequently, further compositions are produced, which are examined tribologically and in the machining process. To analyze the wear mechanisms, corresponding wear tests are also carried out regarding, among other things, abrasion and surface fatigue. The relationship between the manufacturing process, microstructure, mechanical and tribological properties as well as the performance behavior in the machining process is addressed by evolution-based process parameter adaption. Finally, all the results are deployed to develop a fundamental simulation model of the machining process in relation to the heat distribution and stresses in the NbC cutting tool, which takes the influence of the manufacturing process on its structure and mechanical properties into account.

• DFG Programme: Research Grants
• Ehemalige Antragstellerin: Dr.-Ing. Daniela Hübler, until 6/2023