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Microstructure and properties of Ti-TiN in-situ composites prepared by reactive ball milling of Ti in ammonia followed by hot pressing

Conference Paper


Abstract


  • Titanium nitride is widely used in the form of an inexpensive coating to improve wear properties and thermal conductivity of cutting tools. However, the thin TiN surface layer generally either degrades or is removed after a period of time limiting useful tool life. This paper describes a method of fabrication of solid cutting tips of Ti-TiN composite. Preliminary results show that reactive ball milling of Ti in nitrogen or ammonia under controlled conditions eventually results in the formation of nanostructural TiN. Furthermore, by ending the reaction after an appropriate period a homogeneous and uniform mixture of Ti and TiN phases can easily be produced. Due to the highly reactive, nanostructural nature of the powder product this synthesis route has the potential to eliminate wetting problems generally associated with the current technology of conventional liquid-phase sintering. Moreover, by controlling nitriding gas pressure changes during milling good control of both the Ti to TiN ratio and final crystallite size distributions can be achieved. It was found that the precursor Ti-TiN nanostructural powders in this way can be successfully sintered using a rapid liquid phase sintering method without sintering aids. Such compacts show high densities and nanoindentation hardnesses in the range of 18-23 GPa. Structural characterization was performed using x-ray analysis, transmission and scanning electron microscopy as well as optical microscopy. The mechanical properties were characterized using micro- and macroindentation techniques.

Publication Date


  • 2000

Citation


  • Wexler, D., Calka, A., & Mosbah, A. Y. (2000). Microstructure and properties of Ti-TiN in-situ composites prepared by reactive ball milling of Ti in ammonia followed by hot pressing. In Materials Science Forum Vol. 343.

Scopus Eid


  • 2-s2.0-17644448026

Volume


  • 343

Abstract


  • Titanium nitride is widely used in the form of an inexpensive coating to improve wear properties and thermal conductivity of cutting tools. However, the thin TiN surface layer generally either degrades or is removed after a period of time limiting useful tool life. This paper describes a method of fabrication of solid cutting tips of Ti-TiN composite. Preliminary results show that reactive ball milling of Ti in nitrogen or ammonia under controlled conditions eventually results in the formation of nanostructural TiN. Furthermore, by ending the reaction after an appropriate period a homogeneous and uniform mixture of Ti and TiN phases can easily be produced. Due to the highly reactive, nanostructural nature of the powder product this synthesis route has the potential to eliminate wetting problems generally associated with the current technology of conventional liquid-phase sintering. Moreover, by controlling nitriding gas pressure changes during milling good control of both the Ti to TiN ratio and final crystallite size distributions can be achieved. It was found that the precursor Ti-TiN nanostructural powders in this way can be successfully sintered using a rapid liquid phase sintering method without sintering aids. Such compacts show high densities and nanoindentation hardnesses in the range of 18-23 GPa. Structural characterization was performed using x-ray analysis, transmission and scanning electron microscopy as well as optical microscopy. The mechanical properties were characterized using micro- and macroindentation techniques.

Publication Date


  • 2000

Citation


  • Wexler, D., Calka, A., & Mosbah, A. Y. (2000). Microstructure and properties of Ti-TiN in-situ composites prepared by reactive ball milling of Ti in ammonia followed by hot pressing. In Materials Science Forum Vol. 343.

Scopus Eid


  • 2-s2.0-17644448026

Volume


  • 343