Synthesis and phase development in the Ct-Al-N system
2009 (English)In: Ceramic Engineering and Science Proceedings, vol 29, no 2, 2009, Vol. 29, no 2, 3-12 p.Conference paper (Refereed)
The ternary nitride system Cr-Al-N has been investigated by sintering different powder compositions. The powder compositions belong to four groups, AIN- + Cr-powder (5 compositions between 20-90 molar% AlN), Al- + Cr 2N-powder (5 compositions between 15-80 molar% Cr2N), AlN-+ Cr2N-powder (50- and 90 molar% Cr2N) and Al- + Cr-powder. The powders were dry mixed and pressed into pellets by uniaxial pressing followed by cold isostatic pressing (ClP). Sintering took place in a graphite lined reaction bonding furnace under nitrogen atmosphere at three different temperatures, 1350C, 1500C and 1800C and in an alumina tube furnace in order to avoid access to carbon. Holding times were varied, from 2 hours up to 72 hours. The phase development was evaluated by thermal analysis and XRD. CrAlN was formed at 1350C but decomposed at higher temperatures. Both pure Al and Cr-powder were prone to react with carbon in the graphite furnace. Thermal analysis showed a sublimation of Cr2N at temperatures around 1050C and nitridation of pure Al-powder between 680-750C and of pure Cr-powder between 610-1080C. Samples with pure Al-powder showed a very large expansion due to melting of aluminium in combination with nitridation. AIN was found to be more stable than Cr 2N at higher temperatures and longer holding times. The mixtures of Al-+Cr-powder produced an intermediate Al-Cr-phase.
Place, publisher, year, edition, pages
2009. Vol. 29, no 2, 3-12 p.
IdentifiersURN: urn:nbn:se:liu:diva-18870DOI: 10.1002/9780470456361.ch1ISBN: 978-0-470-34492-7OAI: oai:DiVA.org:liu-18870DiVA: diva2:221957
Mechanical Properties and Processing of Ceramic Binary, Ternary, and Composite Systems - 32nd International Conference on Advanced Ceramics and Composites; Daytona Beach, FL; United States