The effect of nitrogen flow rate on Acrawax C decomposition and its removal during sintering of Alumix 431D grade powder

ABSTRACT

Alumix 431D pre-alloyed powder (ECKA Granules GmbH) containing 1.5 mass% of Acrawax C was used to study the effect of nitrogen flow rate on delubrication and sintering evolution. Mass loss of compacts during heating was controlled by the TG method using a STA Netzsch apparatus coupled with a mass spectrometer. The latter was used to identify the volatile lubricant’s decomposition products. Macro- and microstructural observations of sintered compacts were also performed. The results documented a strong influence of nitrogen flow rate on delubrication and thus on the sintering behaviour of examined powder. High nitrogen flow rate is required to produce the desired sintered compacts. In contrast, at low nitrogen velocity, the lubricant removal is not complete, which leads to the formation of carbonaceous residuals in the form of soot, which in turn significantly impedes densification and deteriorates the sintered products.

KEYWORDS:

• Aluminium powder metallurgy
• delubrication
• thermal analysis
• mass spectrometry
• sooting

Acknowledgements

Authors are thankful to Dr Marek Hebda from Cracow University of Technology for providing the results of QMS experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The research was supported by Ministry of Higher Education and Scientific Research the grant POIG No. 01.01.02-00-015/09-00.