Abstract
Wettability of glass-like carbon substrate (Cglc) by molten Al-10 wt.% Sr alloy (AlSr10) has been examined by a sessile drop method at 700-800 °C for 120 min under vacuum. Non-contact heating to the test temperature combined with the removal of oxide film from the alloy drop was done using capillary purification procedure by squeezing the liquid alloy from a capillary. The influence of the type of capillary on wetting behavior of AlSr10/Cglc couples was noticed. Molten AlSr10 alloy does not wet Cglc at about 700 °C forming the contact angles of 111° with graphite capillary and 141° with alumina capillary. At 800 °C with alumina capillary, non-wetting-to-wetting transition takes place resulting in a final contact angle of 70°. After testing at 800 °C, the AlSr10/Cglc interface was revealed at the test temperature directly in the vacuum chamber by the drop suction procedure. Structural characterization of the interfaces by scanning and transmission electron microscopy combined with energy-dispersive x-ray spectroscopy and by scanning probe microscopy combined with Auger electron spectrometry did not show any new phases formed with Sr. It suggests that the dominant role in wettability improvement by alloying Al with 10 wt.% Sr was related with significant lowering of the surface tension of liquid metal and adsorption of Sr at the interface.
Highlights
Information about factors affecting the interaction between liquid aluminum and aluminum alloys with carbon is of practical importance for the development of light-weight aluminum matrix composites of Al-C type reinforced with different carbon materials (C—fibers, graphite or diamond particles, carbon nanotubes) using different liquid-assisted processes
Despite the fact that these results are in agreement with those obtained by Emadi et al (Ref 20) for Al alloy containing 10 wt.% Sr at 685 °C, we suggest that the value of surface tension given by Emadi et al for the Al-10Sr alloy is overestimated and corresponds to much lower Sr content in molten Al-Sr alloy
The observations of the solidified drop/substrate couples after wettability tests were performed by scanning electron microscopy (SEM) using Hitachi TM3000 device as well as Hitachi SU70 unit, both equipped with energy-dispersive x-ray spectroscopy (EDS) analyzers
Summary
Information about factors affecting the interaction between liquid aluminum and aluminum alloys with carbon is of practical importance for the development of light-weight aluminum matrix composites of Al-C type reinforced with different carbon materials (C—fibers, graphite or diamond particles, carbon nanotubes) using different liquid-assisted processes It is widely recognized (Ref 1-10) that at industrially important temperatures (T < 900 °C) and short-time contact, liquid Al and most Al alloys do not wet carbon materials, independently on their allotropic form. Candan (Ref 18) suggested that the smallest effect on wetting properties observed for Al-1.4Pb alloy is related with the decrease in surface tension of liquid metal, while the strongest effect noted for Al-8.6Mg and Al-13.9Mg alloys is dominated by interfacial reaction and the formation of Mg2Si. On the contrary, Alonso et al (Ref 19) reported that the addition of only 1 wt.% Pb to aluminum causes the 75% reduction in the threshold pressure needed for infiltration of different ceramic particulates (SiC, TiC, Al2O3). This study is focused on examination of the influence of alloying Al with high amount of strontium (10 wt.%) as well as temperature on the interaction between liquid Al alloy and glass-like carbon substrates (Cglc) and their effects on wetting behavior, reactivity, and interfaces in the Al/Cglc system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
