New anhydrous aluminum nitride dispersions as potential heat-transferring media

Aluminum nitride was found to be of great significance in advanced ceramics. A widely applicable semiconductor, AlN is also commonly known for its considerable heat conductivity, as high as 320 W/(m·K). The idea behind the studies was to use AlN dispersions as a heat transferring liquid in closed systems. Such a liquid heat-carrier should give a proper rheological response when under variable shear-temperature conditions. Contrary to other systems reported in literature, i.e. nanofluids [1–20], the systems presented consisted of AlN micropowder and some novel base liquids: poly(propylene glycols) with an average molecular weight of 425 and 2000. The optimal result was to produce dispersions which display Newtonian-like flow at increased temperature and shear rate, as well as a suitable AlN concentration with sustained time-stability. This compilation of research assumptions should result in intensified heat exchange capabilities of liquid transferring media made on the basis of aluminum nitride.

Aluminum nitride – poly(propylene glycol) dispersions were prepared in order to obtain potential heat-transferring fluids of proper rheological properties. It has been succeeded to obtain highly concentrated and mostly stable dispersions of micro-AlN powder in PPG 425 and PPG 2000. All of the suspensions have been shear-thinned and their viscosity have strongly depended on temperature.Figure optionsDownload as PowerPoint slideHighlights
► Highly loaded AlN-PPG suspensions were successfully obtained.
► The systems prepared were of shear-thinning flow and high time-stability.
► Increased temperature and shear rate provided nearly Newtonian flow to the systems.
► AlN-PPG suspensions were valuated as promising ones in heat transfer technology.