Pk. Rohatgi et al., PRESSURE INFILTRATION TECHNIQUE FOR SYNTHESIS OF ALUMINUM FLY-ASH PARTICULATE COMPOSITE, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 244(1), 1998, pp. 22-30
Beds of nickel coated and uncoated cenosphere fly ash can be successfu
lly infiltrated by molten aluminum under very low pressures. The densi
ty of the resultant composite is approximate to 1.4 and 1.2 g cm(-3) r
espectively, compared to 2.68 g cm(-3), the density for aluminum. The
threshold pressure was found to be between 20.68 and 27.58 kPa for inf
iltration of molten pure aluminum into uncoated By ash. and around 6.7
kPa for Ni-coated fly ash. These data were used to back calculate an
effective wetting angle between molten pure aluminum and fly ash using
Young's and Washburn equations. The average value of the wetting angl
e calculated for uncoated fly ash is 111 degrees. The microstructures
and chemical composition of the composites made with coated and uncoat
ed fly ash were studied using optical and scanning microscopy; they sh
ow good infiltration except for regions between contacting cenospheres
. They also show transport of nickel from the bottom to the top of the
sample when nickel coated particles were used. (C) 1998 Elsevier Scie
nce S.A. All rights reserved.