N. Sonwalkar et al., ICE SOLID ADHESION ANALYSIS USING LOW-TEMPERATURE RAMAN MICROPROBE SHEAR APPARATUS, Applied spectroscopy, 47(10), 1993, pp. 1585-1593
In order to understand the molecular mechanics involved in the adhesio
n of a bimaterial interface bond, a Raman microprobe shear apparatus h
as been designed and fabricated. The apparatus is fabricated to perfor
m a pure shear experiment on a bimaterial interface produced by the va
por deposition of a thin film of ice on a cold metallic substrate unde
r a controlled temperature, humidity, and vapor-flow rate environment.
The textures of four metal surfaces (titanium, copper, aluminum, stai
nless steel) and one polymer surface have been investigated with the u
se of the scanning electron micrograph. The shear experiment is optica
lly coupled to a Raman microprobe at the 180-degrees and 135-degrees s
cattering geometry. The Raman spectra provide in situ information rega
rding the molecular structure and vibrational modes at the bimaterial
interface before and after the shearing event. The results indicate th
at the adhesive bonds are formed primarily by the interaction of oxyge
n atoms in the ice lattice with the atoms of the solid surface. A soli
d, which displays good lattice matching with ice, shows good adhesive
strength. The adhesive strength is found to be proportional to the ext
ent of mechanical interlocking and inversely proportional to the conta
ct angle of the water droplet. An activation energy analysis of the ad
hesive strength shows that the failure of the ice/metal bond is rate s
ensitive while the ice/polymer bond is relatively insensitive to the s
train rate. The failure of the ice/metal bond is cohesive while the fa
ilure of the ice/polymer bond is interfacial. The structure of the ice
layers on metals is polycrystalline, which is marginally influenced b
y the crystalline structure of the substrate and shows increased order
ing in vibrational modes. The sheared ice has a larger number of defec
ts as reflected by the increase in the half-power band-width of the Ra
man peaks.