Abstract:
Grease is a solid or semi-solid product which contains three main components such as base oil,
thickener and an additive package. While reducing the contact resistance, repelling moisture and
inhibiting the corrosion, the Electro-Conductive Grease (ECG) can prevent static buildup. Hence,
they can be used as a gap filler in the moving parts of the electrical circuits. However, electric and
electronic apparatus with moving parts generate heat and it is necessary to maintain ambient
conditions for the normal operation. Therefore, to overcome such issues thermally stable ECG has
been taken more attention recently. Most widely used silicone grease has dimethyl silicone oil as the
base oil and can be performed -50 °C – 170 °C temperature range but unable to serve as conductors.
Graphite is anisotropic, being a good electrical and thermal conductor within the layers. Further, the
carbon layers can slide with respect to one another quite easily, thus making graphite a good
lubricant. Therefore, mixing graphite and silicone grease would preferably combine the electro-
conductive nature of graphite and thermal stability of silicone grease. Powdered natural vein graphite
and the silicone grease were mixed at different weight ratios and stirred well. Three sample series
were prepared based on different graphite powder sample sizes such as 75μm, 63μm and below
63μm. Each sample was tested with DC electrical conductivity and thermal stability. X-ray
diffraction pattern of raw graphite was exhibited that availability of impurities such as pyrite which
help to improve electrical conductance nature. Carbon content analysis showed that highest grade of
graphite was used to develop the grease. The FTIR spectra were exhibited that characteristic
stretching vibrations of functional groups attached to the samples. Out of the 3 sample series, the
sample with 35% of 75μm size graphite powder with 65% of silicone grease shows the highest
electrical conductivity of 2.86 x 10-7 Scm-1 and able to show the wide service temperature range of
10°C to 120°C.
Keywords: Electro-conductive grease; Sri Lankan vein graphite; Silicone grease
