The fuel cell is considered to be a promising alternative energy source for the near future. A bipolar plate, which is the major component of the fuel cell, is always exposed to the moisture during operation, because one of the important functions of the bipolar plate is to facilitate
water management within the cell. In order to use graphite composite materials as bipolar plate material for PEMFC, the effect of the moisture environment on the mechanical properties of bipolar plate is studied. Two types of specimens, one made of particulate graphite 90%-epoxy 10% composite
'with' woven carbon fabric, and the other 'without' carbon fabric, were fabricated. Both types of specimens were kept in three different environmental conditions: (1) dry at room temperature, (2) immersed in 85° C water for 100 h, and (3) immersed in 85° C water for 300 h. A series
of experiments were performed with the samples of the two types: water absorption rate, strength and modulus from the bending and tensile tests were measured. The results showed that a steep increase of water absorption rate occurred at the beginning of the test followed by a slow increase
afterwards. Total water absorption rate was lower for the specimens with fabric since the inserted carbon fabric has lower porosity and lower water absorption than the specimens without fabric made of graphite/epoxy composite. Bending strength and modulus decreased for both types of specimens.
However, addition of carbon fabrics to the graphite-particle/epoxy composite increased the tensile strength significantly.
High Safety Vehicle Core Technology Research Center, Inje University, Gyeongnam 621-749, Korea 2:
School of Mechanical and Aerospace Engineering and Institute of Advanced Machinery and Design, Seoul National University, Seoul 151-742, Korea 3:
Department of Mechanical Engineering, Inje University, Gyeongnam 621-749, Korea