R Taherian - Department of Material Engineering of Shiraz university, Shiraz, Iran
A Nozad Golikand - Corrosion La. & Material Research Institute, NSTI, Tehran, Iran
M.J Hadianfard

This paper investigates the effects of pressure, filler contents and type of fillers on through-plane and in-plane electrical conductivity, mechanical properties (flexural strength and hardness), density, porosity and water absorption of Phenolic resin/Graphite composite. This composite is a candidate for employing in bipolar plate. The composite was manufactured by hot compaction method. In this research two pressure 15 and 740 bars have been applied in 20, 30, 40, 50, 60, 70 and 80 %wt graphite contents as filler. The Characterization was also conducted by an optic microscope, a stereoscope (for porosity characterization) and SEM (for characterizing fracture mechanism). The results showed that the pressure considerably affect on all of properties and can dramatically change the porosity percentage of composite. The mechanical properties were maximized in about 40%wt. It was found that the single reinforcing filler constituent composite plates do not provide the requisite properties for the purpose of being used as the bipolar plate. Hence the Phenolic resin/Graphite composite plates were modified by nanosheet expanded graphite and carbon fiber (in order to improve electrical conductivity and mechanical strength respectively). These samples were fabricated in 5, 10 and 20%wt of expanded graphite and 5%wt of carbon fiber. In the optimum composition (P/40%G/5%EG/5%CF), the in-plane electrical conductivity, through-plane electrical conductivity and flexural strength of composite bipolar plates were produced with of 1518 S/cm, 76 S/cm and 84 Mpa respectively that perform DOE guideline. In this work contact resistance between bipolar plate and GDL (gas diffusion layer) was determined by changing pressure.

Bipolar Plate, PEMFC, Nano Composite, Polymer, Graphite