Development of O-ring from the NR/EPDM Filled Silica/CB Hybrid Filler for Use in the Solid Oxide Fuel Cell Testing System

Abstract

This research presents the effects of oxygen gas and ambient temperatures on the O-rings molded from a semi-EV exposed to the inlet (27 to 31°C) and outflow (53 to 58°C) pipe of oxygen gas diffusion in SOFC testing system. Mixing of NR/EPDM were prepared with the proportion of silica/CB hybrid filler of 00/60, 10/50, 20/40, 30/30, 40/20, 50/10 and 60/00 phr. The fabricated O-ring complies with the industrial product standard for O-ring (TIS 2728-2559) with the minimum hardness of 65-75 Shore A and the tensile strength of 7 MPa. The mechanical properties of the NR/EPDM filled silica/CB compound before and after aging were carried out and the best compound were chosen to make the O-rings and test in the SOFC testing system. The surface and cross-section morphology of the NR/EPDM filled silica/CB O-rings were also investigated and compared with the standard O-ring after testing in SOFC testing system. As a result, the compound with the ratio of the silica/CB of 40:20 provides the best mechanical properties and pass the standard O-ring (TIS 2728-2559) (P-value of standard with prepared O-rings: 60/00 0.273, 50/10 = 0.273, 40/20 0.144, 30/30 = 0.465, 20/40 = 0.465, 10/50 = 1.000 and 00/60 = 0.273 > significant level 0.05) and the price of prepared O-ring is cheaper than the standard O-ring due to the very low price of NR used in the formulation of prepared O-ring. After testing in SOFC, still the prepared and standard O-rings can be used to test in SOFC although there are some inner cracks after 1 hour and 6 hours, slight facture after 12 hours and shallow and deep traverse inside the O- ring after 24 hours testing.