<em>In Situ</em> High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure

Abstract

High pressure hydrogen gas is known to adversely affect metallic components of compressors, valves, hoses, and actuators. However, relatively little is known about the effects of high pressure hydrogen on the polymer sealing and barrier materials also found within these components. More study is required in order to determine the compatibility of common polymer materials found in the components of the hydrogen fuel delivery infrastructure with high pressure hydrogen. As a result, it is important to consider the changes in physical properties such as friction and wear in situ while the polymer is exposed to high pressure hydrogen. In this protocol, we present a method for testing the friction and wear properties of ethylene propylene diene monomer (EPDM) elastomer samples in a 28 MPa high pressure hydrogen environment using a custom-built in situ pin-on-flat linear reciprocating tribometer. Representative results from this testing are presented which indicate that the coefficient of friction between the EPDM sample coupon and steel counter surface is increased in high pressure hydrogen as compared to the coefficient of friction similarly measured in ambient air.

A Review on Applicability, Limitations, and Improvements of Polymeric Materials in High-Pressure Hydrogen Gas Atmospheres

“…This set-up allows the reciprocating motion of a steel ball or a pin on the polymeric specimen in a rubbing or sliding motion. They observed a higher friction and wear behavior for specimens made of an EPDM [120] and an NBR [121] grades in 28 MPa of high-pressure hydrogen compared with experiments in air. Nevertheless, they did not mention this behavior as an effect of high-pressure hydrogen gas exposure, as they had less information to explain this whole phenomenon within the tested conditions.…”

“…[119] In addition, valves, compressors, liners in storage tanks, and pipes are made from polymeric materials and cyclic gas exposures and temperature changes cause possible back and forth motions between the polymeric and counter metallic surfaces, repeatedly. [120] Duranty et al [121,122] developed an in-situ tribometer and test method to be used in high-pressure hydrogen atmospheres, measuring the wear and friction properties of polymeric materials. This set-up allows the reciprocating motion of a steel ball or a pin on the polymeric specimen in a rubbing or sliding motion.…”

“…Nevertheless, they did not mention this behavior as an effect of high-pressure hydrogen gas exposure, as they had less information to explain this whole phenomenon within the tested conditions. [120,121] Therefore, this study needs to be expanded to understand the pressure, temperature effects as well as the chemical interaction between hydrogen and the polymeric material. Using the same in-situ tribometer test set up, Kuang et al [123] conducted pin-on-flat tribology measurements under high-pressure hydrogen (27.6 MPa) exposure at RT for EPDM and NBR grades identifying the effects of blended filler (CB) and/or plasticizer on the surface properties.…”

Effect of Functional Fillers on Tribological Characteristics of Acrylonitrile Butadiene Rubber after High-Pressure Hydrogen Exposures

“…These studies contribute to the understanding of the tribological characteristics of polymers under hydrogen gas. For elastomers, in situ tribological experiments under high-pressure hydrogen have been actively conducted in the last few years [ 21 , 22 , 23 , 24 , 25 ]. Experiments on various types of rubber have been conducted; however, only a few studies were conducted on fillers contained in rubber [ 25 ].…”