COMBATING HYDROGEN EMBRITTLEMENT WITH GRAPHENE BASED COATINGS

Hydrogen embrittlement (HE) is an epidemic problem for high strength medium carbon low alloy steel causing reduction in mechanical strength and useful service lifetime. Hydrogen embrittlement of high strength steel is concern for various industrial components used in critical applications. Unpredictable & sudden failure of mechanical equipment/components made of high strength steel (HSS) below designed allowable stress and without appreciable deformation resulted in many catastrophic accidents.HSS being used in various engineering applications such as Aerospace, Nuclear, marine and Transportation etc. Components typically affected by hydrogen embrittlement are pressure vessels, boilers, automobile frame, fasteners & hardware, shafts, axles, rotors, pipelines etc. Extensive research has been done by scientists & engineers to explore various ways to prevent hydrogen embrittlement. Some of them are i) addition of alloying elements ii) selection of material with less susceptibility to hydrogen iii) use of barrier layers to prevent hydrogen diffusion iv) change in manufacturing process and application environment v) use of advance Nano coatings to minimize hydrogen penetration etc. Out of all these methods of controlling hydrogen embrittlement, use of advance coatings appears to be more practical, less intricate and economical. In current decade Graphene has achieved a great attention from engineering world because of its excellent chemical, physical, mechanical & thermal properties. Graphene can act as a protective barrier against many environmental induced degradation of alloy steels because of its extraordinary impermeability. This review article summaries the current state of research & available commercial solutions for mitigations of hydrogen embrittlement using graphene based Nanocoatings. Authors have conducted experiments on several available coatings including graphene to investigate the behavior in an environment promoting hydrogen embrittlement and compared the effect on mechanical properties and ductility of high strength steel (EN24/AISI4340/34CrNiMo6)