Fabrication and Characterization of Graphene Reinforced Tungsten Carbide-Cobalt Composite
Gorti Vasu Kiran1, Golla Sairam1, B. Bhavani Shankar1, Kantubhukta Jyothi1, Kokkiligadda Jhansi1, Ramesh S. Rao2, A.O. Surendranathan1*
1Department of Metallurgical & Materials Engineering, National Institute of Technology Karnataka, Surathkal, P.O.Srinivasnagar-575025, India.
2R&D in Materials Sciences, Kennametal India Limited, Bangalore, India.
Graphene being very strong could be applied as reinforcement in cemented carbides. Mixing of graphene with tungsten carbide could act as a diffusion barrier to prevent grain growth during sintering. Graphene being impermeable to gases could be used as a protective coating against oxidation and also it used as a potential alternative to carbon black for carburization. WC powder with 6% cobalt (Co) and graphene (0.2%) in the form of graphene nanoplatelets (GPLs) was prepared by high energy rate ball milling and ultrasonification. The mixture was sintered using spark plasma sintering at 1250 ºC for 10 min. To study, the effects of graphene reinforcement and spark plasma sintering was studied by analyzing the physical (density), magnetic (coercivity, and magnetic saturation), microstructural (porosity) and mechanical properties (hardness, fracture toughness). It is concluded that the spark plasma sintering of GNP-reinforced WC-Co composite resulted in significant increase in toughness. It gave higher hardness (~400 Hv) and it makes the grain size distribution narrower. Reaction of graphene is limited in spark plasma sintering (SPS) and Graphene acts as a protective coating against oxidation.
Key words: Fabrication and Characterization, Graphene, Tungsten Carbide, Cobalt, Composite.