Next Generation Heat-Resistant Cast Ni-Cr Alloy with Improved Carburization Control

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The overarching goals of the partnership between KUBOTA Materials Canada Corporation and McMaster University are to: (i) develop the next generation heat-resistant cast UCX (48Ni-41Cr) alloy with improved carburization resistance as radiant furnace coil tubes for ethylene production via steam cracking, and (ii) provide experiential training opportunity for a PhD-level HQP with the development of advanced materials with improved performance for harsh environments. Benefits from improved control of carburization of radiant furnace coil tubes in ethylene production via steam cracking include: (i) reduced energy use, (ii) reduced CO2 production and (iii) extended tube lifetime (by up to 50%). The new direction proposed involves developing the next generation UCX alloy by adding large cation diameter reactive rare earth elements (Ce and/or La), whilst simultaneously "dealloying" with Si, with improved chromia scale protection (better adhesion and reduced internal oxidation/carburization). Two key benefits of large cation diameter reactive element addition include (i) enhanced selective oxidation of Cr and (ii) improved adhesion with the substrate. Chromia scale protection improvements associated with reactive element additions have been demonstrated for Ni-25Cr alloys, but not for cast alloys, with higher Cr contents, such as UCX.