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Mulholland, Michael Damian

Publications and source records attributed to Mulholland, Michael Damian.

Microstructure development of novel composite heating elements for steel decarbonization

The iron and steel industry is critical for the modern world but is also responsible for 7% of the total energy sector CO2 emissions. It is a difficult industry to decarbonize due to the high temperature heat required for the production of steel, such as reheating steel slabs to ~1250 °C for hot rolling. Electrification of this process using resistive heating is currently not possible due to the poor creep resistance of MoSi2 heating elements, which need to be operated well below their maximum temperatures when mounted horizontally. To solve this problem, novel MoSi2 composite heating elements with SiBCN ceramic reinforcements are being developed using high energy ball milling and electric field assisted sintering (EFAS). The microstructure and density of the composites after sintering depends on the sintering parameters chosen. Herein we present the effects of EFAS sintering parameters on the microstructure and density of the MoSi2-SiBCN composites.

36 - MATERIALS SCIENCE↗

Nuclear Structural Component Relevant Properties of Nickel-Based Alloys Produced via Additive Manufacturing

Idaho National Laboratory initiated examination of nickel-based alloys manufactured via three different additive manufacturing methods for potential applications in nuclear, high temperature structural components. The three methods analyzed included laser powder bed fusion, blown powder laser directed energy deposition, and wire-fed gas metal arc directed energy deposition. With the rapid push towards additive manufacturing, codes do not exist that definitively define what is or is not tolerable for each process and application, such as with conventional, wrought products. This report contains the initial work to understand possible manufacturing methods for high temperature alloys, and specifically, void formation, microstructure evolution, corrosion, and mechanical properties. To generate mechanical test data, specimens were tested irrespective of voids and microstructures were analyzed to better understand how to negate/improve these issues. The preliminary results showed major decreases in mechanical performance for material tested. Test specimens will continue to be produced to further improve each additive manufacturing processes, quantify void acceptance, and better understand the most suitable high temperature alloys receptive to additive manufacturing and high temperature nuclear applications.

36 MATERIALS SCIENCE↗