ACerS Robert B. Sosman Award Symposium: From Carbides to Carbons - from Bulk to Nano: Session II
Program Organizers: Babak Anasori, Purdue School of Eng. & Tech., IUPUI

Wednesday 2:00 PM
October 2, 2019
Room: Portland Ballroom 253
Location: Oregon Convention Center

Session Chair: Bastian Etzold, Technische Universitšt Darmstadt; Babak Anasori, Indiana University-Purdue University Indianapolis

2:00 PM  Invited
Ordered Multi-transition Metal Carbides and their MXenes: Babak Anasori1; 1Indiana University- Purdue University Indianapolis
    Nanolaminated ordered double transition metal carbides - MAX phases and their MXenes - are among the latest additions to the carbide family. In the ordered MAX phases, such as Cr2TiAlC2, Mo2TiAlC2, and Mo2Ti2AlC3, one or two layers of a transition metal (e.g., Ti) are sandwiched between the layers of another transition metal (e.g., Cr or Mo) in a MAX phase structure. Beyond MAX phases, we have been able to selectively etch the aluminum layers from these ordered MAX phases to synthesize ordered 2D MXenes, e.g., Cr2TiC2Tx and Mo2TiC2Tx. The ordered double-M MXenes have shown different electronic, electrochemical, and optical properties from the well-studied Ti3C2Tx MXene. Very recently, we synthesized a new nanolaminated ternary carbide, (W,Ti)4C4-x, via an aluminum-catalyzed reaction, adding more possibilities to the ordered multi-transition metal carbides. In this talk, the synthesis routes and the unique properties of the ordered carbides and their MXenes will be discussed.

2:30 PM  Invited
Preferential Oxidation in a High Entropy Carbide Ultra-high Temperature Ceramic: Lavina Backman1; Elizabeth Opila1; 1University of Virginia
    High entropy carbides are a novel class of Ultra High Temperature Ceramics for extreme environment applications. Oxidation resistance of these materials is critical for their implementation. Thermodynamic calculations using FactSage software and databases were performed for oxidation reactions of the constituent carbides in an equimolar, five-component carbide, (HfZrTiTaNb)C. The relative stability of the oxide phases formed from the constituent carbides and from multicomponent carbide solutions was used to investigate preferential oxidation in the multi-component materials. The thermodynamic predictions were compared to experimentally determined oxidation behavior of the five-component carbide. (Hf,Zr,Ti) oxides were observed to form while the underlying material was depleted of these group IV elements leaving Ta- and Nb-rich carbides, in agreement with thermodynamic calculations. It was concluded that, given any high entropy material, even a slight relative favorability for a given oxide formation reaction will result in preferential oxidation, reducing the configurational entropy in the remaining material.

3:00 PM  Invited
Redesigning Grain Boundaries in Ceramic Materials: Clive Randall1; 1Pennsylvania State University
     Cold sintering enables new opportunities to design intergranular nanocomposite-based structures. This has already been demonstrated with both thermoplastic and thermoset polymers, and more recently, we have considered the use of 2D MXene phases.1 These types of concepts will be discussed in more detail in the presentation. 1. “Cold Sintered Ceramic Nanocomposites of 2D MXene and Zinc Oxide,” J. Guo, B. Legum, B. Anasori, K. Wang, P. Lelyukh, Y. Gogotski, and C.A. Randall, Adv. Mats. 30 (32), 1801846 (2018).