2018 - Sustainable Industrial Processing Summit & Exhibition
4-7 November 2018, Rio Othon Palace, Rio De Janeiro, Brazil
| Hydrogen Segregation in Palladium: Influence of Hydrogen Content, Temperature and Defects Tahir Cagin1; Han Leng2; Hieu H. Pham2; 1TEXAS A&M UNIVERSITY, College Station, United States; 2TEXAS A&M UNIVERSITY, College Station, United States; PAPER: 216/Manufacturing/Regular (Oral) SCHEDULED: 15:15/Mon./Sao Conrado (50/2nd) ABSTRACT: Atomistic simulations were carried out to investigate the properties of Pd crystals as a combined function of structural defects, hydrogen concentration and high temperature. These factors are found to individually induce degradation in the mechanical strength of Pd in a monotonous manner. In addition, defects such as vacancies and grain boundaries could provide a driving force for hydrogen segregation, thus enhance the tendency for their trapping [1,2]. The simulations show that hydrogen maintains the highest localization at grain boundaries at ambient temperatures. This finding correlates well with the experimental observation that hydrogen embrittlement is more frequently observed around room temperature [3]. The strength-limiting mechanism of mechanical failures induced by hydrogen is also discussed, which supports the hydrogen-enhanced localized plasticity theorem. We will also report on the influence of hydrogen content on thermodynamic properties such as melting point, heat capacity and thermal expansion coefficient and mechanical properties such as elastic modulus and Young's modulus as a function of temperature. References: [1] R. B. McLellan and L. Yang, Acta Metallurgica et Materialia 43 (6), 2463-2467 (1995). [2] T. Mütschele and R. Kirchheim, Scripta Metallurgica 21 (2), 135-140 (1987) [3] H. Conrad, G. Ertl, and E.E. Latta, Adsorption of Hydrogen on Palladium Single-Crystal Surfaces. Surface Science, 41(2), 435-446 (1974). |
