2017 Technical Division Young Professional Poster Competition: Functional Materials Division (FMD)
Sponsored by: TMS Extraction and Processing Division, TMS Functional Materials Division, TMS Light Metals Division, TMS Materials Processing and Manufacturing Division, TMS Structural Materials Division
Program Organizers: TMS Administration

Monday 6:00 PM
February 27, 2017
Room: Hall B1
Location: San Diego Convention Ctr

YP-1: Influence of Dissolved Oxygen Content on the Oxidation Behavior of Ni-based Alloys in High Temperature Water Vapor: Yang Zhen1; 1Xi an Thermal Power Research Institute
    The oxidation behavior of several Ni-based alloys in high temperature steam was studied in order to evaluate the suitability of these alloys for use in 700 oC A-USC coal-fired power plants. The exposure test in steam at 750 oC was performed with GH 2984, CCA617 and Inconel 740H and the dissolved oxygen (DO) was controlled at about 20 ppb and 5 ppm. Oxidation kinetics were determined by weight gain measurements and oxide scales were characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results showed that these alloys were oxidized following a parabolic law and the oxidation rate was increased with increasing dissolved oxygen concentration. The oxide formed on the alloys was generally consisted of Cr2O3. Underneath the scale, internal oxidation of Al occurred. Both the external and internal oxides formed at 20 ppb DO were smaller in size in comparison with those formed at 5 ppm DO.

YP-2: Isothermal and Non-isothermal Studies of Pt-Rh Thermocouple Failure Caused by Two Phosphorus Diffusion Mechanisms: Anna Nakano1; Jinichiro Nakano1; James Bennett2; 1U.S. Department of Energy. National Energy Technology Laboratory/ AECOM; 2U.S. Department of Energy. National Energy Technology Laboratory
    Certain gases bearing elements such as arsenic, silicon, and sulfur, are known to cause Pt-Rh alloy degradation that leads to thermocouple failure at elevated temperatures. The detrimental effects of phosphorous, another element found in carbon feedstock, ores, and refractory bricks used in metallurgical and gasification processes, is, however, not well reported. In this work, gaseous phosphorous interactions with Pt-Rhx (x = 0–30 wt.%) alloys were studied isothermally and non-isothermally at various oxygen partial pressures. The analysis indicated material degradation was initiated by a combination of the Pt-Rh liquidus lowering and the formation of an intermediate phase at grain boundaries or gas/solid interfaces through two distinct phosphorous interdiffusion routes, critically depending on the amount of Rh in platinum. Based on the experimental result, a new partial isothermal section of the Pt-Rh-P system is proposed; along with unique transient degradation mechanisms of P in the Pt-Rh thermocouple alloys.