In Situ Investigation of Pt–Rh Thermocouple Degradation by P-Bearing Gases
Gases bearing elements such as As, S, and Si are known to degrade Pt and Pt–Rh alloys, leading to thermocouple sensor failure during industrial operations. While the corrosive impact of As, S, and Si gases have been discussed in the literature, the impact of P has not been well studied. P may originate from the carbon feedstock, ores, additives, and refractory bricks used in metallurgical and gasification processes. In this work, gaseous P interactions with Pt–Rh (Rh = 6 and 30 wt%) alloys were isothermally investigated at 1012° C in situ using a customized environmental white light/confocal scanning laser microscope. Changes in microstructure and P-diffusion into the Pt–Rh alloys are discussed based on real-time images recorded during the exposure tests and electron probe microscopy analysis from the quenched samples.
KeywordsPlatinum Rhodium Phosphorous Sensor failure Corrosion Thermocouples
This work was performed in support of the U.S. Department of Energy’s Fossil Energy Advanced Gasification Program. The research was executed through NETL Research and Innovation Center’s Advanced Gasification effort. Research performed by AECOM Staff was conducted under the RES contract DEFE0004000. The authors acknowledge Prof. J.E. Morral (The Ohio State University) for valuable discussions, Mr. K. Collins (NETL) for SEM-EPMA, and M. Fortner (NETL) for metallography.
This project was funded by the Department of Energy, National Energy Technology Laboratory, an agency of the U.S. Government, through a support contract with AECOM. Neither the U.S. Government nor any agency thereof, nor any of their employees, nor AECOM, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof.
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