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Microstructure and properties of the new Pt-Rh based alloys for high temperature applications Zbigniew M. Rdzawski and J

Microstructure and properties of the new Pt-Rh based alloys for high temperature applications Zbigniew M. Rdzawski and Jerzy P. Stobrawa The Non-Ferrous Metals Institute ul. Sowińskiego 5 44-100 Gliwice. PLAN OF THE PRESENTATION. Introduction

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Microstructure and properties of the new Pt-Rh based alloys for high temperature applications Zbigniew M. Rdzawski and J

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  1. Microstructure and properties of the new Pt-Rh based alloys for high temperature applications Zbigniew M. Rdzawski and Jerzy P. Stobrawa The Non-Ferrous Metals Institute ul. Sowińskiego 5 44-100 Gliwice

  2. PLAN OF THE PRESENTATION • Introduction • Working environment of platinum and rhodium alloys • Results of alloys examination after taking them out of service • Results of examination of microstructure and properties of the modified PtRh10-based alloys • Conclusions

  3. INTRODUCTION • Platinum and its alloys are used for manufacture of: • catalyst gauzes for ammonia oxidation and for processes of • hydrogen cyanide production • tools for liquid glass defibering • crucibles for glass melting • wires for thermoelements • laboratory equipment • chemical compounds for various applications

  4. 40 x 40 x WORKING ENVIRONMENT OF PLATINUM AND RHODIUM ALLOYS Nitric industry Glass industry Input: 6,7% NH3 + air temp. of mixture ca. 200oC Output: 12% NO, 71% N2, 11% H2O, 6% O2 temp. of mixture 900oC, pressure 5 bar alloys: PtRh5, PtRh8, PtRh10 Liquid glass, temp. 1250oC PtRh10, PtRh20 ODS(Oxide Dispersion Strenghtened) ZGS (Zirconia Grain Stabilised) DPH(Dispersion Particle Hardened)

  5. 100 x 300 x 3000 x 3000 x RESULTS OF ALLOYS EXAMINATION AFTER TAKING THEM OUT OF SERVICE Tools for liquid glass defibering

  6. 100 x 1000 x Images of surface of PtRh10 catalyst gauze after taking it out of industrial service SEM

  7. 1000 x 1000 x Reactor border Reactor centre Surface of catalyst gauge wire from PtRh8 alloy after taking it out of industrial service SEM

  8. 1100 x Ew Platinum arrangement • Image of catalytically etched surfaces of PtRh8 alloy gauze wire and electron images of platinum and rhodium arrangement Rhodium arrangement

  9. 100 x 1000 x 3000 x Image of PtRh10 alloy knitted gauze of excessive brittleness SEM

  10. line of analysis 2300 x EW • Platinum, rhodium and oxygen arrangement along the line of analysis on the lenghtwise section of PtRh10 gauze wire

  11. 2000 x 40 x 40 x PtRh10 EW Lp Pt [%] Rh [%] O2 [%] 1 89,67 10,33 - 2 83,27 16,73 - 3 7,50 74,01 18,49 4 4,55 76,79 18,66 40 x PtRh10 Image of the third (knitted) PtRh5 gauze Observation in direction opposite to the flow of gasses PtRh5 Image of surface of PtRh alloys gauzes wires after taking them out of industrial service (5974 hours) SEM

  12. Results of examination of mechanical properties of the PtRh10, PtRh10B and PtRh10Y alloys

  13. PtRh10 PtRh10B PtRh10Y Exemplary microstructure images of platinum alloys in the initial state and after annealing at the temperature of 9500C for 1, 10 and 100 hours. Optical microscope, chemically etched specimen. Magnification 120x.

  14. Results of grain size examination

  15. Microstructure of PtRh10B and PtRh10Y alloys with marked points of analysis of the boron and yttrium contents

  16. 200 nm Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 46,43 mm)

  17. 200 nm Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 0,52 mm)

  18. 200 nm Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 0,61mm)

  19. Microstructure of PtRh10Y alloy. HRTEM.

  20. Microstructure of PtRh10Y alloy. HRTEM. Different place.

  21. CONCLUSIONS • Addition of boron into PtRh10 alloy in the amount of ca. 5 ppm inhibits excessive growth of grains in high temperature. • Has a positive influence on stability and homogeneity of microstructure as well as on improvement of mechanical properties. • Gives possibilities for increase of service live of the catalysts gauzes. • There is a possibility of elevating the temperature of gauzes operation, which may increase efficiency and selectivity of ammonia oxidation and limit N2O emission to the atmosphere. • Addition of yttrium into PtRh10 alloy in the amount of 0,2% significantly inhibits excessive growth of grains in high temperature. • Has a positive influence on stability and homogeneity of microstructure as well as on improvement of mechanical properties in high temperatures. • Application of that alloy in production of tools for liquid glass defibering should significantly increase their service life. • Production costs of the modified alloys are comparable with production costs of classical PtRh10 alloy.

  22. THANK YOU FOR YOUR ATTENTION

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