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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 - PowerPoint PPT Presentation
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Microstructure and properties of the new Microstructure and properties of the new Pt-Rh based alloys for high temperature Pt-Rh based alloys for high temperature
applicationsapplications
Zbigniew M. Rdzawski and Jerzy P. Stobrawa
The Non-Ferrous Metals Institute
ul. Sowińskiego 5
44-100 Gliwice
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
PLAN OF THE PRESENTATIONPLAN OF THE PRESENTATION
INTRODUCTIONINTRODUCTION
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
WORKING ENVIRONMENT OF PLATINUM AND RHODIUM WORKING ENVIRONMENT OF PLATINUM AND RHODIUM ALLOYSALLOYS
40 x 40 x
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, PtRh20ODS (Oxide Dispersion Strenghtened) ZGS (Zirconia Grain Stabilised)DPH (Dispersion Particle Hardened)
RESULTS OF ALLOYS EXAMINATION AFTER TAKING THEM OUT OF RESULTS OF ALLOYS EXAMINATION AFTER TAKING THEM OUT OF SERVICESERVICETools for liquid glass defibering
300 x
3000 x
100 x
3000 x
100 x
1000 x
Images of surface of PtRh10 catalyst gauze after taking it out of industrial service SEM
Reactor border Reactor centre
1000 x1000 x
Surface of catalyst gauge wire from PtRh8 alloy after taking it out of industrial service
SEM
1100 x
EwPlatinum arrangement
Rhodium arrangement
Image of catalytically etched surfaces of PtRh8 alloy gauze wire and electron images of platinum
and rhodium arrangement
100 x
3000 x
1000 x
Image of PtRh10 alloy knitted gauze of excessive brittleness SEM
EW
Pt
Rh O2
line of analysis
2300 x
Platinum, rhodium and oxygen arrangement along the line of analysis on the lenghtwise section of
PtRh10 gauze wire
40 x
Image of surface of PtRh alloys gauzes wires after taking them out of industrial service (5974 hours) SEM
PtRh10
PtRh10
PtRh5
40 x
40 x
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
EW
1
42
3
2000 x
Image of the third (knitted) PtRh5 gauze Observation in direction opposite to the
flow of gasses
Results of examination of mechanical properties of the PtRh10, PtRh10B and PtRh10Y alloys
AlloysNo Processing stage Property PtRh10 PtRh10B PtRh10YRm [MPa] 665,1 671,0 734,0R0,2 [MPa] 588,6 608,0 683,71
Initial state, after cold-workingwith 80 % reduction (roomtemperature tests) A [%] 5,7 3,1 3,1
Rm [MPa] 314,1 408,7 461,0R0,2 [MPa] 123,4 181,1 -2 After annealing 9500C/10 h
(room temperature examination ) A [%] 40,0 38,6 26,6Rm [MPa] 224,0 261,0 410,03 After annealing 9500C/100 h
(room temperature examination) A [%] 10,7 15,5 17,6Rm [MPa] 300,0 - 445,0
4 After annealing 11500C/2 h(room temperature examination) A [%] 40,0 - 37,0
Rm [MPa] 273,7 - 376,5R0,2 [MPa] 113,0 - 206,85 After annealing 12500C/10 h
(room temperature examination) A [%] 22,6 - 26,6
Rm [MPa] 162,0 - 311,76 Examination at 6000CA [%] 40,0 - 40,0
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.
After annealing at 9500C for 1 hour
After annealing at 9500C for 10 hours
After annealing at 9500C for 100 hours
Results of grain size examination
Average diameter of flat grain [mm]Annealing time [hours]Material
1 10 100Annealing temperature - 9500C
PtRh10PtRh10BPtRh10Y
0,035 – 0,0450,035 – 0,045
~ 0,010
0,060 – 0,0700,045 – 0,050
~ 0,015
0,070 – 0,0900,060 – 0,070
~ 0,025Annealing temperature - 12500C
PtRh10PtRh10BPtRh10Y
0,090 – 0,1200,090 – 0,1200,060 – 0,070
0,150 – 0,2000,150 – 0,2000,120 – 0,150
~ 0,800~ 0,200
0,150 – 0,200
PtRh10B PtRh10Y
200 m 10 m
Analyze pointElement1 2 3 4 5 6 7 8 9 10 11
Boron [%] 0,030 0,000 0,000 0,000 0,040 0,060 0,070 0,040 0,050 0,080 0,000Ytrium [%] 0,174 0,155 0,238 0,061 0,005 0,198 0,228 0,203 0,208 0,262 0,257
Microstructure of PtRh10B and PtRh10Y alloys with marked points of analysis of the boron and yttrium contents
0,0
5,0
10,0
15,0
20,0
25,0
30,0
35,0
10 20 30 40 50 60 70 80 90 100
Equivalent diameter [m]
Rel
ative
freq
uenc
y [%
]
200 nm
Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 46,43 m)
0
5
10
15
20
25
0 200 400 600 800 1000 1200 1400
Equivalent diameter [nm]
Relat
ive fr
eque
ncy
[%]
200 nm
Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 0,52 m)
0
2
4
6
8
10
12
14
16
18
20
0 200 400 600 800 1000 1200 1400 1600
Equivalent diameter [nm]
Relat
ive fr
eque
ncy
[%]
200 nm
Microstructure (TEM) and grain size distribution in the PtRh10 alloy (average equivalent diameter = 0,61m)
Microstructure of PtRh10Y alloy. HRTEM.
Microstructure of PtRh10Y alloy. HRTEM. Different place.
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.
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