Title: The Corrosion of Titanium and its Alloys at High Temperatures and Pressures
1The Corrosion of Titanium and its Alloys at High
Temperatures and Pressures
- James Vaughan
- Peter Reid
- Akram Alfantazi
- David Dreisinger Desmond Tromans
- Mimoune Elboudjaini
2Outline
- Introduction
- Results
- Conclusions
Introduction
3Titanium Information
- Abundant on Earth
- Very reactive
- Alloyed for mechanical properties
- (Mo, Ni, Al, V)
- Alloyed for corrosion resistance
- (Pd, Ru, Mo, Ni)
Introduction
4Motivation
- Ti and Ti-alloys are used as the liner and
internal components of autoclaves - Corrosion repairs
- require expensive
- process downtime
- Knowledge of corrosion at these conditions is
limited
Introduction
5HPAL Conditions
Introduction
6Materials Tested
Introduction
7Objectives
- Explore the electrochemical behaviour of
Titanium and its alloys at high temperatures and
pressures in H2SO4 - Characterize the corrosion products
Introduction
8Approach
- Develop E-pH stability diagrams
- Polarization techniques
- XPS and AES
Introduction
9Results
- E-pH Stability Diagrams
- 298, 498 Kelvin
- Ti ion activity 1X10-6
- Potential vs. SHE (298 Kelvin)
Results
10E-pH Diagram, 298 Kelvin
Results
11E-pH Diagram, 498 Kelvin
Results
12Results
Electrochemical Tests (lt 373 K) SR 0.5 mV /
s Reference Hg / Hg2SO4 Corrected for LJP
Results
13Open Circuit Potential Ti-1, 100 gpL H2SO4, 298
Kelvin
Results
14Potentiodynamic Scan Ti-1, 100 gpL H2SO4, 298
Kelvin
Results
15Anodic Scans Ti-1
Results
16Results
Electrochemical Tests (gt 423 K) CANMET MTL 30
gpL H2SO4 463, 498 and 523 K
Results
17Open Circuit Potential, High Temperature During
the autoclave warm-up
Results
18E-pH Diagram, 498 Kelvin
Results
19Potentiodynamic Scan, Ti-7, High Temperature
Results
20Potentiodynamic Scan, Ti-12, High Temperature
Results
21Potentiodynamic Scan, Ti-18, High Temperature
Results
22Oxide Film Characterization
XPS and AES Immersion Sample Conditions 30 gpL
H2SO4 498 K 3 Hours
Results
23XPS Chemical Analysis, Ti-12
Results
24AES Chemical Depth-Profile, Ti-12
Scan Rate 300 A/min
Titanium
Oxygen
Carbon
Results
25AES Chemical Depth-Profile, Ti-18
Scan Rate 300 A/min
Titanium
Oxygen
Carbon
Results
26Conclusions
- There was no rapid general corrosion or
localized corrosion of the samples at the
conditions tested -
-
-
Increased stability of the oxide with temperature
Inhibitor ions from the autoclave walls
Conclusions
27Conclusions
- The alloyed samples exhibited a higher open
circuit potential than the unalloyed samples - The oxide thickness of the Ti-12 immersion test
sample was greater than for the Ti-18 -
Conclusions
28Acknowledgements
- CANMET Materials Technology Laboratories
- TIMET (Titanium Metals Corporation)
- NSERC
Conclusions