Seminário apresentado pelo doutor Santiago Corujeira Gallo, na UCS (Caxias do Sul, RS) em
28 de setembro de 2009. Público: estudantes, professores e pesquisadores da Pós-Graduação em Materiais (PGMat -UCS)
2. Birmingham - UK
Founded in middle age (7th century)
Population ca 2,500,000
Traditional industrial centre
Cultural diversity
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3. University of Birmingham
Founded in 1900
Research oriented
Ranked 12th in UK (RAE)
Multicultural
over 4000 Intl students
from 150 countries
Colleges
Arts and Law
Engineering and Physical Sciences
Life and Environmental Sciences
Medical and Dental Sciences
Social Sciences
4. Surface Engineering Group (2007)
Composition of the group:
1 Professor
1 Senior Lecturer / Reader
2 Research fellows
1 Visiting research fellow
7 PhD students
2 MSc students
2 Undergraduate students
Topics of research:
- Plasma diffusion treatments
- Thermal oxidation
- PVD coatings
- Nanoindentation
5. Active screen plasma surface engineering
of austenitic stainless steel for enhanced
tribological and corrosion properties
• Austenitic stainless steel
• Plasma surface engineering
• Tribological and corrosion properties
• Active screen
8. Plasma surface engineering
C or N containing gas
Conventional gas nitriding ~ 550oC
Treated substrate
Conventional gas carburising ~ 950oC
C or N containing gas
at low pressure
- -
Cr23C6
+
Cr1-2N -
Treated substrate - cathode (-)
21. Wear conclusions
• The wear resistance of carbon expanded austenite
is 2 orders of magnitude higher than AISI 316 UT
• The wear mechanism changes from adhesive wear
in AISI 316 UT to oxidational wear in AISI 316 PC
• The layer of carbon expanded austenite reduces
the subsurface deformation and supports the
protective oxide layer
27. Corrosion conclusions
• Carbon expanded austenite exhibits higher corrosion
resistance to boiling sulphuric acid than AISI 316 UT
• The corrosion mechanisms are defect-controlled
(MnS inclusions, slip bands and grain boundaries)
• The AS treated samples performed better than the
DC ones through the elimination of edge effects
28. Active screen plasma treatments
Active Screen experimental
setting inside a conventional
DC plasma furnace / reactor
Nitriding mechanisms of
Active Screen - schematics
33. Benefits of AS treatment
DC – edge effect DC – arcing damage AS – feature less
AS –rusty components before ASPN AS – rusty components after ASPN
34. Active Screen conclusions
• AS plasma treatments can produce superior
surface quality than DC treatments (no edge effect or
arcing damage)
• AS treatments are less sensitive to the surface
condition of components (rust, oil, etc.)
• AS plasma shows potential to further improve the
results obtained with DC or other plasma treatments
35. Acknowledgements
This project was sponsored by:
EU scholarships for Latin America
Techint group
The University of Birmingham
Universidad Tecnológica Nacional