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- Title
Microstructure and polarisation behaviour of TiN-TiB<sub>2</sub> matrix coating prepared by reactive plasma spraying.
- Authors
Ma, J.; Mao, Z. P.; Sun, B. D.; Wang, J.
- Abstract
Two TiN-TiB2 matrix coatings were prepared by reactive plasma spraying with two spraying powders (Ti+B4C+Cr, Ti+B4C). Their microstructure, phases, microhardness and polarisation behaviours in 3·5 wt-% NaCl solution have been investigated by SEM, XRD, hardness tester and electrochemical analyser. The thermodynamics analysis for reactive plasma spraying was discussed and the effect of addition of Cr on adiabatic temperature of TiB2 forming reaction was also analysed. The thermodynamics analysis shows that the reaction temperature during reactive spraying process is >2030 K. To satisfy the criterion of self-propagating high temperature TiB2 forming reaction, the addition of Cr should be >192·6 wt-% of the total weight of Ti and B4C. The experimental results show that the addition of Cr decreases the stress in the coating so as to the cracks of coating at the expense of microhardness, yet the microhardness of both two coatings is a high value. The corrosion resistance of TiN-TiB2 matrix coating was greatly improved. The anodic polarisation curve of TiN-TiB2 coating includes a narrow activation zone and a broad passivation zone, which indicates the stability of coating is very excellent. The addition of Cr increases the corrosion potential of coating, yet an overpassivation zone appears, which is due to the breakage of passivation film.
- Subjects
MICROSTRUCTURE; CORROSION resistance; TITANIUM compounds; PLASMA spraying; METAL coating
- Publication
Materials Science & Technology, 2010, Vol 26, Issue 5, p615
- ISSN
0267-0836
- Publication type
Article
- DOI
10.1179/174328409X443272