| 1. |
- Govindarajan, S., et al.
(författare)
-
In situ particle generation and splat formation during solution precursor plasma spraying of yttria-stabilized zirconia coatings
- 2011
-
Ingår i: Journal of The American Ceramic Society. - 0002-7820 .- 1551-2916. ; 94:12, s. 4191-4199
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal barrier coatings (TBCs) based on Yttria-stabilized Zirconia (YSZ) deposited by the solution precursor plasma spray (SPPS) technique have been claimed to exhibit superior durability compared to conventional plasma spraying and even electron-beam physical vapor deposition. This has been attributed to the interesting features, like vertical cracks, nanosized pores, and fine splats that are inherent to SPPS-deposited YSZ coatings. However, the mechanism of coating formation during SPPS processing is not yet well understood. This study is aimed at understanding the influence of some key SPPS process variables on in situ generated particles and subsequent splat formation to augment the current level of understanding. The plasma power employed was found to play a major role in governing the morphology and phase constitution of in situ generated particles. The shape and size of the YSZ splats were also significantly influenced by the plasma power, but the substrate pre-heat was also noted to be a major determining factor. It was further observed that the SPPS typically involved in situ generation of very fine particulates (50-500 nm) and splats (typically 200-2000 nm), which lead to its nano-porous and homogeneous microstructure. The YSZ coating characteristics were also found to correlate well with the above results. © 2011 The American Ceramic Society.
|
|
| 2. |
- Govindararajan, S., et al.
(författare)
-
Understanding the Formation of Vertical Cracks in Solution Precursor Plasma Sprayed Yttria-Stabilized-Zirconia Coatings
- 2014
-
Ingår i: Journal of The American Ceramic Society. - 0002-7820 .- 1551-2916. ; 97, s. 3396-3406
-
Tidskriftsartikel (refereegranskat)abstract
- Yttria-stabilized zirconia (YSZ) deposition by the solution precursor plasma spraying (SPPS) route has been of interest for potential thermal barrier coating (TBC) applications. It has been surmised that realization of unique microstructural features like vertical cracks, nanosized pores and fine splats in the TBCs can significantly enhance coating durability and performance. However, satisfactory control over the YSZ coating microstructure has been elusive in the absence of an adequate understanding of the mechanism responsible for coating deposition in SPPS. This study demonstrates the ability to tailor microstructure of deposited YSZ coatings over a wide range, from nano-porous coatings to a vertically cracked microstructure. Varying of precursor flow rate has been shown to dictate the pyrolysis events occurring in situ and, adopting this approach, YSZ coatings with widely varying microstructural features have been developed. The coatings have been characterized in detail and the observations correlated with in-flight particle generation and splat formation. These studies also provide useful insights into the possible origin of vertical cracks in the coating for which a mechanism is proposed.
|
|
| 3. |
- Joshi, S. V., et al.
(författare)
-
Hybrid Plasma-Sprayed Thermal Barrier Coatings Using Powder and Solution Precursor Feedstock
- 2014
-
Ingår i: Journal of thermal spray technology (Print). - 1059-9630 .- 1544-1016. ; 23:4, s. 616-624
-
Tidskriftsartikel (refereegranskat)abstract
- A novel approach of hybridizing the conventional atmospheric plasma spraying (APS) technique with the solution precursor plasma spray (SPPS) route to achieve thermal barrier coatings (TBCs) with tailored configurations is presented. Such a hybrid process can be conveniently adopted for forming composite, multi-layered and graded coatings employing simultaneous and/or sequential feeding of solution precursor as well as powder feedstock, yielding distinct TBC microstructures that bear promise to further extend coating durability. TBC specimens generated using conventional APS technique, the SPPS method and through APS-SPPS hybrid processing have been comprehensively characterized for microstructure, phase constitution, hardness and thermal cycling life, and the results were compared to demonstrate the advantages that can ensue from hybrid processing.
|
|
| 4. |
|
|
| 5. |
- Sivakumar, G., et al.
(författare)
-
A novel approach to process phase pure α-Al2O3 coatings by solution precursor plasma spraying
- 2013
-
Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 33:13-14, s. 2823-2829
-
Tidskriftsartikel (refereegranskat)abstract
- The present work represents a significant new approach in the field of thermal spraying to deposit nanostructured phase-pure α-Al2O3 coatings in a single step. In order to understand the mechanism of coating formation, a detailed investigation of in flight formed particles and splat morphologies has been carried out. A plausible deposition mechanism has been proposed based on the understanding derived from the above studies that can form the basis for developing novel ceramic coatings employing the solution precursor plasma spray technique. © 2013 Elsevier Ltd.
|
|
| 6. |
- Sivakumar, G., et al.
(författare)
-
Effect of SPPS Process Parameters on In-Flight Particle Generation and Splat Formation to Achieve Pure α-Al2O3 Coatings
- 2015
-
Ingår i: Journal of thermal spray technology (Print). - : Springer New York LLC. - 1059-9630 .- 1544-1016. ; 24:7, s. 1221-1234
-
Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the role of process conditions in developing phase-pure α-Al2O3 coatings using solution precursor plasma spraying. Different precursor combinations were employed and two key parameters, namely plasma power and substrate pre-heat temperature, were varied. Detailed studies of in-flight formed particles and splat characteristics were found to correlate well with the Al2O3 coating characteristics. The Al2O3-forming precursor formulation was also found to be crucial in determining the phase constitution of the deposited coatings. © 2015 ASM International
|
|
