| 1. |
- Ray, A. K., et al.
(författare)
-
Mechanical property and characterization of a NiCoCrAlY type metallic bond coat used in turbine blade
- 2009
-
Ingår i: Materials Science and Engineering A. - : Elsevier BV. - 0921-5093. ; 505:1-2, s. 96-104
-
Tidskriftsartikel (refereegranskat)abstract
- This paper highlights some of the results obtained while studying Ni20Co18Cr12.5Al0.6Y (NiCoCrAlY) type metallic bond-coat properties of a thermal-barrier coated (TBC), AE-437A Ni base superalloy mostly employed for manufacturing compressor and stationary stator blades in aero turbines. Experiments were mainly focused in the area of evaluation of microstructure, residual stress, shear strength, hardness and with special emphasis in establishing the ductile to brittle transition temperature (DBTT) of the bond coat by using acoustic emission technique during room temperature and high temperature tensile tests. Results reveal that the residual stress was tensile in nature in the TBC layer and compressive in the bond coat as well as in the substrate. The DBTT of this bond coat is around 650 °C, which is in close proximity to the value reported in literature for CoCrAlY type of bond coat. Finite element technique was used to analyze the equivalent stresses in the bond coat, the result of which revealed the highest order of equivalent stress 800 °C, as the bond coat is ductile above 650 °C. Shear strength of the bond coat is in close proximity with that of the bond strength reported in literature for CoCrAlY and Ni22Co17Cr12.5Al0.6Y types of bond coat. © 2009 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Venkataraman, Nagaiyanallur V., et al.
(författare)
-
Spatial tuning of the metal work function by means of alkanethiol and fluorinated alkanethiol gradients
- 2009
-
Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:14, s. 5620-5628
-
Tidskriftsartikel (refereegranskat)abstract
- Surface-chemical gradients composed of self-assembled monolayers (SAM) of deeanethiol (DT) and a partially fluorinated decanethiol (PFDT) on gold, exhibiting gradual changes in surface concentration of one or both components, have been prepared by a simple, controlled-immersion process. Infrared spectroscopic studies on a single-component PFDT gradient indicate a change in average molecular orientation with increasing surface coverage, whereas on a two-component gradient, the orientation remains invariant over the entire length of the gradient. X-ray photoelectron spectroscopic measurements on a single-component PFDT gradient show a systematic decrease in the fluorine (F Is) binding energy with increasing surface coverage, whereas a single-component DT gradient shows an increase in the carbon (C Is) binding energy. In two-component (DT-PFDT) gradients, the molar ratios of the two components at any particular location on the sample surface determine the magnitude of the binding-energy shifts at that location. Such shifts, which are on the order of 1 eV, are shown to be a consequence of work-function changes in the underlying gold upon SAM formation. These results are discussed in light of the surface-potential measurements on a DT-PFDT gradient by Kelvin Probe Force Microscopy and XP spectra acquired on "floating" and grounded samples.
|
|
