Thermal fracture resistance of a functionally graded coating with periodic edge cracks

2008 ◽  
Vol 202 (17) ◽  
pp. 4189-4197 ◽  
Author(s):  
Z.-H. Jin ◽  
Y.Z. Feng
Keyword(s):  
Fracture Resistance ◽  
Functionally Graded ◽  
Thermal Fracture ◽  
Functionally Graded Coating ◽  
Graded Coating ◽  
Edge Cracks

scholarly journals Thermal fracture of functionally graded thermal barrier coatings with pre-existing edge cracks and multiple internal cracks imitating a curved interface

2021 ◽  
Author(s):  
Vera Petrova ◽  
Siegfried Schmauder
Keyword(s):  
Fracture Toughness ◽  
Functionally Graded ◽  
Multiple Cracks ◽  
Mixed Mode Fracture ◽  
Thermal Fracture ◽  
Graded Coating ◽  
Crack Tips ◽  
Edge Cracks ◽  
System Of Cracks ◽  
Curved Interface

AbstractThis work is devoted to the problem of thermal fracture of a functionally graded coating on a homogeneous substrate (FGC/H) with an emphasis on the analysis of a special system of cracks that simulates a curved interface. The FGC/H structure contains the pre-existing crack system in the FGC, both edge cracks (which are often seen in FGC/H structures) and internal cracks. The stress intensity factors are calculated. (Generally, both Mode I and Mode II are nonzero.) Then, using the appropriate fracture criterion for mixed-mode fracture conditions, the crack propagation direction (so-called fracture angles) and critical loads, when this propagation is initiated, are determined. The application of fracture criteria requires knowledge of the fracture toughness near the crack tips. Thus, it is assumed that the fracture toughness of an FGC, as well as other material properties, continuously varies through the thickness of the coating. For multiple cracks, it is also important to know the weakest crack that starts to propagate first, and the initial direction of this growth. Therefore, the main attention is paid to the evaluation of the fracture angles for the cracks for different parameters of the FGC/H structure. Both cases of a homogeneous semi-infinite medium with a system of cracks imitating a curved interface and FGC/H structures with identical crack systems are studied.

Influence of Material Continuity of Functionally Graded Coating on Interface Crack

2012 ◽  
Vol 503-504 ◽  
pp. 760-763 ◽  
Author(s):  
Chang Qing Sun ◽  
Hua Wei ◽  
Hong Gao
Keyword(s):  
Elastic Modulus ◽  
Interface Crack ◽  
Fracture Resistance ◽  
Base Material ◽  
Functionally Graded ◽  
Functionally Graded Coating ◽  
Fracture Behaviors ◽  
Graded Coating ◽  
Practical Engineering ◽  
Functionally Graded Layer

In this paper, aiming at three material parameter functions of functionally graded coating (FGC) which have different continuities, the influence of functionally gradient coating material continuity on the fracture behaviors of the crack on the interface between the base material and coating is studied. The results show that when the functionally graded coating structure is under a tension load, if the ratio of maximum elastic modulus of the FGC to the elastic modulus of the base is less than 10, the functionally graded layer which has C02 continuity can help to improve the fracture resistance of the interface crack, and if the ratio increases continuously, the functionally graded layer which has C13 continuity can help to improve the fracture resistance of the interface crack, which is of great guiding significance for practical engineering design.

Development of Functionally Graded Coating by Thermal Spray Deposition

2015 ◽  
pp. 121-162
Author(s):  
Jyotsna Dutta Majumdar ◽  
Indranil Manna
Keyword(s):  
Thermal Spray ◽  
Spray Deposition ◽  
Thermal Spraying ◽  
Chemical Vapor ◽  
Solid Substrate ◽  
Functionally Graded ◽  
Functionally Graded Coating ◽  
Energy Applications ◽  
Graded Coating ◽  
Gradient Coatings

Functionally Gradient Coatings (FGCs) are emerging materials with an improved service life and have a promising future for the production of (a) tailored components for applications subjected to large thermal gradients, (b) smart coating with improved corrosion and wear resistance, (c) improved fatigue wear, and (d) improved material structures for energy applications like batteries, fuel cells, etc. FGCs may be developed by physical/chemical vapor deposition, electro/electroless deposition, thermal spray deposition technique, etc. Thermal spraying refers to the technique or a group of techniques whereby molten or semi-molten droplets of materials are sprayed onto a solid substrate to develop the coating. In this chapter, detailed overviews of the development of functionally graded coating by thermal spray deposition techniques are presented. In addition, a few research results on the development of functionally graded coating for tribological and thermal barrier applications are presented.

Analysis on Functionally Graded Material Coating Interface Crack

2012 ◽  
Vol 602-604 ◽  
pp. 1596-1599
Author(s):  
Bo He ◽  
Chang Qing Sun
Keyword(s):  
Elastic Modulus ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Interface Crack ◽  
Functionally Graded ◽  
Physical Parameters ◽  
Mode I ◽  
Modulus Ratio ◽  
Functionally Graded Coating ◽  
Graded Coating

It is assumed that the physical parameters of functionally graded coating material accords with the variation of degree n polynomial, and based on this material model, the behavior of crack fracture on the interface of functionally graded coating is studied. The results show that when the functionally graded coating structure bears a tension load, stress intensity factors of mode I and mode II exist at the same time generally, and the intensity factor of mode I occupies a leading position all along. Besides, when the elastic modulus ratio of the base to the functionally graded coating top is 5 and the elastic modulus of functionally graded coating varies linearly, the stress intensity factor of interface crack is the smallest, and with the increasing of elastic modulus ratio, the optimal non-uniform parameter tends to be larger than 1.

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