Computational Evaluation of Adhesion and Mechanical Properties of Nanolayered Erosion-Resistant Coatings for Gas Turbines

2010 ◽  
Vol 133 (4) ◽  
Author(s):  
Mariusz Bielawski ◽  
Kuiying Chen
Keyword(s):  
Fracture Toughness ◽  
Gas Turbines ◽  
Density Functional ◽  
Interfacial Fracture ◽  
Computational Method ◽  
Work Of Adhesion ◽  
Transition Metal Nitrides ◽  
Interfacial Fracture Toughness ◽  
Metallic Behavior ◽  
Brittle Behavior

A computational method to evaluate fracture toughness of prospective erosion-resistant coatings using a combination of first-principles density functional theory (DFT) calculations and fracture mechanics is proposed. Elastic coefficients C11, C12, and C44, the ideal work of adhesion Wad, bulk modulus B, shear modulus G, and Young’s modulus E of transition metal nitrides with a cubic structure such as TiN, CrN, ZrN, VN, and HfN are calculated. Both the G/B ratio and Cauchy pressure C12−C44 indicate brittle behavior for TiN, ZrN, and HfN and more metallic behavior for CrN and VN. The fracture toughness KIC and interfacial fracture toughness KICInt for bilayer combinations of these five nitrides is calculated along the [100] and [110] directions. The largest KIC value is obtained for HfN (2.14 MPa m1/2) in (100) orientation and for TiN (2.16 MPa m1/2) in (110) orientation. The lowest fracture toughness, in both orientations, is found for CrN. Among ten coherent interfaces of the five investigated nitrides the largest value of interfacial fracture toughness KICInt=3.24 MPa m1/2 is recorded for the HfN/TiN interface in the (110) orientation.

Computational Evaluation of Adhesion and Mechanical Properties of Nanolayered Erosion-Resistant Coatings for Gas Turbines

2010 ◽  
Author(s):  
Mariusz Bielawski ◽  
Kuiying Chen
Keyword(s):  
Fracture Toughness ◽  
Gas Turbines ◽  
Density Functional ◽  
Interfacial Fracture ◽  
Computational Method ◽  
Work Of Adhesion ◽  
Transition Metal Nitrides ◽  
Interfacial Fracture Toughness ◽  
Computational Evaluation ◽  
Cauchy Pressure

A computational method to evaluate fracture toughness of prospective erosion-resistant coatings using a combination of first-principles density functional theory (DFT) calculations and fracture mechanics is proposed. Elastic coefficients C11, C12 and C44, the ideal work of adhesion Wad, bulk moduls B, shear moduls G, and Young’s moduls E of transition metal nitrides with a cubic structure such as TiN, CrN, ZrN, VN and HfN are calculated. Both the G/B ratio and Cauchy pressure C12-C44 indicate brittle behaviour for TiN, ZrN and HfN and more metallic behaviour for CrN and VN. The fracture toughness KIC and interfacial fracture toughness KICInt for bi-layer combinations of these five nitrides is calculated along the [100] and [110] directions. The largest KIC value is obtained for HfN (2.14 MPa·m1/2) in (100) orientation and for TiN (2.16 MPa·m1/2) in (110) orientation. The lowest fracture toughness, in both orientations, is found for CrN. Among ten coherent interfaces of the five investigated nitrides the largest value of interfacial fracture toughness, KICInt = 3.24 MPa·m1/2, is recorded for the HfN/TiN interface in the (110) orientation.

Continuous Microindentation and Microscratch Measurements of Metal-Ceramic Adhesive strengths

1991 ◽  
Vol 239 ◽  
Author(s):  
S. Venkataraman ◽  
D. L. Kohlstedt ◽  
W. W. Gerberich
Keyword(s):  
Fracture Toughness ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Interfacial Fracture ◽  
Interfacial Shear ◽  
Work Of Adhesion ◽  
Interfacial Fracture Toughness ◽  
Heat Treated ◽  
Metal Ceramic

ABSTRACTTo investigate the effect of heat-treatment on the adhesion of Pt thin films to NiO substrates, the strain energy release rate, interfacial fracture toughness and interfacial shear strength were determined from continuous microscratch and continuous microindentation experiments. Samples were prepared by sputtering Pt onto single crystals of NiO, followed by a heat-treatment at temperatures of 300, 500 and 800°C and an oxygen partial pressure of either 0.21 or 10-5 atm. Continuous microscratch tests were performed by driving a conical indenter with either a 1 or 5 μm tip radius simultaneously into and across the Pt film. From the magnitude of the critical load at the point of film delamination and the area of the delaminated piece of the thin film, the strain energy release rate (practical work of adhesion) and interfacial fracture toughness were calculated. The practical work of adhesion and interfacial fracture toughness increased from 0.2 J/m2 and 0.2 MPa√m, respectively, for as-sputtered samples to 4.6 J/m2 and 1 MPa√m for samples heat-treated at 500°C and 10-5 atm. Preliminary analysis of continuous microindentation results for Pt/NiO samples yielded interfacial shear strengths of 270 MPa for as-sputtered samples and 725 MPa for samples heat-treated at 500°C and 10-5 atm. While these values are in good agreement with those determined by other methods for metal-ceramic systems, there are sufficient differences in test method for a single system to require additional analysis of the proposed models.

On Relating Thermodynamic Work of Adhesion to Interfacial Fracture Toughness

1996 ◽  
Vol 445 ◽  
Author(s):  
Raymond A. Pearson ◽  
Thomas B. Lloyd
Keyword(s):  
Fracture Toughness ◽  
Strain Energy Release ◽  
Interfacial Fracture ◽  
Work Of Adhesion ◽  
Interfacial Fracture Toughness ◽  
Package Design ◽  
Silicon Chips ◽  
Interfacial Fracture Mechanics ◽  
Thermodynamic Work ◽  
Thermodynamic Work Of Adhesion

AbstractOrganic adhesives are commonly used in the microelectronics industry to bond silicon chips to a wide variety of substrates. The substrates include copper, silver, nickel / palladium, polyimide, and glass‐filled epoxies. The surfaces of these substrates are affected by the processing steps used in the manufacturing process used to produce the final package. The most common adhesives used in the assembly of microelectronic packages are epoxy‐based and there are numerous grades and types to chose from. Therefore, the packaging engineer is faced with the dilemma of what criterion to use to select the best adhesive for a particular package design.At the crux of the problem is how does one predict adhesion and how does one measure it? It is proposed that the surfaces play an important role in forming the interfacial bond and that strength of the mating surfaces can be characterized in terms of the thermodynamic work of adhesion. Roughness is also a factor but will not be dealt with here. The thermodynamic work of adhesion describes the energy to reversibly separate two surfaces (elastic). Interfacial fracture mechanics may be used to quantify the strain energy release rate for separating two surfaces and contains both elastic and inelastic contributions. This talk will contain a discussion of our studies on the use of a three liquid probe method to determine the thermodynamic work of adhesion and a mixed‐mode bending method to measure interfacial fracture toughness. Moreover, we will comment on the perils of relating the thermodynamic work of adhesion to the interfacial fracture toughness.

scholarly journals Evaluation of the Interfacial Fracture Toughness of Anodic Bonds

2007 ◽  
Vol 73 (735) ◽  
pp. 1266-1272 ◽  
Author(s):  
Yoshiaki NOMURA ◽  
Masaki NAGAI ◽  
Toru IKEDA ◽  
Noriyuki MIYAZAKI
Keyword(s):  
Fracture Toughness ◽  
Interfacial Fracture ◽  
Interfacial Fracture Toughness

scholarly journals Evaluation of Interfacial Fracture Toughness and Interfacial Shear Strength of Typha Spp. Fiber/Polymer Composite by Double Shear Test Method

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2225 ◽  
Author(s):  
Ikramullah ◽  
Samsul Rizal ◽  
Yoshikazu Nakai ◽  
Daiki Shiozawa ◽  
H.P.S. Abdul Khalil ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Epoxy Composite ◽  
Interfacial Fracture ◽  
Interfacial Shear ◽  
Composite Model ◽  
Interfacial Fracture Toughness ◽  
Double Shear ◽  
The Matrix

The aim of this paper is to evaluate the Mode II interfacial fracture toughness and interfacial shear strength of Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite by using a double shear stress method with 3 fibers model composite. The surface condition of the fiber and crack propagation at the interface between the fiber and the matrix are observed by scanning electron microscope (SEM). Alkali treatment on Typha spp. fiber can make the fiber surface coarser, thus increasing the value of interfacial fracture toughness and interfacial shear strength. Typha spp. fiber/epoxy has a higher interfacial fracture value than that of Typha spp. fiber/PLLA. Interfacial fracture toughness on Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite model specimens were influenced by the matrix length, fiber spacing, fiber diameter and bonding area. Furthermore, the interfacial fracture toughness and the interfacial fracture shear stress of the composite model increased with the increasing duration of the surface treatment.

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