Interfacial Fracture Toughness of a Plasma Sprayed Hydroxyapatite Coating Used for Orthopedic Implants

1998 ◽  
Vol 550 ◽  
Author(s):  
Y. Sugimura ◽  
M. Spector
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Adhesion Strength ◽  
Unit Area ◽  
Interfacial Fracture ◽  
Orthopedic Implants ◽  
New Method ◽  
Aqueous Environment ◽  
Interfacial Fracture Toughness ◽  
Plasma Sprayed

AbstractThis study introduces a new method for evaluating the adhesion strength of a coating on a substrate. The interfacial fracture toughness, Γi is used to assess the work per unit area required to separate an interface. Γi is measured for the as-received specimens of hydroxyapatite plasma sprayed on Ti-6A1-4V substrate. Calculation of the interfacial fracture toughness requires that the elastic modulus of the coating to be known. The Young's modulus of the plasma sprayed hydroxyapatite is assessed using a bend test. The effect of aqueous environment on the interfacial fracture toughness is also investigated.

Effect of Moisture on the Elastic Modulus and Interfacial Adhesion of Polymer-Metal Components in Microelectronic Assemblies

2003 ◽  
Author(s):  
Timothy P. Ferguson ◽  
Jianmin Qu
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Interfacial Adhesion ◽  
Interfacial Fracture ◽  
Moisture Diffusivity ◽  
Bending Test ◽  
Interfacial Fracture Toughness ◽  
Moisture Concentration ◽  
Polymer Metal ◽  
Effect Of Moisture

Moisture poses a significant threat to the reliability of microelectronic assemblies and can be attributed as being one of the principal causes of many premature package failures. It is a multi-dimensional concern in electronic packaging, having an adverse effect on package reliability by changing both the mechanical properties and interfacial adhesion of the microelectronic assembly. In this paper, a study has been conducted to evaluate the moisture-induced degradation of both the elastic modulus of a commercially available no-flow underfill and the interfacial adhesion of the underfill to a copper alloy substrate. Three different levels of moisture preconditioning, 85C/50%RH, 85C/65%RH, and 85C/85RH%, were implemented in this study. Diffusion coefficient test specimens were constructed to experimentally measure the moisture diffusivity into the underfill resin and obtain the moisture saturation concentration for each level of moisture preconditioning. Flexural bend test specimens were made to characterize the effect of moisture on the elastic modulus of the underfill adhesive. Last, interfacial fracture toughness specimens with prefabricated interface cracks were used in a four point bending test to quantify the effect of moisture on interfacial fracture toughness. The results of this study will aid in the development of more robust microelectronic assemblies, demonstrating how both the elastic modulus and interfacial toughness change as a function of moisture concentration.

scholarly journals Mode II Fracture Analysis of GNP/Epoxy Nanocomposite Film on a Substrate

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2823
Author(s):  
Shiuh-Chuan Her ◽  
Kai-Chun Zhang
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Nanocomposite Film ◽  
Epoxy Matrix ◽  
Interfacial Fracture ◽  
Mode Ii ◽  
Interfacial Fracture Toughness ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
Film Substrate

Epoxy resin with excellent mechanical properties, chemical stability, and corrosion resistance has been widely used in automotive and aerospace industries. A thin film of epoxy deposited on a substrate has great application in adhesive bonding and protective coating. However, the intrinsic brittleness of epoxy with a relatively low fracture toughness limits its applications. In this work, graphene nanoplatelets (GNP) were added to the epoxy resin to enhance its toughness, hardness, and elastic modulus. A series of nanocomposites with different loadings of GNP were fabricated. Ultrasonic sonication in combination with surfactant Triton X-100 were employed to disperse GNP in the epoxy matrix. A nanocomposite film with a thickness of 0.3 mm was deposited on an Al substrate using a spinning coating technology. The hardness and elastic modulus of the nanocomposite film on the Al substrate were experimentally measured by a nanoindentation test. Analytical expression of the mode II interfacial fracture toughness for the nanocomposite film on an Al substrate with an interfacial edge crack was derived utilizing the linear elastic fracture mechanics and Euler’s beam theory. End-notched flexure (ENF) tests were conducted to evaluate the mode II fracture toughness. It was found that the hardness, elastic modulus, and mode II fracture toughness of the nanocomposite film reinforced with 1 wt % of GNP were improved by 71.8%, 63.2%, and 44.4%, respectively, compared with the pure epoxy. The presence of much stiff GNP in the soft epoxy matrix prompts toughening mechanisms such as crack deflection and crack pinning, resulting in the improvements of the fracture toughness, hardness, and elastic modulus. Microscopic observation for the nanocomposite was examined by scanning electron microscopy (SEM) to investigate the dispersion of GNPs in the epoxy matrix. The performance of a nanocomposite film deposited on a substrate was rarely studied, in particular, for the interfacial fracture toughness of the film/substrate composite structure. Utilizing the theoretical model in conjunction with the ENF experimental test presented in this study, an accurate determination of the mode II interfacial fracture toughness of film/substrate composite structure is made possible.

Measurement of the Mode Mix Dependent Interfacial Fracture Toughness for a Ti/Si Interface Using a Modified Decohesion Test

2003 ◽  
Author(s):  
Mitul B. Modi ◽  
Suresh K. Sitaraman
Keyword(s):  
Fracture Toughness ◽  
Crack Surface ◽  
Unit Area ◽  
Interfacial Fracture ◽  
Analytical Models ◽  
Interfacial Fracture Toughness ◽  
Testing Methods ◽  
Available Energy ◽  
Test Parameters ◽  
Toughness Testing

The Modified Decohesion Test (MDT), developed by the authors, eliminates shortcomings of current interfacial fracture toughness testing methods. In this approach, a highly stressed super layer is used to drive delamination and create any mode mix at the crack tip. MDT uses the change in crack surface area to vary the available energy per unit area for crack growth and thus to bound the interfacial fracture toughness. Therefore, this technique uses a single sample to measure the interfacial fracture toughness, as opposed to the decohesion test that uses several samples to be able to bound the interfacial fracture toughness. Since the deformations remain elastic, a mechanics-based solution can be used to correlate test parameters to the energy release rate. Common IC fabrication techniques are used to prepare the sample and execute the test, thereby making the test compatible with current microelectronic or MEMS facilities. In this paper, the mechanics based solution used in the MDT to correlate test parameters to the fracture metrics is discussed and compared against other analytical models. Interfacial fracture toughness results are provided for a Ti/Si interface at several mode mixes.

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