Nondestructive Characterization and Bond Strength of Solid-Solid Bonds

Buck, O.; Rehbein, D. K.; Thompson, R. B.; Palmer, D. D.; Brasche, L.

doi:10.1007/978-1-4613-0817-1_247

Cited by 5 publications

(3 citation statements)

References 6 publications

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“…al. correlated the electromechanical reciprocity theorem and a spring-mass-damping model to bond strength in copper-copper diffusion bonds (7). A method utilizing transfer functions and eigenvectors was introduced by Kato and Abe which showed moderate success in predicting strength of steel/titanium diffusion bonds (8).…”

Section: Prior Workmentioning

confidence: 99%

Ultrasonic evaluation of beryllium-copper diffusion bonds

Jamieson¹

2000

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SummaryConventional peak amplitude ultrasonic techniques have proven to be unreliable when used to evaluate solid state bonds. Of particular concern are bonds of intermediate strength that would pass a typical ultrasonic examination. These are commonly called "kissing bonds." Several advanced ultrasonic techniques were compared to determine the best technique for predicting the bond strength of diffusion bonded beryllium-copper. After an extensive literature search, several advanced ultrasonic techniques were chosen for inclusion in this study. Integrated backscatter calculations, frequency domain reflection coefficients, and time-of-flight variance techniques, which showed varying degrees of success on other material interface systems, were compared in their ability to characterize the bond strength of twenty-two beryllium-copper diffusion bond samples with varying bond qualities. Modifications to previously reported time-of flight histogram and reflection coefficient techniques were also suggested and implemented as a part of this study.Correlation of integrated backscatter calculations and time-of-flight variance with bond strength was good for low, intermediate, and high strength bonds. Correlation of the slope of the frequency based reflection coefficient was poor when considering all bond strengths; however, some correlation was found for medium and high strength bonds. The Y-intercept of the frequency based reflection coefficient curve showed moderate correlation for all bond strengths. 2 Discussion Scope and PurposeDiffusion bonding is a joining process that is becoming increasingly popular as a metallurgical joining method, and offers many advantages over other processes such as fusion welding and brazing. It allows similar and dissimilar metals to be joined at temperatures that are not only far below their melting temperature, but in many cases below their heat treating and annealing ranges. It can also avoid the drastic changes in microstructure typically seen in and adjacent to fusion welds, and the numerous undesirable conditions that can occur during the solidification process. The diffusion bonding process involves applying pressure at an elevated temperature to two samples which have their mating surfaces prepared as flat and smooth as possible. Initially, diffusion begins where contact is made between the two surfaces at the highest points. As the pressure and heat are increased, plastic deformation causes the interface to transform into one of isolated voids, thus increasing the contact area and the rate of diffusion. The voids are then reduced in size until they are completely closed, at which time the rate of atomic diffusion is a maximum. This process is accomplished principally by interstitial or vacancy diffusion, depending upon the materials at the interface (1,2).The quality of a diffusion bond, as in other bonds, is of critical importance in ensuring the proper performance of the bond for its intended application. Nondestructive test methods, particularly ultrasonic techniques,...

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Section: Prior Workmentioning

confidence: 99%

Ultrasonic evaluation of beryllium-copper diffusion bonds

Jamieson¹

2000

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“…Next the samples were destructively tested to measure their strengths. To relate the ultrasonic data with bond strength, the digitized ultrasonic signals are processed with various transform techniques to determine frequency content (3,4,5). Changes in the frequency spectra are quantified and a set of features is generated.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Ultrasonic Characterization of Assemblies,TLL{_}9

Thomas¹,

Chinn²

2000

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The solid state bonded joint between two components; called an autoclave bond, is critical to the performance of a weapon system. A nondestructive method to assess the integrity of these joints is needed to certify the weapon for extended life. This project is developing ultrasonic technologies for bond quality assessment. Existing ultrasonic technology easily maps totally unbonded areas in a bond line. As an example, Figure 1 is an ultrasonic image of the bondline in a tensile specimen that was taken from a surrogate autoclave bond. We enhanced this technology to quantify the mechanical properties of a bond. There are situations when a bond interface appears intact by existing inspection methods, but fails under minimal loading. We developed an ultrasonic technique to eliminate this problem and assess the durability of the bond. Our approach is based on advanced signal processing and artificial intelligence techniques that extract information from the ultrasonic signal after it interacts with the bondline. We successfully demonstrated this technique on surrogate samples. We also designed and began assembly of an ultrasonic system to evaluate weapon components. Our next step is to acquire ultrasonic data on real parts and tailor the bond classification algorithm to detect and image defective bond regions.

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“…The ultrasonic data can now be related to the strength of a bond. The digitized ultrasonic signals are processed with various transform techniques to determine frequency content (3,4,5). Changes in the frequency spectra are quantified and a set of features is generated.…”

Section: Introductionmentioning

confidence: 99%

Signal analysis approach to ultrasonic evaluation of diffusion bond quality

Thomas¹,

Chinn²

1999

AIP Conference Proceedings

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Solid state bonds like the diffusion bond are attractive techniques for joining dissimilar materials since they are not prone to the defects that occur with fusion welding. Ultrasonic methods can detect the presence of totally unbonded regions but have difficulty sensing poor bonded areas where the substrates are in intimate contact. Standard ultrasonic imaging is based on amplitude changes in the signal reflected from the bond interface. Unfortunately amplitude alone is not sensitive to bond quality. We demonstrated that there is additional information in the ultrasonic signal that correlates with bond quality. In our approach we interrogated a set of dissimilar diffusion bonded samples with broad band ultrasonic signals. The signals were digitally processed and the characteristics of the signals that corresponded to bond quality were determined. These characteristics or features were processed with pattern recognition algorithms to produce predictions of bond quality. The predicted bond quality was then compared with the destructive measurement to assess the classification capability of the ultrasonic technique

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Nondestructive Characterization and Bond Strength of Solid-Solid Bonds

Cited by 5 publications

References 6 publications

Ultrasonic evaluation of beryllium-copper diffusion bonds

Ultrasonic evaluation of beryllium-copper diffusion bonds

Enhanced Ultrasonic Characterization of Assemblies,TLL{_}9

Signal analysis approach to ultrasonic evaluation of diffusion bond quality

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