Joining Technology Innovations at the Macro, Micro, and Nano Levels

Abstract

With the growing joining requirements of emergent engineering materials and new applications, conventional welding continues to evolve at all scales spanning from the macrodown to the micro-and nanoscale. This mini review provides a comprehensive summary of the research hot spots in this field, which includes but is not limited to selected papers from the international nanojoining and microjoining conference (NMJ) held in Nara, Japan on 1-4 December 2018. These innovations include the integration of nanotechnology, ultrafast laser, advanced manufacturing, and in situ real-time ultra-precision characterization into joining processes. This special issue may provide a relatively full picture of the state-of-the-art research progress, fundamental understanding, and promising application of modern joining technologies.

Diffusion Bonding of Ti6Al4V to Al2O3 Using Ni/Ti Reactive Multilayers

“…Several approaches have been developed in order to reduce the bonding conditions for the diffusion bonding of titanium alloys. The use of varying pressure, interlayers with ceramic nanoparticles or reactive interlayers has been referred to as a potential approach for overcoming the problems in dissimilar diffusion bonding [22][23][24][25][26][27][28]. The use of interlayers in diffusion bonding can reduce the processing conditions and promote the formation of a joint with good mechanical properties.…”

Impulse Pressure-Assisted Diffusion Bonding (IPADB): Review and Outlook

“…As a result, a bond that has a higher melting point than the initial TLP bonding temperature is formed [5][6][7][8]. Using nanostructured interlayers that have a high surface energy as a result of their large surface to volume ratio is a clever way to reduce the bonding time (and often even the bonding temperature) in diffusion bonding or related processes such as vacuum brazing [9][10][11].…”

Wettability, Diffusion Behaviors, and Modeling of Ni Nanoparticles and Nanowires in Brazing Inconel 718

“…The noisy EDS data were smoothed with a Savitzky-Golay filter (SG). ðy k Þ smooth ¼ P 0.5ðnÀ1Þ i¼À0.5ðnÀ1Þ A i y kþi P 0.5ðnÀ1Þ i¼À0.5ðnÀ1Þ A i (7) ðy k Þ smooth is the smoothed data point and y k is the raw data point. n is the number of points used for smoothing (20 points for this study).…”

“…Nanomaterials are being explored (i.e., nanobrazing materials) as a substitute for conventional brazing alloys due to multiple advantages. [ 7 ] First, an advantage that nanomaterials have over conventional brazing alloys is the lack of a need for melting point depressants such as boron and silicon which negatively affect the mechanical properties of the brazed joint. Nanomaterials exhibit inherent melting point depression due to the Gibbs–Thompson effect where the melting point of the particle decreases as the particle diameter decreases.…”