Partial Transient Liquid-Phase Bonding, Part I: A Novel Selection Procedure for Determining Ideal Interlayer Combinations, Validated Against Al2O3 PTLP Bonding Experience

Abstract

Partial transient liquid-phase (PTLP) bonding is a bonding process that can bond hard-to-join materials, such as ceramics. The process uses a multi-layer interlayer composed of a thick refractory core and thin diffusant layers on each side. Upon heating, the diffusant material melts, and diffusion occurs until the liquid isothermally solidifies. Selecting interlayer materials is a key problem in producing strong, reliable PTLP bonds; materials are usually selected empirically or system by system. This article presents a novel selection procedure that provides a generalized, comprehensive, first-principles-based approach. Components of the selection procedure are linked directly to key characteristics of PTLP bonding. A filtering routine that provides structure for the selection procedure is summarized in this article and detailed in a companion article. Specific capabilities of the routine, such as non-symmetric bonds, add to its effectiveness in identifying additional PTLP bond candidates. By way of example, output from the selection procedure, in conjunction with sessile drop data, is used to analyze all Al2O3 PTLP bonds in the current literature. All analyzed bonds are included in various outputs from the selection procedure, validating its comprehensiveness. Also, Al2O3 PTLP bonds are analyzed as a whole, leading to the identification of important trends that result in increased bond strength. Finally, additional interlayer combinations for PTLP bonding of Al2O3 are presented based on output from the selection procedure and existing sessile drop data.