Gold Brazing Zirconia to Titanium Using a Niobium Interlayer
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Solution Overview
Problem
The mechanical strength of zirconia/titanium brazing joints is insufficient due to poor wetting and adhesion, particularly when using gold solders, and existing methods require complex surface modification and double metallization, complicating the process.
Innovation Solution
A method involving chemical etching of titanium, deposition of a niobium layer on the titanium element, and using a gold or gold alloy solder, which reacts to form intermetallics of the AuNbTi system and a thin oxide layer, enhancing wetting and adhesion without the need for zirconia metallization or stress relief heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct brazing of zirconia with titanium using gold solder is performed, then the process is simple, but the mechanical strength and adhesion are insufficient due to poor wetting
Solution Approach 1:
A niobium layer is deposited on the titanium substrate before brazing to prepare the surface for better solder wetting and adhesion. This preliminary metallization layer modifies the interface properties to enable stronger bonding without complicating the overall brazing procedure
Solution Approach 2:
The niobium layer acts as an intermediary between titanium and gold solder, facilitating better wetting and forming a transition zone that improves adhesion. The niobium-gold intermetallics formed at the interface serve as a bridge that enhances the mechanical strength of the joint
2Strength
If zirconia surface is metallized with titanium and niobium layers, then adhesion improves, but the process complexity increases due to double metallization and stress relief heat treatment
Solution Approach 1:
The complex double metallization process on zirconia (titanium layer plus niobium layer) is eliminated. Only a single niobium layer is deposited on the titanium substrate, removing unnecessary process steps while maintaining strong adhesion through the niobium-gold intermetallic formation
Solution Approach 2:
The niobium layer on titanium substrate self-organizes during brazing to form the necessary intermetallic compounds with gold solder, eliminating the need for additional stress relief heat treatments or complex surface modifications on the zirconia side
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves strong and biocompatible zirconia/titanium assemblies with improved mechanical strength, exceeding previous direct brazing values and simplifying the process by eliminating the need for surface alteration and double metallization.
Implementation Method 1
heating the assembly to a temperature above the melting point of the solder, then cooling the assembly, whereby an assembly is obtained comprising the zirconia part and the titanium element assembled by a solder joint comprising a first part gold or a gold alloy, a second part formed of a reaction layer comprising intermetallics of the AuNbTi system
Implementation Method 2
brazing is an assembly technique that consists of positioning a filler material, called solder or brazing alloy, between or near the parts to be joined, then melting it so that it fills the gap between the parts. After cooling, it forms a bond between the parts to be soldered
Implementation Method 3
the active element Ti is supplied by the titanium substrate by dissolution and diffusion of Ti through the solder. This is enriched with titanium element which will react with the zirconia to form a wettable reaction product (titanium oxide)
Implementation Method 4
titanium element which will react with the zirconia to form a wettable reaction product (titanium oxide)
Data Source
Figure 1A~2
Figure 3~5
Figure 6A~7
AI summary
A method for assembling a zirconia part (20) with a titanium element (10) using a braze, the method comprising the following steps: - coating a surface of the titanium element (10) with a layer (30) of niobium, - positioning a braze (40) between the zirconia part (20) and the niobium layer (30), the braze (40) being gold or a gold alloy, - heating the assembly to a temperature above the melting temperature of the braze (40), then cooling the assembly, thereby obtaining an assembly comprising the zirconia part (20) and the titanium element (10) joined by a braze joint comprising a first part (40) of gold or a gold alloy, a second part formed of a reaction layer (35) comprising intermetallics of the AuNbTi system, and a third part formed of a reaction layer of oxide.