Active Brazing Material for Ceramic Joints
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Solution Overview
Problem
Active brazing processes for ceramic components are time- and energy-intensive, leading to coarse-grained structures and inhomogeneities in joints, which impair their strength, and existing methods using reactive multilayer systems result in joints that are too thick for capacitive ceramic pressure sensors.
Innovation Solution
An active brazing material composed of layer sequences with thin layers of brazing material and exothermically reacting layers, where the reaction layers have a high enthalpy of formation, are used to generate heat locally, allowing for efficient brazing at lower temperatures and reducing cooling time, thereby producing more homogeneous and stronger joints with reduced height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional active brazing is used to join ceramic components, then a strong chemical bond is achieved, but the process is time- and energy-intensive leading to coarse-grained structures and inhomogeneities that impair joint strength
Solution Approach 1:
The brazing material is segmented into multiple thin layers (5-50 nm each) with alternating reactant layers, allowing distributed exothermic reactions throughout the joint rather than requiring prolonged heating of the entire assembly
Solution Approach 2:
The invention utilizes phase transitions through exothermic chemical reactions in the reactant layers, where the reaction enthalpy (≥45 kJ/mol) provides localized heat generation to melt the brazing material rapidly, achieving strong bonds in significantly reduced time compared to conventional thermal brazing
2Strength
If conventional active brazing is used to join ceramic components, then a strong chemical bond is achieved, but high energy consumption is required to maintain brazing temperature over extended periods
Solution Approach 1:
The reactant layers within the brazing material perform self-service by generating their own heat through exothermic reactions, eliminating the need for external energy input to maintain brazing temperature. The reaction enthalpy of ≥45 kJ/mol ensures sufficient heat generation to melt the brazing material and create strong joints
Solution Approach 2:
The invention exploits phase transitions through exothermic chemical reactions, where the rapid release of reaction enthalpy provides the necessary thermal energy to melt and flow the brazing material, achieving strong bonds with minimal external energy input
3Productivity
If reactive multilayer systems are used to reduce brazing time and energy, then faster cooling and finer grain structures are achieved, but the joint height becomes too large for capacitive ceramic pressure sensors
Solution Approach 1:
The invention applies local quality by concentrating the exothermic reactions within the thin brazing material layers themselves (5-50 nm per layer), ensuring that heat generation and melting occur precisely where needed for bonding, rather than requiring a thick reactive multilayer system that would increase joint height
Solution Approach 2:
The invention uses thin film structures with multiple layers of 5-50 nm thickness to achieve the reactive brazing function. This thin-film approach enables fast cooling and fine grain structures while maintaining joint height suitable for capacitive ceramic pressure sensors, unlike conventional thick reactive multilayer systems
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 active brazing material enables energy-efficient joining of ceramic components with significantly less time and energy, resulting in fine-grained, homogeneous, and stronger active-brazed connections with lower heights, suitable for capacitive ceramic pressure sensors.
Implementation Method 1
each of which comprises at least one first reaction layer (Ra) consisting of a first reactant and at least one second reaction layer (Rb) consisting of a second reactant that reacts exothermally with the first reactant, wherein a reaction enthalpy of the exothermic reaction of the reactants is greater than or equal to 45 kJ/mol
Implementation Method 2
The active brazing material can be produced by applying the individual layers to one another by consecutive vapor deposition
Data Source
AI summary
An active brazing material for the energy-efficient production of active-brazed connections that consists of layer sequences arranged on top of one another, the layer sequences of which consist of layers arranged on top of on another, the layer sequences of which each comprise at least one layer of brazing material, wherein the layers of brazing material of each layer sequence each contain at least one component of a base active braze and, in conjunction with each other, contain all components of the base active braze, the layer sequences of which each comprise at least one first reaction layer consisting of a first reactant to which at least one second reaction layer is directly adjacent in the active brazing material and consists of a second reactant that exothermally reacts with the first reactant, wherein an enthalpy of formation of the exothermic reaction of the reactants is greater than or equal to 45 kJ/mol—in particular, greater than or equal to 50 kJ/mol.