Ignition Electrode Diffusion Bonding for Corrosion-Resistant Joints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ignition devices, such as spark plugs, suffer from corrosion, cavities, cracking, and detachment of precious metal electrodes due to non-uniform weld bonds, leading to high maintenance intensity and reduced lifetime.
Innovation Solution
A process that forms a two-dimensional metallic bond between the electrode and carrier materials by diffusing atoms or ions below the materials' melting temperatures, avoiding intermetallic phases and thermal stresses, using induction, radiative heat, or thermal conduction, and optionally with a solder or intermediate material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is used to bond precious metal electrodes to nickel carrier, then bond strength is improved, but corrosion resistance deteriorates and weld seam cavities occur
Solution Approach 1:
The patent changes the bonding parameters by using friction stir welding instead of laser welding, operating below the melting temperature of the materials. This parameter change transforms the bonding mechanism from melting and fusion to plastic deformation and diffusion, eliminating cavities and improving corrosion resistance while maintaining bond strength
Solution Approach 2:
The patent replaces the thermal field-based laser welding process with a mechanical field-based friction stir welding process. The mechanical energy from rotating tool creates friction heat and plastic deformation, fundamentally changing the bonding mechanism to avoid the harmful effects of conventional welding while achieving reliable bonds
2Strength
If welding processes are used to join electrodes and carrier, then bond strength is improved, but weld seam cavities and cracking occur reducing bond quality
Solution Approach 1:
The patent changes the bonding parameters by operating in the solid state below melting temperature, using plastic deformation and diffusion mechanisms instead of fusion. This eliminates cavity formation and cracking while creating uniform bonds throughout the bonding zone
Solution Approach 2:
The patent transitions from surface-level welding to three-dimensional plastic deformation and diffusion throughout the bonding zone. The friction stir welding process creates a volumetric bonding region with uniform properties, eliminating the two-dimensional weld seam limitations
3Strength
If conventional welding is used to create bond between materials, then joining is achieved, but thermal stresses and warpage occur due to nonuniform heat dissipation
Solution Approach 1:
The patent changes the temperature parameter by operating below the melting point of the materials, using solid-state diffusion and plastic deformation instead of fusion. This controlled temperature regime prevents excessive thermal gradients and the resulting warpage and internal stresses
Solution Approach 2:
The patent introduces a friction stir welding tool as an intermediary that mechanically mixes and bonds the materials through controlled plastic deformation. This mechanical intermediary facilitates bonding without requiring the materials to melt and resolidify, preventing thermal stress-induced distortion
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 process results in a strong, corrosion-resistant bond with reduced material thickness, enhancing the ignition device's lifetime and reducing maintenance needs, while allowing for thinner, less costly electrodes.
Implementation Method 1
diffusion of individual atoms or ions of the materials into the respective other material, for example of the carrier material into the electrode material or vice versa, is brought about
Implementation Method 2
the amount of heat which is released to the joining face, especially the carrier material and the electrode material, to raise them to the joining temperature is generated by induction
Implementation Method 3
the amount of heat which is released to the joining face, especially the carrier material and the electrode material, to raise them to the joining temperature is generated by induction, radiative heat
Implementation Method 4
the amount of heat which is released to the joining face, especially the carrier material and the electrode material, to raise them to the joining temperature is generated by induction, radiative heat or thermal conduction
Data Source
AI summary
A method produces an electrode for an ignition device. A metal electrode material is placed against a metal support material at a joining surface, and the support material and the electrode material are pressed against each other at the joining surface using a defined surface pressure and are positioned in a chamber in which a negative pressure and/or a defined atmosphere is generated and applied in the chamber. The joining surface is heated uniformly to a joining temperature, the joining temperature is maintained for a joining time such that a connection between the support material and the electrode material is produced on the joining surface. The support material and the electrode material form a flat uniform connection with each other on the basis of the joining surface. Accordingly, the joining temperature lies below the melting temperature of the support material and of the electrode material.