Spark Plug Base Material Composition for Peeling Resistance
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Solution Overview
Problem
Spark plugs with a diffusion layer between the discharge member and the base material face challenges in peeling resistance due to thermal stress and oxidation of iron oxide, leading to potential discharge member detachment.
Innovation Solution
A spark plug design with a base material composition of 50% Ni or more, 8-40% Cr, 0.05-2% Si, 0.01-2% Al, 0.01-2% Mn, 0.01-0.1% C, and 0.001-0.04% Fe, which suppresses iron oxide generation and reduces stress on the diffusion layer, enhancing peeling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a diffusion layer is used between the discharge member and base material, then bonding is achieved, but thermal stress causes crack generation and peeling
Solution Approach 1:
The invention changes the chemical composition parameters of the base material, specifically limiting Fe content to 0.001-0.04 mass% and optimizing Si content to 0.05-2 mass%, along with other elements (Al, Mn, C, Cr, Ni) to prevent iron oxide formation and reduce thermal stress, thereby resolving the contradiction between bonding strength and peeling resistance
Solution Approach 2:
The invention creates a composite material system with a specifically composed base material containing multiple alloying elements (Ni, Cr, Si, Al, Mn, C, Fe) in controlled proportions, where the composite structure provides both bonding capability through the diffusion layer and resistance to peeling by suppressing oxidation and thermal stress
2Strength
If Fe content in base material is increased to improve high-temperature strength, then strength improves, but iron oxide generation increases causing peeling
Solution Approach 1:
The invention inverts the conventional approach by severely limiting Fe content to 0.001-0.04 mass% instead of increasing it, and compensates for strength requirements through optimized combinations of other elements (Cr: 8-40 mass%, Ni: 50-80 mass%, Si: 0.05-2 mass%, Al: 0.01-2 mass%, Mn: 0.01-2 mass%, C: 0.01-0.1 mass%), thereby eliminating iron oxide generation while maintaining high-temperature strength
Solution Approach 2:
The invention converts the harmful effect of Fe (which causes iron oxide generation and peeling) into a benefit by using trace amounts of Fe in combination with Si and other elements to create a stable diffusion layer that actually protects against oxidation, while the primary strength comes from the Ni-Cr-Si-Al-Mn-C system rather than Fe
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 specified base material composition effectively prevents discharge member peeling by reducing iron oxide formation and maintaining the strength of the diffusion layer, ensuring reliable spark plug performance under high temperatures.
Implementation Method 1
If oxygen enters the crack, the oxygen binds to Fe derived from the base material, and an iron oxide is generated in the bonded part between the base material and the discharge member
Implementation Method 2
a first electrode including a base material and a discharge member having at least a portion thereof bonded to the base material with a diffusion layer interposed therebetween
Data Source
AI summary
A spark plug capable of avoiding a discharge member bonded to a base material from peeling off easily is provided. The spark plug includes: a first electrode including a base material and a discharge member having at least a portion thereof bonded to the base material with a diffusing layer interposed therebetween; and a second electrode facing the discharge member with a spark gap interposed therebetween. The base material contains 50 mass % or more of Ni, 8 mass % or more and 40 mass % or less of Cr, 0.05 mass % or more and 2 mass % or less of Si, 0.01 mass % or more and 2 mass % or less of Al, 0.01 mass % or more and 2 mass % or less of Mn, 0.01 mass % or more and 0.1 mass % or less of C, and 0.001 mass % or more and 0.04 mass % or less of Fe.