Spark Plug Electrode Nickel Alloy Composition for Heat Conduction
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Solution Overview
Problem
Spark plugs for internal-combustion engines face challenges in heat conduction performance, leading to pre-ignition issues due to electrode overheating, despite requiring high oxidation resistance to withstand high-temperature combustion gases.
Innovation Solution
A spark plug design featuring a nickel alloy for the center and ground electrodes with specific compositions and void percentages, optimizing chromium, silicon, rare earth elements, and iron content to enhance oxidation resistance and heat conduction, thereby reducing the likelihood of pre-ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel alloy with high chromium content (12-34%) is used to improve oxidation resistance, then oxidation resistance is improved, but heat conduction performance deteriorates leading to pre-ignition
Solution Approach 1:
The patent changes the compositional parameters of the nickel alloy by adding specific amounts of silicon (0.01-2.0% by mass) and rare earth elements (0.01-2.0% by mass) to the existing chromium-containing nickel alloy. This parameter modification allows the material to maintain both high oxidation resistance and adequate heat conduction performance, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite nickel alloy material that combines multiple elements (nickel, chromium, silicon, and rare earth elements) in specific proportions. This composite material achieves synergistic effects where the combination of elements provides both oxidation resistance and heat conduction capabilities that individual elements cannot achieve alone, thus resolving the technical contradiction.
2Reliability
If silicon and aluminum content is increased to improve oxidation resistance, then oxidation resistance is improved, but the total content must be limited to 1/10 or less of chromium content which restricts heat conduction improvement
Solution Approach 1:
The patent modifies the compositional parameters by introducing rare earth elements as a new variable, allowing the silicon and aluminum content to be optimized within the constraint of being 1/10 or less of chromium content. The rare earth elements provide additional oxidation protection without violating the compositional constraints, enabling improved heat conduction performance.
3Reliability
If noble metal tips are added to improve wear resistance, then wear resistance is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the material composition parameters of the electrode itself by adding silicon and rare earth elements to the nickel alloy, creating a wear-resistant material that does not require additional noble metal tips. This approach maintains structural simplicity while achieving the desired wear resistance through material composition optimization.
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 optimized nickel alloy composition improves heat conduction performance while maintaining sufficient oxidation resistance, effectively reducing the occurrence of pre-ignition in internal-combustion engines.
Implementation Method 1
the decrease in thermal conductivity due to the presence of voids can be reduced, thus improving the heat conduction performance of the electrode and thereby reducing the likelihood of pre-ignition
Implementation Method 2
Center electrodes and ground electrodes require high oxidation resistance since they are exposed to high-temperature combustion gases in internal-combustion engines
Data Source
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AI summary
A spark plug having a center electrode and a ground electrode that form a gap therebetween. At least one of the center electrode and the ground electrode includes a portion formed of a nickel alloy containing nickel as a major component and 20% by mass or more of chromium. In the portion, formed of the nickel alloy, of the electrode, the content of silicon is 0.1% by mass or more, the total content of one or more particular elements selected from the group consisting of rare earth elements is 0.01% by mass or more, and the area percentage of voids in the total area of a cross-section parallel to a longitudinal direction is 1% or less.