Nickel Alloy Spark Plug Electrode Oxide Layer Control

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Solution Overview

Problem

Conventional spark plug electrodes made of nickel alloys face challenges with high temperature resistance, corrosion resistance, and spark erosion due to the formation of a heat-insulating and electrically conductive oxide layer, which leads to reduced performance and shorter service life, making them less economical compared to precious metal alternatives.

Innovation Solution

A spark plug electrode material composed of nickel with specific additives such as Y, Hf, Ce, La, Zr, Ta, Si, Na, K, Li, Ti, Ag, or Cu, with controlled oxygen content and oxide layer electrical resistance, forming a thin and stable oxide layer that reduces electrical resistance and enhances corrosion and erosion resistance, achieving performance comparable to precious metal electrodes without the high costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If nickel alloys are used as base material for spark plug electrodes, then high temperature resistance and corrosion resistance are improved, but the formation of thick oxide layers leads to increased electrical resistance and reduced service life

Engineering Contradiction:
Improvetemperature resistanceVSAvoidservice life
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the nickel alloy by adding specific elements (Y, Hf, Ce, La, Zr, Ta, or Yb at 0.1-0.3 wt%, and Si, Na, K, Li, Ti, Ag, or Cu at 0.5-3.0 wt%) to control the oxidation behavior and oxide layer properties, transforming the harmful thick oxide layer into a beneficial thin protective layer with lower electrical resistance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite material system where nickel serves as the base material combined with multiple alloying elements that work synergistically: the rare earth elements (Y, Hf, Ce, La, Zr, Ta, Yb) control oxidation kinetics while the secondary elements (Si, Na, K, Li, Ti, Ag, Cu) modify the oxide layer structure and electrical properties, resulting in a composite alloy with superior overall performance

Inventive Principle:
Principle #40Composite materials

2Reliability

If precious metal alloys such as platinum or platinum-iridium are used, then resistance to spark erosion and electrode life are significantly improved, but the cost increases enormously

Engineering Contradiction:
Improveelectrode lifeVSAvoidcost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The invention replaces expensive precious metals (platinum, iridium) with a cost-effective nickel-based alloy system that achieves comparable or superior electrode life through optimized composition and controlled oxide layer formation, making the electrode economically viable while maintaining high performance

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention fundamentally changes the material composition parameters from precious metal-based to nickel-based with specific alloying elements, achieving similar protective oxide layer formation and spark erosion resistance at a fraction of the cost of platinum or platinum-iridium alloys

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a thick oxide layer forms on the electrode surface, then corrosion resistance is improved, but heat insulation and increased electrical resistance reduce spark performance

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidelectrical conductivity
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The invention optimizes the oxide layer parameters by controlling its thickness to be extremely thin (much thinner than conventional nickel alloys) while maintaining protective corrosion resistance, and by modifying its chemical composition through alloying elements to reduce electrical resistance and improve heat conductivity, thereby eliminating the trade-off between corrosion protection and electrical performance

Inventive Principle:
Principle #35Parameter changes

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 solution provides a cost-effective spark plug electrode with significantly reduced wear and extended service life, maintaining high temperature resistance and electrical conductivity, thus overcoming the limitations of conventional nickel alloy electrodes.

Implementation Method 1

the oxide layer formed on the surface of the electrode material has an electrical resistance R which is less than or equal to that defined by the following equation: R≤a·b3·exp(3200/T)

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a large part of the nickel surface as well as some of the nickel inside the electrode material reacts with the surrounding oxygen. This creates a thick nickel oxide layer

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP2514052B2Spark plug electrode produced from improved electrode material
Publication Date: 2018.08.22 ROBERT BOSCH GMBH
  • EP2514052B2 patent drawingFigure 1~2
  • EP2514052B2 patent drawingFigure 3~4
  • EP2514052B2 patent drawingFigure 5

AI summary

The invention describes spark plug electrodes, which are characterized by improved oxidation and corrosion resistance, spark erosion resistance, and thermal conductivity.