Two-Layer Anodic Oxide Coating for Piston Heat Insulation

Solution Overview

Problem

Anodic oxide coatings for aluminum-based materials face challenges in achieving both high heat insulation and corrosion resistance, particularly when used in pistons for internal combustion engines, as they often require high durability and impact resistance while maintaining water and oil repellency.

Innovation Solution

A two-layer anodic oxide coating structure is formed, where a porous first coating is created using direct-current electrolysis and a dense second coating using AC-DC superimposition electrolysis, with the second coating acting as a lid to enhance heat insulation and corrosion resistance without filling the pores of the first coating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a porous anodic oxide coating is formed to improve heat insulation properties, then heat insulation is improved, but corrosion resistance deteriorates due to pore penetration

Engineering Contradiction:

Improveheat insulation propertiesVSAvoidcorrosion resistance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The coating is divided into multiple layers with different functions: the first anodic oxide coating (formed by DC electrolysis) provides heat insulation with its porous structure, while the second anodic oxide coating (formed by AC-DC superimposition electrolysis) provides corrosion resistance with its dense structure. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite anodic oxide coating system combining two different coating structures formed by different electrolysis methods. The porous first coating and dense second coating are combined in a single integrated structure, leveraging the advantages of both porous (heat insulation) and dense (corrosion resistance) configurations.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a dense anodic oxide coating is formed to improve corrosion resistance, then corrosion resistance is improved, but heat insulation properties deteriorate due to scarce pores

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidheat insulation properties

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The coating is divided into multiple layers with different functions: the first anodic oxide coating (formed by DC electrolysis) provides heat insulation with its porous structure, while the second anodic oxide coating (formed by AC-DC superimposition electrolysis) provides corrosion resistance with its dense structure. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite anodic oxide coating system combining two different coating structures formed by different electrolysis methods. The porous first coating and dense second coating are combined in a single integrated structure, leveraging the advantages of both porous (heat insulation) and dense (corrosion resistance) configurations.

Inventive Principle:

Principle #40Composite materials

3Temperature

If multiple cylindrical pores are present in the anodic oxide coating surface, then heat insulation is improved, but corrosion resistance cannot be achieved simultaneously

Engineering Contradiction:

Improveheat insulation propertiesVSAvoidcorrosion resistance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The coating is divided into multiple layers with different functions: the first anodic oxide coating (formed by DC electrolysis) provides heat insulation with its porous structure, while the second anodic oxide coating (formed by AC-DC superimposition electrolysis) provides corrosion resistance with its dense structure. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite anodic oxide coating system combining two different coating structures formed by different electrolysis methods. The porous first coating and dense second coating are combined in a single integrated structure, leveraging the advantages of both porous (heat insulation) and dense (corrosion resistance) configurations.

Inventive Principle:

Principle #40Composite materials

4Ease of manufacture

If direct-current electrolysis is used to form anodic oxide coating, then the coating formation is simple, but the coating lacks sufficient durability and impact resistance

Engineering Contradiction:

Improvecoating formation simplicityVSAvoiddurability and impact resistance

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The coating is divided into multiple layers with different functions: the first anodic oxide coating (formed by DC electrolysis) provides heat insulation with its porous structure, while the second anodic oxide coating (formed by AC-DC superimposition electrolysis) provides corrosion resistance with its dense structure. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite anodic oxide coating system combining two different coating structures formed by different electrolysis methods. The porous first coating and dense second coating are combined in a single integrated structure, leveraging the advantages of both porous (heat insulation) and dense (corrosion resistance) configurations.

Inventive Principle:

Principle #40Composite materials

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

This configuration achieves high heat insulation, corrosion resistance, durability, and impact resistance, preventing fuel and unburned material adherence, thus reducing engine trouble and maintaining reliable performance in harsh combustion conditions.

Implementation Method 1

a porous anodic oxide coating is formed on a surface of an aluminum-based material by direct-current electrolysis

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Implementation Method 2

forming a second anodic oxide coating by application of AC-DC superimposition electrolysis to an aluminum-based material

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Data Source

PatentUS10179956B2Anodic oxide coating, treatment method therefor, and piston for internal combustion engine

Publication Date: 2019.01.15 SUZUKI MOTOR CORP

AI summary

Provided are an anodic oxide coating for an aluminum-based material, a treatment method therefor, and a piston for an internal combustion engine, the anodic oxide coating having both high heat insulation properties and high corrosion resistance, high durability and high impact resistance, and high water-repellent and oil-repellent functions. The treatment method includes the steps of: forming a second anodic oxide coating 2b by application of AC-DC superimposition electrolysis to an aluminum-based material 1; and, after the step, forming a first anodic oxide coating 2a by application of direct-current electrolysis to the aluminum-based material 1, wherein the second anodic oxide coating 2b is formed on the first anodic oxide coating 2a.