Amorphous Carbon Coating with Silicon Gradient for Wear Resistance

Solution Overview

Problem

Hard amorphous carbon films used for wear resistance tend to be aggressive against mating members, leading to wear and damage.

Innovation Solution

An amorphous-carbon coated member with a compositionally gradient film, where silicon concentration increases towards the substrate for hardness and adhesion, and hydrogen concentration decreases towards the substrate for reduced aggressiveness, forming a film with continuous gradients rather than stepwise composition changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hard amorphous carbon film is used to improve wear resistance, then wear resistance is improved, but aggressiveness against mating member increases

Engineering Contradiction:

Improvewear resistanceVSAvoidaggressiveness against mating member

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a compositionally gradient film where silicon concentration varies continuously from the surface to the substrate interface. The surface region has lower silicon concentration for reduced aggressiveness, while the substrate interface has higher silicon concentration for enhanced adhesion and hardness. This spatial variation in composition allows different regions to serve different functions, resolving the contradiction between wear resistance and aggressiveness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the compositional parameter (silicon concentration) continuously through the film thickness rather than using uniform composition or stepwise layers. By controlling silicon concentration to gradient from surface to substrate, the film achieves both low surface hardness (reducing aggressiveness) and high interface hardness (improving wear resistance and adhesion), thus resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Strength

If silicon concentration is increased to improve hardness and adhesion, then hardness and adhesion are improved, but aggressiveness against mating member increases

Engineering Contradiction:

ImprovehardnessVSAvoidaggressiveness against mating member

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a compositionally gradient film where silicon concentration varies continuously from the surface to the substrate interface. The surface region has lower silicon concentration for reduced aggressiveness, while the substrate interface has higher silicon concentration for enhanced adhesion and hardness. This spatial variation in composition allows different regions to serve different functions, resolving the contradiction between wear resistance and aggressiveness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the compositional parameter (silicon concentration) continuously through the film thickness rather than using uniform composition or stepwise layers. By controlling silicon concentration to gradient from surface to substrate, the film achieves both low surface hardness (reducing aggressiveness) and high interface hardness (improving wear resistance and adhesion), thus resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If uniform composition is used throughout the film, then manufacturing is simplified, but both wear resistance and reduced aggressiveness cannot be achieved simultaneously

Engineering Contradiction:

Improvefilm formation simplicityVSAvoidsimultaneous wear resistance and low aggressiveness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the compositional parameter (silicon concentration) continuously through the film thickness rather than using uniform composition or stepwise layers. By controlling silicon concentration to gradient from surface to substrate, the film achieves both low surface hardness (reducing aggressiveness) and high interface hardness (improving wear resistance and adhesion), thus resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7427439B2Amorphous-carbon coated member

Publication Date: 2008.09.23 JTEKT CORP

AI summary

An amorphous-carbon coated member includes a conductive substrate, and an amorphous carbon film. The amorphous carbon film is fixed onto a part of a surface of the substrate at least, and includes a compositionally gradient film. The compositionally gradient film has an outer side and a substrate side, and is composed of carbon, silicon and hydrogen. The silicon concentration inclines continuously from the lowest to the highest in the direction away from the outer side to the substrate side. The hydrogen concentration inclines continuously from the highest to the lowest in the direction away from the outer side to the substrate side. The amorphous-carbon coated member exhibits not only good wear resistance but also low aggressiveness against mating member simultaneously.