Low-Friction Coating via Tribochemical Reaction

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Solution Overview

Problem

Existing low-friction sliding mechanisms require additional lubricants and fail to achieve stable low friction coefficients in dry lubrication conditions.

Innovation Solution

A method involving a sliding surface coated with an amorphous carbon-based film, where a hydroxyl group-containing compound and hydrogen/nitrogen atmosphere are used to form a low-friction coating through Hertzian contact stress, allowing sliding without additional lubricants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a liquid lubricant is supplied to a sliding surface to reduce friction, then the friction coefficient is reduced, but additional lubricant supply is required and the system cannot achieve low friction in dry lubrication conditions

Engineering Contradiction:

Improvefriction reduction capabilityVSAvoidoperational simplicity without additional lubricant

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The sliding surface itself generates the low-friction coating through the interaction between the amorphous carbon film and the gas atmosphere during sliding. The system serves itself by using the sliding action and atmospheric components to create the lubricating layer, eliminating the need for external lubricant supply mechanisms

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention replaces the mechanical lubricant supply system with a chemical/physical process where the amorphous carbon film reacts with the gas atmosphere under Hertzian contact stress to form a low-friction coating in situ, substituting mechanical lubrication with a surface transformation mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If additional lubricants are used to achieve low friction, then friction is reduced, but the system complexity increases due to lubricant supply mechanisms

Engineering Contradiction:

Improvefriction reduction capabilityVSAvoidsystem structure with lubricant supply

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the essential lubricating function from the complex lubricant supply system and concentrates it in the amorphous carbon film that transforms into a low-friction coating through simple exposure to the gas atmosphere during sliding, eliminating the need for external lubricant delivery mechanisms

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The amorphous carbon film serves multiple functions: it provides the base coating structure, reacts with the gas atmosphere to form the low-friction layer, and enables the system to operate in both lubricated and dry conditions, replacing multiple specialized components with a single multi-functional material

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If a low-friction coating is formed on the sliding surface, then friction is reduced, but the coating must be formed under specific atmospheric conditions

Engineering Contradiction:

Improvelow friction coefficientVSAvoidatmosphere requirement for coating formation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention utilizes changes in local parameters (pressure, temperature, chemical composition) under Hertzian contact stress to enable the formation of the low-friction coating only in the sliding zone where these conditions exist, allowing the coating to form adaptively under varying atmospheric conditions

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

This method stably achieves a low friction coefficient, reducing frictional losses and enabling efficient sliding without additional lubricants, thereby enhancing the reliability and performance of sliding systems.

Implementation Method 1

a low-friction coating production method for producing a low-friction coating, and a sliding method for sliding a sliding surface against an amorphous carbon based film

Methodology Applied

Scientific EffectTribochemical reaction:

Implementation Method 2

relatively sliding the sliding surface against the slid surface due to Hertzian contact stress of 1.0 GPa or more

Methodology Applied

Scientific EffectHertzian contact stress:

Implementation Method 3

In order to reduce friction of a sliding system, it has been proposed to dispose a solid lubricant film on a sliding surface of a sliding member. For example, a DLC (Diamond Like Carbon) film is known as such a solid lubricant film

Methodology Applied

Scientific EffectSolid lubrication:

Data Source

PatentUS10450527B2Low-friction coating production method and sliding method

Publication Date: 2019.10.22 JTEKT CORP

AI summary

A method including substituting an atmosphere in a space, in which a sliding surface formed of a metal or a ceramic material, and a slid surface are disposed, with a gas atmosphere containing a hydroxyl group-containing compound and at least one of hydrogen and nitrogen, and relatively sliding the sliding surface against the slid surface by a Hertzian contact stress of 1.0 GPa or more in the space under the gas atmosphere containing the hydroxyl group-containing compound at least one of hydrogen and nitrogen. As a result, it is possible to form, on the sliding surface, a low-friction coating that stably exhibits a significantly low friction coefficient, for example, of 10−4 order (less than 0.001).