Thermal Spray Adhesion via Cylinder Bore Compression

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Solution Overview

Problem

Existing thermal spray coating processes often result in poor adhesion to surfaces, leading to premature cracking or peeling, despite the durability of the coating material, due to inadequate surface preparation methods that are time-consuming and costly.

Innovation Solution

A method and tool that create a specific surface profile on engine cylinder bores by compressing the inner surface with rollers to form helical grooves and dimples, enhancing the texture and residual stress for improved adhesion of thermal spray coatings, using a roller assembly with multiple rollers to maintain bore concentricity and achieve a developed interfacial area ratio greater than 100%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If surface material is removed to increase roughness prior to thermal spray application, then adhesion is improved, but processing time increases and expensive tools are required

Engineering Contradiction:

Improveadhesion strengthVSAvoidprocessing time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The invention changes the surface treatment approach from material removal to material compression, altering the surface parameters (roughness, porosity, residual stress) through a different physical mechanism that is faster and less costly

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of removing surface material to create roughness (conventional approach), the invention compresses surface material to create the desired surface profile, inverting the traditional method of surface preparation

Inventive Principle:

Principle #13The other way round (Inversion)

2Strength

If surface material is removed to increase roughness prior to thermal spray application, then adhesion is improved, but equipment cost increases

Engineering Contradiction:

Improveadhesion strengthVSAvoidequipment cost

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The compression technique uses simpler, less expensive tools compared to the expensive equipment required for material removal processes, making the surface preparation more cost-effective

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If conventional surface preparation is used, then processing is simpler, but adhesion is insufficient leading to coating failure

Engineering Contradiction:

Improveprocess simplicityVSAvoidcoating adhesion

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the surface parameters through compression rather than removal, achieving both simplicity and improved adhesion by creating a surface profile with enhanced mechanical interlocking capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The surface compression is performed as a preliminary action before thermal spray application, preparing the surface in advance to ensure strong adhesion while maintaining process simplicity

Inventive Principle:

Principle #10Preliminary action

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 enhanced surface texture significantly improves the adhesion of thermal spray coatings, ensuring they remain integral to the surface, increasing the durability and service life by maintaining compressive residual stress and promoting strong bonding.

Implementation Method 1

compressing the inner surface to create a surface profile on the inner surface

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

creating compressive residual stress in the cylinder bore

Methodology Applied

Scientific EffectResidual stress:

Implementation Method 3

Thermal spraying is a coating process which applies material heated and typically melted by combustion or an electrical plasma or arc to a substrate

Methodology Applied

Scientific EffectThermal spray:

Data Source

PatentUS10526996B2Adhesion of thermal spray using compression technique

Publication Date: 2020.01.07 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

An improved surface activation technique improves the adhesion of thermal spray coatings, which is useful for engine cylinder bores. The new method includes compressing the cylinder bore surface to create a surface profile on the surface, such as through rolling a roller along the surface. An engine block is also provided, which includes a plurality of cylinder bores, each cylinder bore having an inner surface, and each inner surface having a surface profile that includes a helical groove and other surface profiles formed in the inner surface. A thermal spray coating is formed on the inner surface of each cylinder bore, the thermal spray coating being adhered to the surface profile of the inner surface. A roller assembly for activating the surface is also provided.