Barbed Surface for Thermal Spray Adhesion

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Solution Overview

Problem

The existing methods for preparing surfaces for thermal spray coatings are costly and inefficient, requiring expensive tooling and hazardous materials, and often result in imperfections that reduce adhesion and coating life, especially in applications like internal combustion engines with cast aluminum blocks.

Innovation Solution

A method involving cutting a first series of grooves and rolling a second series of grooves at an angle to form spaced barbs, which are then coated with a thermal spray to mechanically secure the coating, reducing tool wear and overspray, and eliminating the need for cylinder liners to enhance engine efficiency and fuel economy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If specialized broaching or machining tools are used to create continuous undercuts, then adhesion of thermal spray coating is improved, but tool wear increases and requires frequent tool replacement

Engineering Contradiction:

Improveadhesion of thermal spray coatingVSAvoidtool wear and replacement frequency

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The continuous undercut is segmented into a series of discrete, spaced barbs formed by intersecting grooves. This segmentation allows the thermal spray coating to adhere to multiple discrete anchor points along the surface, maintaining strong adhesion while eliminating the need for continuous material removal that causes tool wear.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using complex specialized tools to create continuous undercuts, the invention inverts the approach by using simple intersecting groove patterns that form barbs. This inversion simplifies the tooling from specialized broaching/machining tools to standard groove-forming tools, reducing tool wear and maintenance.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If flux or chemical bond coat is applied prior to thermal spray, then adhesion is improved, but manufacturing cost increases and hazardous materials are used

Engineering Contradiction:

Improveadhesion of thermal spray coatingVSAvoidmanufacturing cost and hazardous materials

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention replaces chemical adhesion methods (flux or bond coat) with a mechanical adhesion system. The spaced barbs create physical undercuts that mechanically interlock with the thermal spray coating, eliminating the need for chemical treatments and their associated costs and hazards.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The spaced barb structure is self-adhesive through its geometric design. The intersecting grooves naturally form barbs that provide mechanical interlocking without requiring any additional chemical processing steps, making the surface preparation self-sufficient for achieving adhesion.

Inventive Principle:

Principle #25Self-service

3Reliability

If continuous undercuts are created along the length of grooves, then thermal spray coating adhesion is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveadhesion of thermal spray coatingVSAvoidtooling complexity with multiple inserts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The continuous undercut is divided into discrete spaced barbs formed by the intersection of groove patterns. This segmentation simplifies the tooling requirements from complex multi-insert tools to simpler groove-forming tools that create the barb pattern through intersecting linear features.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spaced barb pattern serves multiple functions: it provides adhesion anchor points for thermal spray coating, simplifies tooling requirements, and reduces manufacturing complexity. This universal pattern can be applied to various surface geometries using standard groove-forming tools.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 provides a strong mechanical bond between the thermal spray coating and the surface, reduces tool wear and manufacturing costs, and improves engine efficiency by minimizing weight and overspray, while ensuring long-term adhesion and coating life.

Implementation Method 1

thermal spray processes are used to provide a hard smooth surface on a base material

Methodology Applied

Scientific EffectThermal spray: Plasma Spray

Implementation Method 2

spray coating the surface and mechanically securing the spray coating to the barbs

Methodology Applied

Scientific EffectMechanical bonding: Mechanical Fastener

Data Source

PatentUS9162418B2Method of making a barbed surface for receiving a thermal spray coating and the surface made by the method

Publication Date: 2015.10.20 FORD GLOBAL TECH LLC

AI summary

A method is disclosed for preparing a surface for mechanically securing a spray coating to a surface. A first series of grooves formed in the surface are intersected with a second series of grooves formed in the surface. A plurality of barbs are formed at the intersections. The spray coating is mechanically secured to the barbs that overhang the first series of grooves. The surface includes the first series of grooves and the second series of groves that intersect the first series of groves. The second series of groves form an undercut portion, or barb, at the intersections of the grooves that mechanically anchor the spray coating.