Hot Work Tool Coating Adhesion via Surface Profiling
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Solution Overview
Problem
Existing hot tools, such as piercing mandrels and rolling bars, face issues with coating adhesion due to rough surfaces, leading to peeling off under thermal or mechanical stress, which reduces their service life and increases production costs for seamless tubes.
Innovation Solution
A thermochemical treatment process is applied to the tool's surface to create a primary protective layer of iron oxide, followed by an outer layer that fills gaps, enhancing adhesion and preventing peeling, while the surface is structured with undercuts and webs to improve coating retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface is roughened by blasting to improve coating adhesion, then the adhesion should be improved, but the coating still peels off under thermal or mechanical stress
Solution Approach 1:
A surface profile with elevations and depressions is created on the tool body before coating application. This preliminary structuring provides a mechanical foundation for improved coating retention, addressing the adhesion problem before the coating is even applied.
Solution Approach 2:
A multi-layer coating system is implemented consisting of a primary protective layer applied to the structured surface and an outer protective layer that fills the gaps between elevations. This composite structure combines mechanical interlocking with material protection to prevent peeling under stress.
2Duration of action of stationary object
If a coating is applied to protect the tool body, then the service life should be extended, but the coating peels off under thermal or mechanical stress
Solution Approach 1:
The surface profile is created on the tool body before coating application, establishing a mechanical foundation that prevents coating peeling under subsequent thermal or mechanical stress during the tool's service life.
Solution Approach 2:
A multi-layer coating system with a primary protective layer and an outer protective layer is applied to the structured surface. This composite structure ensures the coating withstands thermal and mechanical stress, extending tool service life by preventing coating failure.
3Reliability
If the surface is machined smoothly and structured with elevations and depressions, then the coating adhesion should be improved, but the process complexity increases
Solution Approach 1:
The surface profile with elevations and depressions is created on the tool body before coating application. This preliminary structuring, achievable through conventional machining operations, provides a mechanical foundation for improved coating retention without requiring excessively complex processing equipment.
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 improved bond between the tool body and coating significantly extends the tool's service life, enhances mechanical grip, and reduces production costs by ensuring the coating withstands thermal and mechanical stress effectively.
Implementation Method 1
a primary protective layer of converted material is first produced by using a thermochemical treatment process from part of the material of the base body along the structured surface, with the width of the elevations and the depth changing of the indentations is reduced, and wherein the thermo-chemical conversion comprises in particular the production of an iron oxide, particularly preferably scale
Implementation Method 2
an outer protective layer which fills the gaps in the indentations remaining between the elevations is applied to the primary material layer thus converted
Implementation Method 3
The application of the coating according to step b) above can also be carried out, for example, by flame spraying or plasma spraying
Data Source
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AI summary
The invention relates to a hot work tool, in particular a piercing mandrel or a rolling bar for producing seamless pipes or a forging mandrel for hot forging tubular workpieces made of metal, said tool having a main tool body (2), wherein at least one working area of the main tool body (2) is provided with a coating (4). In order to achieve an improved strength of the coating (4) on the main tool body, according to the invention the main tool body (2) has a profiled surface (5) and the coating (4) is applied to the profiled surface (5). The invention further relates to a method for producing such a hot work tool.