Restoring MMC Strength via Chemical Etching and Shot Peening
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Solution Overview
Problem
Metal matrix composites (MMC) exposed to long-term high temperature and pressure cycling, such as in gas exhaust nozzles, develop micro cracks that lead to erosion and loss of binder material, resulting in decreased strength and wear resistance.
Innovation Solution
A method involving chemical etching with an iron chloride acid solution to remove micro cracks from the metallic binder, followed by shot peening to compress the ceramic filler particles and potentially adding new binder material via sputtering to restore the MMC's strength and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MMC is used in high temperature and pressure cycling applications, then strength and wear resistance are improved, but micro cracks develop in the binder leading to material loss
Solution Approach 1:
The patent removes the cracked binder layer from the MMC surface through chemical etching, extracting the harmful defective portion while preserving the intact ceramic filler particles and sound binder material underneath. This extraction eliminates the micro cracks and prevents further material loss.
Solution Approach 2:
The patent applies preliminary chemical etching to remove cracked binder before the damage propagates deeper into the component. By performing this preventive action, the integrity of the remaining binder and ceramic particles is preserved, avoiding more extensive damage.
2Reliability
If binder material is removed to eliminate micro cracks, then reliability is improved, but the component requires complex repair procedures
Solution Approach 1:
The patent replaces complex mechanical removal methods (such as grinding or machining) with chemical etching to remove the cracked binder. This substitution simplifies the repair process, makes it more controllable, and allows for precise removal of only the defective material.
Solution Approach 2:
The patent changes the state of the binder material through chemical etching, transforming it from a solid cracked material into a dissolved chemical state. This parameter change enables selective removal of the binder while preserving the ceramic filler structure.
3Ease of repair
If chemical etching is used to remove cracked binder, then ease of repair is improved, but new binder material must be added to restore original properties
Solution Approach 1:
The patent discards the cracked binder material through chemical etching and then recovers the component by adding new binder material. This two-step process ensures that the defective material is completely removed while restoring the necessary binding properties to achieve original strength and wear resistance.
Solution Approach 2:
The patent works with composite materials consisting of binder and ceramic filler particles. The chemical etching selectively affects the binder phase while preserving the ceramic filler, and the subsequent binder addition restores the composite structure's integrity and properties.
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 effectively restores the strength and wear resistance of MMCs by removing micro cracks and compressing ceramic particles, allowing for economic and portable restoration without disassembly, extending the lifespan of components like gas exhaust nozzles.
Implementation Method 1
adding a chemical solvent to the surface for dissolving binder containing micro cracks
Implementation Method 2
the metallic matrix ceramic is compressed by a compression operation for achieving a dense outer layer, wherein the filler particles are close to each other
Implementation Method 3
the intermediary operation is a sputtering operation
Data Source
AI summary
The present invention relates to a method and an arrangement for restoring strength and wear resistant of a metallic matrix ceramic (1) comprising a metallic binder (2) and ceramic filler (3) particles, which metallic matrix ceramic (1) has been exposed for long term high temperature and pressure cycling, for example in a gas exhaust nozzle (6), whereby micro cracks (4) are developed in the outer layer (5) of the metallic binder (2) According to the invention this is achieved by virtue of the fact that the outer layer (5) of the metallic binder (2), partly or fully, is removed from the MMC part (1) by a chemical operation, where after the outer layer (5) is compressed by a compression operation for achieving a dense outer layer (5), in which filler (3) particles are close to each other.