Supercritical Water Surface Roughness Reduction
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Solution Overview
Problem
Existing methods for reducing surface roughness in internal passages of components, such as mechanical polishing, electrochemical polishing, and chemical polishing with strong acids, face challenges like difficulty in small dimensions, uneven results, environmental and health hazards, and infeasibility on complex geometries.
Innovation Solution
A method using near-critical or supercritical water solutions to clean internal passages by contacting the workpieces with a working fluid at or near supercritical conditions, which is highly corrosive to dissolve surface asperities, followed by rinsing and optional drying, utilizing an apparatus with a fluid flow circuit and heating device to control pressure and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing is used, then surface roughness is reduced, but it becomes difficult as internal passage dimensions shrink and produces uneven results around curves and dead zones
Solution Approach 1:
The patent replaces mechanical polishing with a chemical dissolution process using supercritical water. The supercritical fluid penetrates complex internal geometries and dissolves surface asperities through chemical reaction, eliminating the need for mechanical contact that fails in small passages and dead zones.
Solution Approach 2:
The patent utilizes changes in water's physical and chemical properties at supercritical conditions (temperature and pressure above critical point). At these parameters, water becomes highly corrosive and effective at dissolving metal surface asperities, providing uniform treatment throughout complex geometries regardless of passage size or shape.
2Manufacturing precision
If electrochemical polishing is used, then surface roughness is reduced, but it requires insertion of an electrode near the surface which is not feasible on complex internal geometries
Solution Approach 1:
The patent replaces the electrochemical process requiring electrode insertion with a purely chemical dissolution process using supercritical water. This eliminates the need for complex electrode positioning equipment and makes the process feasible for complex internal geometries where electrode access is impossible.
Solution Approach 2:
The supercritical water acts as an intermediary substance that can penetrate and contact all surfaces within complex geometries without requiring direct electrical contact. The chemical dissolution occurs uniformly throughout the internal passages through the mediating action of the supercritical fluid.
3Manufacturing precision
If chemical polishing using strong acids is used, then surface roughness is reduced, but it presents significant environmental, health, and safety challenges
Solution Approach 1:
The patent uses water at supercritical parameters instead of strong acids. By changing the physical state and parameters of water (temperature and pressure above critical point), it achieves highly corrosive properties effective for dissolving surface asperities without the environmental and health hazards associated with traditional strong acid chemicals.
Solution Approach 2:
The patent converts the normally benign substance (water) into a highly corrosive and effective cleaning agent by changing its parameters to supercritical conditions. This eliminates the need for harmful strong acids while achieving the same surface roughness reduction effect, turning a harmless substance into a beneficial tool for precision cleaning.
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 reduces surface roughness in complex internal geometries, is environmentally friendly, and produces consistent results without leaving residues, suitable for components with curved passages and additive manufacturing processes.
Implementation Method 1
contacting the internal passages with a working fluid at or near supercritical conditions, which is highly corrosive to dissolve surface asperities
Implementation Method 2
the working fluid at or near supercritical conditions, which is highly corrosive to dissolve surface asperities
Data Source
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AI summary
A method of reducing surface roughness in an internal passage (P) of a workpiece (W) includes contacting (100) the internal passage (P) with a corrosive working fluid (F) comprising water at or near supercritical conditions. The method further comprises rinsing (102) the internal passage, subsequent to contacting the internal passage with the working fluid.