Porous Metal Member via Solid-State Interdiffusion
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Solution Overview
Problem
The molten metal refining method results in coarse microgaps and porous layers forming in unintended areas, including deep portions of the member, and phase transformation and crystal grain coarsening occur at the metal bath temperature, deteriorating characteristics where no porous layer is formed.
Innovation Solution
A method involving solid metal bodies with specific heat of mixing properties, where interdiffusion occurs between a first and third component, allowing selective removal of non-second component portions to produce a porous member with nanometer-sized microgaps, focusing on surface modification while maintaining internal characteristics, using heat treatment and etching to control microgap size and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If molten metal refining method is used with rapid elution, then productivity is improved, but manufacturing precision deteriorates due to coarse microgaps
Solution Approach 1:
The patent changes the physical state parameter of the metal bath from liquid to solid, and controls the temperature parameter to be below the solidifying point. This transforms the rapid elution process into a controlled solid-state diffusion process, achieving both nanometer-sized microgaps and acceptable production efficiency
Solution Approach 2:
The patent utilizes phase transition by controlling the metal bath temperature to be below the solidifying point of the first component, maintaining the bath in a solid or semi-solid state. This phase control enables precise microgap formation through solid-state diffusion rather than rapid liquid-state elution
2Reliability
If molten metal refining method is used, then porous layer formation is achieved, but manufacturing precision deteriorates due to porous layers forming in deep portions
Solution Approach 1:
The patent applies local quality by forming porous layers only at the surface region through controlled solid-state diffusion. The diffusion depth is limited by controlling temperature and time, ensuring porous structure forms only where needed (surface) and not in deep portions, achieving precise spatial control
3Reliability
If metal bath temperature is used for porous layer formation, then porous layer formation is achieved, but manufacturing precision deteriorates due to phase transformation and crystal grain coarsening
Solution Approach 1:
The patent changes the temperature parameter to be below the solidifying point of the first component, preventing phase transformation and crystal grain coarsening. This temperature control enables porous layer formation through solid-state diffusion while preserving the material characteristics of non-porous regions
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 produces a porous member with smaller microgaps and a porous surface layer while preserving the characteristics of non-porous regions, allowing for precise control over microgap size and location, and preventing phase transformation and crystal grain growth.
Implementation Method 1
performing heat treatment at a predetermined temperature for a predetermined length of time, so as to diffuse the first component to the metal material side and diffuse the third component to the metal body side
Implementation Method 2
performing heat treatment at a predetermined temperature for a predetermined length of time
Data Source
Figure 1(a)~2
Figure 3(a)~3(d)
Figure 4(a)~4(b)
AI summary
A method for producing a porous member, whereby a member having smaller microgaps can be produced, and additionally, the outermost surface alone can be made porous and a porous layer can be formed on the surface while maintaining the characteristics of portions in which no porous layer is formed, is provided. A solid metal body 11 comprising a first component, and a solid metal material 12 comprising a compound, an alloy or a non-equilibrium alloy that simultaneously contains a second component and a third component having a positive heat of mixing and a negative heat of mixing, respectively, relative to the first component are brought into contact with each other, and then heat treatment is performed at a predetermined temperature for a predetermined length of time. The first component is diffused to the metal material 12 side, and the third component is diffused to the metal body 11 side by heat treatment, portions other than portions mainly composed of the second component are selectively removed from the portions in which the first component and/or third component is diffused, and thus a member having microgaps is obtained.