Hydrogen Purifier Sealing with Low-Temperature Indium Alloy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydrogen purifiers face challenges in forming hermetic seals due to high processing temperatures, which can cause intermetallic diffusion, alter the crystal structure of the membrane, and lead to leakage issues, especially when using thin membranes like Pd60Cu40 and Pd77Ag23.
Innovation Solution
The use of a low-temperature melting element or alloy that forms a higher melting temperature alloy upon heat treatment, such as Indium-Copper or Indium-Palladium combinations, to create seals without subjecting the hydrogen permeable membrane to excessive temperatures, thereby preventing unwanted metallurgical changes and interdiffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature brazing or welding is used to form seals, then sealing effectiveness is improved, but intermetallic diffusion and crystal structure alteration of the membrane occur
Solution Approach 1:
A low-melting-point alloy (e.g., indium-based) is introduced as an intermediary sealing material between the membrane and housing. This intermediary melts at lower temperatures (below 550°C) to form hermetic seals without exposing the Pd-based membrane to high temperatures that would cause intermetallic diffusion or crystal structure changes, thus resolving the contradiction between seal effectiveness and membrane composition stability.
Solution Approach 2:
The sealing process temperature parameter is changed from high temperature (brazing/welding) to low temperature (melting point of low-melting-point alloy). This parameter change allows seal formation at temperatures below 550°C, preventing thermal damage to the membrane while maintaining sealing effectiveness through the phase change of the sealing alloy.
2Productivity
If thin membranes are used to improve hydrogen permeability, then hydrogen flux is improved, but mechanical strength and sealability deteriorate
Solution Approach 1:
The low-melting-point alloy acts as an intermediary that bonds to the thin membrane at low temperatures, providing mechanical support and sealability without requiring high-strength joining processes. This allows thin membranes to be used for high hydrogen flux while the intermediary alloy compensates for the reduced mechanical strength through effective sealing and structural support.
3Temperature
If low-melting-point alloys are used for sealing, then processing temperature is reduced, but seal strength at high operating temperatures may be compromised
Solution Approach 1:
The low-melting-point alloy undergoes a phase transition from solid to liquid during sealing, then re-solidifies to form a hermetic seal. The alloy is selected so that its melting point is below the membrane's maximum service temperature, ensuring the seal remains stable and maintains strength at high operating temperatures while enabling low-temperature processing.
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 allows for the formation of effective seals that maintain hydrogen permeability and prevent leakage, even at elevated operating temperatures, while keeping the fabrication temperature below 550°C, thus addressing the limitations of prior art methods like brazing and welding.
Implementation Method 1
the seals are formed by first melting a metal with a low temperature melting point, and then allowing the metal to form a subsequent alloy which has a melting temperature above the operational temperature of the purifier
Implementation Method 2
allowing the metal to form a subsequent alloy which has a melting temperature above the operational temperature of the purifier
Implementation Method 3
hydrogen purifiers utilize a thin, hydrogen-permeable metal membrane to effectively separate hydrogen from a gaseous mixture containing hydrogen
Data Source
AI summary
A hydrogen purifier utilizing a hydrogen permeable membrane, and a gas-tight seal, where the seal is uses a low temperature melting point metal, which upon heating above the melting point subsequently forms a seal alloy with adjacent metals, where the alloy has a melting point above the operational temperature of the purifier. The purifier further is constructed such that a degree of isolation exists between the metal that melts to form the seal and the active area of the purifier membrane, so that the active area of the purifier membrane is not corrupted. A method of forming a hydrogen purifier utilizing a hydrogen permeable membrane with a seal of the same type is also disclosed.