Heat Pipe Wick Formation Using Intermetallic Compounds
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Solution Overview
Problem
Conventional heat pipes require high temperatures for sintering the porous wick, leading to potential deterioration of the pipe casing due to oxidation or other processes, necessitating a method to form the wick and sealing members at lower temperatures to prevent casing damage.
Innovation Solution
A heat pipe configuration using intermetallic compounds formed from a first metal (Sn or Sn-based alloys) and a second metal (CuNi, CuMn, or CuCr alloys) with a melting point higher than Sn, allowing the formation of porous wicks and sealing members at temperatures below the sintering point, thereby reducing casing deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the porous wick is formed by sintering copper grains inside the pipe casing, then the porous wick can be successfully formed with appropriate porosity and capillarity, but the pipe casing needs to be heated to a temperature slightly lower than the melting point (1084°C) of the copper grains, causing high temperature exposure
Solution Approach 1:
The patent changes the material parameter from copper grains to low-melting-point metal grains (e.g., Pb, Sn, Zn) with melting points below 450°C. This parameter change allows the sintering process to occur at lower temperatures, resolving the contradiction between forming a functional porous wick and avoiding excessive temperature exposure of the pipe casing.
Solution Approach 2:
The patent uses low-melting-point metals that can be easily sintered and then discarded or integrated into the final product. These metals serve their purpose during the sintering process to create the porous structure, and their lower melting points enable the process to occur without damaging the pipe casing.
2Reliability
If the pipe casing is sealed by welding or brazing, then the pipe casing can be effectively sealed, but the pipe casing needs to be heated to a high temperature (e.g., 450°C in the case of brazing), causing deterioration (oxidation or the like)
Solution Approach 1:
The patent applies preliminary action by first forming the porous wick using low-melting-point metal grains before performing the sealing operation. This sequence allows the wick to be created at lower temperatures, and then the sealing can be performed separately. The pre-formed wick structure enables subsequent sealing at controlled temperatures without requiring the pipe casing to withstand both sintering and sealing temperatures simultaneously.
Solution Approach 2:
The low-melting-point metal grains act as an intermediary material that facilitates the formation of the porous wick structure without requiring the pipe casing to be exposed to high temperatures. This intermediary approach separates the wick formation process from the sealing process, allowing each to be optimized independently.
3Manufacturing precision
If the porous wick is formed by sintering at high temperature, then the wick structure can be properly formed, but the manufacturing process becomes complex and requires precise temperature control to avoid casing damage
Solution Approach 1:
By changing the material parameter from copper grains to low-melting-point metal grains, the sintering temperature parameter is reduced from above 1000°C to below 450°C. This parameter change simplifies the manufacturing process by eliminating the need for complex high-temperature control systems and specialized equipment, while still achieving proper porous wick structure formation.
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 method effectively suppresses pipe casing deterioration and maintains high heat resistance and thermal conductivity of the porous wick and sealing members, ensuring the heat pipe's functionality even under reflow conditions.
Implementation Method 1
at least the first metal and the second metal react with each other by being heated at a temperature equal to or higher than the melting point of the first metal, so that an intermetallic compound containing at least the first metal and the second metal is produced
Implementation Method 2
The porous wick has a plurality of pores, and generates capillarity for the working fluid
Implementation Method 3
The working fluid is constituted of a substance that undergoes phase transformation at a predetermined temperature
Implementation Method 4
the working fluid is evaporated by heat of the heat generating body at the heating portion to become a gas
Implementation Method 5
The gas passes through the cavity and moves to the cooling portion, and its heat is dissipated in the cooling portion to be liquefied
Data Source
AI summary
A heat pipe that includes a pipe casing, a porous wick, and sealing members. Both end portions of the pipe casing are sealed by the sealing members, respectively. The sealing members each comprise a first metal foil and an intermetallic compound phase. The inside of the pipe casing is filled with a working fluid. The porous wick generates capillarity for the working fluid by a plurality of pores. The porous wick is provided inside the pipe casing. As a result, the pipe casing and the porous wick form a cavity extending in a longitudinal direction of the pipe casing. The porous wick comprises first metal grains, second metal grains, and an intermetallic compound phase.