Heat Exchanger Plate Bonding Using Transition Liquid Phase Alloy Layers
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Solution Overview
Problem
Conventional methods for bonding plates in heat exchangers, such as solid phase bonding and brazing, are complex, require strict surface roughness management, high vacuum, and high pressure, and can result in poor bonding due to bubble formation and precipitate issues.
Innovation Solution
Transition liquid phase bonding using an alloy layer with melting point depression elements like B, Si, and P, formed through electroless plating or thermal spray coating, allows for bonding under milder conditions of 1 × 10^-4 to 1 × 10^-3 torr vacuum and 900 to 1200°C temperature for 0.1 to 6 hours, preventing defects and ensuring high-quality bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid phase bonding is used to bond plates, then bonding strength can be achieved, but strict surface roughness management and high vacuum conditions (≥10^-4 torr) are required, increasing process complexity
Solution Approach 1:
The invention changes the bonding mechanism from solid phase diffusion to liquid phase bonding by introducing an alloy layer with melting point depression elements. This parameter change allows bonding at lower vacuum levels (1×10^-4 to 1×10^-3 torr) and eliminates the need for strict surface roughness control, while maintaining strong bonding through liquid phase infiltration and solidification
Solution Approach 2:
An alloy layer containing melting point depression elements (B, Si, P) is introduced as an intermediary between the plates. This intermediate layer melts at a lower temperature than the base metal, creating a liquid phase that facilitates bonding by filling surface irregularities and forming strong metallurgical bonds upon solidification, thereby simplifying the overall bonding process
2Strength
If brazing is used with filler metal, then bonding can be achieved, but bubbles and precipitates form during organic binder volatilization, reducing bonding quality
Solution Approach 1:
The invention changes the filler material composition by using inorganic alloying elements (B, Si, P) instead of organic binders. These elements create a eutectic system that melts at a controlled temperature, allowing the filler to transition from solid to liquid phase smoothly without organic decomposition, thereby eliminating bubble and precipitate formation
Solution Approach 2:
The alloy layer undergoes a controlled phase transition from solid to liquid at the eutectic temperature during bonding. This phase transition allows the filler material to flow and wet the plate surfaces effectively, then solidifies upon cooling to form a strong, defect-free bond, avoiding the harmful volatilization effects of organic binders
3Strength
If conventional bonding methods are used, then plates can be bonded, but high vacuum (≥10^-4 torr) and high pressure conditions are required, increasing manufacturing cost and complexity
Solution Approach 1:
The invention changes the bonding mechanism to liquid phase bonding, which allows operation at lower vacuum levels (1×10^-4 to 1×10^-3 torr) compared to conventional solid phase bonding. This parameter change in the bonding process conditions significantly reduces equipment requirements and manufacturing complexity while maintaining effective bonding capability
Solution Approach 2:
The alloy layer acts as a mediator that enables bonding under milder conditions. By introducing this intermediate material with specific melting characteristics, the process can proceed at lower vacuum and pressure levels, making the manufacturing process simpler and more cost-effective while achieving reliable bonds
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 enables simple, efficient, and cost-effective bonding of heat exchanger plates with high-quality bonding portions, avoiding defects and reducing manufacturing complexity, while maintaining heat exchanger efficiency and economic viability.
Implementation Method 1
performing bonding heat treatment by heating and maintaining the laminated plates under conditions of a degree of vacuum of 1 × 10 -4 to 1 × 10 -3 torr and a temperature of 900 to 1200°C for 0.1 to 6 hours, thereby bonding the plates to each other by transition liquid phase bonding
Implementation Method 2
The forming an alloy layer is performed by electroless plating or thermal spray coating
Implementation Method 3
The forming an alloy layer is performed by electroless plating or thermal spray coating
Data Source
Figure 1A~3
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Figure 6~7
AI summary
A heat exchanger includes a plurality of plates bonded by transition liquid phase (TLP) bonding. Since the plates are bonded by the transition liquid phase bonding a good bonding portion may be formed reducing defects therein, thereby enabling the heat exchanger to have a high quality. In addition, since the bonding process is performed under a mild condition, it is possible to easily employ a bonding condition and more improve production efficiency.