Nickel-Interlayer Tungsten Composite for Heat-Resistant Joining
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Solution Overview
Problem
Conventional composite materials exhibit low heat resistance at the joining portion, leading to fractures and inadequate utilization of tungsten's high melting point and density due to inferior brazing materials with lower melting points, resulting in low mechanical properties and strength.
Innovation Solution
A composite material comprising an iron-based alloy layer, an intermediate layer of pure nickel or nickel alloy with controlled composition, and a tungsten-containing layer, optimized for thickness and density to enhance heat resistance and adhesion, using a three-layer structure with a thin intermediate layer to minimize thermal stress and voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional brazing materials are used to join tungsten-containing layer to iron-based alloy layer, then joining is achieved, but heat resistance at joining portion is low due to inferior brazing materials with lower melting points
Solution Approach 1:
The patent introduces a nickel-based intermediate layer as a mediator between the tungsten-containing layer and iron-based alloy layer. This intermediate layer has a melting point of 1455°C, which is significantly higher than conventional brazing materials, thereby achieving high heat resistance at the joining portion while maintaining mechanical strength. The intermediate layer composition is specifically controlled to prevent brittle intermetallic compound formation and ensure good adhesion to both adjacent layers.
Solution Approach 2:
The patent creates a composite material structure consisting of three distinct layers: tungsten-containing layer, nickel-based intermediate layer, and iron-based alloy layer. Each layer has specifically controlled composition and thickness to achieve synergistic effects. The composite structure allows the system to utilize the high melting point of nickel for heat resistance, the high density of tungsten for radiation shielding, and the mechanical properties of iron-based alloy for structural strength.
2Strength
If intermediate layer thickness is increased to improve adhesion, then joining strength is improved, but thermal stress increases leading to fractures
Solution Approach 1:
The patent optimizes the thickness parameter of the intermediate layer to a specific range (5-50 μm) to balance adhesion strength and thermal stress. This parameter optimization ensures sufficient contact area for strong bonding while minimizing the volume that generates thermal stress during heating and cooling cycles. The thickness control prevents fracture while maintaining adequate joining strength.
3Ease of manufacture
If conventional brazing materials with lower melting points are used, then joining process is easier, but tungsten's high melting point and density properties are not effectively utilized
Solution Approach 1:
The patent changes the melting point parameter of the joining material from conventional brazing materials (lower melting points) to a nickel-based intermediate layer with a melting point of 1455°C. This parameter change enables the system to withstand high temperatures and effectively utilize tungsten's high melting point and density properties for radiation shielding applications, while still achieving reliable joining.
Data Source
AI summary
A composite material includes: an iron-based alloy layer; an intermediate layer provided on the iron-based alloy layer; and a tungsten-containing layer provided on the intermediate layer, wherein the intermediate layer is composed of pure nickel or is an alloy that contains at least one selected from a group consisting of copper, cobalt, and iron at more than 0 mass % and less than or equal to 71 mass % in total, and that contains nickel at more than or equal to 29 mass % and less than 100 mass %.