Multi-Wall Steel Pipe with Nickel-Solder Bonding Without Cyanide
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for coating steel strips with solder layers for producing multi-walled pipes require the use of cyanide in electroplating, which is toxic and leads to adhesion issues, contamination sensitivity, and complex processes, resulting in poor quality or uneconomical production.
Innovation Solution
A cyanide-free method involving the application of a nickel starting layer on a steel strip, followed by a solder layer using electroplating in cells with constant electrolyte flow, ensuring good adhesion and economic production, where the nickel layer acts as an adhesion promoter and diffusion barrier, and the solder layer is predominantly copper with high current densities and balanced electrolyte baths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyanide is added to the electroplating bath to achieve sufficient adhesion of the solder layer to steel, then adhesion quality is improved, but toxicity and environmental harm increase
Solution Approach 1:
A nickel intermediate layer is introduced between the steel substrate and the solder layer. This nickel layer acts as a mediator that provides excellent adhesion to both the steel base layer and the solder layer, eliminating the need for cyanide in the electroplating bath while maintaining strong bonding throughout the metal composite structure
Solution Approach 2:
The harmful cyanide component is completely removed from the electroplating process. The patent achieves adhesion without cyanide by using a nickel intermediate layer that can be applied through standard electroplating methods, thereby extracting the toxic element while preserving the functional requirement of strong adhesion
2Object-affected harmful factors
If alternative methods are pursued to avoid cyanide addition, then toxicity is reduced, but adhesion quality deteriorates
Solution Approach 1:
The nickel layer serves as an intermediary that bridges the steel substrate and solder layer, providing excellent adhesion properties without requiring cyanide. The nickel forms strong metallurgical bonds with both the steel base layer and the solder layer, ensuring high reliability in the absence of toxic chemicals
3Reliability
If electroplating baths are made sensitive to impurities to improve coating quality, then adhesion is improved, but process complexity and economic viability worsen
Solution Approach 1:
The nickel intermediate layer acts as a sacrificial or consumable layer that can be applied using standard, simple electroplating processes. This layer absorbs the complexity of achieving good adhesion, allowing the subsequent solder layer to be applied using conventional, economically viable electroplating methods without requiring highly sensitive or complex bath compositions
4Reliability
If strong oxidizing agents are added to improve solder adhesion, then adhesion is improved, but process safety and simplicity deteriorate
Solution Approach 1:
The nickel intermediate layer provides the necessary adhesion promotion without requiring strong oxidizing agents. The nickel can be deposited using standard electroplating processes that are safe and easy to operate, eliminating the need for hazardous chemicals while maintaining strong bonding between the steel substrate and solder layer
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 achieves robust and high-quality multi-walled pipes with improved adhesion, reduced brittleness, and enhanced corrosion protection, allowing for efficient and cost-effective production without the use of cyanide.
Implementation Method 1
the nickel layer acts as an adhesion promoter
Implementation Method 2
the nickel layer acts as an adhesion promoter and diffusion barrier
Implementation Method 3
a nickel base layer is applied to at least one side of the steel base layer, wherein a solder base layer is applied to one of the nickel base layers
Implementation Method 4
the copper is melted by heating the multi-walled pipe, causing the coiled walls to be soldered together, resulting in a high-quality, metallurgical bond
Implementation Method 5
the walls of the tubes are soldered by means of heating
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a multi-walled tube (1), wherein the tube (1) is formed from at least one multi-layered metal strip (3) or from at least one section of a multi-layered metal strip (3) by rolling, wherein each wall (6) of the tube (1) comprises a steel layer (8), which steel layer (8) is coated on one or both sides with a solder layer (9), wherein the steel layers (8) have a region (10) with increasing nickel concentration in the direction of the solder layers (9) and wherein the solder layers (9) have a region (10) of increasing nickel concentration in the direction of the steel layers (8).