Vacuum Deposition Sonic Jet for Stable Zn-Mg Alloy Coatings
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Solution Overview
Problem
Existing methods for vacuum deposition of metal alloy coatings on substrates face challenges such as instability in coating composition over long lengths, complexity and cost of diffusion heat treatment, and difficulty in achieving constant layer thickness, particularly for materials like bake-hardening steel strips.
Innovation Solution
A process and installation for vacuum deposition using a sonic jet of metallic vapor from a bath with a controlled composition of zinc and magnesium, ensuring constant vapor flux and composition during deposition, which allows for continuous coating of substrates with a metal alloy layer of predetermined magnesium content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If successive deposition of elements followed by diffusion heat treatment is used, then alloyed coating can be obtained, but the process becomes complex and expensive due to large quantities of inerting gas required
Solution Approach 1:
The invention divides the coating process into two separate vacuum deposition chambers: a first chamber for depositing the base metal layer and a second chamber for depositing the alloying element layer. This segmentation eliminates the need for complex diffusion heat treatment and large quantities of inerting gas, while still achieving stable alloyed coating composition through controlled sequential deposition.
Solution Approach 2:
The invention introduces a transfer mechanism (such as a transfer roller or belt) as an intermediary between the two vacuum deposition chambers. This intermediary allows the substrate to move from the first chamber to the second chamber without exposure to atmospheric conditions, enabling continuous process operation without complex heat treatment steps.
2Object-affected harmful factors
If diffusion heat treatment is performed immediately after magnesium deposition, then oxidation is prevented, but the process requires continuous operation without air exposure
Solution Approach 1:
The invention segments the deposition process into distinct stages in separate vacuum chambers, allowing each chamber to be optimized for its specific function. The first chamber handles base metal deposition, while the second chamber handles alloying element deposition, enabling independent process control and eliminating the need for immediate continuous operation.
Solution Approach 2:
The invention maintains continuous vacuum protection throughout the transfer and deposition process, ensuring that the substrate remains protected from oxidation without requiring immediate heat treatment. The continuous vacuum environment allows for flexible production scheduling while preventing harmful oxidation.
3Stability of the object's composition
If precise control of layer thickness is maintained, then constant coating composition is achieved, but the process becomes difficult to control over long substrate lengths
Solution Approach 1:
The invention incorporates feedback control mechanisms for the vapor flux from the alloying element source, using sensors to monitor deposition rate and composition in real-time. This feedback system automatically adjusts deposition parameters to maintain constant coating composition over long substrate lengths, simplifying process control while ensuring composition stability.
Solution Approach 2:
The invention controls coating composition by adjusting vapor flux parameters (such as source temperature, deposition rate, and chamber pressure) rather than relying solely on physical layer thickness control. This parameter-based control method provides more flexible and easier control of coating composition over varying substrate lengths.
4Quantity of substance
If high evaporation temperatures are used for both zinc and magnesium, then sufficient vapor flux is obtained, but the temperature difference between elements complicates the process
Solution Approach 1:
The invention separates the evaporation processes for base metal and alloying elements into different vacuum chambers, allowing each chamber to be optimized for its specific temperature requirements. This segmentation enables independent temperature control for each element source, simplifying the process despite the temperature difference between zinc and magnesium.
Solution Approach 2:
The invention adjusts evaporation temperature as a controllable parameter for each element source independently. By optimizing the temperature parameter for each chamber based on the specific element being deposited, sufficient vapor flux is achieved for both zinc and magnesium without being constrained by their temperature difference.
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 industrial implementation of stable and uniform metal alloy coatings on varied substrates, avoiding the complexities of diffusion heat treatment and ensuring compatibility with different metallurgies, while maintaining high corrosion resistance and material yield.
Implementation Method 1
a vapor obtained by evaporation of a metal bath based on zinc and initially comprising a predetermined proportion of magnesium
Implementation Method 2
a process for continuously coating a substrate and an installation for the vacuum deposition of coatings formed from metal alloys
Data Source
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AI summary
The invention relates to a method for coating a substrate (S) by continuously depositing on said substrate (S) a layer of a metal alloy including at least two metallic elements using a vacuum deposition facility (1) that comprises a vapour jet coating device (7) for spraying the substrate (S) with a vapour containing the metallic elements in a predetermined and constant relative proportion, wherein the vapour is previously accelerated to a sonic speed. The method is particularly intended for depositing Zn-Mg coatings. The invention also relates to a continuous metal alloy vacuum deposition facility (1) for implementing said method.