Protective Coating Slurry for Crack-Free Vertical Surface Melting
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Solution Overview
Problem
Conventional methods for applying protective layers to workpieces face issues such as shrinkage leading to cracks, excessive flowability causing droplet formation on vertical surfaces, and the inability to melt in an air atmosphere.
Innovation Solution
A method using a nickel-based alloy mixed with an iron-based alloy and cellulose to create a melting slip that is applied and dried, allowing for controlled shrinkage in one direction and enabling melting in an air atmosphere, with an enamel layer providing oxidation protection and sealing the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high melting temperatures are used to prevent crack formation, then the protective layer can be applied, but the layer material forms drops due to excessive flowability
Solution Approach 1:
The patent changes the chemical composition parameters of the melting alloy by adding aluminum (5-15 wt%) and controlling nickel content (40-60 wt%), which modifies the melting behavior and flow characteristics of the coating material, allowing it to maintain adequate flowability for crack prevention while reducing excessive dripping
Solution Approach 2:
The patent creates a composite melting alloy system combining nickel, aluminum, and other elements, where aluminum forms aluminum oxide on the surface that acts as a flux, modifying the melting behavior and reducing surface tension to control flowability and prevent droplet formation while maintaining crack-free coating
2Reliability
If conventional protective layers are applied, then coating can be achieved, but shrinkage in three spatial directions causes cracks in the layer
Solution Approach 1:
The patent modifies the chemical composition of the coating material by incorporating aluminum and controlling the nickel content, which changes the melting and solidification behavior of the layer, resulting in controlled shrinkage primarily in the thickness direction rather than lateral shrinkage that causes cracking
Solution Approach 2:
The composite alloy system with aluminum creates a melting slip that exhibits controlled volumetric shrinkage characteristics during melting, where the aluminum oxide formation and eutectic reactions modify the shrinkage pattern to occur predominantly in the thickness direction, preserving lateral dimensional stability and preventing cracks
3Reliability
If conventional methods are used, then protective layers can be applied, but vacuum furnaces or protective gas furnaces are required, increasing process complexity
Solution Approach 1:
The patent introduces aluminum as an intermediary element that forms aluminum oxide during melting, which acts as a protective flux layer that prevents oxidation of the underlying coating material, thereby enabling the use of simpler air-atmosphere furnaces instead of complex vacuum or protective gas systems while maintaining coating quality
Solution Approach 2:
The patent utilizes controlled oxidation of aluminum in the alloy during the melting process, where aluminum reacts with oxygen to form aluminum oxide that serves as a protective layer, enabling the melting process to proceed in air atmosphere without requiring vacuum or protective gas environments
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 approach minimizes shrinkage, prevents crack formation, and allows for reliable coating on complex geometries and vertical surfaces without droplet formation, while enabling melting in ambient air, resulting in a stable and wear-resistant protective layer.
Implementation Method 1
The workpiece provided with the melting slip in this way is exposed to a temperature of more than 1000° C. in the melting range of the melting alloy, so that the melting alloy is melted.
Implementation Method 2
Due to the high flowability, the layer material tends to close the cracks on its own.
Implementation Method 3
The original powder coating is subject to an apparent reduction in volume during the melting process, which can lead to cracks in the layer created.
Data Source
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AI summary
A method for applying a protective layer (A) to a workpiece (B), wherein the protective layer at least partially comprises particles of an iron-based alloy and a nickel-based alloy, the method comprising the following process steps: providing a powder mixture (PM), wherein the powder mixture (PM) comprises a first powder (P1) of the nickel-based alloy and a second powder (P2) of the iron-based alloy; processing the powder mixture (PM) into a melting slurry (S, St), applying the melting slurry (S, St) to the workpiece (3), heating the melting slurry (ES, ESt) to a process temperature (TA) above a solidus temperature (T1u) of the first powder (P1) and below a solidus temperature (T2u) of the second powder, wherein the heating is carried out in particular under ambient air, cooling the workpiece (B) after a predetermined melting time.