Cold Spray Refractory Metal Coating for Oxidation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for applying refractory metal coatings, such as thermal spraying and deposition-welding, often result in oxidation and the introduction of impurities, leading to high energy consumption, distortion, and limited applicability to complex components, especially when using processes like vacuum plasma spraying which introduces tungsten and copper impurities from electrodes.
Innovation Solution
A cold spray process is employed, where a gas-powder mixture of refractory metals like niobium, tantalum, or tungsten is accelerated to supersonic speeds and deposited onto a surface without melting, using inert gases like argon or helium to minimize oxidation and impurity introduction, allowing for the application of dense and corrosion-resistant coatings with low oxygen and nitrogen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal spraying or deposition-welding is used to apply refractory metal coatings, then the coating material can be deposited onto the substrate, but the metal melts and readily oxidizes or absorbs gaseous impurities, resulting in high oxygen and impurity content in the coating
Solution Approach 1:
The patent employs an inert gas atmosphere (such as argon or nitrogen) during the cold spray deposition process to prevent oxidation and impurity absorption by the refractory metal coating material. This inert environment maintains low oxygen and impurity content in the coating without requiring vacuum conditions, thereby improving coating purity while avoiding the harmful effects of oxidation and contamination that occur in conventional thermal spraying methods
2Reliability
If vacuum plasma spraying is used to apply coatings, then the coating can be deposited under protected conditions, but tungsten and copper impurities from electrodes are introduced into the coating, reducing protective effect
Solution Approach 1:
The patent eliminates the electrode component from the deposition system by using a cold spray process where refractory metal powder is accelerated through a supersonic nozzle. This extraction of the electrode element completely removes the source of tungsten and copper impurities that would otherwise be introduced into the coating during vacuum plasma spraying, thereby maintaining the coating's protective effect without electrode contamination
Solution Approach 2:
The patent replaces the thermal-energy-based vacuum plasma spraying system with a mechanically-driven cold spray system that uses supersonic gas flow to accelerate powder particles. This substitution of the deposition mechanism avoids the use of plasma arcs and electrodes, thereby eliminating the generation of electrode impurities while still achieving effective coating deposition
3Manufacturing precision
If laser melting of powder particles is used to form coatings, then coating can be applied to surface, but high energy is introduced into the component causing distortion and porosity
Solution Approach 1:
The patent fundamentally changes the deposition parameter from high-energy laser melting to low-energy cold spray deposition. By using supersonic gas flow to accelerate powder particles and deposit them onto the substrate without melting, the process achieves dense coating formation with excellent adhesion while minimizing energy input to the component, thereby avoiding thermal distortion and reducing porosity compared to laser-based methods
4Ease of manufacture
If conventional thermal processes are used for coating application, then coating material can be deposited, but the outlay in terms of apparatus is high and component size is limited
Solution Approach 1:
The patent employs a cold spray gun with supersonic nozzle that can be easily positioned and maneuvered, replacing complex vacuum chamber systems. The process uses readily available inert gases and simple powder feed mechanisms, significantly reducing apparatus complexity and cost while enabling coating of large or complex components that would be difficult to accommodate in vacuum chambers
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 dense, corrosion-resistant coatings with low impurity content, suitable for complex components, reducing energy consumption and avoiding the distortion issues associated with traditional methods, while maintaining high mechanical strength and purity.
Implementation Method 1
a gas flow is formed into a gas-powder mixture with a powder of a material selected from the group consisting of niobium, tantalum, tungsten, molybdenum, titanium, zirconium, mixtures of at least two thereof or their alloys with one another or with other metals, the powder has a particle size of from 0.5 to 150 μm, wherein a supersonic speed is imparted to the gas flow and a jet of supersonic speed is formed
Implementation Method 2
a gas flow forms a gas-powder mixture... a supersonic speed is imparted to the gas flow and a jet of supersonic speed is formed, which ensures a speed of the powder in the gas-powder mixture of from 300 to 2000 m/s
Data Source
AI summary
Disclosed is a process for the reprocessing or production of a sputter target or an X-ray anode wherein a gas flow forms a gas/powder mixture with a powder of a material chosen from the group consisting of niobium, tantalum, tungsten, molybdenum, titanium, zirconium, mixtures of two or more thereof and alloys thereof with at least two thereof or with other metals, the powder has a particle size of 0.5 to 150 μm, wherein a supersonic speed is imparted to the gas flow and the jet of supersonic speed is directed on to the surface of the object to be reprocessed or produced.