Rare Earth Compound Cold Spraying for Corrosion Resistance
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Solution Overview
Problem
Conventional cold spraying methods for forming ceramic coatings are inefficient, and coatings made from TiO2 powders lack corrosion resistance to halogen-based gases, resulting in altered physical properties and unsatisfactory color.
Innovation Solution
A cold spraying material comprising a rare earth element compound with a specific surface area of 30 m2/g or more, produced using methods that preserve the compound's physical properties, such as yttrium oxide, fluoride, or oxyfluoride powders, which are then used to create coatings with enhanced corrosion resistance and desired color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma thermal spraying is used to form a coating from rare earth compound powder, then the coating can be formed, but the powder is altered during thermal spraying and desirable physical properties including color are unlikely to be obtained
Solution Approach 1:
The patent replaces plasma thermal spraying (thermal field) with cold spraying (mechanical field). In cold spraying, particles are accelerated to high speed and collide with the substrate mechanically, avoiding thermal alteration. This substitution of the energy field mechanism resolves the contradiction by maintaining material composition stability while achieving coating formation with desired physical properties and corrosion resistance.
Solution Approach 2:
The patent changes the fundamental parameter of the spraying process from thermal energy (plasma) to mechanical energy (kinetic). By controlling particle velocity and impact energy rather than temperature, the coating is formed without altering the rare earth compound's physical properties, thus resolving the contradiction between forming a protective coating and maintaining material integrity.
2Productivity
If conventional rare earth compound powder is used for cold spraying, then the coating efficiency is low and sufficient coating thickness cannot be formed, but using TiO2 powder provides good coat-forming properties
Solution Approach 1:
The patent optimizes particle size parameters and specific surface area (30 m2/g or more) of the rare earth compound powder to enhance cold spraying efficiency. By controlling these physical parameters, the coating efficiency is improved while maintaining the corrosion resistance property, resolving the contradiction between productivity and reliability.
3Ease of manufacture
If TiO2 powder is used to form a coating using cold spraying method, then the coating can be formed with good coat-forming properties, but the coating obtained is yellower and desired color cannot be obtained
Solution Approach 1:
The patent replaces TiO2 powder (which causes color alteration) with rare earth compound powder that maintains its original color properties. This substitution uses a different material that inherently possesses the desired color stability, resolving the contradiction between ease of coating formation and color preservation.
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
The method produces coatings with improved corrosion resistance to halogen-based plasma and maintains the original physical properties of the rare earth compound, achieving a whiter color and increased coating thickness.
Implementation Method 1
Cold spraying methods are systems for producing a coating by accelerating particles as a raw material to a speed close to a sonic speed and causing the particles kept in a solid phase to collide against a substrate
Implementation Method 2
a specific surface area of 30 m2/g or more as determined by a BET single-point method
Data Source
AI summary
A material for cold spraying contains a powder of a compound of a rare earth element with a specific surface area of 30 m2/g or more as determined by a BET single-point method. The powder preferably has a volume of pores with a pore size of 3 to 20 nm of 0.08 cm3/g or more as determined by a gas absorption method. The powder also preferably has a crystallite diameter of 25 nm or less. The powder also preferably has a repose angle of from 10 to 60°. In the L*a*b* color system, the powder also preferably has a value L of 85 or more, a value a of from −0.7 to 0.7, and a value b of from −1 to 2.5.