Cold Spray Powder Coating Apparatus for Uniform Deposition
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Solution Overview
Problem
Conventional coating methods face challenges in achieving uniform and continuous coating of powders on substrates due to factors like particle size, specific weight, temperature, and aerodynamic drag, particularly when coating ceramics and carbon nanotubes, leading to inefficiencies and poor adhesion strength.
Innovation Solution
A method and apparatus that use a controlled flow of carrier air to consistently feed a fixed amount of powder to a nozzle, ensuring uniform velocity and density, regardless of substrate size or material, and operate in a low vacuum state to prevent thermal shock and aerodynamic drag, using a system that includes an air supply unit, air treatment, feeder, and spray nozzle to achieve consistent coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal spraying is used to achieve thick coating layer in short time, then coating speed is improved, but coating quality deteriorates due to voids, cracks, and poor adhesion
Solution Approach 1:
The invention changes the fundamental parameters of the coating process by using cold spray technology instead of thermal spray. The carrier gas temperature is controlled to remain below the melting point of the powder material, and the gas velocity is increased to supersonic speeds (Mach 1.0-2.5) to achieve coating deposition through kinetic energy rather than thermal melting, thereby producing dense, defect-free coatings with excellent adhesion
2Productivity
If high temperature is used in thermal spraying to melt powder, then coating formation is accelerated, but substrate and powder properties deteriorate due to thermal shock
Solution Approach 1:
The invention fundamentally changes the temperature parameter from high temperature (thermal spray) to low temperature (cold spray). The carrier gas temperature is maintained below the melting point of the powder material, eliminating thermal shock to the substrate while still achieving rapid coating formation through supersonic gas velocity and kinetic energy transfer
3Object-affected harmful factors
If cold spray is used to coat particles by kinetic energy, then thermal shock is reduced, but coating efficiency decreases due to aerodynamic drag
Solution Approach 1:
The invention applies dynamic principles by using a de Laval nozzle to accelerate the carrier gas to supersonic speeds (Mach 1.0-2.5). This dynamic acceleration overcomes aerodynamic drag and enables efficient coating deposition at low temperatures. The system transitions from subsonic to supersonic flow regime, creating a high-velocity jet that maintains particle velocity and coating efficiency
4Manufacturing precision
If electrospray coating is used to deposit particles at vacuum, then coating precision is improved, but material versatility is limited to electrically charged particles
Solution Approach 1:
The invention uses carrier gas as an intermediary medium to transport and deposit powder particles. Unlike electrospray that relies on electrostatic forces, this system uses the kinetic energy of supersonic carrier gas flow to overcome aerodynamic drag and deposit particles. This intermediary approach enables coating of any powder material regardless of electrical charge, including ceramics and carbon nanotubes, while maintaining coating precision through controlled gas flow and velocity
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 solution enables uniform and continuous coating of various powders on large substrates, improving coating efficiency and adhesion strength by controlling flow rate, pressure, and temperature, and eliminating thermal shock and aerodynamic drag issues.
Implementation Method 1
coat solid powder on the substrates such as plastics, glasses, alloys, metals, ceramics, etc. continuously and uniformly by spraying powder entrained on carrier air
Implementation Method 2
The weakness of cold spray is that particles are not coated because their velocity decreases by the aerodynamic drag occurring after gas impinges upon the substrate
Implementation Method 3
operates in a low vacuum state to prevent thermal shock and aerodynamic drag
Data Source
AI summary
The present invention relates to a method and an apparatus by which powder is evenly dispersed and is coated on a substrate uniformly and continuously so that a uniform layer may be formed. More specifically the present invention provides a method and an apparatus for forming a coating layer that powder is coated on an entire surface of a substrate uniformly and continuously, regardless of the material or the size of the substrate, as a uniform amount of powder entrained on the carrier air which is generated by carrier air and powder transported to a carrier pipe at a certain rate is consistently fed in to a nozzle, regardless of the size, morphology, and specific weight of the powder particles.