Supersonic Cold Spray Coating Uniformity
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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, and temperature, particularly with ceramics and carbon nanotubes, leading to inefficiencies and poor adhesion strength.
Innovation Solution
A method and apparatus that utilize 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, using a system that includes an air supply unit, air treatment, feeder, and spray nozzle, operating in a low vacuum environment to coat substrates uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal spraying is used to achieve thick coating layer in short time, then productivity 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 velocity is controlled to be supersonic (Mach number > 1) while maintaining gas temperature below the melting point of powder particles, fundamentally altering the deposition mechanism from melting/adhesion to kinetic energy-driven plastic deformation and mechanical interlocking.
Solution Approach 2:
The invention replaces the thermal field (high temperature plasma or flame) with a mechanical field (supersonic gas flow). The kinetic energy of the supersonic carrier gas particles directly accelerates the powder particles, eliminating the need for thermal energy to melt and deposit the coating material.
2Object-affected harmful factors
If cold spray is used to coat particles by kinetic energy, then thermal shock is avoided, but coating efficiency decreases due to aerodynamic drag after gas impinges on substrate
Solution Approach 1:
The invention divides the coating process into two distinct spatial zones: an acceleration zone where the carrier gas is accelerated to supersonic velocity and powder particles are entrained and accelerated, and a deposition zone where the supersonic flow impinges on the substrate. This segmentation allows the supersonic flow to maintain its velocity and coating efficiency while still achieving the benefit of controlled thermal conditions.
Solution Approach 2:
The invention introduces dynamic control of the carrier gas flow by adjusting the Mach number to be greater than 1, creating a supersonic flow regime. This dynamic approach allows the gas flow to overcome aerodynamic drag effects and maintain sufficient velocity for effective particle delivery to the substrate, thereby improving coating efficiency while avoiding thermal shock.
3Strength
If conventional coating methods are used, then adhesion strength is affected by temperature and particle properties, but uniform coating is difficult to achieve regardless of substrate size or material
Solution Approach 1:
The invention creates a universal coating system that can effectively coat various types of substrates (different sizes, materials, and geometries) and various powder materials (metals, ceramics, polymers) using the same supersonic cold spray mechanism. The supersonic carrier gas flow adapts to different substrate conditions while maintaining consistent particle acceleration and deposition characteristics, achieving both strong adhesion and coating uniformity across diverse applications.
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 enables continuous and uniform coating of various powders on large substrates, improving coating efficiency and adhesion strength while avoiding thermal shock and aerodynamic drag issues, allowing for the use of different materials and sizes without compromising coating quality.
Implementation Method 1
a first section, a second section, a third section, a fourth section, and a fifth section; a region where a shock wave is generated by the supersonic air in the second section of the carrier pipe; wherein powder is fed into the minus pressured region
Implementation Method 2
a region where a shock wave is generated by the supersonic air in the second section of the carrier pipe
Implementation Method 3
spraying powder entrained on carrier air onto substrates to form a coating layer
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.