Atmospheric Pressure Pulsed Arc Plasma Source for Low-Temperature Coating
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Solution Overview
Problem
Existing atmospheric pressure plasma coating systems operate at high temperatures and produce thick, porous coatings, making them unsuitable for large structures and inefficient in terms of deposition quality.
Innovation Solution
An atmospheric pressure pulsed arc plasma source using a housing with an insulator tube and conductive tube, a nozzle, and a pulsed DC power supply to generate a discharge stream with a temperature of less than 50°C, allowing for the deposition of metallic or ceramic coatings at lower temperatures and reduced porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If atmospheric pressure plasma spray is used to deposit coatings, then the process can treat large structures without a vacuum chamber, but the coatings produced are thick and porous with high temperature
Solution Approach 1:
The patent applies pulsed DC power supply to generate periodic arc discharges instead of continuous DC operation. The pulse frequency ranges from 10 Hz to 10 kHz, with each pulse creating a brief high-temperature arc that vaporizes coating material, followed by a cooling period. This periodic action allows the plasma jet to cool between pulses, reducing the overall temperature of the discharge stream while maintaining effective deposition. The result is coating formation at lower substrate temperatures with reduced porosity and improved coating quality, while still treating large structures at atmospheric pressure.
Solution Approach 2:
The patent fundamentally changes the temperature parameter of the plasma discharge by switching from continuous high-power DC operation to pulsed DC operation. This parameter change allows the plasma jet to reach high temperatures during the arc pulse for effective material vaporization, then cool rapidly during the off-period. The average temperature of the discharge stream is reduced significantly compared to continuous operation, enabling coating deposition on temperature-sensitive substrates while maintaining atmospheric pressure operation for large structures.
2Temperature
If high power DC mode is used in plasma spray, then flame temperature reaches 6,650°C to 11,000°C to melt and deposit metallic powder, but the resultant coating is thick and porous
Solution Approach 1:
The pulsed DC power supply creates periodic arcs that generate high temperature only during the pulse duration (microseconds to milliseconds), sufficient to vaporize coating material. Between pulses, the plasma jet cools significantly, reducing the average temperature exposure on the substrate. This periodic heating and cooling cycle allows material deposition without sustained high-temperature exposure that causes excessive porosity and thick coatings, improving coating quality while maintaining deposition efficiency.
Solution Approach 2:
By operating at high pulse frequencies (10 Hz to 10 kHz), the patent maintains continuous deposition action while controlling temperature exposure. The high frequency ensures that coating material is continuously supplied and deposited without long idle periods, maintaining productivity. However, the short duty cycle of each pulse (microseconds to milliseconds) limits the total heat input, preventing excessive porosity formation while keeping the coating process continuous and efficient.
3Manufacturing precision
If vacuum chamber is used for PVD or PACVD coating deposition, then coating quality is high, but the process is cumbersome and nearly impossible for large structures
Solution Approach 1:
The patent changes the pressure parameter from vacuum (low pressure) to atmospheric pressure operation. By using pulsed DC arc discharge, the system generates sufficient plasma at atmospheric pressure to achieve effective material vaporization and deposition. This eliminates the need for complex vacuum chambers while maintaining coating quality. The pulsed arc creates a concentrated, high-temperature plasma jet that can penetrate and coat large structures directly in atmospheric conditions, simplifying the overall system while preserving coating performance.
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 system enables the formation of coatings with improved deposition efficiency and reduced porosity at lower process temperatures, suitable for large structures without the need for a vacuum chamber.
Implementation Method 1
an arc gas feed... electrical and water connections... ignited the arc gas and achieve a flame temperature in the range of 6,650° C. to 11,000° C.
Implementation Method 2
plasma spray system... ignite the arc gas and achieve a flame temperature... so that metallic powder used in the coating may be melted and deposited
Implementation Method 3
the consumable feed stock is vaporized and the discharge stream includes the vapor. The vapor is deposited onto the substrate to form a coating
Data Source
AI summary
An atmospheric pressure pulsed arc plasma source and method of using including a housing having a housing opening therein; an insulator tube having an insulator tube opening therein, retained within the housing opening; and a conductive tube, retained within the insulator tube opening. A nozzle is retained by the housing. A feed path is defined in the conductive tube and the nozzle and a gas feed port is operatively coupled to the feed path. Feedstock is provided in the feed path and electrically coupled to the conductive tube. A pulsed DC power source provides a pulsed voltage to the conductive tube. The plasma source emits a discharge stream having a temperature that is less than 50° C. from the nozzle and a coating is formed on a substrate.