Plasma Spray Temperature Control via Local Heating Zones
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Solution Overview
Problem
In plasma spraying, maintaining uniform substrate temperature is challenging due to thermal expansion mismatch and complexity of workpieces, leading to potential thermal shock and defects in multi-layer coatings.
Innovation Solution
A plasma spray system with a temperature control subsystem using an infrared camera for measurement, an infrared heater for heating, and a compressed air chiller for cooling, all arranged in zones of equal size (0.5 inches in diameter) to maintain optimal temperature for uniform coating application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plasma torch is scanned over the substrate to deposit multi-layer coatings, then different materials can be applied for enhanced coating performance, but the substrate temperature becomes non-uniform due to workpiece complexity and material switching time, leading to thermal shock and coating defects
Solution Approach 1:
The patent applies local heating and cooling zones positioned upstream and downstream of the application zone to maintain uniform substrate temperature locally across different workpiece geometries. Temperature sensors monitor specific locations and control systems adjust heating/cooling intensity at each zone independently to compensate for thermal variations caused by material switching and workpiece complexity.
Solution Approach 2:
The system pre-heats or pre-cools the substrate in zones upstream of the application zone before material deposition occurs. This preliminary temperature adjustment ensures the substrate is at the optimal temperature range when the plasma torch arrives, preventing thermal shock and ensuring uniform coating quality during material transitions.
2Manufacturing precision
If sufficient time is allotted for the torch to reach steady state during material switching, then coating process defects are minimized, but substrate temperature decreases non-uniformly due to workpiece complexities
Solution Approach 1:
Temperature sensors continuously monitor substrate temperature at multiple locations, and the control system uses this feedback to dynamically adjust the intensity and duration of heating and cooling zone activation. During material switching, the system maintains temperature uniformity by compensating for heat loss variations across different workpiece regions, ensuring steady-state conditions are achieved uniformly.
Solution Approach 2:
The system dynamically changes operational parameters including heating power, cooling flow rate, and zone activation timing based on the specific workpiece geometry and material being deposited. This allows the temperature control strategy to adapt to different thermal mass and heat conduction characteristics, maintaining uniform temperature distribution during material transitions.
3Temperature
If the workpiece is rotated on a turntable with continuous distance adjustment, then thermal shock is reduced and temperature distribution is improved, but the system complexity increases for multi-layer coating material switching
Solution Approach 1:
The temperature control system is segmented into independent heating zones, cooling zones, and sensor positions that can be individually controlled and activated. This modular approach allows the system to manage complex multi-layer coating processes by activating only the necessary zones for each material transition, reducing overall system complexity while maintaining effective temperature control.
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 system ensures stable and uniform temperature control during plasma spraying, reducing thermal shock and enhancing coating microstructure and adherence by maintaining the workpiece at optimal temperatures for each layer application.
Implementation Method 1
A temperature control subsystem includes a temperature sensor such as an infrared camera to sense a temperature at a measurement zone on the workpiece
Implementation Method 2
a heater such as an infrared heater to heat a zone on the workpiece upstream of the application zone
Implementation Method 3
a chiller including a compressed air system to spray cool air
Data Source
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AI summary
A plasma spray system including a temperature sensor (72) operable to determine a temperature of the workpiece (W) at a measurement zone (92); a heater (74) operable to selectively heat the workpiece (W) at a heating zone (94) downstream of the measurement zone (92); a plasma spray subsystem operable to plasma spray a workpiece (W), the plasma spray defines an application zone (90) on the workpiece (W) downstream of the heating zone (94) and a control (70) in communication with the plasma spray subsystem, the temperature sensor (72), and the heater (74), the control (70) operable to control the heater (74) to heat the workpiece (W) in the heating zone (94) to a desired temperature in response to a temperature determined by the temperature sensor (72).