Plasma Gun Nozzle Coating for Micro-Boiling Corrosion Control
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Solution Overview
Problem
Conventional plasma gun nozzles experience corrosion due to micro-boiling of cooling water, leading to instability and decay of the plasma arc voltage, which affects the thermal state and operational life of thermal spray and chemical processing applications.
Innovation Solution
A water coolable surface coating, comprising materials like nickel, chromium, cadmium, vanadium, platinum, gold, silver, or molybdenum, is applied to the nozzle surfaces to prevent corrosion from micro-boiling, with a thickness between 2.54 µm and 25.4 µm, formed through methods such as chemical bath deposition or physical vapor deposition, to maintain arc voltage stability and extend hardware life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water is circulated through the plasma gun to prevent melting of the nozzle wall, then the nozzle can withstand extreme temperatures, but micro-boiling occurs along the surface causing formation of bubbles and corrosive attack
Solution Approach 1:
A water-coolable surface coating is applied to the nozzle exterior surface to act as an intermediary layer between the cooling water and the copper nozzle body. This coating prevents direct contact between the cooling water (with impurities) and the copper surface, thereby eliminating the corrosive attack caused by micro-boiling while still allowing thermal conduction for effective cooling.
Solution Approach 2:
The invention uses a composite structure consisting of the copper nozzle body combined with a protective surface coating layer. The coating material is selected to be resistant to corrosion from cooling water while maintaining thermal conductivity, creating a composite material system that combines the high thermal conductivity of copper with the corrosion resistance of the coating material.
2Use of energy by moving object
If the copper nozzle is used without coating, then heat transfer efficiency is maximized, but the thermal heat transfer coefficient changes as corrosion occurs, altering the plasma arc
Solution Approach 1:
The protective coating is applied in advance to the nozzle surface before the corrosion process begins. This preliminary protective action prevents the degradation of thermal properties that would otherwise occur during operation, ensuring consistent heat transfer efficiency and plasma arc stability throughout the nozzle's service life.
Solution Approach 2:
The surface coating serves as a stable intermediary layer that maintains consistent thermal interface properties between the cooling water and nozzle body. By preventing corrosion and surface degradation, the coating ensures that the thermal heat transfer coefficient remains constant, thereby maintaining plasma arc voltage stability.
3Object-affected harmful factors
If a protective coating is applied to the nozzle surface, then corrosion resistance is improved, but the coating thickness must be controlled to avoid limiting heat flow from the nozzle body to the cooling water
Solution Approach 1:
The coating thickness is optimized to a specific range (2.54 μm to 25.4 μm) to balance two opposing requirements: providing sufficient corrosion protection while maintaining adequate thermal conductivity. This parameter optimization ensures that the coating is thick enough to prevent corrosion but thin enough to allow efficient heat flow from the nozzle body to the cooling water.
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 coating effectively prevents corrosion and maintains arc voltage stability, extending the operational life of the nozzle and ensuring consistent plasma arc performance during thermal spray and chemical processing.
Implementation Method 1
the water coolable surface coating can prevent corrosion due to micro-boiling of the cooling water at the water coolable surface
Implementation Method 2
the water coolable surface coating can have a coating thickness to avoid limiting heat flow from the nozzle body to the cooling water
Data Source
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AI summary
Nozzle for thermal spray gun, thermal spray gun and method for forming nozzle. Nozzle includes a nozzle body having a central bore and an exterior surface structured for insertion into a thermal spray gun and a water coolable surface coating applied onto at least a portion of the exterior surface. The water coolable surface coating is structured to protect the exterior surface from a chemical interaction with cooling water guided through the thermal spray gun.