Thermal Spray Liquid Injection for Suboptimal Particle Removal
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Solution Overview
Problem
Conventional thermal spray processes face challenges in reducing suboptimal feedstock deposition and in-situ removal of debris during coating, leading to entrapment of particles with suboptimal properties, which affects coating adhesion and integrity.
Innovation Solution
A thermal spray apparatus that uses a gas stream column with defined volumetric regions to separate optimal and suboptimal feedstock, injecting a liquid into the suboptimal region to reduce temperature and prevent adherence, and utilizing the liquid as an abrasive to remove debris, enhancing the removal of suboptimal deposits and surface preparation grit particulates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermal spray processes are used, then coating deposition is achieved, but suboptimal feedstock particles are entrained in the coating, reducing adhesion and integrity
Solution Approach 1:
The gas stream column is divided into two volumetric regions: a first region (core) and a second region (outer annular region). Feedstock is selectively injected into different regions to separate optimal and suboptimal particles spatially, allowing only optimal particles to reach the substrate while suboptimal particles are removed by liquid injection
Solution Approach 2:
Different regions of the gas stream column are given different functions: the first region delivers optimal feedstock particles to the substrate, while the second region receives liquid injection to cool and remove suboptimal particles. This local differentiation ensures high coating quality while preventing adhesion failures
2Productivity
If feedstock particles of various sizes are used, then coating thickness can be achieved, but larger particles require more heat and momentum, resulting in suboptimal deposition
Solution Approach 1:
The feedstock stream is segmented by particle size through selective injection into different volumetric regions of the gas column. Optimal sized particles are injected into the first region while suboptimal particles are injected into the second region, achieving size separation without requiring complex feedstock preparation
Solution Approach 2:
The invention changes the spatial distribution parameter of feedstock particles within the gas stream column by controlling injection positions and gas flow patterns, effectively separating particles by size and ensuring only optimally sized particles deposit on the substrate
3Reliability
If surface preparation grit is applied, then substrate adhesion is improved, but grit particles become embedded in the coating, creating defects
Solution Approach 1:
The liquid injection system extracts and removes suboptimal particles including embedded grit from the substrate surface and coating. The liquid cools these particles, causing them to detach and be carried away by the gas stream, preventing them from becoming permanent defects in the coating
Solution Approach 2:
The liquid injection converts the harmful effect of embedded grit particles into a beneficial cleaning action. By cooling the grit particles, the liquid causes them to detach from the substrate and coating, transforming them from adhesion promoters to removable contaminants that clean the surface
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 ensures that only optimally sized feedstock particles adhere to the substrate with optimal temperature and velocity conditions, reducing suboptimal deposits and improving coating strength by continuous in-flight reduction and in-situ removal of debris, thereby enhancing coating adhesion and integrity.
Implementation Method 1
The hot gas stream transfers heat and momentum to the powder, causing it to melt and impact on the substrate surface to form a coating
Implementation Method 2
The hot gas stream transfers heat and momentum to the powder, causing it to melt and impact on the substrate surface to form a coating
Implementation Method 3
the liquid reducing the temperature of the suboptimal portion of the feedstock entrained within the second region of the stream, and the temperature reduction being sufficient to reduce or prevent the suboptimal feedstock adherence on the substrate surface
Implementation Method 4
the liquid impacts the substrate removing debris on and embedded in the substrate
Data Source
AI summary
A thermal spray system and method includes a hot gas generator with nozzle accelerating heated gas towards a substrate in the form of a gas column projecting onto the substrate surface as a spot. One or more feedstock injectors proximate the nozzle exit, directed towards the gas column, are connected to a feedstock source. The hot gas stream transfers heat and momentum to the feedstock, causing the feedstock particles to impact onto a substrate to form a coating. The system further comprises one or more liquid injectors proximate the nozzle exit, directed towards the axis, and connected to a source of liquid. The system controls the flow and velocity with which the liquid is injected, permitting control of the depth of penetration of the liquid into the gas column. The method selectively prevents suboptimal feedstock particulates from adhering to the substrate and provides for the in-situ removal of suboptimal deposits.