Thermal Spray Suspension Flashpoint Safety
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Solution Overview
Problem
Current suspension thermal spraying technologies face challenges with the handling and safety of alcohol- and water-based formulations, which are either flammable or require high-energy input for evaporation, limiting their suitability for producing columnar thermal barrier coatings.
Innovation Solution
A suspension formulation with solid ceramic particles and an organic solvent having a flashpoint of at least 60°C, low viscosity, and a concentration range of 5 wt% to 95 wt%, allowing for safe handling and production of columnar microstructure coatings without the need for further dilution or modifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low-molecular-weight alcohols (ethanol, isopropanol) are used as solvents, then the suspension has low viscosity and low surface tension enabling easy atomization and fine spray particles, but the solvent is highly flammable and explosive requiring restrictions on transportation, storage and handling
Solution Approach 1:
The patent changes the flashpoint parameter of the solvent from below 60°C (flammable alcohols) to at least 60°C (less flammable solvents). This is achieved by selecting solvents with higher flashpoints such as C6-C15 monoalcohols, glycols, glycol ethers, or hydrocarbons, thereby reducing fire hazards while maintaining suspension performance
Solution Approach 2:
The patent replaces hazardous flammable solvents with less hazardous alternatives that have similar or better performance characteristics. The new solvents provide the same atomization benefits without the safety restrictions, effectively substituting a dangerous material with a safer one
2Object-affected harmful factors
If water is used as solvent, then the suspension has no specific safety regulations for handling, but water requires high-energy input for evaporation and provides no additional energy to the spray process
Solution Approach 1:
The patent changes the evaporation energy parameter by selecting organic solvents with lower evaporation energies than water. Solvents like C6-C15 monoalcohols, glycols, and glycol ethers have lower latent heats of vaporization than water, reducing the energy input required for evaporation while maintaining safe handling characteristics
Solution Approach 2:
The patent creates a composite solvent system that combines the safety benefits of water-based suspensions with the energy benefits of organic solvents. By selecting organic solvents with flashpoints of at least 60°C, the suspension achieves both safe handling and reduced evaporation energy requirements
3Manufacturing precision
If small suspension droplet size is achieved through low viscosity and surface tension, then small depositing particles are formed resulting in columnar microstructure coatings, but the solvent becomes highly flammable
Solution Approach 1:
The patent changes the flashpoint parameter to at least 60°C while maintaining the viscosity and surface tension parameters necessary for small droplet formation. This is achieved by selecting specific organic solvents (C6-C15 monoalcohols, glycols, glycol ethers, hydrocarbons) that have appropriate rheological properties combined with high flashpoints
Solution Approach 2:
The patent replaces flammable solvents with less flammable alternatives that provide the same droplet size control capabilities. The new solvents enable fine atomization and small depositing particle formation without the fire hazards that would restrict their use
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 solution enables the production of thermal barrier coatings with a columnar microstructure, ensuring safe handling and processing while achieving the desired coating properties, as demonstrated by SEM images showing effective coating formation.
Implementation Method 1
said suspension has a flashpoint of at least 60° C.
Implementation Method 2
said suspension has a viscosity of below 20 mPa*s
Implementation Method 3
the liquid vaporizes while the original solid particles agglomerate and thereby increase in size. The spray particles melt in the hot plasma gas
Implementation Method 4
The spray particles melt in the hot plasma gas or flame
Implementation Method 5
the spray particles are flattened into so called splats, cool down, solidify and form the thermally sprayed coating
Data Source
AI summary
The present invention relates to a suspension for suspension thermal spraying, comprisinga. solid ceramic particles having an average particle size of 2 μm or below, wherein the average particle size refers to the d50 value determined from the volume based particle size distribution measured with laser diffraction particle analysis method; andb. a liquid phase comprising an organic solvent,characterized in that said suspension has a flashpoint of at least 60° C., preferably at least 65° C., and at most 400° C., preferably at most 300° C., determined with the Pensky-Martens closed cup device according to the DIN EN ISO 2719,wherein said suspension has a viscosity of below 20 mPa*s, as measured according to the specification,and wherein the concentration of said solid ceramic particles in said suspension ranges from 5 wt % to 95 wt %.