Pyrolytic Spray Coating Suspension Particle Size Control
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Solution Overview
Problem
The existing pyrolytic spray coating process using aqueous suspensions of metal acetylacetonates results in optically thin coating films with limited durability due to uneven crystal size distribution and melting point variations among the precursors, leading to incomplete melting and disrupted crystal growth.
Innovation Solution
A method is developed to create a pyrolytic coating suspension by determining the melting temperatures and particle size distributions of metal acetylacetonates, with the precursor having the lowest melting temperature as the base and others adjusted by a particle size factor less than 1, ensuring uniform particle sizes in the suspension to improve crystallinity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If metal acetylacetonates with different melting points are used as precursors, then the coating can be formed with multiple metal components, but the crystal growth is disrupted due to uneven melting and particle size distribution
Solution Approach 1:
The patent applies local quality by adjusting the particle size of each metal acetylacetonate precursor individually based on its specific melting point. Precursors with higher melting points are reduced to smaller particle sizes, while those with lower melting points maintain larger particle sizes. This localized adjustment ensures that all precursors melt uniformly during pyrolysis despite their different intrinsic melting points, resolving the crystal growth disruption issue while maintaining multi-metal coating capability.
Solution Approach 2:
The patent changes the physical parameter of particle size for different precursors systematically. By establishing a relationship between melting point and optimal particle size, the invention transforms the uniform particle size approach into a differentiated particle size distribution approach. This parameter change enables synchronized melting of multiple precursors with different melting points, thereby achieving uniform crystal growth in the final coating.
2Ease of manufacture
If uniform particle size is maintained for all metal acetylacetonates, then the suspension is easier to prepare, but the coating durability is reduced due to incomplete melting of high melting point precursors
Solution Approach 1:
The patent changes the particle size parameter from a uniform value to a differentiated value based on the melting point of each precursor. This parameter change ensures that all precursors, regardless of their melting point, achieve complete and uniform melting during the pyrolytic coating process. The result is improved coating durability through complete precursor decomposition and uniform crystal formation, while the suspension remains relatively easy to prepare using standard milling techniques.
3Quantity of substance
If high melting point metal acetylacetonates are used, then the coating achieves desired metal composition, but the crystal structure is compromised due to incomplete melting
Solution Approach 1:
The patent applies local quality by tailoring the particle size of each metal acetylacetonate precursor to its specific melting point characteristics. High melting point precursors are milled to smaller particle sizes, while low melting point precursors are kept at larger sizes. This localized optimization ensures that during pyrolysis, all precursors melt completely and uniformly, enabling the formation of a coherent crystal structure that incorporates all metal components in the desired proportions without structural defects from incomplete melting.
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 improved suspension achieves a more uniform crystal structure with smaller crystal sizes, enhancing the density and durability of the coating films, and increasing resistance to foreign substance migration, thereby extending the coating's lifespan.
Implementation Method 1
The heat from the glass substrate decomposes the organometallic precursors
Implementation Method 2
the metals from the precursors oxidize and bond to the surface of the substrate
Implementation Method 3
the aqueous suspension is passed through the nozzles of a coating apparatus, e.g. of the type disclosed in U.S. Pat. No. 4,111,150, to apply or deposit one or more optically thin coating films on the surface of a glass substrate
Data Source
AI summary
The durability of a transparent pyrolytic spray applied coating is improved by providing a spray solution of metal acetylacetonates having different particle size distribution. More particularly, the particle size distribution of each of the metal acetylacetonates is a function of its melting temperature, and optionally of its melting temperature and solubility.