Extending the applicability of the four-flux radiative transfer method

Area of Science:

• Materials Science
• Optics
• Chemical Engineering

Background:

• Complex composite coatings require accurate modeling for spectral reflectance tuning.
• Understanding the interplay of scatterers, binders, and multilayer structures is crucial for optimizing optical properties.

Purpose of the Study:

• To present a generalized four-flux method for modeling and tuning spectral reflectance of composite coatings.
• To explore maximizing visible and near-infrared (IR) spectral reflectance in paints by considering diverse ingredient structures.

Main Methods:

• Developed a generalized four-flux model incorporating scatterer properties (composition, size, fill factor) and binder absorption.
• Implemented an explicit matrix algorithm for analyzing multilayer stacks with depth-dependent pigment fill factors.
• Validated model accuracy against experimental data for dried single-layer paint profiles.

Main Results:

• The model accurately predicts spectral reflectance and absorptance, including contributions from scattering pigments and binders.
• Demonstrated the impact of varying pigment fill factor with depth on spectral properties.
• Showcased a novel consideration of how scattering affects matrix absorptance.

Conclusions:

• The generalized four-flux method provides a robust framework for designing and optimizing composite coatings for specific spectral reflectance targets.
• Accurate modeling of multilayer structures and ingredient interactions is key to achieving desired optical performance in paints.