Acktar Fractal BlackTM as a Dual-Function Thermal-Optical Control Coating and Structural Primer-compressed

The article evaluates Acktar’s Fractal Black, an ultra black vacuum-deposited black coating designed for dual functionality in advanced space applications. The main goal is to conclude the functionality of the Fractal Black as a stray light control coating on titanium-zirconium-molybdenum (TZN) substrates. Furthermore, evaluation of its potential as a foundation for structural bonding.

Fractal Black exhibits the darkest black appearance by achieving high absorptivity (≈0.98) and emissivity (≈0.90) across a wide spectrum. These properties are crucial for minimizing stray light and enhancing the precision of IR astronomical observations. Moreover, Acktar’s black coated surfaces maintain superior adhesion compared to conventional spray coatings, especially on complex geometries with micron-level tolerances.

The study subjected Fractal Black to various standard aerospace qualification tests. For instance, thermal shock and adhesion cycles were performed and a cleanability test was completed according to the classic cleaning methods. More tests that examined the thermal optical properties of the coating were performed as well.

Moreover, Fractal Black was tested as a structural primer, bonding TZM substrates with aerospace-standard adhesives. The coated samples demonstrated shear strength comparable to conventional primers, while offering the additional advantage of stray light suppression. Although some variance was noted in failure modes, performance remained within acceptable industry standards.

The results demonstrated excellent performance as a thermal optical coating and a structural primer, as desired, while at the same time, confirming its resilience under extreme conditions. The Fractal Black exhibited high emissivity and strong adhesion under thermal shock. In addition, the cleanability tests had a bigger influence on the emissivity. However, the post-inspections haven’t caused damage to the surface.

Acktar’s super black material explicates the manufacturing processes for the space industry by reducing the need for separate coatings and primers. By combining thermal management and optical performance into a single black coating, Acktar’s darkest black technology represents a significant advancement for future space missions demanding high-performance surfaces.

N. Hatcher, M. Hwang, and R. Blank, “Acktar Fractal Black™ as a Dual-Function Thermal-Optical Control Coating and Structural Primer,” in Proc. IEEE Aerospace Conf., 2024, pp. 1–7.