Improving Powder Characteristics by Surface Modification Using Atomic Layer Deposition

The particulate properties of a material after primary manufacturing have a large impact on the secondary manufacturing processes. Especially, powder characteristics leading to poor flowability are critical and need to be controlled at the late steps of primary operations. The surface properties of the primary particles are hereby one of the determining factors for the behavior of particulate systems. Materials with different particulate properties were coated using atomic layer deposition (ALD) to apply an ultrathin film of TiO2 on the primary particles. The presence of TiO2 coating was confirmed using X-ray photoelectron spectroscopy. Five TiO2 ALD layers on the particle surface were enough to quadruple the flowability of a partially crystalline material and to triple the flowability of an amorphous material. The coating process did not change the solid form of the materials and did not affect other critical characteristics related to the functionality of the materials. Altogether, the ALD coating of powders provides new possibilities as a scalable and potentially continuously operating process that can solve problems related to powder flowability during handling of bulk powders.