Coupling powder bed additive manufacturing and vapor phase deposition methods for elaboration of coated 3D Ti-6Al-4V architectures with enhanced surface properties

Abstract

We propose an innovative process coupling powder bed additive manufacturing by Electron Beam Melting (EBM) with Chemical Vapor Deposition (CVD) and Atomic Layer Deposition (ALD) to develop 3D Ti-6Al-4V structures covered with AlN coating. Despite of the high reactivity of Ti-6Al-4V with nitrogen, thick ( 10 µm) and conformal AlN films are deposited by CVD on Ti-6Al-4V substrates with high surface roughness. An AlN under-layer deposited by ALD is necessary to mitigate the reaction between Ti-6Al-4V and the nitrogen precursor NH 3(g) and to limit the formation of brittle titanium nitride phases. We have thus achieved an adherent coating without any modification of the Ti-6Al-4V microstructure at the core of the substrate. We show that a 7 µm thick AlN coating is efficient in protecting Ti-6Al-4V against cyclic oxidation at 650°C for at least 650 h. This study opens new opportunities for the design of coated 3D Ti-6Al-4V structures for use in high temperature oxidizing environments.

Metallic Coatings through Additive Manufacturing: A Review

“…However, larger-sized products can be manufactured easily through this process irrespective of the substrate plate’s size. In a recent study, AlN coatings were produced over Ti6Al4V substrate through EB-PBF technology [ 149 ]. The authors achieved an adherent coating on the substrate without altering the core’s microstructure.…”

Nanometric 3D Printing of Functional Materials by Atomic Layer Deposition

“…Moll et al also coupled powder bed additive manufacturing with CVD and ALD of nitrides, to prepare 3D Ti-6Al-4 V structures highly resistant to hightemperature oxidizing environments. Coupling CVD and ALD on the 3D printed objects permitted to obtain thick coating and roughness reduction by CVD, and filling of narrow defects and reactivity mitigation by ALD [72].…”