The role of nanocrystalline binder metallic coating into WC after additive manufacturing

• Published in: Applied surface science Vol. 427; pp. 131 - 138
• Main Authors: Cavaleiro, A.J., Fernandes, C.M., Farinha, A.R., Gestel, C.V., Jhabvala, J., Boillat, E., Senos, A.M.R., Vieira, M.T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2018
• Subjects: Martensitic stainless steel; Nanocrystallinity; Selective laser sintering; Sputtering; Martensitic stainless steel; Selective laser sintering; WC; Nanocrystallinity; Sputtering
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2017.08.039

[Display omitted] •Surface modified micrometric WC powder by a nanocrystalline stainless steel coating was used for Selective Laser Sintering.•The power density plays an important role for the densification and stratification of the Stainless Steel binder.•It was possible to produce consolidated and semi-dense WC/SS composites using SLS of WC sputter-coated powders.•The composites presented original micrometric WC, submicrometric WC and M6C phases, bonded by the metallic binder. Tungsten carbide with microsized particle powders are commonly used embedded in a tough binder metal. The application of these composites is not limited to cutting tools, WC based material has been increasingly used in gaskets and other mechanical parts with complex geometries. Consequently, additive manufacturing processes as Selective Laser Sintering (SLS) might be the solution to overcome some of the manufacturing problems. However, the use of SLS leads to resolve the problems resulting from difference of physical properties between tungsten carbide and the metallic binder, such as laser absorbance and thermal conductivity. In this work, an original approach of powder surface modification was considered to prepare WC-metal composite powders and overcome these constraints, consisting on the sputter-coating of the WC particle surfaces with a nanocrystalline thin film of metallic binder material (stainless steel). The coating improves the thermal behavior and rheology of the WC particles and, at the same time, ensures a binder homogenous distribution. The feasibility of the SLS technology as manufacturing process for WC powder sputter-coated with 13wt% stainless steel AISI 304L was explored with different laser power and scanning speed parameters. The SLS layers were characterized regarding elemental distribution, phase composition and morphology, and the results are discussed emphasizing the role of the coating on the consolidation process.