Multilayer CVD Diamond Coatings in the Machining of an Al6061-15 Vol % Al2O3 Composite

abstract

Ceramic cutting inserts coated with ten-fold alternating micro- and nanocrystalline diamond (MCD/NCD) layers grown by hot filament chemical vapor deposition (CVD) were tested in the machining of an Al based metallic matrix composite (MMC) containing 15 vol % Al2O3 particles. Inserts with total coating thicknesses of approximately 12 mu m and 24 mu m were produced and used in turning: cutting speed (v) of 250 to 1000 m.min-1; depth of cut (DOC) from 0.5 to 3 mm and feed (f) between 0.1 and 0.4 mm.rev-1. The main cutting force increases linearly with DOC (ca. 294 N per mm) and with feed (ca. 640 N per mm.rev-1). The thicker coatings work within the following limits: DOC up to 1.5 mm and maximum speeds of 750 m.min-1 for feeds up to 0.4 mm.rev-1. Flank wear is predominant but crater wear is also observed due to the negative tool normal rake. Layer-by-layer wear of the tool rake, and not total delamination from the substrate, evidenced one of the advantages of using a multilayer design. The MCD/NCD multilayer diamond coated indexable inserts have longer tool life than most CVD diamond systems and behave as well as most polycrystalline diamond (PCD) tools.

keywords

METAL-MATRIX COMPOSITES; CARBIDE REINFORCED ALUMINUM; COATED CUTTING TOOLS; FATIGUE-STRENGTH; PERFORMANCE; MACHINABILITY; WEAR; HARDMETAL; ADHESION; INSERTS

subject category

Materials Science

authors

Shabani, M; Sacramento, J; Oliveira, FJ; Silva, RF

our authors

acknowledgements

Leichtmetall Kompetenzzentrum Ranshofen (LKR, Braunau am Inn, Austria) of the Austrian Institute of Technology is acknowledged for gently ceding the workpiece cylinder. Financial support for the conduct of the research was given by project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.

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