Abstract
In this article, a CrCoNbB thin film metallic glass (TFMG) is fabricated by DC power magnetron sputtering. Its microstructure, surface properties, mechanical properties and thermal stability are characterized. Results are compared with sputter-deposited chromium (Cr) coating which is an industrial popular choice of hard coating by physical vapor deposition (PVD). We obtained a fully amorphous Cr48Co31Nb7B14 TFMG with glass transition (Tg) and crystallization (Tx) temperatures at 530 ? and 615 ?, respectively. Nanoindentation revealed that Cr(48)Co(31)Nb(7)B(14)TFMG has significantly lower surface roughness and higher hardness than Cr. Also, in nano scratch test with normal load applied between 0.5 mN ~ 9 mN, Cr48Co31Nb7B14 TFMG has a lower coefficient of friction (CoF) than Cr. Annealing the TFMG above Tg at 550 C for 60 min showed no sign of crystallization, implying excellent thermal stability. Contact angle analysis also revealed that the TFMG has very low surface free energy (SFE), specifically a low polar component. We also discovered that spreading of molten low-density polyethylene (LDPE) on Cr48Co31Nb7B14 TFMG is weaker than on Cr film as a consequence of its low SFE. In summary, Cr48Co31Nb7B14 TFMG has advantages such as high hardness and thermal stability, low roughness, friction and surface energy compared to PVD Cr coating. Low adhesion to molten LDPE also suggests its potential in applications such as injection mold coating where lower friction and higher wear resistance is preferred.
NSTL
Elsevier