The Tribo-Mechanical Properties of Glass with a Thin Niobium Oxide Coating
(Room Exhibit Hall A)
30 Apr 19
2:30 PM
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4:00 PM
It is well known that fracture of glass can occur for loads well below the fracture stress in a humid ambient, and the reaction of water molecules with the silicon-oxygen bonds at the extreme of the surface micro-cracks has been extensively studied. However, there have been few studies concerning the effect of thin films on the fracture and wear resistance of glass. Here we report the increase of the fracture resistance, under conditions of high humidity, of niobium oxide coated glass as a function of the applied load. The fracture resistance was studied by measuring the time to fracture of coated and uncoated glass samples under four-point flexion tests. The wear resistance was measured using ball cratering as a function of the applied loads. The 200 nm thick niobium oxide coatings were deposited by DC magnetron sputtering with a niobium target in an Ar/O2 atmosphere, under optimal conditions to produce dense films with a high electrochemical corrosion resistance. The niobium oxide coated samples had a wear resistance of up to 70% less than the uncoated samples, even though the wear crater was deeper than the coating thickness, and an improved fracture resistance which decreased with increasing applied stress.