کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
618790 | 1455033 | 2010 | 11 صفحه PDF | دانلود رایگان |
In this paper, we investigate the failure mechanism under scratch testing of glass samples coated with an Si3N4 monolayer deposited by magnetron sputtering. We demonstrate that applying a thin Si3N4 layer considerably compromises the effective glass strength. Contact and fracture mechanics conspire to produce this result when a stiff and well adherent film is deposited on a more compliant substrate. Three major phenomena have been identified: (i) the Si3N4 layer generates a high friction coefficient which enhances the tensile stress at the trailing edge of the contact zone, (ii) the stiff film enhances the in-plane tensile stress due to elastic mismatch and (iii) when a through-thickness crack hits the interface, the elastic mismatch provides a strong driving force for the crack to cross the interface and penetrate into the glass substrate. A specific type of damage, where a hierarchy of cracks is observed in the trail of the indenter instead of the more usual homogeneous series of so-called Hertzian cracks, is also discussed.
Journal: Wear - Volume 269, Issues 5–6, 19 July 2010, Pages 351–361