tribofilm on ferrous material surface under RT sliding. This is shown in Figure 6-7(c) by the absence of the elements of the ZDDP Zn, S and P respectively on the wear surface. – The abrasive lines on the wear surface on the flat sample lubricated with rapeseed oil and the NPs is evidence of abrasive wear action of the NPs on the contact as shown in Figure 6-7(b). But the wear track of the flat sample lubricated with rapeseed oil, ZDDP and the NPs mixture has the evidence of formation of the tribofilms made of both the NPs Si and O, as well as – the ZDDP Zn, S, and P. This agrees with observations of similar synergy between ZDDP – and NPs additives [, , ]. Figure 67: Wear surface morphology and chemistry for tests at RT with the lubricants: (a) Rapeseed oil only (b) Rapeseed oil with the NPs additives, (c) Rapeseed oil with ZDDP and (d) Rapeseed oil with both ZDDP and the NPs additives. The wear surface lubricated with mineral oil and the NPs additives has the elements, Si and O from the NPs present on the wear surface along with the elements, P, S and Zn from the ZDDP usually present in fully formulated engine lubricant, SAE 15W40. This is shown in Figure (b). The surface lubricated with mineral oil only has the elements, P, S, and Zn from the ZDDP as shown in Figure 6-8 (a). Figure 68: Wear surface morphology and chemistry for tests at RT with the lubricants: (a) Mineral oil, (b) Mineral oil and the NPs additives.
tribofilm on ferrous material surface under RT sliding. This is shown in Figure 6-7(c) by the absence of the elements of the ZDDP – Zn, S and P respectively on the wear surface. The abrasive lines on the wear surface on the flat sample lubricated with rapeseed oil and the NPs is evidence of abrasive wear action of the NPs on the contact as shown in Figure 6-7(b). But the wear track of the flat sample lubricated with rapeseed oil, ZDDP and the NPs mixture has the evidence of formation of the tribofilms made of both the NPs – Si and O, as well as the ZDDP – Zn, S, and P. This agrees with observations of similar synergy between ZDDP and NPs additives [, , ]. Figure 67: Wear surface morphology and chemistry for tests at RT with the lubricants: (a) Rapeseed oil only (b) Rapeseed oil with the NPs additives, (c) Rapeseed oil with ZDDP and (d) Rapeseed oil with both ZDDP and the NPs additives. The wear surface lubricated with mineral oil and the NPs additives has the elements, Si and O from the NPs present on the wear surface along with the elements, P, S and Zn from the ZDDP usually present in fully formulated engine lubricant, SAE 15W40. This is shown in Figure (b). The surface lubricated with mineral oil only has the elements, P, S, and Zn from the ZDDP as shown in Figure 6-8 (a). Figure 68: Wear surface morphology and chemistry for tests at RT with the lubricants: (a) Mineral oil, (b) Mineral oil and the NPs additives.