Indentation-induced Cracking Research Articles

270. X-ray diffraction by multilayered thin film structures and their diffusion: J B Dinklage, J Appl Phys, 38 (9), 1967, 3781-3755

Coatings of boron carbide (B4C) and B4C–Molybdenum (Mo) were co-deposited using magnetron sputtering, both with and without bias-assist. Coatings were indented using a Rockwell C Brale indenter to enable a ranking of the relative coating–substrate interfacial toughness and cracking mode. It was observed that co-sputtered B4C–Mo coatings fabricated with a higher atomic percentage (at.%) of metal and with bias exhibited the smallest cracking diameters around the indent and a less-severe cracking mode (circumferential cracking). Reciprocating sliding wear tests were performed on the coatings using a tungsten carbide–cobalt (WC–Co) ball. As for the indentation test results, lowest wear factors were calculated for bias co-sputtered B4C and high at.% Mo coatings. In addition, very mild wear damage and only occasional wear debris were observed after the wear test of the best bias co-sputtered B4C–49 at.% Mo coating. Correlations between cracking diameters from indentation and calculated wear factors were made, with lower wear factors for coatings with smaller indentation-induced cracking (i.e. higher toughness). It was observed that the application of bias during sputtering had a more beneficial effect on tribological performance than the addition of Mo, but the synergistic effect of both processing variables resulted in coatings with the best overall performance.

275. Application of a quartz resonator for thin film thickness measurements: B T Bokyo et al, Zavodsk Lab, 33 (9), 1967, 1152–1153 ( in Russian)

Coatings of boron carbide (B4C) and B4C–Molybdenum (Mo) were co-deposited using magnetron sputtering, both with and without bias-assist. Coatings were indented using a Rockwell C Brale indenter to enable a ranking of the relative coating–substrate interfacial toughness and cracking mode. It was observed that co-sputtered B4C–Mo coatings fabricated with a higher atomic percentage (at.%) of metal and with bias exhibited the smallest cracking diameters around the indent and a less-severe cracking mode (circumferential cracking). Reciprocating sliding wear tests were performed on the coatings using a tungsten carbide–cobalt (WC–Co) ball. As for the indentation test results, lowest wear factors were calculated for bias co-sputtered B4C and high at.% Mo coatings. In addition, very mild wear damage and only occasional wear debris were observed after the wear test of the best bias co-sputtered B4C–49 at.% Mo coating. Correlations between cracking diameters from indentation and calculated wear factors were made, with lower wear factors for coatings with smaller indentation-induced cracking (i.e. higher toughness). It was observed that the application of bias during sputtering had a more beneficial effect on tribological performance than the addition of Mo, but the synergistic effect of both processing variables resulted in coatings with the best overall performance.

267. Hall effect in thin metal films: K L Chopra and S K Bahl, J Appl Phys, 39 (9), 1967, 3607–3610

Coatings of boron carbide (B4C) and B4C–Molybdenum (Mo) were co-deposited using magnetron sputtering, both with and without bias-assist. Coatings were indented using a Rockwell C Brale indenter to enable a ranking of the relative coating–substrate interfacial toughness and cracking mode. It was observed that co-sputtered B4C–Mo coatings fabricated with a higher atomic percentage (at.%) of metal and with bias exhibited the smallest cracking diameters around the indent and a less-severe cracking mode (circumferential cracking). Reciprocating sliding wear tests were performed on the coatings using a tungsten carbide–cobalt (WC–Co) ball. As for the indentation test results, lowest wear factors were calculated for bias co-sputtered B4C and high at.% Mo coatings. In addition, very mild wear damage and only occasional wear debris were observed after the wear test of the best bias co-sputtered B4C–49 at.% Mo coating. Correlations between cracking diameters from indentation and calculated wear factors were made, with lower wear factors for coatings with smaller indentation-induced cracking (i.e. higher toughness). It was observed that the application of bias during sputtering had a more beneficial effect on tribological performance than the addition of Mo, but the synergistic effect of both processing variables resulted in coatings with the best overall performance.