Fig. 1 shows the SEM micrographs of the indentation morphologies of the two composite coatings. By comparing the indentation of the two coatings, it was found that the diagonal indentation length of the coating obtained by the Ti-SiC(ht) powders was smaller than that of the Ti-SiC coating, which also proved that the hardness of the Ti-SiC(ht) coating was higher than that of the Ti-SiC coating. It was can be seen from Fig. 1a that the indentation of the Ti-SiC coating had obvious fragment and warpage phenomenon, which was related to the large number of holes in the Ti-SiC coating. When the coating was under pressure, the existence of holes or holes were easy to induce crack growth, which made the coating prone to collapse, breakage and warping. From Fig. 1b, it was found that the indentation profile of the Ti-SiC(ht) coating was clear without obvious breakage and warpage, but there was a relatively tortuous crack on the left side of the indentation. The more tortuous the crack growth path is, the more energy is consumed by the crack growth, so the toughness of the coating is higher. Comprehensive comparison shows that the toughness of Ti-SiC(ht) coating was better than that of Ti-SiC coating.
Fig. 1. SEM micrographs of the indentation impressions of the two coatings: (a) Ti-SiC and (b) Ti-SiC(ht).
In order to explore the wear resistance of the two coatings, the wear profile, wear rate and wear scar morphology of the two coatings were compared and analyzed. Fig.2 shows a comparison of the wear profiles of the two composite coatings. As can be seen from Fig. 2, the wear depth of Ti-SiC(ht) coating was less than that of Ti-SiC coating.
The wear rate can directly reflect the wear degree of the coating. The higher the wear rate is, the more weightless the coating is in the sliding wear test, so the worse the wear resistance is. Fig. 3 shows the comparison of wear rate of the two composite coatings. It can be seen from Fig. 3 that the wear rate of the coating obtained by plasma spraying Ti-SiC(ht) composite powders was reduced by 48.6% compared with the Ti-SiC coating. The wear resistance of the coating is related to the density, hardness and toughness of the coating. The coating obtained by plasma spraying Ti-SiC(ht) composite powders had higher density, hardness and toughness, so the wear resistance of Ti-SiC(ht) coating was better than that of Ti-SiC coating.
Fig. 2. Wear surface profile of two system composite coatings.
Fig. 3. Sliding wear rate of two system composite coatings.
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