Three series of ternary alloys of the {M-30Cr-xC}-type with M = Co, Ni or Fe and x ranging from 2.5 to 5 wt% were elaborated by casting. Their microstructure characterizations by XRD and SEM show that very high volume...Three series of ternary alloys of the {M-30Cr-xC}-type with M = Co, Ni or Fe and x ranging from 2.5 to 5 wt% were elaborated by casting. Their microstructure characterizations by XRD and SEM show that very high volume fractions in chromium carbides (even more than 50%) may be obtained in a metallic matrix by this way. However graphite may also appear in very low quantities in the carbon-richest alloys. The hardness increases with the carbon content (up to 1000 Hv30kg) but it may be a little lowered when graphite is also present. The results show that very hard alloys may be simply obtained by casting of rather cheap elements.展开更多
Using Ni/Cr/graphite powder blends as raw powders,a Ni matrix composite coating reinforced by in-situ carbide,was fabricated on the surface of Q235 by means of laser cladding. These microstructure and properties were ...Using Ni/Cr/graphite powder blends as raw powders,a Ni matrix composite coating reinforced by in-situ carbide,was fabricated on the surface of Q235 by means of laser cladding. These microstructure and properties were discussed. The result of phase analysis( XRD) and microstructure investigation( SEM) showed that the coatings consist mainly of Cr_3 C_2,Cr_7 C_3 and γ-( Ni,Cr),which are consistent with the thermodynamic calculations. The wear morphology of the coatings was also examined. The results of dry sliding wear tests of different Cr/C ratio show that the wear resistances of the Cr_3 C_2-reinforced coating,respectively,are 13. 4,9. 5,9. 1 and 6. 5 times higher than that of the substrate and the main wear mechanisms of the coatings are adhesion and abrasive wear with slight oxidation.展开更多
文摘Three series of ternary alloys of the {M-30Cr-xC}-type with M = Co, Ni or Fe and x ranging from 2.5 to 5 wt% were elaborated by casting. Their microstructure characterizations by XRD and SEM show that very high volume fractions in chromium carbides (even more than 50%) may be obtained in a metallic matrix by this way. However graphite may also appear in very low quantities in the carbon-richest alloys. The hardness increases with the carbon content (up to 1000 Hv30kg) but it may be a little lowered when graphite is also present. The results show that very hard alloys may be simply obtained by casting of rather cheap elements.
基金supported by National High Technology Research and Development Program of China(863 Program)(2015AA034404)Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents(2013RCJJ004)Distinguished Taishan Scholars in Climbing Plan(tspd20161006)
文摘Using Ni/Cr/graphite powder blends as raw powders,a Ni matrix composite coating reinforced by in-situ carbide,was fabricated on the surface of Q235 by means of laser cladding. These microstructure and properties were discussed. The result of phase analysis( XRD) and microstructure investigation( SEM) showed that the coatings consist mainly of Cr_3 C_2,Cr_7 C_3 and γ-( Ni,Cr),which are consistent with the thermodynamic calculations. The wear morphology of the coatings was also examined. The results of dry sliding wear tests of different Cr/C ratio show that the wear resistances of the Cr_3 C_2-reinforced coating,respectively,are 13. 4,9. 5,9. 1 and 6. 5 times higher than that of the substrate and the main wear mechanisms of the coatings are adhesion and abrasive wear with slight oxidation.
