| Texto completo | |
| Autor(es): |
Kolawole, Funsho Olaitan
;
Kolawole, Shola Kolade
;
Fukumasu, Newton Kiyoshi
;
Varela, Luis Bernardo
;
Vencovsky, Paulo Konrad
;
Ludewigs, Danilo Assad
;
de Souza, Roberto Martins
;
Tschiptschin, Andre Paulo
Número total de Autores: 8
|
| Tipo de documento: | Artigo Científico |
| Fonte: | COATINGS; v. 14, n. 9, p. 19-pg., 2024-09-01. |
| Resumo | |
This study investigates the impact of temperature on the tribological performance of duplex layer CrN/DLC and nano-multilayers DLC-W coatings deposited using hybrid PVD-PECVD techniques on carburized and hardened 16MnCr5 discs cut from internal combustion engines valve tappets. Reciprocating dry sliding experiments were conducted at 25 degrees C, 150 degrees C, 200 degrees C, and 250 degrees C to analyze the high-temperature tribological behavior of the coatings. The wear mechanisms were characterized using SEM, EDS mapping, Raman spectroscopy, and nanoindentation. The lowest coefficient of friction was obtained for CrN/DLC at 25 degrees C. The CrN/DLC coefficients of friction (COF) increase with temperatures due to increasing adhesive wear. Similarly, DLC-W exhibited a comparable trend with increasing temperature from 25 degrees C to 250 degrees C. Both coatings' wear resistance decreased with higher temperatures due to the transformation of sp3 C bonds to sp2 C bonds, facilitating the plastic deformation of the coatings and afterward of the substrate. The CrN/DLC displayed superior wear resistance to the DLC-W coating across all temperatures. The DLC-W multilayer coating showed poor wear resistance above 150 degrees C, being completely removed during the testing. Compared to both coatings, the uncoated 16MnCr5 discs exhibited higher coefficients of friction and wear rates at all temperatures. Predominant wear mechanisms observed in the coated discs were adhesive and abrasive. The study revealed a decrease in the coatings' structural and mechanical properties with rising temperatures. Hard abrasive WC particles were identified as contributing to increased wear rates in the multilayer DLC-W coatings. (AU) | |
| Processo FAPESP: | 19/18572-7 - Novos materiais de carbono: suas aplicações espaciais, ambientais e spin offs relevantes |
| Beneficiário: | Evaldo Jose Corat |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |