RESUMO
The life of metal forming dies and the efficiency of tooling industries depends on the mechanical and wear properties of tool steel. These properties can be further improved by depositing the ceramic coating on heat-treated tool steel. Numerous coating materials with various excellent features are already available commercially; however, the selection of the best coating material is still an immense challenge for users. Compared to various studies related to material selection problems in the contrasting area of utilization, remarkably, little research work has been done in tooling industries. In the present work, we have identified eight coating materials (alternatives) and nine evaluation criteria under the consultation of an expert in the tooling application and tribological field. To deal with this coating material selection problem, an integrated fuzzy-multi attributed decision-making method is proposed which comprises best worst method and fuzzy-Measurement Alternatives and Ranking according to the Compromise Solution method. This integrated fuzzy- multi attributed decision-making method is used to evaluate the alternatives, and the obtained results were scrutinized via utilizing various sensitivity analysis procedures. In the first phase of analysis, seven scenarios of criteria weight change were used, which was derived by the best-worst method; dynamic matrices are used in the second phase of analysis. In the third and fourth phases, obtained ranks were compared with those obtained by different weight calculation methods and ranking methods, respectively. In the present study, AlCrN/TiAlN coating (alternative Cm5) was found to be the best coating material based on the results obtained after sensitivity analysis. Further, in this study, we have proposed a novel method that helps to solve the coating material selection problem or any kind of selection complications.
RESUMO
Ag-doped Cr/DLC coatings were deposited on medical grade 316 LVM stainless steel using DC magnetron sputtering. Morphological study of the coating indicated the formation of island of Ag clusters owing to the inability of Ag to form carbides, which is also corroborated from the XRD analysis. The composite coating showcased elastic nature suggestive from the p-h curve obtained from the nanoindentation test. However, the coating possesses 33% ductility, which is an important virtue for stress relieving attributed to Ag in the carbon matrix. The coating registered improved adhesion due to Cr3C2 carbide formation in the interlayer. The composite coating was subjected to lubricated sliding in physiological fluid against carbon fiber reinforced PEEK (CFRPEEK) friction pair to realize a closer scenario to hip implant articulation. A lubricious film of Ag with scattered particles of PEEK was formed in the sliding interface resulting in a long run-in process during sliding. The composite coating suffered mild wear on the Ag-doped DLC top layer with few gullies of wear scar deep into the interlayer due to graphitization of carbon in the film. A statistically significant difference was observed in the hardness, H3/E2, elastic work, and plastic work; however, there was no statistically significant difference in H/E attribute between the unworn and worn surface. What is more, Raman spectra of the worn (ID/IG = 1.9 ± 0.2) and unworn surface (ID/IG = 2.1 ± 0.1) were indicative of no significant loss in the structural integrity of the composite coating.
