RESUMO
Sustainability deals with the impact of various processes and products on the economy, environment, and society. Due to the outburst of deadly coronavirus disease (COVID-19), sustainability which has three dimensions i.e., economy, environment, and social have been severely afflicted. Logistics has been stopped due to the spread of COVID-19 by which disruption in supply and demand takes place. This paper involves the study of the impact of COVID-19 on sustainability enablers. Also, the sub-attributes of sustainability enablers are studied and the performance index is calculated for pre and during COVID-19 with the help of the Graph-theoretic approach (GTA). With the help of the graph-theoretic approach (GTA), the inter-relationship between the sustainability enablers pre and during COVID-19 has been studied thereby quantitatively measuring the extent to which COVID-19 has an impact on sustainability enablers. The objective of this study is to identify a performance index by analyzing different sub-attributes of sustainability enablers. Also, digraphs are shown for the whole system and sub-systems representing inter-relationships and dependencies between various enablers and attributes to interpret the performance of the sustainability enablers before and during the time of COVID-19. This paper provides the impacts of COVID-19 on these three factors and provides the framework how to identify the performance index pre and during COVID-19.
RESUMO
The chromium nitride coating is a hard coating used to improve the sliding friction and wear behavior and is applied to engine components in various operating conditions even at an elevated temperature. In this study, chromium nitride was deposited by a physical vapor deposition process onto the cast iron substrate. All tribological tests were performed on linear reciprocating tribometer with a stroke length of 5 mm in a dry condition at variable temperature levels of 28 °C, 100 °C, 200 °C, and of 300 °C corresponding to loads of 10 N, 20 N, 30 N, and 40 N against the cylinder liner material. The worn surfaces of chromium nitride(CrN) coatings after friction tests were analyzed by scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS). The results showed that friction coefficients (COF) ranged from 0.93 to 0.34 from room temperature to 300 °C against the cylinder liner material as a counter-body of 6 mm in diameter; higher temperature results in the positive tribological performance of CrN, with at least 0.34 COF at 300 °C. The wear mechanisms of CrN and counter-body surfaces are abrasive wear accompanied by the slight oxidation. This study guides the wear behavior of cylinder liner coatings in an environment similar to the engine.
