Influence of Copper Frictional Material Composition on Structure and Tribotechnical Properties

2019 ◽  
Vol 40 (6) ◽  
pp. 495-500
Author(s):  
A. V. Leshok ◽  
L. N. Dyachkova ◽  
A. F. Ilyushchenko ◽  
A. N. Rogovoy ◽  
N. A. Alekseenko
2020 ◽  
Vol 4 (141) ◽  
pp. 157-163
Author(s):  
IL’YA ROMANOV ◽  
◽  
ROMAN ZADOROZHNIY

When applying coatings using various methods on the surfaces of moving parts that work in joints, it is important to make sure that the coatings are strong and wear-resistant in order to return them to their original resource. All existing hardening technologies and materials used to perform coatings have their own characteristics, therefore, the quality of the resulting coatings can be judged only after specific tests. (Research purpose) The research purpose is in evaluating the properties of the coating obtained by the method of electric spark hardening, and its ability to resist friction and mechanical wear. (Materials and methods) Authors conducted tests on the basis of the "Nano-Center" center for collective use. A coating was applied on the BIG-4M unit with a VK-8 hard alloy electrode, tribological properties were evaluated on a CSM Instruments TRB-S-DE-0000 tribometer, the width of the friction track was measured after the test using an inverted OLYMPUS gx51 optical microscope, and samples were weighed before and after the test on a VLR-200 analytical balance. Conducted research in accordance with GOST 23.224-86 and RD 50-662-88 guidelines. (Results and discussion) The article presents performed tests on the run-in and wear resistance of the coating. The samples were worked on with a step-by-step increase in the load. During the tests, the friction force was drawed on the diagram. Authors compared the results with the reference sample, an uncoated surface. (Conclusions) The resulting coating has better run-in and wear resistance compared to the standard, and the increase in wear resistance in dry friction conditions is very significant.


2020 ◽  
Vol 54 (2) ◽  
pp. 215-233
Author(s):  
Ayham Dalal

AbstractLiterature in Human Geography has given much attention to “encounters” and their impact on negotiating difference in everyday life. These studies, however, have focused solely on cities, while “other” spaces like refugee camps have received little attention to date. In this paper, I highlight the significance of “encounters” in camps by exposing three main types: the “refugee-refugee,” the “refugee-humanitarian,” and the “refugee-more-than-human” encounters. Using empirical examples from Zaatari camp in Jordan, I show that the “refugee-refugee” encounters cannot be fully understood without taking refugees’ culture, background, and urban identities into consideration. I also explain how the “refugee-humanitarian” encounters result in new types of behaviors and might harden the boundaries between both groups. And lastly, I demonstrate how the “refugee-more-than-human” encounters can inform us about refugees’ unique experiences with shelters, space, and materiality. Building on the examples given for each type, this article suggests that “encounters” have the ability to generate knowledge and learnings, which contributes to shaping the space of the camp by either enforcing boundaries between different groups and/or by allowing new and hybrid spatialities to emerge. This not only confirms that “encounters” are an important entry point in understanding the socio-spatial and material composition of refugee camps, but also that further studies in this regard are direly needed. It also suggests that architects and planners need to allow for the “new” to emerge as a result of these encounters and, therefore, to enable flexibility and adaptability within camps’ design and planning.


2020 ◽  
Vol 38 (6) ◽  
pp. 1138-1156
Author(s):  
Derek S Denman

Images of police armored vehicles in Ferguson and Baltimore have been influential in a public conversation about the militarization of the police. However, recent critical and abolitionist work on policing rejects the concept of “militarization” for obscuring the longstanding histories and institutional connections between military and police apparatuses. By following the transfers of armored vehicles to police, this article illuminates the logistical pathways that connect colonial warfare and domestic policing, adding an account of the material composition of police power to the historical work of critical and abolitionist thinkers. The article proceeds through a critical reading of records of the Defense Logistics Agency, tracking the transfer of surplus armored vehicles to the police. Designated as “high-visibility property” by the Defense Logistics Agency, these vehicles testify to the materiality of police power. The article then tracks the visibility and materiality of these vehicles as they are deployed in urban and suburban spaces and considers their unique capacity to suppress the democratic energies of crowds. Tracking the armored vehicle provides a way to ask how the rigid lines of fortified urban space are organized into mobile vectors and where ongoing processes of colonization enter these spatial processes.


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