On the mechanism of the synergistic effect of PTFE and copper in a lithium grease lubricant Stanisław Krawiec Article information:To cite this document: Stanisław Krawiec, (2011),"On the mechanism of the synergistic effect of PTFE and copper in a lithium grease lubricant", If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to find a reason of a very high lubrication effectivity of a lithium grease filled with PTFE and copper powders when used as a lubricant between contacting steel surfaces under mixed friction conditions. Design/methodology/approach -The paper presents the results of the differential thermal analysis (DTA) of a lithium grease lubricant filled with 6 wt% PTFE and 6 wt% Cu and of a 1:1 mass mixture of PTFE and copper powders alone. The chemical composition analysis of post-DTA residual substances was carried out using the x-ray microanalysis. The same method was employed for the examination of the chemical composition of the posttest friction area in the balls of a four-ball apparatus. The balls were lubricated with three greases: without any fillers (the base 1S lithium grease), with one filler (6 wt% Cu), and with two fillers (6 wt% PTFE and 6 wt% Cu). For the latter compound, the load was 500 daN, for the remaining compositions, the load was 126 daN. Findings -The results of the analyses done confirmed a thesis that the synergism of PTFE and Cu in the tested grease under mixed friction conditions is possible due to the thermal decomposition of PTFE and creation -as a result of a reaction of this decomposition products with an earlier formed platering layer -of new layers that are (to a high probability) complexes containing copper, fluorine, and sulphur. Practical implications -PTFE and copper powders when used as fillers for a lithium grease form a very effective lubrication compound for steel sliding pairs. The application of this compound results in an overall reduction of friction and wear that is greater than a simple summation of gains obtained when using these two additives separately. Originality/value -It was proved that a dominant factor contributing to the synergistic effect of PTFE and copper in a lithium grease when used for the lubrication of steel surfaces ...

Summary. The programing documents of the European Union determine the direction of transport systems development, including large cities and agglomerations. The context of these actions which aim to transform into ecologically clean and sustainable transport system is a significant reduction of greenhouse gas emissions. Assuming that public transport will significantly reduce the use of combustion-powered buses, studies on urban logistic enabling the use of electric buses for public transport are needed. The article presents the variants and scenarios for electric buses implementation in urban public transport, as well as the decision algorithm to support electric bus implementation based on technological, organisational, economic and ecological variables. TRANSPORT PUBLICZNY W AGLOMERACJACH Z WYKORZYSTANIEM AUTOBUSU ELEKTRYCZNEGO -TENDENCJE ROZWOJUStreszczenie. Dokumenty programowe Unii Europejskiej wytyczają kierunki rozwoju systemu transportowego także w dużych miastach i aglomeracjach. Kontekstem tych działań, mających na celu przemianę systemu transportowego w transport ekologiczny i zrównoważony, jest znaczące ograniczanie emisji gazów cieplarnianych. Zakładając, że w transporcie publicznym nastąpi znaczne ograniczenie wykorzystania autobusów z napędem spalinowym, niezbędne są badania nad logistyką miejską, umożliwiające wykorzystanie autobusów elektrycznych do transportu publicznego. W artykule przedstawiono warianty i scenariusze wdrażania autobusów elektrycznych w publicznym transporcie zbiorowym oraz zaprezentowano algorytm wsparcia decyzji na podstawie zmiennych technicznych, organizacyjnych, ekonomicznych i ekologicznych.

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