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1

The influence of montmorillonite content on change the physicochemical properties of lubricating greases produced from vegetable base oil

Kozdrach Rafał

Nafta-Gaz

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2020

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R. 76, nr 4

270--278

EN

The publication presents the results of investigations into the influence of different amounts of a modifying additive on the physicochemical properties of selected lubricating compositions. Montmorillonite, as a representative of stratified silicates, was used to modify lubricating grease produced from a vegetable base oil, and lithium stearate was used to thicken it. Investigations of the physicochemical properties of the base lubricating grease were carried out and compared with the results obtained for lubricating greases containing the modifying additive. The selected parameters were penetration, penetration after prolonged kneading, dropping point, emission of oil from grease, anticorrosive properties by dynamic method, and mechanical stability – an attempt to roll out and oxidize the lubricant with a PetroOxy apparatus. Based on the results of physicochemical tests, it was determined that the applied modifying additive causes an increase in the dropping point, which limits the applicability of lubricating greases, as well as a decrease in oil emission, which was responsible for the lubricating effectiveness of the tested lubricants. It had a positive effect on mechanical stability and the tested lubricants were not disqualified from use in established applications, reducing the degree of corrosion on ball bearings working in the presence of the lubricating greases during testing. This had a positive effect on the condition of machines and devices where the lubricating greases are used and increased the oxidative stability when its content in the lubricating grease was at least 5%. This figure represents the upper limit of the modifying additive content in the lubricating greases.

PL

W publikacji przedstawiono wyniki badań wpływu różnej ilości dodatku modyfikującego na właściwości fizykochemiczne wybranych kompozycji smarowych. Do modyfikacji smaru plastycznego wytworzonego na bazie roślinnej i zagęszczonego stearynianem litu zastosowano montmorylonit, przedstawiciela krzemianów warstwowych. Wykonano badania właściwości fizykochemicznych smaru plastycznego bazowego oraz smarów plastycznych zawierających dodatek modyfikujący, a otrzymane wyniki porównano. Wyznaczono penetrację, penetrację po przedłużonym ugniataniu, temperaturę kroplenia, wydzielanie oleju ze smaru, właściwości przeciwkorozyjne uzyskane metodą dynamiczną, stabilność mechaniczną – próba wałkowania oraz utlenialność na aparacie PetroOxy. Na podstawie analizy otrzymanych wyników badań fizykochemicznych stwierdzono, że zastosowany dodatek modyfikujący powoduje wzrost temperatury kroplenia, która decyduje o granicy stosowalności wytworzonych smarów plastycznych oraz wpływa na spadek wydzielania oleju ze smaru, który świadczy o skuteczności smarowania elementów trących badanymi kompozycjami smarowymi. Dodatek wpływa korzystnie na stabilność mechaniczną, zmniejsza stopień skorodowania łożysk kulkowych pracujących w obecności badanych smarów plastycznych, co z kolei korzystnie oddziałuje na stan maszyn i urządzeń, w których smary te są stosowane, oraz zwiększa stabilność oksydacyjną, gdy zawartość dodatku w smarze wynosi co najmniej 5%.

2

Microstructure-Properties Relationship and Mechanical Stability of Retained Austenite in Thermomechanically Processed Medium-C TRIP Steel at Different Deformation Temperatures

Skowronek A., Kozłowska A., Grajcar A., Morawiec M.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

941--949

EN

The paper presents the effect of deformation temperature on the mechanical stability of retained austenite in a multiphase TRIP steel. Series of static tensile tests were carried out in the temperature range –20 to 140°C in order to simulate the temperatures occurring during stamping process of automotive steel sheets and conditions of their exploitation. Samples deformed at 20°C and 60°C showed the best combination of strength and ductility. It was related to the gradual transformation of retained austenite into martensite. Obtained results revealed that the intensity of TRIP effect is significantly related to the deformation temperature. The amount of retained austenite, which transformed into martensite during plastic deformation decreases as the deformation temperature increases. It was also found that the stability of retained austenite depends on its morphology. The obtained results showed the relationship between deformation temperature and the stability of retained austenite. The chemical composition and microstructure of multiphase steels dedicated to the automotive industry should be designed for providing the maximum TRIP effect at the specific deformation temperatures.

3

FP-(L)APW + lo study of mechanical stability and electronic behavior of CoGe in B20 structure

Timaoui M. A., Bouafia H., Sahli B., Hiadsi S., Abidri B., Bouaza A., Akriche A., Kerroum D.

Materials Science Poland

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2017

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Vol. 35, No. 3

548--559

EN

The aim of this work is a theoretical study of structural, elastic, electronic and thermal properties of CoGe compound in B20 structure using All-electron self-consistent Full Potential Augmented Plane Waves plus local orbital “FP(L)APW + lo” within the framework of Density Functional Theory DFT. GGA-PBEsol is the exchange-correlation potential selected in this work. This choice is motivated by the success of this functional in predicting structural and mechanical properties of solids. The values obtained by the study of structural properties are in very good agreement with those found previously. In this work, the elastic constants have been predicted for the first time and the obtained values confirm the mechanical stability of the CoGe compound in its B20 structure. The electronic part of this work shows that CoGe has metallic behavior with a mixed bonding between cobalt and germanium of covalent-metallic type. The effect of temperature and hydrostatic pressure on the lattice parameter - a0, heat capacity at constant volume - CV, thermal expansion coefficient - α and entropy - S of the CoGe have been studied using Debye model.

4

Warm stretch-formability of 0.2%C-1.5%Si-(1.5-5.0)%Mn TRIP-aided steels

Sugimoto K., Tanino H., Kobayashi J.

Archives of Materials Science and Engineering

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2016

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Vol. 80, nr 1

5--15

EN

Purpose: Warm stretch-formability of 0.2%C-1.5%Si-(1.5-5.0)%Mn transformation-induced plasticity (TRIP)-aided sheet steels with annealed martensite matrix was investigated for automotive applications. Additionally, the warm stretch-formability was related with the retained austenite characteristics. Design/methodology/approach: This study was aimed to enhance the stretchformability by warm forming which stabilizes mechanically a large amount of metastable retained austenite in the steels. Findings: The warm stretch-formability increased with an increase in Mn content. The stretch-formability of 5% Mn steel was improved by warm forming at peak temperatures of 150-300°C, which was the same level as that of 0.2%C-1.5%Si-1.5%Mn0.05%Nb TRIP-aided martensitic steel. The superior warm stretch-formability was caused by a large amount of mechanically stabilized retained austenite which suppresses considerably void initiation and growth at interface between matrix and transformed martensite. Higher peak temperatures for the stretch-formability than that for the total elongation was associated with high mean normal stress on stretch-forming. Research limitations/implications: The effect of warm forming on the stretchformability is smaller than that on the ductility. Practical implications: Investigation results can be easily applied to industrial technology. Originality/value: This paper presents an important result which the stretch-formability of 5% Mn TRIP-aided steel is mainly improved by stabilizing of retained austenite with low stacking fault energy. On the forming, only strain-induced α’-martensite transformation takes place and suppresses the void growth. The strain-induced bainite transformation never occurs during forming in 5% Mn steel, differing from conventional 1.5% Mn TRIP-aided steel.

5

Superwystrzymałe białko śrubuje rekord

Cieplak M

LAB Laboratoria, Aparatura, Badania

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2013

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R. 18, nr 3

18--19

6

Evaluation of the retained austenite mechanical stability in the mediumcarbon TRIP steel

Kokosza A.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 55, nr 2

323--330

EN

Purpose: The aim of this study was to evaluate the inclination to mechanical destabilization of retained austenite in the microstructure of the TRIP steel containing 0.4% C, 1.5% Mn and 1.2% Si. Design/methodology/approach: The new, simple method for evaluating the mechanical stability of retained austenite was proposed, which is based on the bending test and the measurement of volume fraction of retained austenite by X-ray quantitative phase analysis. The relationship between stress and local strain as well as local volume fraction of this phase in selected locations on the surface of the bending sample were revealed. Findings: The applied heat treatment, modified with respect to the classic one, allowed remain approximately 25 vol.% of the retained austenite in the microstructure of the investigated TRIP steel. It was pointed that retained austenite has high mechanical stability if stress is low. Under influence of the higher stress a partial destabilization this phase occurred. It was found that in the examined steel such mechanical destabilization of retained austenite has two - or three-stage nature. Research limitations/implications: Results of this study indicate a significant stability of retained austenite in the investigated TRIP steel. It is advisable to check how will change the stability of this phase when the stress or strain will be higher than those that occurred in this research. Practical implications: The new method of the evaluation of the retained austenite mechanical stability provides the possibility of an easy and effective estimation of this phase tendency to mechanical destabilisation and to martensite transformation in the steel. In addition, this method allows analysing the influence of the stress as well as the strain on changes in this phase volume fraction, which occur during three-point bending. Originality/value: The proposed method may be used for evaluation of susceptibility of retained austenite on transformation under load. Moreover, developed relationships between volume fraction of retained austenite-stress as well as volume fraction of retained austenite-strain, can be used for interpretation and analyze of mechanical properties changes of heat-treated steels.

7

Mechanical stability of retained austenite in unalloyed structural steels of various carbon content

Kokosza A., Pacyna J.

Archives of Metallurgy and Materials

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2010

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Vol. 55, iss. 4

1001-1006

EN

The results of investigations on the influence of stresses on the retained austenite volume fraction in a microstructure of two unalloyed structural steels are presented in the paper. The mechanical stability of retained austenite was estimated on the bases of these results. The relation between stress values, carbon content, retained austenite volume fraction and its stability was revealed. It was established that the retained austenite mechanical destabilization in both examined steels depended on the applied stresses and occured in two stages. The authors observed that retained austenite present in a microstructure of steel of a smaller carbon content, regardless of its smaller fraction, was characterised by a greater mechanical stability (smaller tendency to a mechanical destabilization) than austenite in steel of a greater carbon content. It was pointed out that it was not possible to perform a complete transformation of retained austenite in the examined steels by their mechanical destabilization.

PL

W pracy przedstawiono wyniki badań nad wpływem naprężeń na udział austenitu szczątkowego w mikrostrukturze dwóch stali niestopowych konstrukcyjnych. W oparciu o uzyskane rezultaty w obu badanych stalach dokonano oceny stabilności mechanicznej austenitu szczątkowego. Wykazano związek pomiędzy wielkością naprężeń, stężeniem węgla, udziałem objętościowym austenitu szczątkowego i jego stabilnością. Stwierdzono, że destabilizacja mechaniczna austenitu szczątkowego w obu badanych stalach zależy od wielkości przyłożonych naprężeń i przebiega w dwóch etapach. Zaobserwowano, że austenit szczątkowy, obecny w mikrostrukturze stali o mniejszej zawartości węgla, pomimo mniejszego jego udziału, charakteryzuje się większą stabilnością mechaniczną (mniejszą skłonnością do mechanicznej destabilizacji) od austenitu w stali o większym stężeniu węgla. Wykazano również, że w badanych stalach przez destabilizację mechaniczną nie można dokonać całkowitej przemiany austenitu szczątkowego.

8

Nośniki nieorganiczne

Lasoń E., Ogonowski J.

LAB Laboratoria, Aparatura, Badania

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2009

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R. 14, nr 5/6

6-10

9

Wpływ komponentów na właściwości wysokotemperaturowego smaru plastycznego

Drabik J., Pawelec E.

Problemy Eksploatacji

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2004

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nr 2

191-198

PL

Ustalono i przyjęto, jako weryfikujący, zakres parametrów niezbędnych do dokonania kompleksowej oceny charakterystyki użytkowej opracowanych wysokotemperaturowych smarów plastycznych. Wyznaczono parametry fizykochemiczne, tribologiczne i ekologiczne opracowanych smarów. Smar o najkorzystniejszych właściwościach funkcjonalnych został poddany ocenie toksykologicznej, a także określono jego poziom biodegradacji.

EN

The range of parameters necessary to carry out the complex assessment of utilitarian characteristics of the developed high-temperature plastic greases was assumed as the verifying one. Physical, chemical, tribological and ecological parameters of the developed greases were determined. The grease with the most favorable properties was examined toxicologically and its biodegradation level was defined.

10

Syntetyczne smary plastyczne do różnych zastosowań

Bajer J., Janecki J.

Problemy Eksploatacji

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2004

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nr 2

199-206

PL

W pracy przedstawiono charakterystyki syntetycznych smarów plastycznych opracowanych w Instytucie Technologii Eksploatacji. Omówiono wyniki badań właściwości tribologicznych i wybranych właściwości fizykochemicznych zastosowanych w nich jako bazy faz dyspergujących oraz wytworzonych z ich użyciem środków smarowych. Scharakteryzowano także wpływ modyfikatorów na właściwości opracowanych smarów.

EN

This article presents informations about elaborated in the Institute for terotechnology synthetic greases to different applications. There are compared the results of dispersing agents and elaborated greases. The influence of modifier on properties of greases is presented too.