Wyniki wyszukiwania - Biblioteka Nauki

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Materiały funkcjonalne w łożyskach ślizgowych

100%

Zimowski S. , Rakowski W. , Kot M.

Tribologia

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2007

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tom nr 3-4

433-443

PL

W pracy przedstawiono system diagnostyczny łożyska ze ślizgową warstwą sensorową, która jest materiałem funkcjonalnym. Warstwa ta jest wykonana z kompozytu polimerowego, który ma jednocześnie dobre właściwości tribologiczne i sensorowe - zmienia swoją przewodność elektryczną pod wpływem zmian temperatury i nacisku. Zaprezentowano wyniki badań dwóch kompozytów wykonanych z termoutwardzalnych żywic: poliestrowoimidowej i epoksydowej napełnianych proszkami przewodzącymi prąd elektryczny i proszkami środków smarnych. Wykonano badania tarciowe pary kompozyt/stal z jednoczesnym pomiarem przewodności elektrycznej układu oraz temperatury w strefie styku oraz wyznaczono charakterystyki mechaniczne i rezystancyjne kompozytów. Wyniki badań potwierdzają dobre właściwości ślizgowe i dużą odporność na zużycie oraz odpowiednią czułość pomiarową badanych kompozytów.

EN

Plain bearings are often weak points of several machines, instruments etc., so often need to be controlled and monitored during operation. A number of approaches to real-time sliding system diagnosis have been developed for this reason. The most of diagnostic methods require implementation of sensors, what can be difficult, e.g. installation of classic sensor inside the miniature devices. The proposed solution is to made a bearing bush with a specific functional material, which performs the double function as a sliding material and as a sensor of bearing state. The new functional material has been developed in Laboratory for Tribology and Surface Engineering AGH-UST and has been used in a diagnostic system addressed to kinematic pairs. The system consists of sensor coating of sliding bearing, module of diagnostic signal analysis and actuator. The sliding sensor layer deposited on a bearing bush was made of semi-conductive three-phase polymer composite which include thermosetting resin, carbon and solid lubricant powders. Sensor properties of the composite are revealed as their resistivity dependence on the temperature or load. The examination of two types of composites are reported: TWS-PC consists of polyes-terimide matrix filled with powders of graphite, tin and M0S2; TWS-EK is epoxy matrix filled with powders of graphite, carbon black, SiO2 and SiC. The composites exhibit very good wear resistance and low friction coefficient (0,15-0,25). Electrical resistance of the composites strongly depend on temperature and load, so can be an important diagnostic signal. The neural network has been used for analysis of this signal, produced by the sliding layer of sensitive bearing pad.

2

Structure and properties of CuFe2 alloy

100%

Rdzawski Z. M. , Stobrawa J. P. , Głuchowski W.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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tom Vol. 33, nr 1

7-18

EN

Purpose: The objective of this work was to investigate the changes taking place in the structure and properties of CuFe2 alloy caused by combined heat treatment and metal working. The objective of this paper was to describe phenomena related to the formation of functional properties CuFe2 strips, especially for obtaining hardness in 120-140 HV range and electrical conductivity above 35 MS/m. Design/methodology/approach: The investigated material consisted of two industrial melts of CuFe2. Systematic investigations of selected variants of heat treatment and plastic working operations were carried out. The investigations started with description of microstructure and properties in initial state, after quenching, after cold working, quenching and ageing, after quenching and ageing, after quenching, ageing and cold working and after cold working and annealing - omitting quenching and ageing process. Hardness test (HV) and electrical conductivity were determined on strip samples. Typical tension tests and metallographic investigations were also carried out. Findings: Structure and properties of industrial CuFe2 alloy differs significantly from the literature descriptions, especially after quenching process. It could be assumed, that the dissolved in a melting process alloy additives (in this case a part of dissolved iron) might be supersaturated, but some of them might be precipitated. This theory was confirmed by the results of investigation into mechanical properties, microstructure and electrical conductivity. Practical implications: The presented investigation results, besides their cognitive values, provide many useful information which might be implemented in a industrial practice. Originality/value: It was assumed that cold deformation with rolling reduction 70% and annealing at temperature 480oC for 12 hours provided possibilities to reach maximal electrical conductivity 37 MS/m and maximal hardness 136 HV.

3

Properties and structure of the functional composite materials - Nd-Fe-Co-B powder bonded with polymer

80%

Ziębowicz B. , Dziekońska M. , Dobrzański L. A.

Archives of Materials Science and Engineering

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2011

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tom Vol. 52, nr 2

74-81

EN

Purpose: This paper presents the material and technological solution which makes it possible obtaining functional composite materials based on the nanocrystalline Nd-Fe-Co-B powder with polymer matrix and shows the possibility of application in different branches of the techniques. Design/methodology/approach: For fabrication of composite materials: Nd-Fe-Co-B powder obtained by rapid quenched technique and for matrix - high density pressureless polyethylene (PEHD) and polyamide (PA12) (2.5 % wt.) were used. Composite materials were compacted by the one-sided uniaxial pressing. The complex relationships among the manufacturing technology of these materials, their microstructure, as well as their mechanical and physical properties were evaluated. Materialographic examination of the structure of composite materials and fractures after decohesion were made. Findings: The main purpose of obtaining this kind of composite materials is broadening possibilities of nanocrystalline magnetic materials application that influence on the miniaturization, simplification and lowering the costs of devices. Composite materials show regular distribution of magnetic powder in polymer matrix. Examination of mechanical properties show that these materials have satisfactory compression strength. Practical implications: The manufacturing of composite materials Nd-Fe-Co-B powder - polymer greatly expand the applicable possibilities of nanocrystalline powders of magnetically hard materials however further examination to obtain improved properties of magnetic composite materials and investigations of constructions of new machines and devices with these materials elements are still needed. Originality/value: Manufacturing processes of functional composite materials obtaining Nd-Fe-Co-B - polymer matrix and determination of their mechanical properties. Results are the base for further investigations such composite materials.