Wyniki wyszukiwania - Biblioteka Nauki

1

Microstructural, Corrosion and Abrasive Characteristics of Titanium Matrix Composites

100%

Figiel P. , Garbiec D. , Biedunkiewicz A. , Biedunkiewicz W. , Kochmański P. , Wróbel R.

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tom Vol. 63, iss. 4

2051--2059

EN

Commercially pure titanium is less expensive, generally more corrosion resistant and lower in strength than its alloys, and is not heat-treatable. The use of Ti and its alloys as construction materials under severe friction and wear conditions is limited due to their poor tribological properties. Nevertheless, proper addition of hard ceramic particles into Ti and its alloys has proved to be an efficient way to enhance their mechanical and wear properties. Our purpose in this work was to analyze the corrosion, tribocorrosion, mechanical and morphological effects of combining titanium carbide with titanium metal, to create a unique composite via spark plasma sintering technique (SPS). Composites with different mass percentage (1, 5, 10, 15 and 20 wt %) of ceramic phase were produced. The samples of pure Ti and Ti-6Al-4V alloy were also tested, as a reference. These composites were examined for mechanical properties and corrosion resistance in an environment similar to the human body (Ringer’s solution). Open circuit potential (OPC) and anodic polarization measurements were performed. The properties of titanium composites reinforced with micro- and nanocrystalline TiC powders were compared. It was stated that wear properties were significantly improved with increasing amount of TiC in matrix, especially in the case of nanocrystalline reinforcement. In terms of corrosion resistance, the composites showed slightly worse properties compared to pure titanium and Ti-6Al-4V alloy.

2

Dry sliding wear behaviour of fly ash particles reinforced AA 2024 composites

88%

Babu Rao J. , Venkata Rao D. , Siva Prasad K. , Bhargava N. R. M. R.

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tom Vol. 30, No. 3

204--211

EN

AA 2024 alloy has been melted and cast in a permanent cast iron mould in the form of 18 mm fi fingers. The synthesis of AA2024 alloy - 5wt.% fly ash composite was made by stir cast technique. A uniform distribution of fly ash particles in the matrix phase was obtained. Good bonding between the matrix and reinforcement was also achieved. Dry sliding wear behavior of the alloy and the composite has been investigated using a pin-on-disc wear tester. The investigation was carried out at a fixed sliding velocity of 2.0 m/s, track diameter of 60 mm and load ranging from 0.5 kgf to 1.5 kgf (4.9-14.7 N). SEM studies were carried out to assess the wear behavior of the alloy and the composite. The composite showed better wear resistance than the base alloy for the lower loads. However, for the higher loads and longer sliding distances, the wear in the composite was extensive due to the existence of fractured and dislodged fly ash particles in the alloy matrix.

3

Wpływ obciążenia i prędkości obrotowej na zużycie stali bainitycznej w skojarzeniu ślizgowym na stanowisku Amslera

75%

Bąkowski H. , Służałek G.

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tom nr 3

11-18

PL

Podjęcie problemu zastosowania stali bainitycznej do produkcji szyn kolejowych oraz w jakich warunkach mają być one eksploatowane nie jest łatwym zadaniem. W związku z tym w ramach pracy przeprowadzono badania tribologiczne (na stanowisku Amslera) oraz metalograficzne i profilografometryczne śladów współpracy. Określono wpływ wybranych parametrów eksploatacji, tj. obciążenia (Q) i prędkości obrotowej na zużycie i współczynnik tarcia stali o strukturze bainitycznej w skojarzeniu ślizgowym.

EN

The developing world industry causes an increase in transport and train speeds. In this way, the rolling-sliding contact surface of rails subject to load lead to effort placed on material. The result of effort is increase stresses in subsurface contact. The forming and growing damages on the surface and subsurface in rolling-sliding contact depend on load and stresses and on the characteristic of rail material in the region of most effort of the rail area. Except external factors, the stress levels have an influence on internal stresses of sliding surface topography, since geometrical and structure notch causes stress concentration. The main aims of this work were determining how loads and speeds influence the values of wear and friction coefficients of rail steel of bainitic structure in sliding couples plus graphic interpretation research results from our experience and metalographic research. The scope of our work included performing tests on samples of rail steel of bainitic structure and tribiological research on an Amsler stand. These investigations have been carried out for one-to-one mapping to the wheel-rail system at the beginning of movement. During interaction in wheel-rail system, different effects proceed. Wear rate is different for individual working states depending on loads and speeds.

4

Polymer Blended (Epoxy/Vinylester) Nanocomposites Resistance against Pulling & Sliding Wear Loads

75%

Harisankar P. , Reddy Y. V. M. , Reddy K. H.

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tom Vol. 18

75--90

EN

This paper discloses the development and synthesis of polymer blended nanocomposites filled with nanoclay. The hybridization of epoxy is mixed with vinylester resin (VER) to prepare polymer blend filled with organoclay was studied to enhance mechanical properties of epoxy/VER. Clay loading was done in such a way that with different wt. proportions viz.1, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, & 7.5 w % ratios. Appropriately cured samples gave excellent mechanical and tribological properties. Results showed that the tensile strength of the composites increased with increase in filler content for the range of filler contents (2.5-4 % vol.). The results indicated that at 4 % wt. of filler concentration the tensile strength obtained is good i.e. 47.79 MPa with density 1.37 gm/cm3 and hardness 45.5. Dry Sliding wear tests were also conducted by following a well-planned experimental schedule based on Taguchi’s design of experiments, considering parameters like Filler content, Normal load, Sliding Velocity and Sliding distance, on a Pin-On-Disc set-up (ASTM G-99 standard, Make: DUCOM Engineers, Bangalore, India). In the experimentation composite pins were worn against a rotating steel disc (Europe Norm) EN-31, (Rockwell C Hardness) HRC 60 and (Roughness Average) Ra 0.02 microns. Control factors like Filler Content, Normal Load were found to be significant factors affecting the Wear rate i.e. the inclusion of nanoclay as filler found to be contributed in improving the wear resistance of the composite. SEM observations are made to probe the wear mechanisms involved.

5

Effect of Water Absorption on Tribological Properties of Thermoplastics Matrix Composites Reinforced with Glass Fibres

63%

Walczak M. , Szala M. , Pieniak D.

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2022

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tom Vol. 16, no 2

232--239

EN

The present work investigated the water absorption of thermoplastic matrix composites and their effect on tribological behaviour. Four thermoplastic composites were researched based on Polyamide 6 and Polyamide 66 matrix reinforced with glass fibres. The composites fabricated using the injection moulding technique were immersed in distilled water at room temperature for a water absorption test for 14 days. Dry sliding wear was conducted using a pin-on-disc trbiotester. The coefficient of friction (COF) and the wear rate (K) was determined. The sliding trace was analyzed using a scanning electron microscope (SEM) to reveal the sliding wear mechanism of composites. Studies have shown that polyamide PA6 based composites are less prone to absorb water than PA66 matrix. In addition, the composites richer in fibreglass exhibit lower water absorption. Tribological results indicated that polymer composites showed higher COF and K after water absorption testing. Mean COF and K were in the range of 0.071÷0.321 and 2.51∙10-6÷1.81∙10-4 mm3N-1m-1, respectively. Wear traces SEM analysis revealed that untreated samples are characterized by less intense abrasive and adhesive wear mode than the hydrated polymers. Besides, the degradation process took place primarily at the polymer matrix-fibreglass interfaces.

6

Sliding wear examination of new protecting coatings on railway buffer heads

63%

Gamon W.

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tom Vol. 49, iss. 4

401--419

EN

The paper presents the results of tests of sliding wear of bronze coatings made on the surface of specimen made of S355J2 steel by laser cladding method. On the basis of the conducted tests it was found that the wear of the specimens with CuAl9Fe3 bronze coating is characterized by average values which are close to lubricated specimens. In addition, the registration of friction coefficients of particular couples showed very similar characteristics of these two friction couples and friction coefficient values at a very similar level. This allows to assume that the currently used method of protecting railway buffer heads, consisting of periodically covering their surface with lubricant, can be replaced with another, more durable, based on bronze protection coatings.

PL

W artykule przedstawiono wyniki badań zużycia ściernego powłok z brązów wytworzonych na powierzchni próbek wykonanych ze stali S355J2 metodą napawania laserowego. Na podstawie badań stwierdzono, że zużycie próbek z napoinami z brązu CuAl9Fe3 cechuje się wartościami średnimi zbliżonymi do próbek smarowanych. Ponadto, rejestracja współczynników tarcia poszczególnych skojarzeń wykazała bardzo zbliżone charakterystyki tych dwóch par ciernych oraz wartości współczynników tarcia na bardzo podobnym poziomie. Pozwala to na założenie, że obecnie stosowana metoda zabezpieczania zderzaków kolejowych, polegająca na okresowym pokrywaniu ich powierzchni smarem, może zostać zastąpiona inną, trwalszą, bazującą na wykonywaniu powłok zabezpieczających z brązów.

7

Wear resistance of various type sintered steels

63%

Bidulsky R. , Actis Grande M. , Zago A. , Brytan Z. , Bidulska J.

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tom Vol. 55, iss. 3

623-629

EN

In this work, the influences of the processing conditions (applied load, cooling rate) on the wear resistance of sintered steels were presented. The wear behaviour of various sintered steels, including Astaloy LH, Astaloy CrL, Distaloy AE, PASC60, 316 L and 430 L were carried out by a pin-on-disk test. The effect of chemical composition and different applied loads in vacuum furnace related to a wear resistance (mass loss versus sliding distance) was investigated. The results showed that the microstructure constituents along with relevant hardness values represent an important parameter affecting the wear behaviour of sintered steels and the sinter hardening is suitable heat treatment for improving the wear resistance of sintered steels.

PL

W pracy przedstawiono wpływ parametrów wytwarzania (ciśnienia prasowania, szybkości chłodzenia) na zużycie ścierne stali spiekanych. Mechanizm zużycia ściernego różnych typów stali określono przy użyciu testu pin-on-disk. Zbadano wpływ składu chemicznego oraz ciśnienia prasowania podczas spiekania w próżni na odporność na zużycie ścierne (ubytek masy w funkcji drogi tarcia). Wyniki badań wykazały, że składniki strukturalne wraz z ich charakterystyczną twardością stanowią ważny czynnik wpływający na mechanizm zużycia ściernego, a zastosowanie obróbki cieplnej typu "sinter hardening" jest właściwe dla polepszenia odporności na użycie ścierne stali spiekanych.

8

Cavitation erosion and sliding wear of MCrAlY and NiCrMo coatings deposited by HVOF thermal spraying

51%

Szala M. , Walczak M. , Łatka L. , Gancarczyk K. , Özkan D.

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tom Vol. 20, nr 2(64)

26--38

EN

The investigation into wear resistance is an up-to-date problem from the point of view of both scientific and engineering practice. In this study, HVOF coatings such as MCrAlY (CoNiCrAlY and NiCoCrAlY) and NiCrMo were deposited on AISI 310 (X15CrNi25-20) stainless steel substrates. The microstructural properties and surface morphology of the as-sprayed coatings were examined. Cavitation erosion tests were conducted using the vibratory method in accordance with the ASTM G32 standard. Sliding wear was examined with the use of a ball-on-disc tribometer, and friction coefficients were measured. The sliding and cavitation wear mechanisms were identified with the SEM-EDS method. In comparison to the NiCrMo coating, the MCrAlY coatings have lower wear resistance. The cavitation erosion resistance of the as-sprayed M(Co,Ni)CrAlY coatings is almost two times lower than that of the as-sprayed NiCrMoFeCo deposit. Moreover, the sliding wear resistance increases with increasing the nickel content as follows: CoNiCrAlY < NiCoCrAlY < NiCrMoFeCo. The mean friction coefficient of CoNiCrAlY coating equals of 0.873, which almost 50% exceed those reported for coating NiCrMoFeCo of 0.573. The as-sprayed NiCrMoFeCo coating presents superior sliding wear and cavitation erosion resistance to the as-sprayed MCrAlY (CoNiCrAlY and NiCoCrAlY) coatings.