Filtreler
Effect of ZrSiO4 on the friction performance of automotive brake friction materials

Boz M. | Kurt A.

Article | 2007 | Journal of Materials Science and Technology23 ( 6 ) , pp.843 - 850

Friction-wear properties of the ZrSiO4 reinforced samples were measured and compared with those of plain bronze based ones. For this purpose, density, hardness, friction coefficient wear behaviour of the samples were tested. Microstructures of samples before and after sintering and worn surfaces were also investigated by scanning electron microscopy (SEM), and the wear types were determined. The optimum friction-wear behaviour was obtained in the sample compacted at 500 MPa and sintered at 820°C. Density of the final samples decreased with increasing the amount of reinforcing elements (ZrSiO4) before pre-sintering. However after sin . . .tering, there is no change in density of the samples including reinforcing elements (ZrSiO4). With increasing friction surface temperature, a reduction in the friction coefficient of the samples was observed. However, the highest reductions in the friction coefficients were observed in the as-received samples containing 0, 5% reinforced ZrSiO4. The SEM images of the sample indicated that while bronze-based break lining material without ZrSiO4 showed abrasive wear behaviour, increasing the amount of ZrSiO4 resulted a change in abrasive to adhesive wear mechanism. All samples exhibited friction-wear values, which were within the values shown in SAE-J661 standard. With increasing the amount of reinforcing ZrSiO4, wear resistance of the samples was increased. However samples reinforced with 5% and 6% ZrSiO4 showed the best results Daha fazlası Daha az

Dry sliding wear behaviours of filled welded train rail

Boz M.

Article | 2007 | Metallofizika i Noveishie Tekhnologii29 ( 1 ) , pp.105 - 114

The purpose of this work is to investigate sliding wear behaviour of the wearing train rail welded by the electric-arc welding technique. Samples are obtained from the wearing rail filled by the welding, using a various kind of manual arc-welding metal electrodes. The weld metal is characterized according to filling electrodes in terms of both hardness and microstructure. Wear behaviour of the filling weld metal is investigated in conditions of various loadings and distances. In addition, the friction coefficient of samples is determined according to the applied loadings and wear distances. Experimental results show that the increas . . .e in loading and wear distance exerts the great influence on wear-resistance performances of samples. The samples having higher hardness demonstrate high wear-resistance performances. Also, a metallographic investigation indicates that the samples having the small-size grains display the better wear resistance than the samples containing the larger-size grains Daha fazlası Daha az

High-temperature tensile and wear behaviour of microalloyed medium carbon steel

Gündüz S. | Acarer M.

Article | 2005 | Industrial Lubrication and Tribology57 ( 4 ) , pp.145 - 149

Purpose - To provide new observations about dynamic strain ageing in medium carbon microalloyed steels which are used for automotive applications. Design/methodology/approach - The present work aims to provide theoretical and practical information to industries or researchers who maybe interested in the effects of dynamic strain ageing on mechanical properties of microalloyed steel. The sources are sorted into sections: introduction, experimental procedure, results and discussion, conclusion. Findings - Microalloyed medium carbon steel was susceptible to dynamic strain ageing where serrated flow is observed at temperatures between 2 . . .00 and 350°C. In this temperature regime, ultimate tensile strength and proof stress exhibit maximum values, however, elongation to fracture showed a decrease until 250°C, after which it increased. Above 350°C, a sharp decrease in tensile strength and proof stress were observed. Abrasive wear resistance of the microalloyed medium carbon steel was also increased at temperatures between 200 and 350°C due to dynamic strain ageing. Research limitations/implications - A search of the literature indicated that although there is considerable volume of information related to dynamic strain ageing in mild steel or in low-carbon steel no extensive investigation has been made of dynamic strain ageing in microalloyed steel due to the ease with which nitrogen is combined AlN, VN, NbN, etc. which perhaps increase its implications. Practical implications - A very useful source of information for industries using or planning to produce microalloyed steels. Originality/value - This paper fulfils an identified resource need and offers practical help to the industries. © Emerald Group publishing Limited Daha fazlası Daha az

Comparison of drilling performance of chisel and button bits on the electro hydraulic driller

Su O. | Yarali O. | Akcin N.A.

Article | 2013 | Rock Mechanics and Rock Engineering46 ( 6 ) , pp.1577 - 1587

Electro hydraulic drillers have been widely used in mining for drilling and roof-bolting. In the drilling process, the performance of the machine is predicted by selecting an appropriate bit type prior to drilling operations. In this paper, a series of field drilling studies were conducted in order to examine and compare the performance of chisel and button bits including wear on the bits. The effects of taper angle on chisel bits, which are at angles of 105, 110 and 120, were investigated in terms of rate of penetration, instantaneous drilling rate and specific energy. The results of drilling and abrasivity tests performed in the l . . .aboratory supported the outcome of the field studies. Based on laboratory studies and field observations, it was proven that the conglomerate encountered, though it is very abrasive, is easy to drill. The cutter life in the encountered series is also longer in sandstone formation compared to the conglomerate. Additionally, button bits resulted in lower specific energy and higher penetration rates relative to chisel bits, regardless of their taper angles. The results were also supported with statistical analyses. © 2012 Springer-Verlag Wien Daha fazlası Daha az

Dry sliding wear behaviour of Fe-0.4C-25Cr-XNi cast steels

Sun Y. | Ahlatci H. | Ozdogru E. | Cimenoglu H.

Article | 2006 | Wear261 ( 03.Apr ) , pp.338 - 346

The effect of composition and heat treatment (solutionizing at 1200 °C and aging at 750 °C) on the room temperature mechanical properties (hardness and impact toughness) and dry sliding wear resistance of Fe-0.4C-25Cr-XNi steels (where nominal Ni contents were 4, 12 and 20 wt.%) have been investigated. The steel containing 4 wt.% Ni had ferritic and others (12 and 20 wt.% Ni) had austenitic matrixes along with M23C6 type chromium carbides. The applied heat treatment resulted in precipitation of sigma phase in austenitic matrix, which was accompanied by an improvement in hardness and a decrease in impact toughness. Ferritic matrix st . . .eel exhibited higher hardness and lower impact toughness than austenitic matrix steels. The results of the wear tests conducted on an unlubricated M2 quality tool steel disc revealed that at test pressures lower than 2.2 N/mm2, the dominant wear mechanism was mild wear. However, at high test pressures (>2.2 N/mm2) severe wear mechanism was operative. Increase of hardness and decrease of toughness resulted in a decrease in wear resistance under mild wear conditions. However, these mechanical properties were not effective on wear resistance under severe wear testing conditions. © 2005 Elsevier B.V. All rights reserved Daha fazlası Daha az

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