Eff ect of Tribo-oxide Layers on the Sliding Wear Behaviour of Rutile Reinforced LM13 Alloy Composites at High Temperature and Pressure (original) (raw)
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Study of the Oxidative Wear of the Aluminum Rutile Composites at Higher Contact Pressure
Aluminium alloy matrix composites have found its wide applications in the manufacturing of the various components such as piston, brakes, piston liners and engine where tribological properties are a predominant process. Aluminium alloy reinforced with 5wt.% and 10wt.% of rutile concentration was prepared by liquid metallurgy route. Wear tests were performed at different loads varying from 9.8N to 49N at constant sliding velocity of 1.6m/sec. Materials possessing high wear resistance under dry sliding conditions are associated with a formation of stable tribo-layer on the wearing surface. In this work, a systematic experimental study was performed to analyse the effect of contact pressure on the formation of the tribo oxide layers during sliding. The shape and size of the wear debris clearly demonstrated that how the particles were fractured and comminuted, losing their role as load supporters.
The effect of ceramic tribo-elements on friction and wear of smooth steel surfaces
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 2018
The pin-on-disc dry sliding friction and wear experiments have been made on 42CrMo4 steel in contact with Si3N4, SiC, WC, Al2O3, and ZrO2 ceramic balls. The tests were carried out at sliding speeds of 0.16 m/s, 0.24 m/s, and 0.32 m/s. During the tests, the friction force was monitored as a function of time. Discs and balls wear was measured after the tests using a white light interferometer Talysurf CCI Lite and Altisurf 520 optical profilometer with a CL1 confocal probe. To decrease variations in the experimental results, during the tests, wear debris was continuously removed from the disc surfaces. It was found out that with Al2O3 counterpart the wear volume of the steel discs was the largest. However, the largest wear volume of the balls was observed for Si3N4 ceramic balls.
Role of Different Range of Particle Size on Wear Characteristics of Al-Rutile Composites
The present article describes in detail the wear behavior of rutile-reinforced LM13 alloy composite at elevated temperatures. Rutile particles in different amounts were reinforced into LM13 alloy by stir casting route. The microhardness measured at different areas indicates good interfacial bonding. Wear tests were conducted for composites containing rutile particles in 10wt.% and 15wt.% with variation in particle size (50-75μm and 106- 125μm). The presence of ceramic particle in the matrix improves the hardness, wear resistance, thermal stability as well as durability of the materials. The wear of composite at 200 ºC presented entirely different wear behavior mode than that at 250 ºC. The wear rate of fine size reinforced composite at 200 ºC at higher load was substantially lower than that of coarse size reinforced composite. A transition from mild-to-severe wear at higher load was observed above 150 ºC. The morphology of wear track and debris indicate that nucleation of cracks around the void on the interface of the particles is the main cause of surface damage.
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Wear, 2007
The wear behaviour of two Al 2 O 3 -Mo and two Al 2 O 3 -Nb particulate composites with different Mo particle size and Nb contents, respectively, obtained by hot-pressing, was evaluated. The inverted pin-on-disc tests were performed by making ceramic pins slide against WC discs at different loads with a constant sliding speed and sliding distance. When the load increased the specific wear of alumina-molybdenum composites increased dramatically while the wear of alumina-niobium material remained almost constant inspite of the increase of the applied load. On the other hand, the wear of the WC discs was very low against Al 2 O 3 -Mo but extremely high against Al 2 O 3 -Nb composites. It was also found that the friction coefficient strongly depends on the applied load but weakly on the pin material. The lower the load the higher the friction. A possible explanation of the wear mechanisms is proposed.
High Temperature Sliding Wear of NiAl-based Coatings Reinforced by Borides
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The development of composite materials (CM) in the systems "metal-refractory compound" is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C), it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3-7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl-МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С) coatings NiAl-15 wt.% CrB2 (TiB2, ZrB2).
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In the present investigations, LM13 aluminium alloy reinforced with 15 and 20wt.% rutile mineral of fine (50–75 mm) and coarse (106–125 mm) size range was prepared through stir casting technique. The microhardness on different phase of the composite was measured to check the interfacial bonding of particles with the base material. The wear properties of the samples were studied using pin-on-disc tribometer at high load (49 N) with variation in temperatures from 50C to 300C. Wear results indicated that the composites containing fine size reinforced particles showed around two times higher wear resistance over a wide range of temperature than the composite-containing coarse particles. A transition in wear mode from mild to severe was observed above 200C. Wear track and wear debris were analysed to understand the nature of wear.
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Sliding friction and wear tests were performed for four sintered ceramics including mullite, alumina, silicon carbide and titanium diboride (TiB), in various combinations at room temperature, 500 and 1000 8C in air. The coefficient of friction of the 2 ceramics was nearly constant regardless of sliding combinations and test temperatures. The specific wear rates at room temperature and 500 8C were high, usually of the order of 10 mm yNm, whereas low wear rates of the order of 10 or 10 mm yNm, y4 3 y5 y6 3 or even mass gain, was observed at 1000 8C. SEM observations show that tribofilms are consistently formed on the wear surfaces. A porous tribofilm, generally associated with a high wear rate at room temperature or 500 8C, is formed by compaction of debris particles. A dense tribofilm with a flat and smooth surface, often associated with a very low wear rate of the order of 10 y6 mm yNm or less at 1000 8C, is formed by plastic deformation accompanied by dynamic recrystallization at high temperatures. A 3 locally dense tribofilm, associated with a low wear rate of the order of 10 mm yNm at 1000 8C, is formed from the sintering y5 3 of the reattached debris at high temperatures.
2021
In this study, an investigation on the influence of In-situ tribo-oxide-layer on non-lubricated tribological behaviours of LM27/SiCp composites was carried out at different applied loads. The variations in wear performance and microstructure of brake lining friction material (LM27) with the addition of different amounts and sizes of SiCp are explored. For this purpose, LM27/SiCp composite materials were manufactured by stir casting route varying the amount of particle reinforced from 3wt.% to 12wt.% with a different size range (fine: 1-20µm and coarse: 106-125µm). Non-lubricated dry wear tests of LM27/SiCp composites samples were trialled at different loads from 9.8N to 49N by using a pin-on-disc machine system. At a contact pressure of 0.2-1 MPa, LM27/SiCp composites with 12wt.% reinforcement showed a lower coefficient of friction than other composites. In-situ formation of oxide layers on the contact region of the specimen supports the self-lubrication during the wear test, which ...
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