Dry sliding friction and wear behaviors of Mg_2B_2O_5 whisker reinforced 6061Al matrix composites

The friction and wear properties of Mg2B2O5 whisker reinforced 6061Al matrix composite fabricated via power ultrasonic-stir casting process were investigated using a ball-on-disk wear-testing machine against a GCr45 steel counterface under dry sliding conditions. The reinforcements include as-received Mg2B2O5 whiskers and Mg2B2O5 whiskers coated with CuO and ZnO. The volume fraction of the composites is 2%. The relationship between the wear rate and the coefficient of friction was discussed. The results indicate that the wear rate of the Mg2B2O5 whiskers coated with ZnO reinforced aluminum matrix composites is the lowest among the materials. As the applied load and sliding speed steadily increase the coefficients of friction and wear rates of the as-received matrix alloy and the fabricated composites decrease. As the applied load and sliding speed increase, the wear mechanisms of the composites shift from a mild to a severe regime.

On the role of sliding friction effect in nonlinear tri-hybrid vibration-based energy harvesting

This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting.A proposed sliding-mode triboelectric-electromagnetic-piezoelectric energy harvesting model involves a cantilever beam with a tip mass exposed to magnetic and frictional forces.The experimental findings indicate that the system can achieve its peak inter-well oscillation output within a low-frequency range of 4 Hz–6 Hz.Friction has a lesser impact on the open-circuit voltage output at an excitation acceleration of 1.5g compared with 1g.The distribution of tri-stability changes with the presence of friction.This model provides a deeper understanding of the influence of the dry friction coefficient(0.2–0.5) on the interactive behaviors of different generator units.

Influence of tool rotational speed on microstructure and sliding wear behavior of Cu/B_4C surface composite synthesized by friction stir processing

An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.

Effect of Magnetic Field on the Friction and Wear of Polyamide Sliding against Steel

The present work discusses the friction and wear of polyamide sliding against steel in the presence of magnetic field. Tests were carried out at dry and oil lubricated steel surfaces. Paraffin and vegetable oils such as almond, castor, corn, glycerine, jasmine, olive and sun flower oils were used as lubricants. The friction coefficient and wear were investigated using pin on disc wear tester. Based on the experimental results, it was found that application of magnetic field on the contact area affected both friction coefficient and wear of polyamide sliding against steel at dry and oil lubricated conditions. Magnetic field decreased friction coefficient. Lubricating the sliding surface by paraffin oil as well as almond, castor, corn, glycerine, jasmine, olive and sun flower oils significantly decreased friction coefficient. Generally, friction coefficient increased with increasing applied load. Dry sliding of polyamide against steel surface showed increased wear with increasing load. The lowest wear values at no magnetic field were displayed by jasmine oil followed by sun flower, almond, olive, castor, corn, glycerine and paraffin oils. Under the application of magnetic field, the lowest wear values were displayed by sun flower oil followed by jasmine, castor, glycerine, olive, paraffin, almond and corn oils. It can be concluded that friction and wear decrease observed at dry sliding can be explained on the basis that presence of magnetic field around the contact area decreased the adherence and transfer of polyamide into the steel surface. For oil lubricated sliding, the polar molecules of the tested lubricating oils were much affected by the magnetic field, where they oriented themselves to the polar end directed towards the sliding surface making a close packed multi-molecular layered surface film that could protect the sliding surfaces from excessive wear.

Processing technique and sliding friction and wear behavior of TiB_2/ZA27 composite

In-situ TiB2 particles reinforced ZA27 composite was prepared by the stir-casting technique and a two-step method. TiB2/Al composite was produced by incorporating K2TiF6, KBF4 salts and other agents into Al melt. As a master alloy, TiB2/Al composite was used to manufacture TiB2/ZA27 composite, which results in the generation of well-distributed reinforcing TiB2 phase. The hardness, friction and wear behavior of TiB2/ZA27 composite were investigated. The results show that the hardness of the composite is enhanced with increasing the content of TiB2 particles, the incorporation of TiB2 reduces the wear rate of TiB2/ZA27 composite and improves the friction property under lubricated and dry sliding friction conditions. The worn track width of ZA27 alloy is 1.6 and 2.5 times as long as that of （2.1%）TiB2/ZA27 composite at 150N and 700N load under lubricated conditions, which indicates that TiB2/ZA27 composite possesses higher bearing ability.

Influence of Friction Stir Welding Parameters on Sliding Wear Behavior of AA6061/0-10 wt.% ZrB₂in-situ Composite Butt Joints

Over the last decade attempts have been made to fabricate aluminum matrix composites (AMCs) reinforced with several ceramic particles. Aluminum reinforced with ZrB2 particles is one such AMC. The successful application of new kind of AMCs lies in the development of secondary processes such as machining and joining. Friction stir welding (FSW) is a relatively new solid state welding which overcomes all the setbacks of fusion welding of AMCs. An attempt has been made to friction stir weld AA6061/ 0-10 wt. % ZrB2 in-situ composites and to develop empirical relationships to predict the sliding wear behavior of butt joints. Four factors, five levels central composite rotatable design has been used to minimize the number of experiments. The factors considered are tool rotational speed, welding speed, axial force and weight percentage of ZrB2. The effect of these factors on wear rate (W) and wear resistance (R) of the welded joints is analyzed and the predicted trends are discussed.

Transitions in Wear and Friction of Carbon Fiber Reinforced Copper Matrix Composite Sliding Against AISI-1045 Steel

The friction and wear properties of carbon fiber reinforced copper matrix composite in dry sliding against AISI-1045 steel was evaluated by a block-on-ring test machine. It was shown that the low frictional factor and wear rate of the composite block could be maintained when pressure or velocity was below a certain value. But when the pressure or velocity exceeded the critical value, the friction factor and wear rate tended to increase rapidly with pressure and sliding velocity. The morphologies, elemental compositions, and surface profile of worn composite surfaces at different wear stages were analyzed by means of scanning electron microscopy, energy dispersive spectrometry, and profile-meter. It was found that low values of friction and wear were due to a thin solid film forming on the surface of the composite block which includes carbon and copper at a mild wear stage. The film could impede adhesion and provide some degree of self-lubrication. When the film included more metal elements and were damaged, severe wear happened, and the wear rate increased sharply. As a result, a transition diagram in friction and wear was constructed, which provided pressure and velocity conditions of change from mild wear and low friction to severe wear and high friction for the wear-resisting design.

Sliding wear and friction behavior of ZA-27 alloy reinforced by Mn-containing intermetallic compounds

A ZA 27 alloy reinforced with Mn containing intermetallic compounds was prepared and its tribological behaviors were investigated. By adding Mn, RE, Ti and B into ZA 27 alloy, the test alloy (ZMJ) was fabricated by sand casting. Microstructural analysis shows that considerable amount of Mn containing intermetallic compounds such as Al 5MnZn, Al 9(MnZn) 2 and Al 65 Mn(RE) 6Ti 4Zn 36 are formed. Compared to ZA 27, ZMJ shows better wear resistance, lower friction coefficient and lower temperature rise of worn surface under lubricated sliding condition. ZMJ also shows the lowest steady friction coefficient under dry friction condition. The wear resistance improvement of ZMJ is mainly attributed to the high hardness and good dispersion of these Mn containing intermetallic compounds. It is indicated that the intermetallic compounds play a dominant role in reducing the sever adhesive and abrasive wear of the ZA 27 alloy.

Dry Sliding Friction and Wear Properties and Wear Mechanism of SiC_P/Al Composites

Dry sliding friction and wear properties of A356/SiC composites against AISI D2 were analyzed by means of SEM,XRD and EDS.Results indicated that the wear rate of A356/SiC increased with increase of the applied load.Mild wear took place under lower load,transferring to severe wear at the load heavier than 400 N.Mechanical mixed layer(MML) formed on worn surface during dry sliding friction process,whose thickness became deeper with increasing load.Cracks formed easily in MML and spread transversely,resulting in peeling wear.The wear mechanism of the composite is that oxidation wear mechanism was dominant under low load,with the formation of tiny powdery debris.As the load enhanced,peeling wear was primary due to laminar debris detached from the MML,including oxidation and adhesive wear at the same time,with the load at 350-450 N,adhesive wear with irregular debris and peeling wear were predominant.

Friction Shear Stress on the Surface of Iron-Based Coating/HSS during Sliding Wear of Pin Disk

With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, which is determined by the inherent mechanical properties of high strength steel, makes molds prone to wear failure in the harsh service environments. In this paper, a finite element model is proposed for analyzing the value and distributions law of friction shear stress of contact surface of the pin disk. Through the simulation process of sliding wear, two kinds of different cladding materials of the pin specimens including H13 and Fe65, were experimented under three different loads by using the software ABAQUS. And then the pin-on- disk wear test at elevated temperature was conducted to verify the effectiveness of the simula-tion results. The results showed that the friction shear stress of pin with iron-based cladding and H13 steel was different under different loads, but the distribution was basically the same;the normal friction shear stress increased gradually along the direction of the pin movement, and the tangential shear stress increased gradually from the center of the pin to the outside of the circle;the value of the friction shear stress of the normal joints on the contact surface was periodically fluctuating in the whole dynamic analysis step, while it was basically stable in the tangential direction.

Optimization of friction and wear behaviour of Al-Si_3N_4 nano composite and Al-Gr-Si_3N_4 hybrid composite under dry sliding conditions

The tribological behaviour of gravity die stir cast LM6alloy with graphite(Gr)and silicon nitride nanoparticles was investigated.Al?Gr?Si3N4hybrid composite,Al?Si3N4nanocomposite and Al?Gr nanocomposites were separately fabricated to investigate their frictional and wear characteristics under dry sliding conditions.EDS was used to ensure the uniform presence of nano Si3N4and graphite in the cast.L9orthogonal array method was chosen to conduct the experiments to study the effect of different applied loads(20,30and40N)and sliding distances(1,2and3km).The results showed that the respective wear rate and coefficient of friction(COF)decreased by25%and15%for hybrid composite when compared with those of Al?Si3N4nanocomposite whereas the wear rate and COF of Al?Gr was found to be very minimal.The micro Vickers hardness of the hybrid composite was14%more than that of the simple nanocomposite and there was not much notable variation for Al?Gr and Al?Si3N4nanocomposite materials.Scanning electron microscope was used to analyze the worn surface and subsurface,from which it was noted that the predominant wear mechanisms observed were abrasive for nanocomposite and both abrasive and adhesive mechanism for hybrid composite.Analysis of variance(ANOVA)and F-test were used to check the validity model and to determine the significant parameters affecting the wear rates.

Lows of Wear Process of the Friction Pair “0.45% Carbon Steel—Polytetrafluoroethylene” during Sliding from the Position of Fracture Mechanics

The results of the tests for a friction pair “a cylindrical specimen made of 0.45% carbon steel—a counter specimen-liner made of polytetrafluoroethyleneF4-B” during sliding friction are presented. The test results at different levels of contact load are analyzed using the Archard’s equation and are presented as a friction fatigue curve. The concept of the frictional stress intensity factor during sliding friction is introduced, and an expression that relates the wear rate to this factor and is close in shape to the Paris equation in fracture mechanics is proposed.

Characterization of Al-12Si alloy and its composites in dry sliding friction and wear at elevated temperature

Al 12Si alloy matrix composites reinforced with Al 2O 3 and carbon fibers respectively as well as with the two fibres were fabricated by squeeze infiltration. The elevated temperature (about 400 ℃) friction and wear behaviors of Al 12Si alloy and its composites were investigated.The results show that the hybrid composites reinforced with Al 2O 3 and carbon fibres are of superior high temperature wear resistance.The critical transition temperature from mild wear to severe wear of the composites reinforced only with Al 2O 3 fiber is improved markedly compared with monolithic Al 12Si alloy, from 200 ℃ to 300 ℃.However, the critical transition temperature of the hybrid composites reinforced with Al 2O 3 and carbon fibers is improved further to 400 ℃.The reinforcing fibers have no significant effect on wear mechanisms of Al 12Si alloy.The dominant mechanisms are ploughing grooves and delamination as well as slight adhesion during mild wear regime.The subsurface consists of three regions:non peeling delamination layer, microcrack formation and propagation zone, and unaffected zone.Whereas the dominant mechanism is shifted to severe wear when test temperature exceeds the critical transition temperature.

Dry sliding friction and wear behaviors of TiC_p/ZA- 12 composites

The TiC particle reinforced ZA 12 matrix composites was fabricated by XD TM process combined with stirring casting and its friction and wear properties under dry conditions were investigated using MM 200 wear testing apparatus. The effects of TiC particle content and applied load on the wear resistance properties of the composites were studied. The results show that the friction and wear properties can be greatly improved with an increase in the TiC particle content. The wear mass loss of the composites and the unreinforced ZA 12 matrix alloy increase with increasing applied load, but the increased extent of the former is smaller than that of the latter. Finally the morphologies of worn surface was analyzed using scanning electron microscope(SEM).

Tribological and electric-arc behaviors of carbon/copper pair during sliding friction process with electric current applied

The tribological behaviors of carbon block sliding against copper ring with and without electric current applied were investigated by using an advanced multifunctional friction and wear tester, and the electric-arc behaviors were analyzed in detail. The results show that the normal load is one of the main controlling factors for generation of electric arc during friction process with electric current applied. The strength of electric arc is enhanced with the decrease of normal loads and the increase of electric currents. The unstable friction process and the fluctuated dynamic friction coefficients are strongly dependent upon the electric arc. The wear volumes and the wear mechanism of carbon brush were affected by the electric arc obviously. As no electric arc occurs, no clear discrepancy of the wear volumes of the carbon samples with and without electric current applied could be detected. While the wear mechanisms are mainly mechanical wear. However, under the condition of the electric arc appearance, the wear volume of carbon with electric current applied increases much more rapidly than that without electric current applied and also increases obviously with the increase of electric current strengths and the decrease of normal loads. The wear mechanisms of carbon block are mainly electric arc ablation accompanying with adhesive wear and material transferring.

Wear behavior of high strength and high conductivity Cu alloys under dry sliding

In order to study the wear behavior of different kinds of contact wires,the dry sliding wear behaviors of Cu-Sn,Cu-Ag and Cu-Mg alloys prepared by up-drawn continuous casting and followed continuous extrusion were studied.The research was tested on a block-on-ring wear tester.The results indicate that the friction coefficient is remarkably influenced by the formation of a continuous tribofilm,which consists of oxidation film.The abrasion,adhesion,oxidation and plastic deformation are observed.Oxidation and abrasion wear mechanisms dominate at the lower sliding velocity and load.The combination of oxidation and adhesion play leading roles with the increasing load and velocity.Plastic deformation is detected under higher applied load and sliding velocities.

High temperature frictional wear behaviors of nano-particle reinforced NiCoCrAlY cladded coatings

The NiCoCrAlY coatings strengthened by three nano-particles with the same addition were prepared on a Ni-base super alloy using laser cladding technique. The dry frictional wear behaviors of the coatings at 500 ℃ in static air were investigated. The comparison was made with the coating without nano-particles. The results show that the wear mechanism of the NiCoCrAlY coatings with nano-particles, like the coating without nano-particles, is the delamination wear due to the strong plastic deformation and oxidative wear. However, the frictional coefficient of the coatings increases and presents the decrease trend with the increase of sliding distance after adding nano-particles. Moreover, the wear rate of the coatings with nano-particles is only 34.0%-64.5% of the coating without nano-particles. Among the three nano-particles, the improvement of nano-SiC on the high temperature wear resistance of the coating is the most significant.

Effect of individual and combined additions of Al-5Ti-B,Mn and Sn on sliding wear behavior of A356 alloy

The effect of grain refiner, Mn and Sn additions on the sliding wear behavior of A356 aluminum alloys was investigated. The microstructure and worn surfaces of the studied alloys were characterized by optical microscopy（OM）, scanning electron microscopy（SEM）, and transmission electron microscopy（TEM）. The experimental results indicate that the alloy refined by Al-5Ti-B alloy exhibits equiaxed α（Al） dendrites and performs better wear resistance compared with the alloy without the grain refiner. Moreover, the addition of Mn can change the β-Al5 Fe Si phase to α-Al（Mn,Fe）Si phase and reduce the possibility of crack formation, thus improving the wear resistance. Sn added to A356 aluminum alloy forms Mg2 Sn precipitates after heat treatment. Therefore, the unrealizable precipitation hardening Mg2 Si phase and the softening β-Sn phase can reduce the hardness of the alloy, and finally reduce the wear resistance.

Fretting wear and friction oxidation behavior of 0Cr20Ni32AlTi alloy at high temperature

The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C.Wear scar and debris were analyzed systematically by scanning electron microscopy and X-ray photoelectron spectroscopy.The results show that the friction logs are mixed fretting regime and gross slip regime with the magnitudes of displacement of 10 and 20 μm,respectively.Severe wear and friction oxidation occur on the material surface.A large number of granular debris produced in the fretting process can be easily congregated and adhered at the contact zone after repeated crushes.The resultant of friction oxidation is mainly composed of Fe3O4,Fe2O3,Cr2O3 and NiO.Temperature and friction are the major factors affecting the oxidation reaction rate.The fretting friction effect can enhance the oxidation reaction activity of surface atoms of 0Cr20Ni32AlTi alloy and reduce the oxidation activation energy.As result,the oxidation reaction rate is accelerated.

Friction and wear properties of in-situ synthesized Al_2O_3 reinforced aluminum composites

Al-5%Si-AI2O3 composites were prepared by powder metallurgy and in-situ reactive synthesis technology. Friction and wear properties of Al-5%Si-Al2O3 composites were studied using an M-2000 wear tester. The effects of load, sliding speed and long time continuous friction on friction and wear properties of Al-5%Si-Al2O3 composites were investigated, respectively. Wear surface and wear mechanism of Al-5%Si-Al2O3 composites were studied by Quanta 200 FE-SEM. Results showed that with load increasing, wear loss and coefficient of friction increased. With sliding speed going up, the surface temperature of sample made the rate of the producing of oxidation layer increase, while wear loss and coefficient of friction decreased. With the sliding distance increasing, coefficient of friction increased because the adhesive wear mechanism occurred in the initial stage, then formation and destruction of the oxide layer on the surface of the sample tended to a dynamic equilibrium, the surface state of the sample was relatively stable and so did the coefficient of friction. The experiment shows that the main wear mechanism of Al-5%Si-Al2O3 composites includes abrasive wear, adhesive wear and oxidation wear.