Papers by Keyword: Friction and Wear

Abstract: The friction and wear properties of GCr15/45# steel frictional pairs lubricated by n- Al2O3 additives under ultrasonic vibration or not were studied. The scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS) and energy dispersive spectrometer (EDS) were carried out to analyse the wear scar surface. The effect mechanism of ultrasonic vibration on friction pairs was discussed. The results indicated that ultrasonic vibration could decrease the friction and wear of GCr15/45# friction pairs, when the content of n-Al2O3 was 0.5wt%, the effect of ultrasonic vibration on friction pairs was most obvious. The friction coefficient, wear volume and wear scar depth under ultrasonic vibration decreased 10%, 34% and 13%, respectively. The friction reduction and anti-wear mechanism of n-Al2O3 was single “micro ball bearing” without ultrasonic vibration, and it changed to “micro ball bearing” and adsorption penetration film with ultrasonic vibration, so the friction coefficient and wear volume was reduced.

Abstract: Embedded solid lubricant materials have good self-lubrication characteristics, which can realize lubrication in special some situations such as low-speed, high-load, high-temperature of the machinery without lubricating oil or grease. This paper presents a review concerning the structure of embedded solid lubrication materials, and its lubricating mechanism, the development of embedded solid lubricant materials, the latest research progress of the influence factors such as different types of metal substrates, mosaic, temperature, load, and porous structure and the application example of bearings. The feasibility of embedded solid lubrication materials which may be used in the mechanical seal face is also analyzed.

Abstract: Abstract. Two fluorosilicone oils as additives were evaluated using an Optimol SRV reciprocating friction and wear tester by gray cast iron disc against AISI 52100 steel ball at 20 N and sliding speed of 0.20 m/s, respectively. The morphologies of worn surface of the disc were examined using a scanning electron microscope (SEM). In addition, the elemental compositions and chemical states of several typical elements on the worn surfaces of the gray cast iron discs were examined by means of X-ray photoelectron spectroscopy (XPS). Results indicate that PAO(Poly-alpha-olefin)+F-Si-E exhibite excellent tribological properties. This is partly attributed to material properties and tribological reaction between the lubricant and the sliding surface.

Abstract: By using ordinary lathe, carried out cutting experimental study with cylindrical turning 45# steel on TiB2 ceramic cutting tool. By using Stereo Microscopy and Scanning Electron Microscopy, recorded cutting tool surface’s friction and wear conditions. The results showed that higher cutting speed could made surface roughness decrease and surface quality better; TiB2 ceramic cutting tool’s wear mechanism was abrasive wear, aoxidation wear; wear of blade tip and main flank face were more serious.

Abstract: The effects of hydrogen on friction and wear properties of Ti–6Al–4V alloy sliding against GCr15 steel were investigated through dry sliding friction and wear tests in atmosphere at room temperature. Wear mechanism was determined by studying the morphology and chemical element of worn surface using SEM and EDS. Results show that friction coefficient decreases slightly and wear rate increases after hydrogenation. Wear mechanism is discussed.

Abstract: Copper-graphite composites were fabricated by spark plasma sintering (SPS) and cold-pressed (CP) processing using a mixture of copper and graphite powders mechanically alloyed. Pin-on-disc wear was used to evaluate the tribological behavior of copper-graphite composites. The results show that the coefficient friction and wear rate decreased considerably with increasing graphite content; with increasing the sintering temperature, the coefficient friction and wear rate just decreased in the same way. XPS analysis of worn surface indicated that better tribological properties are due to a lubricious film covering almost entire worn surface. The presence of this tribolayer improves the friction and wear characteristics when the tribolayer covers almost entire wear surface it effectively restricts metal to metal contact between pin and disc.

Abstract: Hot stamping has become the main technology to produce complex-shaped high-strength steel components. However, hot sheet metal forming can cause high rates of die wear and the scratching of the productions. A hot drawing tribo-simulator was designed to investigate the friction and wear behavior of high strength steel at elevate temperature. The value of the friction coefficient was obtained to examine the function of the tribo-simulator. The results prove that the coefficient of friction in hot stamping can be measured using this tribo-simulator. Moreover, the coefficient of friction is able to be used in finite element simulation to improve the accuracy of the modeling results and it is also an important indicator to evaluate the tribological behavior between the die and sheet metal.

Abstract: The tribological performances of mixed PTFE-based composites were evaluated on the MM-200 block-on-ring test rig under dry friction condition. The following filler contents: carbon fiber (CF), flake graphite (FG) and spherical graphite (SG) were adopted to investigate their effects on the tribological performances of the composites. The experiments were carried out by a four levels orthogonal table-L₁₆（4³）, and the experiment data were deal with the methods of range and variance analysis. The results shown that all the filler contents could reduce wear, and the wear rate was stable when the content of fillers were more than 10 wt.%. The degrees of three fillers affecting the wear of composites were CF>FG>SG, and that affecting the friction coefficient were SG>CF>FG. The friction coefficient decreased with increasing the contents of SG, increased with that of CF, first decreased and then increased with that of FG. When the contents of FG is 15 wt.%, the friction coefficient is the lowest. The main worn form was adhesion wear.

Abstract: Aluminum bronze powders with free and 0.1wt%Ce were plasma spray welded on 45# carbon steel substrate, Effects of rare earth Ce on the microstructure and wear resistance of plasma spray welded novel aluminum bronze coatings were investigated. Tribological properties of coatings were tested on reciprocating sliding tester. Results showed that a small amount of Ce (0.1wt %) in novel aluminum bronze coating can refine the coating microstructure and the coating with 0.1wt%Ce process higher wear resistance compared to the Ce-free coating. Both of the coatings have different wear mechanisms.

Abstract: Polyoxymethylene (POM) composites filled with low-density polyethylene (LDPE) and sisal fibers (SF) were prepared by extrusion and injection molding. Sisal fibers were treated by various concentrations of NaOH solution to improve the poor compatibility between SF and matrix. Fourier transform infrared spectroscopy (FTIR) analysis and scanning electron microscope (SEM) test were used to confirm the surface treatment. The effects of SF alkaline treatment on the mechanical and tribological properties of POM composites were determined by using tensile test, impact test and friction and wear test. The worn surfaces of composites were investigated by SEM. Results showed that the composite filled with 12.5% NaOH treated SF exhibited the optimal mechanical and tribological properties among the all composites. The major wear mechanism of the composites was adhesive wear and abrasive grain wear.