Wear Of Steel Surfaces Research Articles

Influence of Temperature on the Fretting Wear of Steel Surfaces

Influence of Temperature on the Fretting Wear of Steel Surfaces

Effect of temperature on fretting wear of steel surfaces

A method is proposed to protect tribocouplings from fretting wear at higher temperatures, which exclude the use of lubricants. It is shown that during fretting wear of steel friction pairs, temperature is the main factor influencing the wear resistance of the joint. An installation is developed for testing samples under a fretting wear with heating. The wear resistance of a steel sample during fretting in tribocoupling with heating to 200 °C was experimentally determined. Keywords:steel, temperature, fretting wear, microstructure, wear resistance, fatigue roschin50@yandex.ru

Rheology and tribology of nanocellulose-based biodegradable greases: Wear and friction protection mechanisms of cellulose microfibrils

Dispersions of microfibrillated cellulose (MFC) in triethyl citrate have been considered as biodegradable lubricants containing 1–7 % MFC. Due to the presence of microfibril entanglements, these dispersions exhibit shear-thinning and shear-thickening behaviors, as well as viscoelastic properties of gels, which makes them typical greases. Moreover, the dispersions maintain their ability to flow at temperatures as low as −50 °C, being potentially applicable as low-temperature lubricants. Microfibrils reduce friction and wear of steel surfaces in two ways. Microfibrils in low concentrations fill irregularities of friction surfaces and decrease their wear, while microfibrils in high concentrations create a smooth chromium-enriched tribological film on the wear surfaces and largely reduce their friction.

Non-halogenated Ionic Liquid Dramatically Enhances Tribological Performance of Biodegradable Oils.

It is demonstrated that a phosphonium orthoborate ionic liquid may serve as a wear reducing additive in biodegradable oils at steel-steel surfaces in the boundary lubrication regime. Tribological tests were performed in a ball-on-three plate configuration. A set of surface characterization techniques—SEM/EDS, FIB and white light interferometry were used to characterize surfaces following the tribotests and to observe the formation of any tribofilms. 11B NMR was used to follow changes in the composition of the ionic-liquid-oil blends and to identify boron-containing decomposition products after the tribotests. The ionic liquid reduces the wear of steel surfaces by up to 92% compared to the neat oil at 90°C; it is shown that the reduction in wear can be correlated with the formation of boron enriched patches in the boundary films.

A Global Tribological Approach of Friction Dry Contact Polymer with SGF on Steel, in Terms of Consequences on Metallic Surface Condition (Comparative Wear Coefficients of Steel Surface)

In this paper, we present a global tribological approach of friction dry contact polymer with SGF on steel, in terms of consequences on metallic surface condition (comparative wear coefficients of polished steel surface) based on extensive experimental determinations between the value and the evolution of the friction coefficient, wear of steel surfaces and contact temperature, in the case of linear dry contact, for thermoplastic material reinforced with short glass fibers (SGF) and various steel surfaces. The aim was to highlight the evolution of the wear process depending on the friction coefficient, as well as the dependence of the loading wear and the sliding speed. Wear depth and volume were calculated based on the “wear imprint” method. As a result, it was possible to graphically illustrate the evolution of the friction coefficient, of the contact temperature, and the change of the wear process, emphasizing the abrasive, adhesive and corrosive wear. The evolution of the plastic material transfer function of the contact temperature, namely of the power lost by friction was highlighted. It has been demonstrated that in the case of a 30% SGF content it can reach and even exceed contact temperatures very close to the yield limit of the plastic material. The influence of the normal load and sliding speed was evaluated in detail. The influence of SGF content, normal load, relative sliding speed and contact temperature over the metal surface wear and over the nature of wear mechanism was recorded. The reaction to wear of different steel surfaces in linear dry friction contact on polymers with SGF (polyamide + 20% SGF, polyamide + 30% SGF and polycarbonate with 20% SGF), observing the friction influence over the metallic surfaces wear. The paper includes also its analysis over the steel’s wear from different points of view: the reinforcement content influence and tribological parameters (load, contact pressure, sliding speed, contact temperature, etc.). Thus, authors' findings related to the fact that the abrasive component of the friction force is more significant than the adhesive component are presented, which generally is specific to the polymers’ friction. Authors’ detections also state that, in the case of the polyamide with 30% glass fibres, the steel surface linear wear rate order are of 10-4mm/h, respectively the order of volumetric wear rate is of 10-6cm3/h. The resulting comparative volumetric wear coefficients are of the order (10-11to 10-12) cm3/cm and respectively linear wear coefficients of 10-9mm/cm.

Effect of Imidazolium Ionic Liquid Additives on Lubrication Performance of Propylene Carbonate under Different Electrical Potentials

Three different ionic liquids (ILs), 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm]BF4), 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIm]PF6) and 1-decyl-3-methylimidazolium hexafluorophosphate ([DMIm]PF6), were used as additives in the base ester propylene carbonate (PC) for the lubrication of AISI 4340 steel surfaces. Ball-on-disk friction tests were done under different electrical potentials to investigate the synergetic effect of IL concentration and electrical potential on lubrication performance, and electrochemical and ellipsometric tests were conducted to explore the adsorption of IL additives at different potentials. The friction reduction and anti-wear performance of the tested three IL/PC solutions illustrated similar dependence on electrical potential. In the potential range from −0.6 to +0.6 V, friction coefficient increases rapidly. When the potential is more negative than −0.6 V, friction coefficient is at the lower level of about 0.13. When the potential is greater than +0.6 V, friction coefficient is at the higher level of about 0.2. The electrochemical test results show that [DMIm]PF6/PC solution is the lowest in corrosion against AISI 4340 steel among the three tested lubricants. The wear of steel surface in 0.5 mM [DMIm]PF6/PC solution is reduced when electrical potential is shifted to −1.0 V comparing with that at open-circuit potential. The potential-dependent friction and wear behaviors are explained in terms of the variation of the adsorbed ion species and the surface concentration of the adsorbed ions under different additive concentration and electrical potential conditions.

Investigations of abrasive wear of steel surfaces strengthened by vibro-arc carbonization/layering

Friction and wear losses can be reduced by arc welding, tempering and other methods. One of these technologies is vibro-arc surface processing. By using this technology surface can be carbonized through the formation of extra layers with supplementary materials. The present work is an investigation of an opportunity to increase abrasive wear resistance of steel surfaces by carbonizing them by vibro-arc (80 and 120 A current) layering with a graphite electrode and by dip-transfer surfacing welded through layers that create paste-like coatings that consist of materials increasing resistance to wear. The investigations have been performed according to the standards of ASTM G65-94—Dry Sand Rubber Wheel Abrasion Test, and ASTM G132—Standard Test Method for Pin Abrasion Testing. Studies have shown that through surface carbonization layers are produced with a higher wear resistance than surfaces formed with the wear resistant powder PG-10N-01. When using carbonization, the wear resistance of steel surfaces increases by forming austenite synthetic (Fe0.94C0.06), cementite (Fe3C), iron oxide (Fe3.71O4) structures. Even with the wear resistance increased up to 39–41%, the carbonization creates just thin layers of 0.1–0.15 mm. Surface welding with current pulses by using additional materials generates high temperature gradients. This deteriorates coating quality resulting in uneven thickness, formed cracks, voids. The formation of austenite synthetic (Fe0.94C0.06), cementite (Fe3C), chromium nickel (Cr2Ni3), chromium iron carbide (Cr21.34Fe1.66C6), carbon iron (C0.09Fe1.91) structures in a layer increases hardness (average 6145–6310MPa). Although the strengthened layer is much harder than steel Hardox 400, under abrasive wear conditions it has only 20–23% less wear resistance than Hardox 400. Due to surface defects, significant increases in hardness have almost no influence on the wear resistance. Surface quality is increased by welding at a lower current. Because just a thin layer is formed, the carbonization process is not an efficient technology to increase the abrasive wear resistance.

Unsaturated Fatty Acids in Alkane Solution: Adsorption to Steel Surfaces

Fatty acids and blends of fatty acids are used as friction modifiers and anti-wear additives in diesel fuels. A large part of some fatty acid blends are unsaturated fatty acids. Even though fatty acids have been thoroughly investigated, the adsorption and tribological behaviour of unsaturated fatty acids are no fully understood. The aim of this thesis was to investigate the influence of fatty acid unsaturation on the adsorption from alkane solution and the tribological properties, such as friction and wear scar characterization, of such systems. To increase the fundamental understanding of the influence of the degree of fatty acid unsaturation the three fatty acids, oleic, linoleic and linolenic acid, have been studied. In boundary lubrication the amount of material and how well the material is bound to the surface can affect the friction and wear of the system. Thus, as a first step the adsorption of fatty acids onto steel surfaces was investigated with the quartz crystal microbalance (QCM). This technique is straight forward to used and is ideal for these samples that are difficult to investigate with optical techniques due to small differences in refractive index between the alkane solvent and fatty acid. To determine the chemical binding to steel surfaces static secondary ion mass spectroscopy (SIMS) has been used. Next, the influence of fatty acid unsaturation on the friction and wear was determined. Two different studies were made, one on a molecular level with the tribological surfaces forces apparatus (T-SFA) and the other one with a technique used for determining friction and wear of diesel fuel additives. The T-SFA technique provides data from which the packing of the fatty acids at mica surfaces can be estimated as well as how the friction is altered due to the packing. For determining the friction and wear of steel surfaces the high frequency reciprocating rig (HFRR) and pin on disc apparatus (POD) were used. The HFRR is a standardized technique, where, if the settings specified in the ISO12156 protocol are used, a diesel fuel additive must provide an average wear scar radius less than 0.230 mm to pass. The wear scars received from the two techniques were further analysed with Raman spectroscopy and also a visual rating of the wear scars was performed. As the project progressed, there was an increasing interest in the influence of water on the adsorption and lubricating properties of the fatty acids. Moisture uptake of the fatty acids was therefore determined gravimetrically as well as with nuclear magnetic resonance spectroscopy (NMR). The adsorption of the moist fatty acids onto steel surfaces was then investigated with QCM and static SIMS, while HFRR and POD were used for investigate the friction and wear.

Experimental study by means of thin layer activation of the humidity influence on the fretting wear of steel surfaces

Wear processes in general are influenced by the surrounding atmosphere, humidity especially. For fretting wear several authors have examined the influence of humidity on the wear scar morphology, the wear volume and the composition of the wear debris. No agreement between the different results has been found, yet. In the present study, the influence of the humidity in the ambient air on the fretting process is examined. The friction, the wear volume and material transfer are measured for the fretting of a bearing steel ball against a flat steel specimen under gross-slip regime, in running-in as well as steady state conditions. The wear and material transfer are quantitatively measured with Thin Layer Activation method. It has been observed that high ambient humidity inhibits adhesion and accompanying material transfer. As a result, high humidity has a beneficial influence on fretting wear, in opposition to generally accepted hypothesis.

A comparative study of different wear measurement techniques applied to fretting wear of a spherical against a flat steel specimen

AbstractOne of the main problems in fretting wear research is accurate measurement of the very small wear volumes (in microgams) produced. Different techniques, with their own advantages and disadvantages, can be used. Classic wear techniques lack sensitivity and often fail to measure the fretting wear volumes at all, or are not accurate enough. The authors have developed a Thin Layer Activation (TLA) method for quantification of the fretting wear of steel surfaces. The same method can also be used to determine material transfer between wear specimens. In this paper, the different methods are reviewed, and their accuracy in terms of the fretting wear measurement of steel surfaces is discussed. It is concluded that TLA has relatively good reproducibility and accuracy in comparison with classic fretting wear measurement techniques, such as normal approach measurement and spherical cap modelling. Modern threedimensional profilometry has better reproducibility than TLA, but is afflicted by systematic errors because of the oxidation of the metal surface. The different methods emphasise different features of the fretting process, and it is advisable to use them together for measuring fretting wear; their combined use provides a better understanding of the fundamentals of the fretting wear process.

The Influence of Humidity on the Fretting Wear of Steel Surfaces Using Thin Layer Activation

It is generally known that the humidity in the surrounding atmosphere influences wear processes in general. For fretting wear several authors examined the influence of humidity on the wear scar morphology and the composition of the wear debris. No agreement between the different results has been found, yet. In the present study, a distinction is made between running-in and steady-state fretting wear. Especially for the running-in stage, the influence of the humidity in ambient air on the friction and wear behavior and material transfer of steel surfaces subjected to contact vibrations has been investigated. The fretting experiments were conducted with a spherical against a flat specimen under gross-slip regime. The fretting wear and accompanying material transfer between the contacting specimens quantitatively are measured with Thin Layer Activation method. It has been observed that high ambient humidity has a beneficial influence on the running-in fretting wear of steel surfaces. It has also been found that the results of several authors concerning the influence of humidity on the fretting wear of steel have to be treated with great care, as classical wear measuring techniques can give erroneous wear results.

Slow Speed Wear of Steel Surfaces Lubricated by Thin Oil Films

Time rates of wear and distance rates of wear are presented as a function of calculated oil film thickness between two cylindrical steel rollers loaded to a maximum Hertz contact stress of 300,000 psi. Wear is divided into a constant wear mode and a transient wear mode depending on the oil film thickness. A negative slope of the curve representing the distance rate of wear versus oil film thickness explains the stabilizing effect on radial surfaces. A positive slope in a narrow range of oil film thickness causes a surface instability due to wear and surface rippling occurs. Transient wear occurs at the thicker oil films. When followed by zero wear rate surface oxide films develop. The total amount worn off during the transient varies greatly with the oil film thickness when using rollers of a given surface finish. Control of oil film thickness by either velocity or viscosity changes due to tempearture produces similar wear effects.