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Impact-sliding experiments were performed by using four self-made lithium-based greases, namely Yangtze Grease 1, Yangtze Grease 2, Yangtze Grease 3, and Yangtze Grease 4. The influence of base oil viscosity, thickener content, and morphology of thickener fiber clusters on the lubricating state were visually explored, combined with field-emission microscopy and two-light interference technology. The grease film distribution at the middle section was measured using Dichromatic Interference Intensity Modulation (DIIM) software. All experiments were executed in a completely flooded environment. The results show that among the components of grease, the base oil's viscosity has the greatest impact on the anti-wear performance of the grease. As the viscosity of the base oil increases, the grease exhibits better anti-wear performance. The grease film thickness under the condition of high-viscosity base oil is about 10 times higher than that under the condition of low-viscosity base oil. Secondly, the content of thickener in the grease needs to be controlled within a reasonable range. The experiments indicate that the effect of thickener content on the grease's film-forming properties becomes more pronounced at higher speeds. From the experiment using YG 4, it can be seen that a higher thickener content under high-speed conditions increases the thickness of the lubricating grease film by about 10 times. The dimensions of the thickener fibers and the density of their entanglement structure significantly influence the rheological properties and load-bearing capacity of the grease. Larger fiber sizes and higher entanglement densities result in reduced grease fluidity and recovery but enhance its load-bearing capabilities. In order to obtain the best anti-wear performance during impact-sliding motion, the size of the thickener fiber and the density of the entanglement structure need to be controlled within an appropriate range. [ABSTRACT FROM AUTHOR]

Impact-sliding experiments were performed by using four self-made lithium-based greases, namely Yangtze Grease 1, Yangtze Grease 2, Yangtze Grease 3, and Yangtze Grease 4. The influence of base oil viscosity, thickener content, and morphology of thickener fiber clusters on the lubricating state were visually explored, combined with field-emission microscopy and two-light interference technology. The grease film distribution at the middle section was measured using Dichromatic Interference Intensity Modulation (DIIM) software. All experiments were executed in a completely flooded environment. The results show that among the components of grease, the base oil’s viscosity has the greatest impact on the anti-wear performance of the grease. As the viscosity of the base oil increases, the grease exhibits better anti-wear performance. The grease film thickness under the condition of high-viscosity base oil is about 10 times higher than that under the condition of low-viscosity base oil. Secondly, the content of thickener in the grease needs to be controlled within a reasonable range. The experiments indicate that the effect of thickener content on the grease’s film-forming properties becomes more pronounced at higher speeds. From the experiment using YG 4, it can be seen that a higher thickener content under high-speed conditions increases the thickness of the lubricating grease film by about 10 times. The dimensions of the thickener fibers and the density of their entanglement structure significantly influence the rheological properties and load-bearing capacity of the grease. Larger fiber sizes and higher entanglement densities result in reduced grease fluidity and recovery but enhance its load-bearing capabilities. In order to obtain the best anti-wear performance during impact-sliding motion, the size of the thickener fiber and the density of the entanglement structure need to be controlled within an appropriate range.

In this article, a new impact-sliding wear test setup was developed to investigate the impact-sliding tribological/wear behavior of manganese (Mn) additive iron-based hardfacings. The effect of increased Mn content from 0 to 13 wt% on the wear characteristics was examined for a constant load of 200 N, 1000 impacts and 50 strokes/min speed. Hardness evaluation tests revealed that the hardness was increased after the impact-sliding wear tests. The worn surfaces of hardfacings/alloys/hardfacing alloys containing 0 and 8 wt% Mn presented a similar mechanism of micro-abrasion, but the damage caused by the abrasion in 8 wt% Mn additive hardfacings was not so effective in comparison to the hardfacing containing 0 wt% Mn. Above 8 wt% Mn addition, oxidative wear became the dominant wear mechanism with the formation of protective tribo-oxide layers and the wear trend exhibited enhancement in the wear resistance of hardfacings. On the other hand, subsurface analysis showed severe damage under the tribo-oxide layer, which revealed that the wear trend is not an exact indicator of wear resistance of the material. Wear behavior of the hardfacings has been successfully correlated with the hardness, morphology of the worn surfaces and subsurfaces. [ABSTRACT FROM AUTHOR]

To compare the impact-sliding wear of different CAD/CAM resin-ceramic materials and tooth enamel, and explore the corresponding wear damage mechanism. Human tooth enamel (EN), Vita ENAMIC (Vita, VE), Lava Ultimate (3 M, LU), and GC CERASMART (GC, CS) were used in this study. The hardness, elastic modulus, and roughness values of the samples were measured. Further, impact-sliding wear tests were performed in a ball-on-flat configuration with spherical zirconia antagonists and the coefficients of friction (CoF) were recorded simultaneously. Additionally, a white light interferometer was used to determine the volume losses and scanning electron microscopy was used to observe the wear morphology of the wear scars and the damage feature in the vertical sections to clarify the damage mechanism during the impact-sliding wear test. EN exhibited the highest elastic modulus and CoF, followed by VE, LU, and CS. The hardness and roughness of EN and VE were similar and were higher than those of LU and CS. Throughout the wear tests, VE exhibited the highest volume loss, whereas CS exhibited the lowest. The wear damage characteristics of VE were similar to those of EN, displaying brittle fractures of inorganic substances and plastic deformation of organic substances in the impact part, exhibiting plough marks in the sliding parts. In the case of LU and CS, the entire wear areas displayed plastic deformation of the resin matrix, exfoliation of the filler particles, and plough marks. Enamel and polymer-infiltrated ceramic network materials exhibit similar wear damage modes. Additionally, the high-density nanocomposite resin material is the most resistant to impact-sliding wear from a tribological perspective. • Enamel and polymer-infiltrated ceramic network have similar wear behaviour. • High density composite resin is the most impact-sliding wear resistant material. • The impact-sliding wear damage pattern of CAD/CAM resin ceramics is closely related to their microstructure [ABSTRACT FROM AUTHOR]

In industrial chain drives, the sleeve slides on the pin and impact loading occurs due to the polygon effect, while the collision between the ball and cage usually produces an impact-sliding motion in the rolling element bearings. Aiming at addressing the occurrence of surface damage caused by the impact-sliding motion, a ball–disk test rig employing optical interference technology was designed and built to realize load variation. Two kinds of commercial grease types, Klüber Centoplex 3 and Centoplex 2EP, were used in the experiments when the glass disk slides at a constant speed while the steel ball collides into them. The sliding and impact motions were controlled by PLC programming. After the experiments, the mid-section grease film distributions were measured using DIIM software. The results show that surface damage can rapidly occur even in the first working cycle, and that the phenomenon is affected by the sliding speed, maximum load, and grease consistency. When the sliding speed is low, multiple contacts of asperity peaks occur in the interior contact region and develop into adhesive wear. When the sliding speed increases, surface wear starts to occur at the side-lobe position of the elastohydrodynamic lubrication (EHL) horseshoe shape and extends with time accompanied by obvious surface scratches. The wear mechanism investigated provides valuable visible information for the further exploration of impact-sliding composite wear. It is suggested that great attention should be paid to impact-sliding wear occurring with grease lubrication since such working conditions are very common in industrial applications. [ABSTRACT FROM AUTHOR]

The impact-sliding wear behavior of steam generator tubes in nuclear power plants is complex owing to the dynamic nature of the mechanical response and self-induced tribological changes. In this study, the effects of impact and sliding velocity on the impact-sliding wear behavior of a 2.25Cr1Mo steel tube are investigated experimentally and numerically. In the experimental study, a wear test rig that can measure changes in the impact and friction forces as well as the compressive displacement over different wear cycles, both in real time, is designed. A semi-analytical model based on the Archard wear law and Hertz contact theory is used to predict wear. The results indicate that the impact dynamic effect by the impact velocity is more significant than that of the sliding velocity, and that both velocities affect the friction force and wear degree. The experimental results for the wear depth evolution agree well with the corresponding simulation predictions. [ABSTRACT FROM AUTHOR]

In industrial chain drives, the sleeve slides on the pin and impact loading occurs due to the polygon effect, while the collision between the ball and cage usually produces an impact-sliding motion in the rolling element bearings. Aiming at addressing the occurrence of surface damage caused by the impact-sliding motion, a ball–disk test rig employing optical interference technology was designed and built to realize load variation. Two kinds of commercial grease types, Klüber Centoplex 3 and Centoplex 2EP, were used in the experiments when the glass disk slides at a constant speed while the steel ball collides into them. The sliding and impact motions were controlled by PLC programming. After the experiments, the mid-section grease film distributions were measured using DIIM software. The results show that surface damage can rapidly occur even in the first working cycle, and that the phenomenon is affected by the sliding speed, maximum load, and grease consistency. When the sliding speed is low, multiple contacts of asperity peaks occur in the interior contact region and develop into adhesive wear. When the sliding speed increases, surface wear starts to occur at the side-lobe position of the elastohydrodynamic lubrication (EHL) horseshoe shape and extends with time accompanied by obvious surface scratches. The wear mechanism investigated provides valuable visible information for the further exploration of impact-sliding composite wear. It is suggested that great attention should be paid to impact-sliding wear occurring with grease lubrication since such working conditions are very common in industrial applications.

Awear test set-up is designed and employed to investigate the damage behavior and failure mechanisms of cemented carbide against Si3N4 ceramic under impact-sliding wear conditions to understand the damage trend of cutting tools under complex relative motions. The wear profile, damage morphology, and chemical components of the cemented carbide are analyzed for different number of test cycles. The results demonstrate that the damage type of the cemented carbide under impact-sliding wear conditions is primarily delamination of the impact area, whereas the damage of the sliding zone is negligible. The damage characteristics of impact-sliding wear of cemented carbide do not change significantly with an increase in the number of cycles, but the wear rate decreases. Oxidative wear is observed in the impact area, producing black wear debris consisting of WO3. The failure of the cemented carbide under impact-sliding wear conditions is primarily mainly caused by delamination induced by fatigue wear, as well as oxidative wear. [ABSTRACT FROM AUTHOR]

Abstract In many industrial devices, impact-sliding wear is caused by a variety of complex vibrations between the contacted interfaces. Under actual conditions, impact and sliding motions do not occur in only one direction, and different complex impact-sliding motions exist on the tribology surfaces. In this study, an impact-sliding wear test rig is developed to investigate the wear effect of different complex motions. Using this rig, multi-type impact-sliding wear effects are realized and measured, such as those derived from unidirectional, reciprocating, and multi-mode combination motions. These three types of impact–sliding wear running behavior are tested and the wear damage mechanism is discussed.

Impact-sliding wear is a typical form of composite wear and occurs in many industrial equipment. The effects of structural stiffness on the impact-sliding wear damage and mechanisms of aluminum alloy were investigated using a bespoke impact-sliding device. The damage evolution and mechanisms of the impact-sliding wear for three different structural stiffness conditions were analyzed. Results showed that the main damage zone gradually shifted along the sliding direction with the increase in the structural stiffness. The wear damage of the material was higher for the low and high structural stiffness conditions and resulted in a very rough surface. However, for the medium structural stiffness, the impact-sliding wear exhibited a slow and linear increase and relatively smooth wear scars were observed. Moreover, the main wear mechanism transformed from delamination to ploughing as the structural stiffness increased. [ABSTRACT FROM AUTHOR]

In many industrial devices, impact-sliding wear is caused by a variety of complex vibrations between the contacted interfaces. Under actual conditions, impact and sliding motions do not occur in only one direction, and different complex impact-sliding motions exist on the tribology surfaces. In this study, an impact-sliding wear test rig is developed to investigate the wear effect of different complex motions. Using this rig, multi-type impact-sliding wear effects are realized and measured, such as those derived from unidirectional, reciprocating, and multi-mode combination motions. These three types of impact-sliding wear running behavior are tested and the wear damage mechanism is discussed. [ABSTRACT FROM AUTHOR]

Abstract This paper focused on the suitability of laser shock peening (LSP) to impact-sliding wear in different system stiffnesses to improve the performance of aluminum alloy (AlSi7Mg0.6) used in high-speed catenary parts that encountered impact-sliding wear failure. The effects of different laser energies or multiple shocks were examined in low, medium and high system stiffnesses. Results showed that low laser energy LSP formed a uniform and consistent strengthening layer and exhibited excellent wear reduction for low and medium system stiffnesses. Higher laser energy or multiple shocks of LSP both improved the micro-hardness and depth of the strengthening layer, but more defects in the form of micro-cracks and voids appeared in the strengthening layer. These defects had negative effects on the wear resistance to delamination, resulting in inferior wear performance under low and medium system stiffnesses. However, LSP with some micro-cracks performed the best wear reduction for high system stiffness, with only 16% wear to the untreated sample. This was due to micro-cracks altering the damage mechanism from ploughing to delamination. The LSP with many void defects exhibited poor wear performance under the three system stiffnesses because voids weakened resistance to both delamination and ploughing. Therefore, LSP was suitable for improving the wear resistance of AlSi7Mg0.6 to impact-sliding wear under different system stiffness conditions, but the parameters must be carefully controlled. Highlights • Suitability of LSP to impact-sliding wear is studied in varied system stiffnesses. • State of strengthening layer strongly influences the suitability of LSP. • Low laser energy LSP with no obvious defects exhibits the best wear performance. • High laser energy or multiple shocks have negative effects on impact-sliding wear. [ABSTRACT FROM AUTHOR]

The role of the S-phase layer formed after low-temperature nitriding on the wear resistance of a 17Cr-10Ni-2Mo stainless steel at room and sub-zero temperatures was investigated by using an impact-sliding wear tester, simulating the progress of surface degradation on engineering components under dynamic loading. While the as-received samples suffered from plasticity-dominated wear, surface cracking was dominant for the nitrided samples. Both of the samples exhibited lower wear rates with decreasing test temperature. The highest contact pressure employed (3 GPa) caused spallation of the ∼3 µm thick S-phase layer at room temperature, unlike sub-zero temperature. Under this highest contact pressure, the thicker S-phase layer (∼6 µm) remained intact with the substrate and provided good protection against wear at room temperature. • Impact-sliding wear behavior of S-phase layer covered ASS was examined. • Lower wear rates were obtained at SZT as compared to RT. • S-phase layer provided good wear protection at SZT under extreme contact pressures. • High contact pressures raised the wear rate at RT upon spallation of S-phase layer. • Thickening of S-phase layer prevented spallation and yielded lower wear rate at RT. [ABSTRACT FROM AUTHOR]

Outer particle collision with certain dynamic objects is not a pure impact wear behavior; it is typically accompanied by sliding wear phenomena. This study is aimed at investigating the impact-sliding wear performance of three different TC17 titanium alloys. One was untreated, and the other two were subjected to laser shock peening (LSP) by 5 and 7 J pulse energy, respectively. The wear test was performed on a novel impact-sliding wear testing rig, which can realize multiple impact-sliding motions by changing motion parameters in the x and z directions. Present results showed that wear resistance of both treated samples improved compared with the untreated alloy. Given the increase in wear cycles, increment in wear rate of the untreated sample was constantly higher than those of the treated samples. All results can be attributed to the increase in surface hardness of the material and residual compressive stress, which was also introduced after LSP.

This study investigates the mechanism of wear damage of human tooth enamel by applying reciprocating impact-sliding wear tests. Two sliding loads (20 N, 49 N) were applied. In general, greater the load, greater the wear damage. The wear tracks could be divided into the impact part and the sliding part, and the wear characteristics of enamel were different between two parts. Impact wear in the impact part displayed plastic deformation, quasi-plastic deformation and brittle fracture. Sliding part with abrasive wear exhibited microscale cutting and plowing processes. The impact motion was the main cause for the loss of enamel in the early stage which led to higher wear rate and a larger enamel loss. The sliding movement was the main reason for the loss of enamel in the later stage of the experiment which led to a steady wear rate and moderate material loss. • The vertical load plays a role in the cycle-dependent wear behavior of enamel under the impact-sliding motion. • Impact wear is the main mechanism for the impact part. • Abrasive wear was responsible for the sliding part. • The impact part displayed plastic deformation, quasi-plastic deformation and brittle fracture. • The sliding part exhibited microscale cutting and plowing processes. [ABSTRACT FROM AUTHOR]

Wear behaviour of quenched and tempered (QT) hot work tool steels (Uddeholm QRO90) was investigated against SAE 52100 grade bearing steel balls after gas nitriding using a dedicated laboratory scale impact-sliding wear test rig. Gas nitriding was employed in a fluidised bed reactor under two alternative regimes: i. "High Temperature Nitriding (HTN)" carried out at 510 °C and ii. "Low Temperature Nitriding (LTN)" carried out at ≤ 400 °C. The HTN process resulted in the formation of ∼2 μm thick external compound layer, whereas the LTN processed steels were free of any surface compound layer formation. After the impact-sliding wear tests employed at room temperature (RT), the prevailing wear mechanisms of the examined steels were assessed as tribo-oxidation and fatigue wear. The testing at 600 °C induced different wear mechanisms for the HTN and the LTN steels. While tribo-oxidation and fatigue wear were preserved for the HTN steel, plastic deformation dominated the wear that progressed on the compound layer free surface of the LTN steel. Impact-sliding wear testing at 600 °C showed that the wear rate of LTN > HTN steels, as opposed to the wear rate at RT where wear rate of HTN > LTN. • Impact-sliding wear tests conducted on nitrided hot work tool steels. • Compound layer free steel exhibits comparatively high wear resistance at RT. • 2 μm thick exterior compound layer provides higher wear resistance at 600 °C. [ABSTRACT FROM AUTHOR]

Abstract: After their introduction by Godet and co-workers, the concept of the third body has been extensively applied to understand the effect of interfacial films arising between sliding bodies, and the effect of oxides is a key factor to explain the friction and wear under oxidative environments. Most of oxides remain into the contact as a protective layer governing the tribological behavior of metallic surfaces. In many industrial applications, and especially in transports, the machinery and equipment are often subjected to combined attacks of impact and sliding leading then to surface damage. An application where these effects are determinant is the valve-seat contact of internal combustion engines, especially the new generation of diesel engines due to very high pressures. The surface of the seat is subjected to repetitive impact actions of the valve, with small amplitude sliding in the interface. Investigating effects of the behavior of materials used in the present under the action of impact-sliding under temperatures up to 400°C would help to gain better understanding of the failure mechanisms and to establish the guidelines for future improvements, namely concerning surface treatments. The present research was carried out to study the combined aspects of impact and sliding wear. [Copyright &y& Elsevier]

Abstract: In nuclear power plants, tubes and guides of the rod cluster control assemblies undergo impacts at low contact pressures, which lead to a specific wear of the contact surfaces. The aim of this paper is to propose a first explanation of this particular wear with the help of finite element simulations and experimental observations. In a first part, we present some experimental observations, obtained using a tribometer specially designed for this application by AREVA NP, which allows to reproduce the wear scars in the same environment and with equivalent loading conditions. In a second part, we detail the numerical model. More specifically, we consider that the impact-sliding process can be modelled by a scratching process of a double-layered material (stainless steel recovered by a friction film) with a rigid spherical asperity. The mechanical behaviour of these materials comes from instrumented nanoidentation tests and the geometric parameters are deduced from experimental observations. From both the numerical results and the experimental observations, a wear mechanism is then proposed. Finally, we conclude on the capability of finite element analysis to improve the understanding of specific wear phenomena when it is combined to experimental results. [Copyright &y& Elsevier]

Various impact-sliding wear behaviors commonly occur among steam generator tubes and their supporters. The main purpose of this study is to investigate the effect of ultrasonic surface rolling process (USRP) on the impact-sliding wear behavior of Inconel 690 alloy tubes. A self-made two-dimensional cycling impact-sliding wear test rig was developed to realize multiple wear patterns by changing motion parameters in both impact and sliding directions. Tests were carried out under different impact and sliding velocities. Results indicated that USRP reduced the impact kinetic energy absorption rate, friction coefficient and increased the wear resistance of Inconel 690 alloy. These can be attributed to the USRP which decreased the grain size of 690 alloy, resulting in the increase of micro-hardness and compressive residual stress. Image 1 • USRP is capable to refine microstructure, improve micro-hardness and compressive residual stresses of 690 alloy tubes. • USRP treated samples showed better wear resistance and lower friction coefficient under impact-wear sliding condition. [ABSTRACT FROM AUTHOR]

Wear behaviors of materials in nuclear power stations are very complex, because they are rarely subject to just pure impact or sliding wear. This study uses a self-made impact-sliding wear test rig to study the influences of impact kinetic energy and sliding velocity on the energy absorption, mechanical response, interface deformation, and damage behavior of nuclear-grade 304 stainless steels (304SS). The results show that an increase in impact velocity causes an increase in absorbed energy, impact force, and friction force, while lowing the friction coefficient. The friction force and friction coefficient increase with an increase in the sliding velocity, whereas no obvious change is seen in impact force and absorbed energy. The dominant wear mechanism in test samples were delamination failure and friction oxidation. Furthermore, numerical study was performed to explain the effect of velocity on the mechanical response of 304SS. • The impact-sliding wear test rig is capable of testing the wear behaviors of different materials under various complex conditions. • Effect of different impact kinetic energies and sliding velocities on the impact-sliding wear behaviors of nuclear material was studied. • Effect of impact kinetic energies on the dynamic response of impact-sliding wear is more obvious than that of the sliding velocities. [ABSTRACT FROM AUTHOR]

Outer particle collision with certain dynamic objects is not a pure impact wear behavior; it is typically accompanied by sliding wear phenomena. This study is aimed at investigating the impact-sliding wear performance of three different TC17 titanium alloys. One was untreated, and the other two were subjected to laser shock peening (LSP) by 5 and 7 J pulse energy, respectively. The wear test was performed on a novel impact-sliding wear testing rig, which can realize multiple impact-sliding motions by changing motion parameters in the x and z directions. Present results showed that wear resistance of both treated samples improved compared with the untreated alloy. Given the increase in wear cycles, increment in wear rate of the untreated sample was constantly higher than those of the treated samples. All results can be attributed to the increase in surface hardness of the material and residual compressive stress, which was also introduced after LSP. [ABSTRACT FROM AUTHOR]