Role In Lubrication Research Articles

In Situ Synthesis of (M:Nb,Ta)C/Ni35 Composite Coating Cladded on 40Cr Steel.

To improve the wear and corrosion resistance of the pump barrel material (40Cr steel), a (M:Nb,Ta)C/Ni35 composite cladding coating by in situ synthesis of composite carbides was conducted. The effects of ceramic micro-particles content on the phase composition, microstructure of the coating, structural characteristics of (M:Nb,Ta)C and the tribology and electrochemical corrosion behavior were systematically studied. The increase of ceramic micro-particles changed the morphology of (M:Nb,Ta)C with the size from sub-micron to micron. The (M:Nb,Ta)C dispersed along the grain boundary inhibits the growth of the grains. During friction, the spherical structure exhibited a rolling lubrication effect and the petal structure provided a stronger attachment ability to resist the shear. The corrosion occurred at the grains, exhibiting corrosion pits, in which the high content ceramic micro-particles were relatively shallow. Moreover, a few dot corrosion pits were distributed along the grain boundaries without (M:Nb,Ta)C. Therefore, to improve the corrosion resistance, a thin composite carbide coating with good wear and corrosion resistance was prepared.

Interfacial interaction induced synergistic lubricating performance of MoS2 and SiO2 composite nanofluid

SiO 2 was employed as an auxiliary lubricant for MoS 2 nanofluid to gain superior lubricating effect. Tribological properties and cold rolling lubrication performance of pure SiO 2 nanofluid, pure MoS 2 nanofluid and the MoS 2 +SiO 2 composite nanofluid were investigated to reveal the synergistic lubrication of MoS 2 nanosheets and SiO 2 nanoparticles. The results of tribological tests indicated that the composite nanofluid with κ (mass ratio of MoS 2 and SiO 2 ) ≥1 showed more excellent tribological properties than pure MoS 2 nanofluid depended on a low shear composite lubricating film formed on steel surface. The formation mechanism of the composite lubricating film was investigated through both experimental characterization and molecular dynamics simulation. During cold rolling process, SiO 2 nanoparticles which did not readily adsorb to steel surface firstly absorbed on the surface of MoS 2 . And then adsorb on the steel surface together with MoS 2 in virtue of the adsorption between MoS 2 and steel surface. A pressurized interlayer slip theory was creatively provided to explain the synergistic lubrication mechanism of the low shear composite lubricating film. The SiO 2 adsorbed on MoS 2 nanosheets changed the contact type between MoS 2 nanosheets from surface contact to point contact. Thus, the normal pressure on the surface of MoS 2 nanosheets was increased. According to the results of molecular dynamics simulation, the increase of normal pressure promoted the interlayer slip and reduced the friction coefficient between MoS 2 nanosheets. The relationship between lubrication mechanism and the mass ratio of MoS 2 and SiO 2 was also investigated to provide a systemic understanding of the synergistic lubrication performance. • SiO 2 could be used as an auxiliary lubricant for MoS 2 nanofluid. • The formation mechanism of the composite lubricating film was investigated. • A pressurized interlayer slip mechanism was creatively provided. • Sustainable lubrication mechanism of the composite nanofluid was studied.

Enhanced lubrication performance of triethanolamine functionalized reduced graphene oxide on the cold‐rolled surface of strips

Triethanolamine functionalized reduced graphene oxide (rGO‐TEA(s)) nanocomposites have been synthesized by the hydrothermal method. The physical and chemical properties of rGO‐TEA(s) with different degrees of functionalization were characterized by transmission electron microscopy, X‐ray powder diffraction, Raman spectroscopy, and X‐ray photon spectroscopy. The cold rolling lubrication of the rGO‐TEA(s) prepared as nano‐lubricant additives were investigated using a two‐high rolling mill. The microscopic topographies of rolled strips were measured and evaluated by several physical characterizations. The results showed that the increase of functionalization time was favored to the reaction of triethanolamine and C–O–C groups on the GO surface, whereas the defects and disorder in graphene structure were repaired according to the intensity ratio of the D band to G band from 1.154 to 1.130. The cold rolling experiment results demonstrated that rGO‐TEA(s) exhibited excellent lubrication properties, especially the rolled surface lubricated by rGO‐TEA‐10h presented few defects and minimum roughness value. The admirable lubrication performance of rGO‐TEA‐10h was attributed to the formation of absorption film and consecutive carbonaceous protective film.

A study of water-based lubricant with a mixture of polyphosphate and nano-TiO2 as additives for hot rolling process

Hot rolling is one of the most widely used hot metal forming processes by shaping the hot workpiece with cylindrical rolls. Its harsh working conditions, including high loading (up to 0.5 GPa), elevated temperature (600–1100 °C) and high speed (above 10 m/s), lead to the problems of high friction, severe wear, oxidation at the tool/workpiece rubbing surfaces. Lubricants are essential to reduce the rolling force, prolong the service life of work rolls, and improve overall process efficiency. In this work, the mixture of sodium polyphosphate and nano-TiO2 as water-based hot rolling lubricants were studied using a laboratory hot rolling mill. Aqueous lubricant with 2 wt.% TiO2 in 20 wt.% sodium polyphosphate demonstrates an excellent lubrication performance with a reduction of a rolling force of 10% compared to pure water lubrication condition. The sodium polyphosphate can not only act as a surfactant to improve the dispersibility of TiO2 nanoparticles in water, but also form an easily sheared glass melt at high temperature to lubricate the workpiece/roller. Focused ion beam and transmission electron microscope analysis of the sliding interface demonstrate that some nano-TiO2 were contained in the polyphosphate melt. The concept that combines the inorganic polymer with nanoparticles to produce the synergy effects of glass lubrication and nanoparticle lubrication can provide new insight into the design of lubricants for the hot metal forming process.

Research and application of approximate rectangular section control technology in hot strip mills

Profile requirements of silicon steel strip are extremely high and the thickness difference of cold-rolled products is usually less than 7 μm, and the profile quality of hot-rolled strip is the key to ensure the thickness difference of cold-rolled products. In order to produce the silicon steel strip with high-precision shape, the concept of quasi-rectangular rolling during hot continuous rolling was put forward; the equipment configuration and technical method of approximate rectangular section control were studied. Through the roughing multi-target load distribution technology and the roll configuration technology for uniform wear of a 4-high rolling mill, the strip crown of transfer bar was reduced and the profile control stability was guaranteed. Configuring variable contact back-up roll technology on all stands in the finishing rolling process, equipped with symmetry variable taper work roll and long-stroke intelligent shifting strategy in the downstream stands, and using side rolling lubrication technology can make the roll wear more uniform, reduce the edge drop of silicon steel strip, improve the profile quality, and make the strip section of finishing exit "quasi-rectangular". In addition, induction furnace and side heater were also equipped to guarantee the temperature uniformity of the strip, so as to improve the stability of profile control. The whole control technology is based on the 1580-mm hot continuous rolling production line, designed, and developed according to the characteristics of equipment and products, and has been successfully applied, which can obtain the approximate rectangular strip section satisfying the flatness quality, and improve the strip section precision of silicon steel and other products.

Tribological Behaviors and Lubrication Mechanism of Water-based MoO3 Nanofluid during Cold Rolling Process

The MoO3 nanofluid was prepared by mixing deionized water with MoO3 nanoparticles and some other organic additives. The tribological behaviors of prepared MoO3 nanofluid in various nanoparticle concentrations were tested by four-ball tribotester. The results obtained therein revealed that the dispersion of the nano-MoO3 in water was conducive to the reduction of friction coefficients and wear volume, and the increase in the load-bearing capacity, especially the optimal concentration of additive was 0.4 wt.%. To investigate the lubrication mechanism of water-based MoO3 nanofluid under steel cold rolling condition, cold rolling lubrication performance of 0.4 wt.% MoO3 in water-based fluid was evaluated using a four-high rolling mill. The rolling outputs such as rolling force, rolling power and reduction were used as measurands for determining the process efficiency. Erosion corrosion was found to happen during steel cold rolling process, MoO3 was transformed to MoO2 and iron was oxidized to iron hydroxide. A lubricating film composed of MoO3, MoO2 and Fe(OH)3 was considered to form on strip surfaces due to chemisorption and deposition of MoO3.

Effect of Shear Strength of Oil on Lubrication of Cold Strip Rolling in Full-Fil Regime

Cold strip rolling is a major deformation process in industry. The need for high quality products and increased production speed, makes the application of the lubricant important. In the present study, oil property effect is investigated in cold rolling using oil lubricant in full-film lubrication regime. The model predicts decisive role of oil property in rolling parameters.

Preparation, characterization, tribological and lubrication performances of Eu doped CaWO4 nanoparticle as anti-wear additive in water-soluble fluid for steel strip during hot rolling

Citric acid-synthesized Eu-doped CaWO4 (CaWO4:Eu3+) nanoparticles in acidity (pH = 1) and alkalinity solutions (pH = 10) were analyzed by SEM, TEM, XRD, and Raman. The tribological and hot rolling lubrication properties of nano-CaWO4:Eu3+ as anti-wear additives in water-based rolling fluid were investigated. Results showed that CaWO4:Eu3+-pH = 10 has excellent load-carrying capacity, wear-resistance and friction-reducing properties in water-based rolling fluid, particularly in the bestconcentration was 0.5 wt%. The WSD value is decreased from 0.62 to 0.39 mm and the COF value is reduced from 0.092 to 0.070, which attributes to the formed tribofilm (~30 nm) on the worn surface is composed of Fe2O3, CaO, WO3 and Eu2O to avoid direct contact with the metals during hot rolling, thus reducing the friction coefficient and the oxide scale.

Research on Tribological Properties of Environment-Friendly Nano-MoS<sub>2 </sub>Water-Based Rolling Liquid

In this research, the four-ball tribometer was examined to evaluate the tribological behavior of environment-friendly nano-MoS2 water-based rolling liquid. This experimental method is used to measure the maximum non-seizure load (PB) and the coefficient of friction (μ). The newly introduced parameter ω can be combined with PB and μ to evaluate the tribological performances of the rolling liquid comprehensively. The rolling lubrication performance of nano-MoS2 water-base lubricant was investigated using a single stand 4-high reversing rolling mill. The surface morphologies and rolling textures of the samples were measured by laser scanning confocal microscope after cold rolling. The results show that when the concentration of nano-MoS2 is 0.4wt.%, the water-based rolling liquid has excellent tribological and lubricating properties. Meanwhile, compared with the surface quality of the rolled strip under other lubrication conditions, the surface quality of the cold-rolled strip using 0.4wt% nano-MoS2 rolling liquid as the lubrication condition is smooth without visible surface defects.

Recycling prospect and sustainable lubrication mechanism of water-based MoS2 nano-lubricant for steel cold rolling process

The water-based MoS2 nano-lubricant was prepared and tentatively applied in cold rolling lubricant recirculation systems to investigate its recycling prospect and sustainable lubrication mechanism. The tribological properties and rolling lubrication performance of recycled nano-lubricants with different cycle stages were preliminarily evaluated using four-ball tribotester and two-high rolling mills. To determine the phase transformation of MoS2 in recycled nano-lubricants, the already used MoS2 nano-lubricant was collected, dried and then analyzed by means of X-ray diffraction (XRD). Molecular dynamics simulation was conducted to analyze the specialized lubrication mechanism of reused MoS2 nano-lubricant. The results revealed that the MoS2 was considered to gradually transform into MoO3 during cold rolling process. Those oxidizing metamorphic MoS2 nano-lubricants still had excellent friction reducing and wear resistance. That indicated MoS2 nano-lubricant could be recycled in cold rolling process. The recirculation of MoS2 nano-lubricant reduced the use of lubricants, the discharge of waste liquid and the production cost. Not only the pollution to environment was relieved, but also resources and costs were saved. The calculation results of adsorption energy between nanoparticles and steel surface further demonstrated the absorbing type of lubricating film in different cycle stages. A lubrication model suitable for MoS2 nano-lubricants under steel strip cold rolling lubrication circulation condition was established to explain their sustainable lubrication mechanism.

Adaptive feedforward thickness control in hot strip rolling with oil lubrication

The application of oil lubrication in hot strip rolling has many advantages for the process, i.e., reduced roll force, reduced energy consumption, better strip surface quality, and reduced roll wear. On the other hand, oil lubrication may also induce severe disturbances for several control loops in a tandem hot rolling mill, which can reduce the final strip quality or might even jeopardize a stable operation of the plant. For example, the widely used automatic gauge control (AGC) has a limited bandwidth to ensure stability in the whole operating range and thus cannot (dynamically) reject the thickness deviations caused by switching on and off the oil lubrication. For this reason, the effect of lubrication is analyzed in detail and mathematically modeled in this work. Based on this dynamic lubrication model together with a hydrodynamic roll gap model and a mill stand model, two feedforward control approaches for the strip thickness are presented. These controllers counteract the negative effects of varying lubrication. Moreover, the feedforward controllers are extended by a moving horizon estimator to track changes of uncertain parameters of the underlying models based on the measured roll force. The estimated parameters are instantly used by the feedforward controller. Simulation studies using an experimentally validated simulation model of a whole mill stand show that the proposed adaptive feedforward control approach provides a significant improvement of the strip exit thickness accuracy for strips with oil lubrication compared to conventional controllers.

Superior lubrication performance of MoS2-Al2O3 composite nanofluid in strips hot rolling

Abstract The novel composite material MoS2-Al2O3 nanoparticles were synthesized via mussel-inspired chemistry of dopamine. Hot rolling lubrication performance of MoS2-Al2O3 in water-based fluid was evaluated using a two-high rolling mill. Results showed that the synthesized MoS2-Al2O3 nanofluid exhibited optimum hot rolling lubrication performance. The finish rolling thickness and rolled surface roughness reached lowest. Meanwhile the rolling force and oxide scale thickness of strips were respectively reduced by 26.9 % and 54.2 % compared with base-fluid lubricating condition. The ratio of Fe2O3 in oxide scale has lowered when rolled with nanofluids, owing to the antioxidation effect of nanoparticles during lubrication. MoS2 has partially oxidized to MoO3 and the excellent lubrication performance of MoS2-Al2O3 nanofluid resulted from the lubricating film formed by these three nanoparticles.

Modeling and Optimization of Rolling Process: A Multi-Objective Approach

In a high-speed cold strip rolling process, it is necessary to optimize the process parameters for improved quality in the product. In this study, two separate multi-objective optimization problems for a cold rolling process are formulated. The objectives in one of the cases are minimum isothermal film thickness and film temperature rise in the inlet zone and in another case it is minimum thermal film thickness and film temperature rise in the inlet zone. Particle swarm optimization algorithm has been used for solving the optimization problem. The key input parameters for the cold rolling process are identified and prioritized through the convergence study and the coefficient of variation analysis. A response analysis is performed on the critical input variables. This study assists the process engineer to understand the lubrication in cold strip rolling at high speed and select an appropriate lubricant for a given combination of strip and rolls.

Compressible fluid film lubrication of rollers with thermal effects

The present paper squarely aims to analyze the squeezing velocity of a hydrodynamic lubrication used for symmetric roller bearings. Hydrodynamic compressible fluid film lubrication of cylindrical rollers is here considered under the influence of non Newtonian power law lubricants with squeezing velocity and cavitations. The changes that show up in lubrication consistency due to pressure, density and temperature are shown via ures and tables. Further, pressure, density, temperature, load, traction and coefficient of traction for various consistency index n and normal speeds are calculated and compared with the previous results. Those results are united with the previous findings.

The Effects of High-Speed Steel Roll and Lubrication on Work Roll Wear and Fatigue During Electrical Steel Strip Hot Rolling

Work rolls in the hot strip mill withstand extreme service conditions, especially when electrical steels are rolled, resulting in severe roll wear and fatigue. High-speed steel (HSS) work rolls and rolling lubrication are applied to the mill to improve roll wear and fatigue. Tests show that HSS work rolls manifest good performance in wear, fatigue and oxidation resistance during electrical steel hot rolling. The wear loss of HSS work rolls decreases remarkably, but the heat dispersion deteriorates. The service period of HSS work rolls can be increased significantly, but the fatigue failure risk increases as well. In addition, rolling lubrication is proven to be effective in alleviating roll wear and fatigue, but high temperature reduces the positive effects of rolling lubrication. Roll wear and fatigue are considered to be parallel and mutual effective processes. The applications of HSS rolls together with rolling lubrication contribute the most to the improvement of work roll wear and fatigue during electrical steel hot rolling.

Tribological evaluation and lubrication mechanisms of nanoparticles enhanced lubricants in cold rolling

Base oils containing different nanoparticles with varying concentrations are prepared, in which SiO2, TiO2 and ZnO (20 nm) nanoparticles are employed to improve the lubrication performance. Their tribological properties are evaluated on a ball-on-disk tribometer. The results show that the nano-additive lubricants exhibit a good friction reduction and anti-wear ability at the optimal concentration of 1.0 wt.%, in which SiO2 nanoparticles can reduce the coefficient of friction (COF) and the area of wear scar (AWS) by 45.6% and 35%, respectively. The SiO2 nanoparticles exhibit the best potential additive tested. The lubrication mechanisms of the nanoparticles can be attributed to the rolling, mending and the protective films.

Nonstationary analytic model of hydrodynamic rolling lubrication

A model of normal oscillations of a roller moving along the surface at a constant speed in the presence of a liquid lubricant layer is considered. The pressure distribution along the lubricant layer is obtained by integrating the Reynolds equation, taking into account both the tangential and normal speed of the roller relative to the support surface. An analytical solution of this equation is constructed by the method of asymptotic expansion in a singular small parameter. The solution contains both regular terms of the expansion in powers of a small parameter and boundary-layer functions that rapidly decay over time.

Effect of Interstand Tensions on Lubrication Regime in Cold Strip Rolling with O/W Emulsion

Oil‐in‐water are cost saving emulsions. These emulsions are widely used in cold rolling mills due to their beneficial characteristics as lubricants and coolants. In this study, an extension of the Reynolds equation for emulsions has been applied to the mixed-film lubrication of cold strip rolling. This model involves solving equations for emulsion in two inlet and working zones plus plastic deformation of the strip considering interstand tensions. In order to achieve a more realistic model, the strain hardening effect of the strip and elastic deformation of the rolls are taken into account. To evaluate the model, an integrated form of simulation program outputs—that is, rolling force and torque—was verified by experimental data from a real tandem rolling mill. Distributed parameters such as rolling pressure and friction, oil concentration, lubricant film thickness along the roll gap, and forward slip were found and presented for different values of backward and forward tensions, supply oil concentration values, and rolling speeds. Results show that the higher oil concentration leads to more lubricant pressure buildup, a thicker film, and a smaller contact ratio, which consequently reduce friction and total rolling pressure. Interstand tensions have a similar effect on film thickness, but results show that backward tension, which is more efficient than forward tension, has a critical effect on determining the lubricant inlet condition, which improves lubrication for the whole roll bite.

Effects of back-up rolls on lubrication in cold rolling of aluminum alloy

Effects of back-up rolls on lubrication in cold rolling of aluminum alloy

Mixed elastohydrodynamic lubrication model for finite roller-coated half space interfaces

Abstract This paper presents a mixed elastohydrodynamic lubrication (EHL) model for finite roller-coated half space interfaces. The model is built with the unified mixed lubrication approach and the influence coefficients (ICs) relating the pressure on a contact surface to surface deformations and subsurface stresses, converted from the frequency response functions (FRFs). The elastic deformation is solved with the discrete convolution and fast Fourier transform (DC-FFT) algorithm. This model is used to explore the EHL performance of rollers subjected to a wide range of operating conditions. A parameters study is conducted to reveal the effects of coatings, macro geometry, and surface roughness on the lubrication of rollers.