Bearing Steel Ball Research Articles

Surface Engineering Design of Alumina/Molybdenum Fibrous Monolithic Ceramic to Achieve Excellent Lubrication in a High Vacuum Environment

Al2O3/Mo fibrous monolithic ceramics are potential candidates for space applications because of their excellent mechanical properties and low density. This study aims at achieving low friction and long life of this material in a high vacuum environment. Three-dimensional composite-lubricating layers were fabricated by considering texture pattern as storage dimples and MoS2 synthesized via hydrothermal method as lubricant. The tribological properties were studied sliding against Si3N4 ceramic and GCr15 bearing steel balls under high vacuum condition. Results showed that the lubricating properties of the Al2O3/Mo fibrous monolithic ceramics were improved greatly by the micro-texture and MoS2 solid lubricant; the friction coefficients were as low as approximately 0.08 and 0.04, respectively, when Si3N4 ceramic and GCr15 bearing steel balls acted as the pairing materials. It was also demonstrated that the low friction coefficient can be realized with various normal loads and sliding speeds, indicating the composite-lubricating layers have good adaptation of working conditions. This excellent performance of the material is mainly because of MoS2 stored in dimples can be easily dragged onto the friction surface to form lubricating and transferring films during the friction process. This work is an extension of studies that were previously published in Tribology Letters journal.

Study on the Correlation Between Dynamical Behavior and Friction/Wear Mechanism Under the Effect of Grooves

In this work, the interfacial friction and wear and vibration characteristics are studied by sliding a chromium bearing steel ball (AISI 52100) over both multi-grooved and single-grooved forged steel disks (20CrMnMo) at low and high rotating speeds in order to reveal the effect mechanism of groove-textured surface on tribological behaviors. The results show that the grooves modify the contact state of the ball and the disk at the contact interface. This consequently causes variations in the normal displacement, normal force, and friction force signals. The changes in these three signals become more pronounced with increasing groove width at a low speed. The collision behavior between the ball and the groove increase the amplitude of vibration acceleration at a high speed. The test results suggest that grooves with appropriate widths could trap wear debris on the ball surface while avoiding a strong collision between the disk and the ball, resulting in an improvement in the wear states.

Effect of Solid Solution- and Mesothermal Phase Transition- Treatment on Microstructure and Mechanical Property of Ball Bearing Steel 8Cr4Mo4V

Effect of Solid Solution- and Mesothermal Phase Transition- Treatment on Microstructure and Mechanical Property of Ball Bearing Steel 8Cr4Mo4V

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

On the precise measurement capability of the direct microscopic measurement method for wear volume characterization

There are plenty of methods for determining the wear volume after a wear test. Due to the geometrical assumptions, some of them could unfortunately lead to mistaken results. It has been shown that a novel method, the direct microscopic measurement, is able to calculate the wear volume on a specimen surface very precisely and accurately [1-2]. It is based on creating a series of line profiles perpendicular to the wear scar. This novel method, however, needs to be characterized in terms of measurement limitations and minimum detectable volume capability. For example, how small or how shallow a wear scar could be calculated or measured with this method, must be determined. For this purpose, it has been prepared a series of wear test specimens exposed to the different amounts of wear in a “pin-on-disk” type test rig. As specimens, two different non-ferrous mold materials, Al bronze alloys, were selected and prepared metallographically. Counterpart materials were inox steel and bearing steel balls with diameter of 6 mm. Normal load was set to 5 N. Test configurations were set to 1, 5, 10 and 100 m of sliding distance values, in turn. Wear tests were conducted in according to ASTM G99 standard. Wear volume results were determined both direct microscopic measurement and also a 3D optical microscope methods. Comparison results showed that the novel method could be successfully used for wear volume calculations even with small amounts of wear volume conditions.

ИССЛЕДОВАНИЕ ВОЗМОЖНОСТИ ОЦЕНКИ СОСТОЯНИЯ СТАЛЬНЫХ ОБРАЗЦОВ С ПРИМЕНЕНИЕМ ДИНАМИЧЕСКИХ СПЕКТРОГРАММ АКУСТИЧЕСКИХ СИГНАЛОВ

The main purpose of this work was to study the possibility of estimating the changes in properties of bearing steel during heat treatment by visualization using dynamic spectrograms (sonograms) that display changes in the spectral characteristics of acoustic signals within time. The changes of spectral characteristics of the point impact acoustic response in the steel specimens were studied depending on the microstructure changes generated in the specimens using heat treatment with various parameters. The analysis and comparison of acoustic response signals were performed using software spectrum analyzer. The informativeness of the applied technique aimed at estimating changes in the microstructure of steel as a result of heat treatment is shown. The analysis of dynamic spectrograms allowed revealing indicative spectral features, such as shifting in the resonant frequencies and change in the damping decrement. A clear dependence of the shift of the resonant frequencies and the damping decrement of the signal on the tempering temperature of the quenched ball-bearing steel specimens was found. After the tempered specimens were re-quenched, reverse changes in the resonant harmonics frequencies and the damping decrement were observed. Changes in the observed indicative spectral characteristics correspond to changes in hardness and microstructure of the steel. This technique can be used for development of nondestructive testing express methods to evaluate changes in the state of steel structural elements and perform quality control during heat treatment.

A New Damage Evolution Model for Cold Forging of Bearing Steel-Balls

As ductile damage has a severe impact on the performance of bearing steel-balls (BSB), it is necessary to apply the ductile damage evolution model for predicting the distribution of ductile damage in BSB. A new ductile damage model was developed using physically-based internal state variables method by considering the effect of two important stress state parameters: stress triaxiality and relative ratio of max principal tension stress, on the ductile damage evolution. The newly developed ductile damage model was implemented into the commercial FE code, DEFORM-3D, via a user defined subroutine and cold forging simulation was operated. BSB formation tests were carried out and the microstructure and micro-damage were examined from the tested samples. FE simulation results of ductile damage were compared with those of tested samples. Good agreements have been achieved, which proves that the newly developed ductile damage model enables micro-damage evolution during cold forging to be well predicted. Some constructive suggestions have been obtained to improve the quality of BSB during cold forging.

Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection.

Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball’s outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified.

Debris trapping and space-varying contact via surface texturing for enhanced noise performance

In this work, groove-textured surfaces with a certain widths and pitches are manufactured on flat cast iron samples. Whereafter, another material (aluminium and steel, respectively) is filled into the grooves to form a special surface which possesses space-varying properties. These surface-treated specimens are tested in a ball-on-flat system and the ensuring friction-induced vibration and noise are measured. The ball sample used in the test is chromium bearing steel ball (AISI 52100). It is found that adding aluminium material into the grooves will increase the friction-induced vibration and noise level of friction system. Conversely, adding steel material into the grooves can stabilize the friction system. Moreover, this space-varying contact state surface is valuable to study the relationship between the trapping wear debris behaviour and stability of texturing surface, which validates our previous speculation that wear debris accumulation on the contact surface will deteriorate the friction-induced vibration and noise behaviour of friction system, and the capability of grooves in trapping wear debris is beneficial for reduction of vibration and noise. Numerical simulation is performed to give reasonable explanations for the experimental phenomenon. This investigation suggests that friction surfaces with grooves filled with suitable materials are able to reduce friction-induced vibration and noise.

Effect on lubrication regimes with silicon nitride and bearing steel balls

The wear characteristics and an effect of lubrication regime between silicon nitride and steel balls sliding against reference material discs under lubricated conditions were studied. The mild wear was observed for silicon nitride balls and the worn out particles confirms the adhesive wear and simultaneous cutting action of worn-out particles. The worn-out surface analysis confirmed the material transfer from steel disc to silicon nitride ball. Eventually the coefficient of friction (COF) value was reduced by 25% for silicon nitride ball when compared to steel ball due to the formation of mixed oil regime between the contact surfaces. The more depletion of anti-wear additives and oxidation was observed for steel ball due to boundary lubrication.

Effect of Temperature on the Dry Sliding Friction and Wear of Rice Bran Ceramics against Different Counterpart Materials

ABSTRACTIn this study, we investigated the effect of temperature on the friction and wear of rice bran (RB) ceramics, a hard porous carbon material made from rice bran, sliding against alumina, stainless steel, and bearing steel balls under dry conditions. Friction tests were performed using a ball-on-disk-type friction tester wherein a ceramic heater was installed in the rotational stage. The surface temperature of the RB ceramic disk specimens was controlled at 20, 100, 150, or 200°C. The normal load was 1.96 N, sliding velocity was 0.1 m/s, and number of cycles was 20,000. The effect of surface temperature on the friction and wear of RB ceramics substantially differed among the ball material types. The friction coefficient for the RB ceramics sliding against an alumina ball decreased with increasing temperature and exhibited an extremely low value (0.045) at 200°C. The friction coefficient in the case of the RB ceramics sliding against a stainless steel ball exhibited a stable value as the temperature was increased to 150°C and slightly decreased as the temperature was increased further, reaching a low value of 0.122 at 200°C. The friction coefficient for the RB ceramics sliding against bearing steel ball drastically increased with increasing temperature, reaching 0.381 at 200°C. The specific wear rate of the RB ceramics increased with increasing temperature; it was lowest when sliding against alumina and highest when sliding against bearing steel. The wear of the alumina ball was the lowest and that of the bearing steel ball was the highest under all investigated temperature conditions. On the basis of these results, we concluded that alumina is a promising counterpart material for RB ceramics sliding at high temperatures (≤200°C).

A Deterministic Stress-Activated Model for Tribo-Film Growth and Wear Simulation

A new model was developed for the simulation of growth and wear of tribo-chemical films by combining a boundary element method-based contact model and a stress-activated Arrhenius tribo-film growth equation. Using this methodology, it is possible to predict the evolution and steady-state thickness of the tribo-film (self-limitation) at various operating conditions. The model was validated using two cases for which experimental data were available in the literature. The first case is a single microscopic contact consisting of a DLC-coated AFM tip and an iron-coated substrate. The second case is a macroscale contact between a bearing steel ball and disk. Subsequently, mild wear (wear after running-in) was modeled by assuming diffusion of the substrate atoms into the tribo-film.

Lipophilic magnetite nanoparticles coated with stearic acid: A potential agent for friction and wear reduction

Lipophilic magnetite nanoparticles (MagNP; d≈10nm) functionalized with stearic acid were synthetized and tested as additive in polyalphaolefin synthetic base oil (PAO8) in a model system. The thermal properties of the starting base oil and of the base oil mixed with nanoparticles were evaluated using TG/DTA under inert and oxidizing atmosphere. The frictional response of the lubricants was evaluated under a broad range of operating conditions at the boundary lubrication regime using a 10mm AISI 52,100 bearing steel ball against the flat face of an AISI H13 steel disc. The results showed that: i) MagNP improved the thermal stability of the base oil; ii) reduced the friction values, mostly during load step transition; iii) reduced significantly the wear marks.

Effect of running-in for delamination and friction properties of self-mating diamond-like carbon coatings in water

Two running-in processes, i.e., polishing a diamond-like carbon (DLC) coated disk and pre-sliding in ambient air, were suggested as a delamination suppression method for self-mating DLC coatings in water, and the effects of these methods were verified using a ball-on-disk tribometer. An a-C:H-type DLC coating was deposited on SUJ2 bearing steel balls and disks using plasma chemical vapor deposition. It was confirmed that delamination of DLC coatings was suppressed because microcracks were not generated by removing droplets on the DLC coated disk using the polishing process. The friction coefficient in that condition was reduced to about one-fifth of that of the untreated disk. The running-in process of pre-sliding in ambient air also suppressed delamination of DLC coatings. Moreover, the friction coefficient after this process was reduced to half of that with the other polishing process in the boundary lubrication condition. It was found that these effects have a relationship with surface smoothness and hydrophilicity.

Friction and wear performance of bearing ball sliding against diamond-like carbon coatings

We have studied the tribological properties of bearing steel ball (Japan standard, SUJ2) sliding against tetrahedral amorphous carbon (ta-C) coatings and amorphous hydrogenated carbon (a-C:H) coatings. The reciprocating sliding testes are performed with ball-on-plate friction tester in ambient air condition. Analysis of friction coefficient, wear volume and microstructure in wear scar are carried out using optical microscopy, atom force morphology (AFM) and Raman spectroscopy. The results show the SUJ2 on ta-C coating has low friction coefficient (around 0.15) but high wear loss. In contrast, the low wear loss of SUJ2 on a-C:H coating with high (around 0.4) and unsteady friction coefficient. Some Fe2O3, FeO and graphitization have been found on the wear scar of SUJ2 sliding against ta-C coating. Nearly no oxide materials exist on the wear scar of SUJ2 against a-C:H coating. The mechanism and hypothesis of the wear behavior have been investigated according to the measurement results. This study will contribute to proper selection and understand the tribological performance of bearing steels against DLC coatings.

SLIDING WEAR BEHAVIOR OF NIOBIUM CARBIDE COATED AISI 52100 BEARING STEEL

Sliding wear behavior of niobium carbide coated AISI 52100 bearing steel balls against AISI 1045 quenched steel discs was investigated. Thermo-reactive diffusion (TRD) treatment was carried out at 1000 °C for 4 hours by pack cementation method. NbC phase with 11 µm in thickness was identified by SEM microscopy and XRD technique. Ball-on-disc wear tests were carried out without lubrication under 2 and 10N load at sliding speeds of 0.1 and 0.3 m/s. A 300% increase in sliding speed resulted in 24% and 27%, increasing in friction coefficient of niobium carbide coated AISI 52100 steel balls for 2N and 10N. Wear resistance of AISI 52100 steel was improved up to 78 times after TRD treatment depending on applied load and sliding velocity. Wear mechanisms are adhesive-oxidative for hardened balls and abrasive-oxidative for coated balls against hardened AISI 1045 steel discs.

Microstructure and Friction Behavior of AISI 52100 and D2 Steels Subjected to Ultrasonic Nanocrystalline Surface Modification (UNSM) Technique at a High Temperature

In this study, two different AISI 52100 bearing and D2 tool steels were subjected to ultrasonic nanocrystalline surface modification (UNSM) technique at ambient and high temperature of 500 °C. The objective of this study is to characterize the microstructure and to investigate the effectiveness of UNSM technique on the friction and wear behavior of those steels. The friction and wear behavior of the specimens against AISI52100 bearing steel ball with a diameter of 10 mm was carried out using a micro-tribo tester under dry conditions. The hardness with respect to depth from the top surface was measured using a microhardness. The change in the microstructure of the specimens before and after UNSM treatment was characterized by scanning electron microscopy (SEM). The findings from this preliminary study are expected to be implemented to the bearings and tools to increase the efficiency and performance of the components.

Self-lubricating Ni-P-MoS2 composite coatings

Abstract Tribological coatings with low coefficients of friction are in high demand by various industries since they can improve machine efficiency and have an environmental impact. A self-lubricating Ni-P-MoS2 composite coating has been successfully deposited on a mild steel substrate by electrodeposition. The effects of MoS2 on the tribological coatings have been investigated. Compared to a pure Ni-P coating, the Ni-P-MoS2 composite coating exhibited a dramatic reduction in friction coefficient against a bearing steel ball from 0.45 to 0.05. Examination and analysis of the worn surfaces and wear debris, the composite coating showed minimum wear and oxidation compared to the severe wear and oxidation observed in the pure Ni-P coating. The evolution of MoS2 particles in sliding wear has been elucidated.

Reducing the high-temperature loss of steel in furnaces

Assessment of the loss of steel in industrial furnaces may be based on the scale thickness. Means of reducing the oxidation of steel are evaluated. Special attention is paid to the difficulty of reducing the steel loss on account of decrease in the oxidant consumption n. Nonoxidative heating of steel in industrial furnaces is shown to be feasible at present. The requirements here are practically molecular mixing of the components in primary combustion (for natural gas with air excess n = 0.48–0.5); synchronous burner operation and constraints on the oxidation n with regulation of the primary fuel combustion (Δn ≤ 0.01); and effective choking of the primary gas flux so as to rule out inverse circulatory motion of the products of incomplete primary combustion from their combustion zone into the metal-heating zone. Design approaches and operating conditions for forging and rolling furnaces are proposed, so as to reduce or suppress steel losses. Particular attention is paid to the internal high-temperature oxidation of silicon in transformer steel and the decarburizing heating of ball-bearing steel.

Effect of Gd addition on the wear behavior of Mg–xGd–3Y–0.5Zr alloys

Abstract