Steel Ball Research Articles

Tribological behaviour of green wood-based unrecycled and recycled polypropylene composites

In this study we evaluated the tribological performance of polypropylene composites with wood-flour fillers obtained as a by-product from the wood-processing industry, which were based on unrecycled and recycled polypropylene polymer matrices. The mechanical properties of polypropylene-wood composites with wood-filler loadings of 0–40 wt % were determined with tensile tests and their friction and wear behaviours were studied with dry reciprocating ball-on-disc sliding tests against 100Cr6 steel balls at room temperature. The addition of the wood fillers resulted in a significant improvement in the tribological performance compared to the neat, unrecycled, and recycled polypropylene materials: the friction coefficient decreased by up to 30%, while the wear resistance was improved by up to two orders of magnitude. While neat unrecycled polymers have better properties than recycled, addition of 40 wt % wood-filler content in both, recycled and unrecycled composites, resulted in almost the same level of coefficient of friction (∼0.25) and wear coefficient (2 × 10−6 mm3/(Nm) to 3 × 10−6 mm3/(Nm)). Even with the addition of as low as 5 wt % of wood fibres the wear resistance was improved for 63% and 43% for unrecycled and recycled composites, respectively, which indicates that the use of wood fillers could be a sustainable and cost-effective way to improve the polymer tribological performance, and could compensate for the normally poorer properties of recycled materials, making the recycled polypropylene-wood composites a suitable sustainable choice for tribological applications.

Non-Destructive Eggshell Strength Assessment Using Hertz Contact Theory—Part II: Implementation and Validation

Eggshell strength is a critical quality factor for consumption eggs as it affects the probability of breakage in practice. In this study, a fast and low-cost methodology for the non-destructive determination of eggshell strength is presented. The method utilized a small steel ball to impact the egg and a microphone to analyse the impact characteristics. Hertz contact theory was applied to relate the measured impact characteristics to the local stiffness of the eggshell. Therefore, a total of 150 eggs were studied on which eight consecutive measurements per egg were taken around the equator at equidistant places. The results showed a strong correlation of 0.93 between the traditional static stiffness measured during quasi-static compression tests and the average stiffness obtained from the new methodology. This paves the way towards fast, low-cost and non-destructive in-line shell strength measurements to reduce the number of cracked eggs reaching the consumer.

Shapes of the noncentrosymmetric TeO5E groups in tellurite glasses with P2O5 additions

Abstract The noncentrosymmetric shapes of the TeO n E units (n = 3, 4, and 5) are important for the nonlinear optical properties of the tellurite glasses (E – lone pair). An earlier diffraction work on the binary (TeO2)1−x (P2O5) x glasses reported Te−O coordination numbers larger than four, which means the rare case of proportions of TeO5E units. The distributions of the Te−O distances in these glasses differ from those known in the related crystal structures. The so far unknown shapes of the TeO5E units are determined by the use of a mechanical analog. Five steel balls can move freely in a spherical bowl. Under the effect of gravity, they take a structure that is equivalent to that of the five oxygen ligands of a TeO5E unit. The average bond lengths of the TeO5E groups obtained for the glasses differ a little from the lengths of this unit. The small differences are attributable to variations based on the uneven tensions caused by the network disorder. The mechanical analog was set up on basis of the present conceptions of the lone pair’s steric effects. The ratio of the ball’s and bowl’s diameters is taken from published analyses of crystal structures.

Investigating the tribological and corrosion behavior of Co–Cr alloy as an implant material for orthodontic applications

The purpose of this research was to investigate the effectiveness of using wrought cobalt-chromium (Co–Cr) alloy as a dental implant through a set of corrosion, immersion, and tribological behavior analyses. An artificial saliva solution was first prepared with varied pH levels between 4.8 and 9. The corrosive behaviors were analyzed from potentiodynamic tests using saliva samples with varied pH concentrations. The corrosion potential (Ecorr) shifted more negatively and had a slightly higher current density observed with a pH 4.8 acidic medium, demonstrating lower corrosion resistance than neutral (pH 6.9) and basic (pH 9) saliva solutions. The effect of artificial saliva on the surface roughness of the Co–Cr samples was investigated with a continuous immersion in the saliva solution for intervals of 7–28 days. Tribological tests were conducted using ball-on-flat type reciprocating friction and wear testing against an AISI 52100 steel ball. Two different sliding velocities under a constant load of 50 N were used to simulate contact conditions on implants under dry and saliva-lubricated conditions. The wear tracks were analyzed after the experiments using interferometry and microscopy techniques to analyze the wear mechanisms. No significant effects due to changing sliding velocity on dry frictional behavior were observed. Oxide layer generation during dry contact conditions and the formation of P and Ca-enriched tribofilms originating from the artificial saliva played a crucial role in the tribological behavior of the Co–Cr samples. The Co–Cr flat wear volume was significantly higher than the steel counterpart in dry conditions, unlike its performance in lubricated conditions, due to the predominant abrasive wear in the dry contacts. Corrosive wear in lubricated conditions using artificial saliva played an important role, along with abrasive and adhesive wear in both flat and ball samples. The deposition of P and Ca on the flat wear track was more predominant than on the steel ball surface. The ratio of wear volume between the steel balls and the Co–Cr flat samples in the lubricated tests was increased notably compared to dry conditions due to the effect of tribo-corrosion since artificial saliva (pH 4.8) had a higher corrosive impact on the steel ball than the Co–Cr alloy. These findings created new insights into the applicability of using a Co–Cr alloy as a dental implant due to enhanced corrosive and tribological properties. This detailed investigation on wrought Co–Cr alloys can be leveraged as a baseline for future Co–Cr alloy-based dental prosthetics development using metal additive manufacturing techniques.

Tribocorrosion behavior of graphene-based solid lubricants biofunctionalized with hyaluronic acid on CoCr surfaces

In this work graphene-based solid lubricants biofunctionalized with hyaluronic acid were deposited on CoCr surfaces to decrease wear-corrosion phenomena. Graphene oxide was electrochemically reduced on CoCr in an aqueous suspension of graphene oxide 4 g/L by cyclic voltammetry. Biofunctionalization in phosphate buffer solution with HA 3 g/L (PBS-HA) for 24 h was performed. A pin-on-disk tribometer with an integrated cell was used for tribocorrosion tests. Wear-corrosion tests were performed against AISI316 steel balls applying normal load 1 N, 120 rpm for 500 m, in PBS and PBS-HA. Coefficients of friction in PBS were higher than in PBS-HA. ErGO and HA-ErGO increased wear rate in AISI316 balls, i.e., ErGO hardens the CoCr surface. Biofunctionalization reduces abrasive properties of ErGO deposits.

Mechanochemical synthesis and structural evaluation of a metastable polymorph of Ti3Sn

Abstract A metastable polymorph of Ti3Sn (called c-Ti3Sn) exhibiting the cubic Cr3Si-type structure was prepared by a mechanochemical route. At temperatures of about 450 °C, it transforms to the well-known hexagonal phase (Ni3Sn type, called h-Ti3Sn). 0.5% of iron was incorporated into the material originating from the steel beaker and the steel balls. However, quantum-chemical calculations show that this should not lead to a stabilization of the Cr3Si type. c-Ti3Sn shows a single signal at an isomer shift of δ = 1.70(1) mm s−1 in its 119Sn Mössbauer spectrum at 78 K.

Recovery of Carbon and Cryolite from Spent Carbon Anode Slag Using a Grinding Flotation Process Based on Mineralogical Characteristics

The aluminum electrolysis industry continually and unavoidably produces hazardous solid waste in the form of carbon anode slag. Carbon anode slag poses a serious environmental pollution risk, and it must be disposed of in a harmless manner. On the other hand, it contains a few valuable resources, as well. In order for the aluminum electrolysis industry to develop in an environmentally friendly and high-quality manner, the harmless disposal of carbon anode slag and its resourceful utilization are of considerable importance. The selective comminution of carbon and cryolite particles in carbon anode slag can be effectively achieved with grinding pretreatment. However, the optimization study of grinding process parameters has yet to be investigated. Therefore, firstly, the mineralogical characteristics and existing mode of carbon anode slag from the perspective of mineralogical properties are analyzed in this study. Then, the effects of grinding time, grinding concentration, and steel ball diameter on the particle size of the ground product (γ−0.074 mm) are investigated using response surface analysis. The results showed that the effect of grinding time was the most significant, followed by grinding concentration and steel ball diameter. In addition, the performance of the multi-stage flotation process for separating the −0.074 mm ground product was analyzed. Cryolite with a purity of 93.12% and a carbon product with an ash content of 10.67% could be simultaneously obtained through multi-stage flotation. It should be pointed out that the deep dissociation and efficient recovery of fine undissociated particles still need to be further explored.

Non-Destructive Eggshell Strength Assessment Using Hertz Contact Theory Part I: Theory and Applicability

In the egg industry, fast and highly reliable quality measurements are crucial. This study presents a novel method based on Hertz contact theory that allows for non-destructive determination of eggshell strength. The goal of the study was to evaluate the material strength (Young's Modulus) and structural strength (stiffness) of eggshells. To this end, an experimental setup was constructed to measure the collision of an eggshell with a small steel ball, which was recorded using a laser vibrometer. The study analyzed a sample of 120 eggs and found a correlation of 0.85 between the traditional static stiffness measured during quasi-static compression tests and the stiffness obtained from the Hertz contact theory. The results show that Hertz contact theory is valid for small steel spheres impacting eggshells, while a sensitivity analysis indicated that the most important factor in determining the strength of the eggshell is the contact duration between the egg and the impactor. These results open up the possibility of grading eggs based on their shell strength in a non-destructive manner.

Modeling of Rapid Response Characteristics of Piezoelectric Actuators for Ultra-Precision Machining

Piezoelectric actuators are characterized by high positioning accuracy, high stiffness and a fast response and are widely used in ultra-precision machining technologies such as fast tool servo technology and ultrasonic machining. The rapid response characteristics of piezoelectric actuators often determine the overall quality of machining. However, there has been little research on the fast response characteristics of piezoelectric actuators, and this knowledge gap will lead to low precision and poor quality of the final machining. The fast response characteristics of a piezoelectric actuator were studied in this work. Firstly, the piezoelectric actuator was divided into a no-load state and a load state according to the working state. A fast response analysis and output characteristic analysis were carried out, the corresponding dynamic model was established, and then the model was simulated. Finally, an experimental system was established to verify the dynamic model of the piezoelectric actuator's fast response by conducting an experiment in which the piezoelectric actuator bounces a steel ball. The experimental results verify the correctness of the model and show that the greater the cross-sectional area and height of the piezoelectric actuator, the higher the bouncing height of the ball, and the better the dynamic performance of the piezoelectric actuator. It is believed that this study has guiding significance for the application of the dynamic characteristics of piezoelectric actuators in the machining field.

Impact-abrasive wear resistance of high alumina ceramics and ZTA

In transport of raw materials abrasive wear resistance is a requirement, which can be met with alumina ceramics. At certain locations additional impact load occurs, exacerbating the wear loss. As literature on impact-abrasive wear of ceramics is scarce this topic will be researched in this work.We selected a variety of commercial alumina ceramics (90–96% Al2O3) and according to literature much more impact resistant – and substantially more expensive – Zirconia Toughened Alumina (ZTA, 20–25% Zr) used for wear resistant linings in impact dominated systems. We selected the Impeller-Tumbler test, an impact-abrasion test for wear evaluation of highly loaded ceramic edges. Two load regimes were evaluated for the abrasive, either corundum particles for severe load or steel balls for extreme load conditions. Correlation of wear results with the fracture toughness (K1C) and Vickers hardness of the materials is intended – material parameters used as measure for brittle failure of ceramics and wear resistance, respectively.The various ceramic materials showed very different wear behaviour under the impact-abrasive load. The 90% Al2O3 was least wear resistant under both load conditions. Interestingly large differences between the 92% types were found at extreme load conditions. The increase of alumina content to 95–96% showed remarkable benefits in both wear regimes. Best wear resistance against severe load was achieved by 25% ZTA, while it is comparable to the 95–96% high alumina types at extreme load.

Mechanical and tribological properties of SiC whisker‐reinforced SiC composites via oscillatory pressure sintering

AbstractSiC whisker (SiCw)‐reinforced SiC composites were prepared by an oscillatory pressure sintering (OPS) process, and the effects of SiCw content on the microstructure and mechanical and tribological properties of such composites were investigated. The addition of SiCw could promote the formation of long columnar α‐SiC, and the aspect ratio of α‐SiC grains first increased and then decreased with the increase of SiCw content. When the SiCw content was 5.42 wt%, the relative density of the SiC–SiCw composite reached up to 99.45%. The SiC–5.42 wt% SiCw composite possessed the highest Vickers hardness, fracture toughness, and flexural strength of 30.68 GPa, 6.66 MPa·m1/2, and 733 MPa, respectively. In addition, the SiC–5.42 wt% SiCw composite exhibited the excellent wear resistance when rubbed with GCr15 steel balls, with a friction coefficient of .76 and a wear rate of 4.12 × 10−7 mm3·N−1·m−1. This could be ascribed to the improved mechanical properties of SiC–SiCw composites, which enhanced the ability to resist peeling and micro‐cutting, thereby enhancing the tribological properties of the composites.

Investigating the effect of operating temperature on the tribo-mechanical behavior of cold rolled superelastic nickel titanium alloy

NiTi alloys are the most important practical shape memory alloys (SMA) with excellent mechanical properties. Austenitic NiTi alloys with superelastic behavior are currently being investigated for load-bearing applications due to their ability to accommodate large elastic strains and better mechanical properties than martensitic SMAs. We conducted dry reciprocating tests against AISI 52100 steel balls to evaluate the tribomechanical behavior of cold-rolled austenitic Ti – 55.7 wt% Ni alloys at various temperatures, including room temperature, 50 °C, 100 °C, and 200 °C. We observed an 18.3% lower friction coefficient with an 86% reduction in wear volume at 200 °C compared to room temperature during reciprocating tests. Material transfer was captured from the steel ball to the NiTi flat at elevated temperatures and from the NiTi flat to the steel ball at lower temperatures. The primary wear mechanisms on NiTi shifted from abrasive to adhesive with increased operating temperature, and the counter balls shifted from adhesive to abrasive. Indentation testing on austenitic NiTi revealed a 12% increase in hardness with a 50% decrease in Young's modulus at 200 °C, resulting in an increased Modell ratio (Hardness/Young's modulus) with increasing temperature. This phenomenon can be attributed to the austenitic NiTi alloy's increased wear resistance with an increase in operating temperature.

Effects of normal load and reciprocating frequency on the tribological behaviors of a Zr-based bulk metallic glass

Bulk metallic glasses (BMGs) are a class of novel engineering materials of high hardness, high strength, and excellent fracture toughness which imply prospective outstanding wear resistance. However, for the non-intrinsic character of tribological properties, the wear behaviors and mechanisms of BMGs remain to be clarified. In this work, linear reciprocating tribological behaviors of a Zr60.14Cu22.31Al9.7Fe4.8Ag3 (at.%) BMG against GCr15 steel balls were characterized in the “ball-on-plate” mode under normal loads of 1–15 N and at reciprocating frequencies of 1–12 Hz with a stroke length of 5 mm. The results indicate that high coefficient of friction (COF) was observed under low normal load plus high reciprocating frequency, whereas low COF was observed under high normal loads or at low reciprocating frequencies, and that the specific wear rate increased with both normal load and reciprocating frequency wherein the reciprocating frequency played a more crucial role. Via systematic examinations on the worn surfaces of both BMG plates and GCr15 steel balls and on the wear debris, transition of the dominating wear mechanisms from oxidative wear and abrasive wear to adhesive wear with increasing normal load and reciprocating frequency was detected and the role played by plastic deformation of BMG in the process was tentatively illustrated. The current work would help to understand the tribological properties of Zr-based BMGs under sliding conditions.

Investigation of Lubrication Characteristics of Virgin and Additive Blended Jatropha Based Grease

Increasing interest in utilizing bio-lubricants has been sparked by pollution caused by the mineral oil-based lubricants and their depletion. This study aimed to assess the effectiveness of Jatropha oil based grease as a basis and sodium thickener as an additive. The grease's lubricating abilities were tested using the ASTM 2266 four ball test and molybdenum disulphide as an additive. According to the findings, adding molybdenum disulphide particles decreased wear and the coefficient of friction, with the latter falling by 69% when compared to virgin Jatropha grease. Given that Jatropha grease passed the four ball test, a simulation of real-world conditions, this indicates that it is a reliable lubricant. Wear examinations were performed on steel balls using an optical microscope and scanning electron microscopy, and the results were consistent. It was found that addition of 0.25% MoS2 to virgin Jatropha grease reduced coefficient of friction to 0.12 (69%) from 0.39. Similarly wear scar diameter reduced from 800.583 µ to 788.44 µ in presence of 0.25% MoS2 blended grease. The study concludes that the grease prepared could an alternative to grease made from mineral oils. The focus on adopting Jatropha grease as a more sustainable and bio-degradable option can preserve the environment.

Analyzing Ball Bearing Capacitance Using Single Steel Ball Bearings

A precise modeling of the capacitance of rolling element bearings is of increasing significance over the last years, e.g. in the context of bearing damage estimation in electric drives. The complexity of a steel bearing as an electrical network makes reliable validation of calculation models under realistic operating conditions nearly impossible. A way to reduce complexity in yet realistic conditions is the use of hybrid bearings with a single steel rolling element. This helps to measure only one current path through the bearing at a time and thus, gives a much clearer picture of the contact capacitance of rolling elements in and out of the load zone. The usage of different materials comes with different thermal expansion coefficients and different elasticities, which cause a significant change in load distribution. For the first time, this work considers both of these effects in calculation and validates them with corresponding experiments using single steel ball bearings.

Dynamic Features of Non-Return Mechanism in Hatch Door of Amphibious Aircraft

The non-return mechanism is the key device that plays the role of braking in the opening-and-closing electric actuator of an amphibious aircraft hatch door. The ball-and-socket contact pair, providing the pressing force, and the multi-disc friction pair, supplying the braking torque, are two core components in the non-return mechanism. In this paper, the dynamic model of the non-return mechanism is established considering the freedom of rotation-translation. Based on MATLAB/Simulink, the solution framework of the overall dynamic model is built. The dynamic response characteristics of the non-return mechanism in the process of reverse load braking, forward load braking, and continuous closing are analyzed. The braking time and the angular displacement of the output shaft in the braking phase have been presented. Compared with forward load braking, reverse load braking has a longer braking time and smaller angular displacement of the output shaft. In addition, the compaction function of the ball-and-socket contact pair is verified by experiment, and the influence of the cone angle, distribution radius of the ball socket, and the steel ball diameter on the pressing force has been discussed. This study provides a theoretical basis and parametric design platform for the design and optimization of non-return mechanisms, which can shorten the product development time.

Experimental and numerical modelling of shear bonding between asphalt layers

Interlayers in asphalt pavements are potential structural damage initiators. In order to better understand the quantitative role of interlayer parameters, such as surface roughness, binder type, binder content and loading type on interlayer shear strength, this paper focuses on the effects of particle interlock and contact conditions on interlayer strength through experimental and numerical modelling. Experimentally, interlayer shear box strength tests on a model material consisting of stiff binder blended with steel balls are performed with and without normal force confinement. A Discrete Element method model of the test is developed using measurements of the model material for calibrating the contact law and for validating the model. It is shown that this model captures adequately the measured force-displacement response of the specimens. It is thus a feasible starting point for numerically and experimentally studying the role of binder and tack coat regarding interlayer shear strength of real asphalt layers.

Mass estimation of loose parts based on virtual experiment

Mass estimation of loose parts in primary coolant system is an important task of loose parts monitoring system. However, it is difficult to carry out drop tests of loose parts in primary coolant system so as to provide the field data for developing a mass estimation model. A virtual experiment approach based on finite element simulation is proposed, which contains three steps: (1) finite element modeling and updating of impacted structural component; (2) simulating the drop tests of loose parts on structural component to generate the virtual experimental data; (3) establishing a mass estimation model using deep belief network based on the virtual experimental data. The flat plate steel ball drop tests are performed to demonstrate the presented approach. The results show that the prediction accuracy of mass estimation model built based on virtual experimental data is quite close to that of the model built based on drop test data.

Enhancement of Double-Pipe Heat Exchanger Effectiveness by Using Porous Media and TiO2 Water

In this paper, the rate of heat transfer by forced convection in a counterflow heat exchanger, at turbulent flow conditions were investigated experimentally, using porous media and TiO2 Nanofluid to observe the behaviour of heat transfer with flow rate and volume concentration of nanoparticles t enhance heat transfer through it. 3 mm Steel balls (ε=39.12%) as a porous media completely filled to the inner pipe (core pipe). The cold and hot water are used as working fluids through the inner and outer pipes. Then using, the TiO2 nanofluid instead of cold water flowing through the porous pipe to enhance heat characteristics. The effects of operating parameters include flow rate (4 LPM, 6 LPM, and 8 LPM), Reynolds number between (3000 – 7000), and nanoparticle volume fraction (0.001, 0.002 and 0.003) on Convective heat transfer co-efficient and Nusselt number. Effective thermal conductivity is increased when the nanoparticle volume fraction is increased. The heat transfer coefficient increases with decreasing nanofluid temperature, but the heating fluid's temperature has no significant effect on the nanofluid's heat transfer coefficient. The results show that porous media and TiO2-based nanofluid's improve heat transfer at flow rate of 4 LPM by 35.4% and improve NTU and effectiveness at flow rate of 4LPM by 12.4%, and 24%, respectively, when compared to pure water without porous media. This improvement in thermophysical properties yielded high heat transfer of heat exchangers used in process industries.

Effect of Cu-Doped Carbon Quantum Dot Dispersion Liquid on the Lubrication Performance of Polyethylene Glycol

Energy saving and reduced consumption of key materials such as bearings in high-end equipment can be realized by synthesizing a new lubricating functional additive, copper-doped carbon quantum dot dispersion liquid (Cu-CQDs) via hydrothermal reaction with glycerol, cupric chloride dihydrate, and choline chloride as raw materials. The influence of the dispersion liquid containing Cu-CQDs nanoparticles on the lubricating properties of polyethylene glycol (PEG200) was investigated on a four-ball friction tester. The wear scars of steel balls after friction were analyzed using a scanning electron microscope accompanied by energy dispersive spectroscopy (SEM/EDS), photoelectron microscopy, and Raman spectroscopy. The results revealed the friction and wear mechanism of Cu-CQDs. Cu-CQDs dispersion liquid can significantly enhance the lubrication performance of PEG. The average friction coefficient of PEG containing 2.0 wt% Cu-CQDs dispersion liquid was 40.99% lower than that of pure PEG. The friction and wear mechanism can be ascribed to friction, inducing Cu-CQDs to participate in the formation of boundary lubricating film, resulting in a low friction coefficient and wear scar diameter.