Stainless Steel Balls Research Articles

Determining the tribological behavior of 316L stainless steel with lubricating micro-channels produced by the selective laser melting (SLM) method

PurposeThis study aims to produce lubricating surfaces with micro-channels by the selective laser melting (SLM) method, and to investigate their tribological behavior.Design/methodology/approachIn this study, three kinds of samples with different geometries were designed, impregnated with oil and then subjected to flow analysis in a virtual environment using Ansys Fluent software. According to the results of these analyses, the best-lubricated surface geometry sample was identified, and a number of geometries were produced by SLM, which is one of the additive manufacturing methods. Tribological tests were performed using a pin-on-disk tribometer with a stainless steel ball as the contact surface. The structural and morphological features were investigated by a three-dimensional profilometer and scanning electron microscopy.FindingsThe results obtained showed that the impregnated oil reached the surface of the sample compared to untreated samples, and it was seen that the wear rates were reduced, and that the impregnated oil samples exhibited the highest wear resistance.Originality/valueIn this study, solid geometries that are difficult to be produced by other methods are produced with additive manufacturing method, and the surfaces have been given lubricating properties.

A novel processing method based on the 3-spot diode laser source for the laser cladding of stainless-steel ball valves

In this paper, aiming to solve the problem of cracks in the laser cladding for stainless-steel ball valves, a novel method for defect-free processing is introduced. To realize this method, a 3-spot high-power diode laser source is developed. These three spots are respectively used for dynamic local preheating, laser cladding processing and dynamic local tempering. Using this high-power diode laser, a cladding processing of the stainless-steel ball valve with Ni60 + WC powder is successfully completed. Compared with the traditional processing approach, the cladded sample is free from any defects such as cracks and pores, which demonstrates the processing effect of this approach. This work provides a new method for the laser cladding of stainless-steel ball valves.

Tribological evaluations of spark plasma sintered Mg–Ni composite

ABSTRACT Elemental nickel particle was incorporated into magnesium matrix using blend-spark plasma sintering powder metallurgy technique without the use of ball milling and its effect on the hardness and tribological behaviour of magnesium was evaluated. Ball-on-disc wear tests were carried out using a 440C hardened stainless steel ball as a counter-face with a constant linear speed of 0.1 m/s under varying normal loads of 2.5, 5 and 10 N, respectively. The wear track on the disk samples was characterised using a FESEM equipped with energy dispersive spectrometer to investigate the wear mechanisms and features. Results showed that the reinforced magnesium composite showed excellent tribological properties as compared to the monolithic samples in terms of a reduction of up to 27.5% in the coefficient of friction and a reduction of up to 53.7% in weight loss. Microstructural analysis of the wear track established different wear mechanisms of abrasion, adhesive, delamination and oxidative wear.

Effect of nitrogen flow on the properties of carbon nitride films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Amorphous hydrogenated carbon nitride (a-CNx:H) films were fabricated via electron cyclotron resonance microwave plasma-enhanced chemical vapor deposition technology using N2 and C2H2 as nitrogen and carbon sources, respectively. The effects of the N2/C2H2 gas flow ratio on the composition, bond structure, scratch resistance, and optical properties of the a-CNx:H films were investigated. X-ray photoluminescence spectroscopy and Raman spectroscopy results indicated that the N/C atomic ratio, carbon 1s sp3/sp2 ratio, and nitrogen 1s sp3/sp2 ratio increased with increasing N2/C2H2 gas ratio. Pin-on-disk wear tests conducted with a pin made of ultrahigh-molecular weight polyethylene indicated that all the a-CNx:H films exhibited good scratch resistance; however, rubbing with a stainless-steel ball weakened the wear resistance of the a-CNx:H films as the N2/C2H2 gas ratio changed from 5/30 to 30/30. The measured transmittance spectra showed that nitrogen incorporation into the carbon films increased their transmittance in the visible to near-infrared regions. The optical bandgap of the a-CNx:H films was obtained by the Tauc method, which demonstrated that when the N2/C2H2 gas flow ratio changed from 0/30 to 30/30, the optical bandgap increased from 1.18 to 1.86 eV. Our results suggest that a-CNx:H films can be used as optical and protective coatings.

Mechanical properties and wear resistance of industrial bearing liners in concentrated boundary-lubricated sliding

The friction and wear behavior were studied for three materials typically found in industrial bearing applications: a Sn-based Babbitt, polytetrafluoroethylene (PTFE) and a polyether ether ketone (PEEK) composite. Test conditions were unidirectional sliding with a ball-on-disc geometry where the counter surface material was a 440C stainless steel ball (6.35 mm dia.). The tests were also in the presence of a lubricant, ISO46 oil, with the sample and contact submerged throughout the test. The relative effects of load and sliding velocities on the wear rates were assessed by means of regression analysis. Connections between wear and the materials mechanical properties, which were measured by instrumented indentation, were also made. The ranking of wear performance of the materials correlated best to the ratio of H/(E*)0.447, where H is the test material's hardness and E* is the reduced modulus for the contact. The power applied to the reduced modulus is that used in previous studies to estimate the oil film thickness for an isoviscous, elastic lubrication regime.

Understanding the Stability and Recrystallization Behavior of Amorphous Zinc Phosphate

Zinc phosphate, an important pigment in phosphate conversion coatings, forms protective films on rubbing surfaces. We have simulated the underlying reactions under shear by ball-milling zinc phosphate and monitored the reaction of hopeite (Zn3(PO4)2·4H2O) and the retarded recrystallization of the amorphous reaction product by powder X-ray diffraction (PXRD) and quantitative infrared (IR) spectroscopy. Abrasion of stainless steel was simulated by addition of pure 57Fe. The results provide insight into the chemistry of phosphate conversion coatings or during battery cycling of metal phosphates and give theoretical guidance for the preparation of amorphous phosphates. Thermal analysis revealed that the release of structural water is a key step during the reaction of hopeite under shear to ball-milled amorphous zinc phosphate. The back-reaction and associated recrystallization kinetics of amorphous zinc phosphate show a classical Langmuir behavior. Fe impurities inhibit the recrystallization of ball-milled amorphous zinc phosphate strongly. 57Fe Mössbauer spectroscopy and PXRD revealed that Fe is oxidized to Fe2+ and Fe3+ during ball-milling and incorporated locally at the tetrahedral and octahedral sites of the structure. Ball-milled amorphous zinc phosphate is metastable as γ-Zn3–xFex(PO4)2. EPR studies showed the incorporation of Fe3+ to be coupled with the formation of Zn2+ vacancies. The Fe3+ defect sites bind water because of their higher Pearson hardness (compared to Fe2+ and Zn2+), thereby reducing water mobility and inhibiting further reactions like the recrystallization to hopeite. Our findings reveal the amorphization mechanism of Zn3(PO4)2·4H2O in stainless steel ball mills at the atomic scale and highlight how the reactivity of amorphous products is affected by impurities associated with the processing method.

Effects of Mechanical Activation on the Bioleaching of Sphalerite and Marmatite for Zn Extraction

Even though mechanical activation is a significant pretreatment technology for the efficient extraction of metals from mineral resources, its effects on the bioleaching of sphalerite and marmatite are rarely discussed. In this study, mechanical activation pretreatment using various grinding media and grinding times was conducted, and particle size distribution, morphology, X-ray diffraction (XRD) and energy dispersive spectrometry (EDS) analyses, as well as batch bioleaching experiments, were carried out. The results suggest that #C conditions (corundum jar with zirconia balls) were more efficient than #S conditions (stainless steel jar with stainless steel balls) for the grinding of both sphalerite and marmatite. Mechanical activation significantly improved the bioleaching of sphalerite; however, it inhibited that of marmatite, possibly due to the formation of reactive oxygen species (ROS). The optimum grinding conditions for the bioleaching of sphalerite and marmatite are proposed.

Temperature and pressure oscillations induced by steam direct contact condensation in a T-junction with porous inner-structures

Steam direct contact condensation (SDCC) has been investigated experimentally with the steam mass flow rate in the range of 2 ~ 60 kg/h, the subcooled water flow rate in the field of 0.5 ~ 2 m3/h and the subcooled water temperature at 30 °C.in an empty T-junction and the T-junction with two porous inner-structures (made up by stainless steel ball with two different diameters). The effects of different porous inner-structures on temperature and pressure oscillations were investigated with different saturated steam mass flow rate and subcooled water flow rate. The results show that the porous inner-structures significantly reduces the temperature fluctuation near the branch pipe. Then, the positive peak value of pressure oscillation increases firstly and then decreases with the increase of porous inner-structures porosity. the intensity (RMS) of pressure oscillations were suppressed by filling the porous inner-structures. Besides, filling the porous inner-structures increases the viscous resistance and inertia resistance of the flow and enhances the intensity of turbulence. So the first dominant frequency increased significantly as the porosity of porous inner-structures decreased. Especially when the porosity ε = 0.318, the increase of the first dominant frequency is particularly evident and the maximum even reached 463 Hz.

Effect of High-Energy Vibrating Ball Milling in the Reduction of the Crystallite Size of TiO<sub>2</sub> Particles

In this work, TiO2 powders were prepared by high energy vibrating ball milling. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Photon cross correlation spectroscopy (PCCS with Nanophox) were used to determine the crystallite size of anatase TiO2. Depending on the grinding conditions (short grinding time, ball diameter, stainless steel ball and grinding powder ratio), the crystallite size decreased from 34 nm to 8 nm. The average diameter of a TiO2 particle with 8 nm crystals was ~221 nm. No structural phase transition was observed during milling.

Burnishing of ultra high molecular weight poly ethylene

Ultra-high molecular weight polyethylene (UHMWPE) has been a choice for knee and hip implants since a very long time due to its outstanding tribological properties. UHMWPE has many applications other than biomedical implants like hydrodynamic bearings and marine applications. The main objective of this research work is to enhance the surface properties of UHMWPE and eventually increase its life expectancy for the implants. For this purpose, the UHMWPE sheet has been milled to give it a required shape and then ball burnished with a carbide ball of 6 mm diameter under two different environments viz. room and cryogenic with three different burnishing strategic patterns. A constant load of 150 N is maintained by the tool on UHMWPE sample with a burnishing feed of 4000 mm/min along with a step over a distance of 0.06 mm after every pass for three different carefully chosen burnishing patterns. To understand the wear behaviour of the material, wear test has been performed on reciprocating wear testing machine with a stainless-steel ball as a pin for 6500 cycles in the medium of Hank’s balanced salt solution (HBSS) as a lubricating agent and to maintain the pH value which is same as in the human body. The lowest average surface roughness (Ra = 0.52 µm) is reported for the second strategy pattern which gets burnished under the cryogenic environment. This sample also exhibited better wear resistance than other samples burnished under different environments and using different strategic patterns.

Self-Powered Miniaturized Acceleration Sensor Based on Rationally Patterned Electrodes

Acceleration sensors have a wide variety of applications for industrial engineering, biology and navigation. However, passive sensing, narrow detection range, large size, and high manufacturing cost curb their further development. Here, we present a miniaturized acceleration sensor (MAS) with rationally patterned electrodes, based on the single electrode triboelectric mechanism, featuring small size, high accuracy, large detection scale, and environmental friendliness. A stainless-steel ball, as the moving part of the MAS, experiences physical movement that is converted into an electrical signal. Equipped with rationally patterned electrodes, the MAS retains the smallest size and lowest weight compared with the currently reported self-powered acceleration sensors. Benefiting from the voltage-relationship-based direction detection mechanism, eight directions can be identified by one TENG module. Consequently, rotated 22.5° relatively, two TENG modules enable the MAS to detect 16 directions. Moreover, accelerations ranging from 0.1 m/s2 to 50 m/s2 can be identified according to the relationship of response time and accelerations in the horizontal direction. The relationship is obtained through the measurements of the sum of output voltages ( VSOC ) for the four bottom electrodes with varying accelerations. In addition, no distinct decrease of VSOC is observed after continuously operating for 2000 circles, presenting excellent robustness. Hence, this cost-effective and rationally patterned MAS reveals great potential for human machine interaction, VR/AR (virtual/augmented reality), sports training, and smart city.

335. Using high temperatures to eradicate prosthetic joint associated biofilms on metal implants using alternating magnetic field: Efficacy and safety implications

BackgroundProsthetic joint infection (PJI) is a significant complication of modern arthroplasty. Revision surgery is frequently required due to the formation pf biofilm. The presence of biofilm makes non surgical treatment difficult in part because traditional antibiotics are unable to penetrate this structure.We have developed a noninvasive way to eradicate biofilm off the outer surface of metal implant utilizing alternating magnetic fields (AMF). AMF creates focused surface heating on metal lic implants and can be delivered in a fashion spares significant heating of surrounding tissue. The study was to determine efficacy and safety of AMF when combined with traditional antibiotics in animal models of implant infection.Methods Pseudomonas aeruginosa (PA) and staphylococcus aureus (SA) were grown individually on stainless steel ball that were implanted into the thigh muscle of the mice. Mice placed in a custom built solenoid coil for AMF treatments. AMD exposures generating peak temperature of 80 or 65 C on the implant were delivered once a day. Treatment groups included AMF alone, antibiotic alone, and combination therapy. Antibiotics tested included ciprofloxacin, ceftraixone and rifampin. Residual biofilm was measured by CFU counts. Histopathology was analyzed to determine area of damage in response to AMF treatment.ResultsCombination of a single AMF pulse with antibiotics lead to a greater biofilm reduction than either treatment alone. PA with AMD (80 C peak) and ciprofloxacin resulted in >2 log reduction of biofilm (p< 0.0001) compared to minimal reduction (AMF or ciprofloxacin alone) at Day 4. Similar treatment outcome was seen with SA and ceftraixone with combination treatment resulting on multi log reduction. Combined treatment effects were seen at lower temperatures (65 C). Histopathologic analysis demonstrates a small area of tissue damage at the end of treatment (Day 4). In mice that were survived fro additional 28-days after the final treatment, the tissue showed no signs of damage.ConclusionAMF combined with antibiotics leads to enhanced reduction of biofilm on metallic implants in vivo. This non invasive approach to eradicating biofilm could serve as a new paradigm in treating these challenging infections.Disclosures All Authors: No reported disclosures

Fatigue resistance of composite resins and glass-ceramics on dentin and enamel

Statement of problemComposite resins and glass-ceramics are both used to restore worn teeth. Which restoration material is more durable is unclear. PurposeThe purpose of this in vitro study was to evaluate the load to failure of thin composite resins and glass-ceramic restorations on enamel and dentin under increasing repetitive loads. Material and methodsGlass-ceramic blocks (IPS e.max CAD; Ivoclar AG) were shaped into cylinders (Ø4.0×1.0 mm), crystallized, and adhesively luted to bovine dentin and enamel substrates that were embedded in polymethyl methacrylate (n=20). Identical direct composite resin restorations (Clearfil AP-X; Kuraray Noritake Dental Inc) were made and directly applied on the same substrates (n=20). All specimens were tested in a pneumatic device with a stainless steel ball that provided a stepwise increase of the load (N) starting at 250 N and increasing by 50 N after every 10 000 cycles to a maximum of 1150 N. Failures were detected by a displacement sensor and defined by chipping of restorative material or catastrophic failure. ResultsOn dentin, composite resin showed a significantly higher fatigue resistance than glass-ceramic. On enamel, no significant difference was found between the 2 materials. ConclusionsWhen bonded to dentin, thin direct composite resin restorations were more durable than glass-ceramics. When bonded to enamel, no difference was found.

Enhanced corrosion and wear resistance of gradient graphene-CrC nanocomposite coating on stainless steel

The preparation of high-efficiency, stable, and low-cost graphene coating on the stainless steel substrate was highly anticipated but remained a challenge. Here, the graphene-CrC nanocomposite coatings were prepared on the 304 stainless steel ball (SS) by using the simple mechanical ball milling, which is in a gradient structure of graphene-CrC towards outside (G/SS). Notably, the graphene coatings could be strongly bonded on the SS surface by C-Cr bonding, which could provide excellent durability. Corrosion analysis revealed that graphene-CrC coatings would remarkably enhance the anticorrosion property of SS at the range of 293–328 K. The corrosion rates of the G/SS were merely 0.0336 × 10−4 mm day−1, which was significantly slower than that of the SS (1.58 × 10−4 mm day−1) at the room temperature. The double-layered coating could slow down the wear rate from 14.1 × 10−6 mm3 N−1 m−1 to 4.82 × 10−6 mm3 N−1 m−1. The present work could light on a straightforward strategy for the development of graphene coatings on metal substrate.

Tribological characterization of epoxy hybrid nanocomposite coatings reinforced with graphene oxide and titania

Epoxies in the form of bulk and coatings have been used throughout the years for a wide spectrum of applications in industries. However, the application of epoxies in demanding tribological applications is often limited by the properties of the pristine epoxy matrix such as low load bearing capacity under severe p-v regimes combined with low thermal conductivity values. In this study, the load bearing capacity of the pristine epoxy coating system applied onto non-textured, plasma treated mild steel substrates was first evaluated under dry sliding conditions. Wear tests were conducted using a ball on disk configuration with a grade 440C hardened stainless steel ball with a diameter of 6.3 mm and a hardness of 62 HRC, as the counterface. Graphene oxide (GO) fillers in varying concentrations of (0.25, 0.5, 1 and 1.5 wt%) were added to the pristine epoxy matrix to produce Epoxy-GO nanocomposite epoxy coatings and tribological evaluation was carried out. Tribological tests revealed that the addition of GO nanoparticles at 0.5 wt% filler loading led to a significant improvement in wear life (~6.5 times) when compared to the pristine epoxy system. In the second phase of this study, titania (TiO2) fillers were added to the optimized epoxy-0.5 wt% GO nanocomposite coating to produce GO-TiO2 hybrid nanocomposite epoxy coatings and tribological evaluation was carried out. However, tribological tests did not indicate any significant increase in the wear life after the addition of TiO2 as compared to the Epoxy-GO nanocomposite epoxy coatings. A detailed study of coating failure and wear mechanisms at significant datapoints were carried out using a combination of techniques namely coefficient of friction graphs for wear life, SEM for wear track imaging, EDS for elemental analysis of the wear track to establish failure, optical profilometry and counterface imaging using optical microscopy.

Open versus Interpenetrated: Switchable Supramolecular Trajectories in Mechanosynthesis of a Halogen-Bonded Borromean Network

Summary Precise control over topologically intricate molecular architectures remains an open challenge for chemists due to their inherent structural complexity. We report a simple solvent-free strategy to selectively prepare two multi-component supramolecular crystalline systems based on the halogen bond, endowed with either an unknot topology or a Borromean-type entanglement. Real-time in situ monitoring of the solvent-free mechanochemical synthesis of these three-component halogen-bonded ionic co-crystals reveals that the choice of milling conditions leads to a switch in the supramolecular reaction trajectory, resulting in the selective formation of an open halogen-bonded network or a halogen-bonded Borromean-type assembly.

Accuracy of complete-arch intraoral scans based on confocal microscopy versus optical triangulation: A comparative in vitro study

Statement of problemFully digital dentistry is contingent on an accurate digital scan of the complete arch; however, the dimensional accuracy of different scanners for digitizing a complete arch is unclear. PurposeThe purpose of this in vitro study was to compare the accuracy of 2 intraoral scanners, TRIOS 3 (TR) and CEREC Omnicam (OC). Accuracy was assessed from changes to reference distances defined along the complete arch of a reference cast including 3 precision balls and 3 prepared teeth. The local accuracy (trueness and precision) of the scanned surface of each prepared tooth was also assessed. Material and methodsEach intraoral scanner was used to scan a metal mandibular reference cast 20 times in a randomized sequence. The complete dental arch of a mandible in which the second left premolar was missing contained 2 prepared teeth, the first left premolar (LP) and the first left molar (LM) to accommodate a fixed partial denture (FPD) with complete crowns. The arch also contained an inlay preparation on the right second premolar (RP). Stainless-steel precision balls (ball centers P1, P2, and P3), which were welded onto the left second molar (P1), the incisal contact point of the central incisors (P3), and the right first molar (P2), were used to determine dimensional changes over the complete arch. Powder (CEREC Optispray) was applied to the reference cast to reduce reflections. Deviations between the reference cast (digitized with high precision before the tests) and the intraoral scans were calculated using Matlab R2015a and Geomagic Design X. To evaluate dimensional changes, the centers of the balls were determined, and their absolute changes in distance (ΔP1P2, ΔP1P3, and ΔP2P3) were calculated. To calculate accuracy (trueness and precision) in relation to the prepared teeth, the mesh deviation between the intraoral scans and the superimposed reference teeth was determined. The data were statistically analyzed by using a nonparametric rank-based 2-way repeated-measures ANOVA, and differences in least square means for pairwise comparisons were calculated (α=.05). ResultsThe following mean absolute changes in distance were determined: ΔP1P2, TR: 74.4 μm, OC: 119.6 μm; ΔP1P3, TR: 24.7 μm, OC: 17.2 μm; ΔP2P3, TR: 68.6 μm, OC: 41.2 μm. The scanner did not have a statistically significant effect (P=.118) for distance, and the different distances differed significantly from each other (P<.001). Both scanners provided results acceptable for the fabrication of inlays and short-span FPDs. A complete-crown scan was more accurate than an inlay scan (P<.001). Accuracy and precision were better for TR than for OC (P<.001). ConclusionsWith maximum discrepancies of 192.5 to 294.6 μm across the dental arch, complete-arch scans cannot yet be recommended for the fabrication of long-span FPDs.

Experimental and Numerical Studies of Thermal Energy Storage using Paraffin Wax Phase Change Materials

The main idea of this work is to design and analyze efficient storage of thermal energy using phase change material. Solar energy is a readily available and renewable source of energy. It is also a clean energy as it does not emit carbon dioxide. However maximum utilization of solar energy is not possible without the use of thermal energy storage (TES). This thermal storage system can form an integral part of solar heating system. In this work a TES tank is designed and fabricated. Paraffin wax is the phase change material used. It is encased in stainless steel balls. The high specific heat capacity of PCM is used to store latent heat which can be used any time. Temperature measurements are taken using T-type thermocouple along with indicator. Numerical analysis is done using the CFD software Ansys Fluent.This work mainly focuses to find the solution for the mismatch of abundant solar energy available during daytime and non-availability of energy during night-time. This project work also forms a part of a wider study to explore the possibility of PCMs to store the energy during off-peak load and releases the same during peak load. In several countries, during the daytime the load will be at peak level which leads to high cost for production. Therefore, cost saving can be achieved if heat pumps can be operated during the off-peak periods to store heat for use during the peak periods.

Microstructure characterization of HfNbTaTiZr High Entropy Alloy Processed in Solid State

This work investigates the alloying degree of HfNbTaTiZr high entropy alloy in equimolar percentages from raw, high purity powder, using solid state processing, for further uses in coating work components in harsh environments like marine, geothermal or oil and gas industry. The combination of elements was chosen according their properties, tailoring the composition for the final purpose. The alloying has been performed in a planetary ball mill with stainless steel vial and balls in a protective argon atmosphere to prevent oxidation, contamination or ignition and N-heptane as a process control agent to improve the material’s behavior during welding and re-welding in mechanical alloying process. Samples were taken at regular periods of time and analyzed to check the alloying degree evolution and to establish the optimum parameters for milling, best results being obtained at a speed of 300 rpm for 180 min (effective time) providing an alloying degree over 50% was achieved.

The Effect of Ball Size on Hardness of Mechanically Alloyed Al-10wt.%Ti Powders

Particle size and hardness of Al-10%wt.Ti powders due to the influence of ball diameter have been carried out using mechanical alloying techniques. The milling device used consisted of a Fritsch Pulverisette-5 planetary type ball mill with the rotational speed of about 360 rpm and balls size of 10, 15 and 20 mm. The materials used are stearic acid which was used as a process control agent, aluminum and titanium powders. A mixture of aluminum and titanium powders has the composition of Al-10wt.%Ti. The Al-10wt.%Ti powders, stearic acid and stainless-steel balls were added to the Fritsch Pulverisette-5 planetary in the argon gas environment. The weight ratio of stainless steel balls to the Al-10wt.%Ti powder was 20 : 1. The mixing time process was carried out for 5, 10, 15, 20 and 30 hours, respectively. Changes in phase compositions of these Al-Ti powders under different ball mill sizes were examined by XRD, and the optimum experimental parameter was obtained: the ball mill size was 20 mm. It was found that from the diffraction patterns of the Al-10wt.%Ti powders, the peaks of titanium begin to disappear with the increasing of the milling time, which indicates the increasing degrees of alloying of titanium atoms in the aluminum matrix. The microhardness test results showed that the hardness increases with increasing ball size.