Increasing Test Duration Research Articles

Quasi-in-Situ Analysis of Electropolished Additively Manufactured Stainless Steel Surfaces

Progress in additive manufacturing is leading to the emergence of new areas of application. Laser Powder Bed Fusion (L-PBF) is increasingly used for the development of metallic medical implants, but for high-risk implants like vascular support structures (stents), surface quality is critical to ensure successful implantation without harming the surrounding tissue and ensure the patients’ health. Therefore, enhancing the surface quality is crucial. Electropolishing is a method for removing surface roughness by smoothing out micro-peaks and valleys. However, L-PBF structures have a high surface roughness due to metal particles adhering on the surface. To achieve a smooth surface for additively manufactured implants like stents using electropolishing, the removal of these particles needs to be studied in more detail.The objective of this study is to examine the electropolishing mechanism of 316L stainless steel samples additively manufactured through Laser Powder Bed Fusion (L-PBF). The main objective is to investigate the removal properties and surface characteristics during electropolishing. To achieve this, various surfaces were characterized for morphology and roughness during Hull cell experiments. Markings are utilized on the Hull cell sample surfaces to identify points of interest during quasi-in-situ measurements. The surfaces are then analyzed after multiple time steps, applying different currents to investigate particle dissolution. The surface characteristics are analyzed through scanning electron microscopy, and surface roughness is analyzed using laser scanning microscopy.The results show that the electropolishing process preferentially removes the adhering particles present on the surface of the samples. Increasing the current density results in faster particle dissolution and a smoother surface (see Figure 1a and b). The mechanism of material removal of various surface features, as shown in Figure 1 (red circle, yellow arrow and red square), was assessed based on the experimental results of the surface structures seen on the SEM images. It was found that different surface features were removed during the experiment at different polishing times and current densities. The amount of charge flowed was found to correlate with surface morphology.Based on the obtained results, various surface features (such as large adherent particles, agglomerates of smaller particles, and valleys) and their changes with increasing test duration and current density were observed by quasi-in situ analyses. A reduction in the diameter of round particles adhering to the surface was observed at both low and higher current densities (see Figure 1a red circle a). Increasing the polishing time resulted in leveling of both large particles and valleys (see Figure 1b red square). Also, dissolution of agglomerates of smaller particles occurred at different polishing times as a function of current density and polishing time (see Figure 1a yellow arrow) are observed.Smoothed surface structures can be observed in regions with equivalent surface charge density (see Figure 2). As a result, comparable surface morphologies may appear at the same area charge density, irrespective of a specific current density. So, it may be adequate to only consider the amount of charge flowed to describe the electropolishing of additive materials.In conclusion, comprehending the dissolution characteristics of particles on L-PBF surfaces is essential for attaining satisfactory surface finish in electropolishing. The results of this study offer valuable perspectives into the electropolishing mechanism of additively manufactured 316L stainless steel and can guide future investigations on surface finishing and polishing of additive manufactured implants like stents. Figure 1

Modified version of Monkman-Grant equation for Gr.91 by incorporating “strain to minimum creep rate” parameter

A modified version of the Monkman-Grant equation, which can provide a more accurate means of predicting creep rupture life than the standard Monkman-Grant formula, has been investigated for Gr.91 using creep data in the NIMS Creep Data Sheets at 450–725 °C. The maximum time to rupture tr was 1.2 × 105 h. The tr versus minimum creep rate ε˙min plot, which is called the Monkman-Grant relation, deviates downward at low stresses and long times. The difference between the maximum and minimum tr at a same ε˙min becomes more significant with decreasing stress and increasing test duration. Better correlation of the tr with the ε˙min is not obtained by the replacement of tr with (tr/εr), where εr is the total or rupture strain. The magnitude of data scattering is larger in the (tr/εr) versus ε˙min plot than in the tr versus ε˙min plot. The (tr/εm), where εm is the strain to minimum creep rate, is inversely proportional to the ε˙min over a wide range of stress, temperature and test duration and the magnitude of data scattering is only a little bit even at low stresses and long times. The (tr/εm) versus ε˙min plot gives us more reliable relation for Gr.91 than the tr versus ε˙min and (tr/εr) versus ε˙min plots.

Can the 20 and 60s All-Out Test Predict the 2000m Indoor Rowing Performance in Athletes?

Purpose: The purpose of this study was to look for a new, simple, and fast method of assessing and monitoring indoor race performance and to assess the relationship between 20 s, 60 s, and 2000 m indoor rowing performances of youth rowers to evaluate their anaerobic profile. Methods: For three consecutive days, 17 young able-bodied male rowers (15.8 ± 2.0 years), performed three tests (20 s, 60 s, and 2000 m) on a rowing ergometer. Mean power (W20, W60, and W2000) and 2000 m time (t2000) were considered for the analysis. In addition, 14 athletes (15–18 years) performed a 20 s, 60 s, and 2000 m tests and used this as a control group. To define the anaerobic profile of the athletes, W20 and W60 were normalized as percentages of W2000. Associations between variables were determined by means of the Pearson correlation coefficient (r). Results: Mean power decreased with increasing test duration (W20 = 525.1 ± 113.7 W; W60 = 476.1 ± 91.0 W; W2000=312.9 ± 56.0 W) and negative correlations emerged between t2000 (418.5 ± 23.1 s) and W20 (r = −0.952, p < 0.0001) and W60 (r = −0.930, p < 0.0001). Conclusion: These findings indicate that W20 and W60 are significant predictors of 2000 m rowing ergometer performances. Furthermore, normalized W20 and W60 can be used to evaluate athletes and as a reference for planning anaerobic training sessions, on a rowing ergometer.

Influence of modern aluminium alloys on the reaction behavior of refractory linings

AbstractFor modern aluminum alloy production, constituents of silicon, zinc, and magnesium contribute mainly to the degradation of refractory furnace linings. The alloy constituents increasingly penetrate the material via the vapor phase. This study intends to enhance understanding, describe and characterize the interactions between refractories used in holding and melting furnaces of the aluminum industry. The damage mechanisms occurring due to corrosion are verified and determined by applying various test methods and atmospheres.The present study focuses on the impact of zinc (Zn) and magnesium (Mg) as a gaseous component on refractory linings. The examined materials of this study are bauxite‐based bricks with phosphate bonding and bricks with either CA6 or sol‐gel bonding, both based on high alumina.The experimental setup of the corrosion tube furnace consists of a crucible filled with solid metal and two identical bars of the refractory sample. Metallic zinc, magnesium, and the Al alloy EN‐AW7075 are within this study's scope. Further conditions are a testing temperature of 1050°C and increasing test duration of 2, 8, 24, and 36 h. The experiments have shown that zinc and magnesium both have an extreme influence, especially on the microstructure, which is accompanied by both positive and negative property changes. These are dependent on both the bonding type and the ambient atmosphere.

Standard automated perimetry using size III and size V stimuli in advanced stage glaucoma: an observational cross-sectional comparative study

ObjectivesIn this study, we sought to evaluate the extent of further visual field that could be assessed when using stimulus size V in standard automated perimetry compared with size III...

Influence of boron nitride inclusions and degradation in creep rupture strength on creep rupture ductility of Gr.122

ABSTRACT The creep rupture ductility has been investigated for Gr.122 at 550 to 650 oC for up to 112,247.8 h. The obtained results are compared with those for Gr.91 and Gr.92. The degradation in reduction of area (RA) in Gr.122 is similar to that in Gr.92 but more significant than that in Gr.91. The boron nitride inclusions are responsible for the degradation in RA in Gr.92 and Gr.122. The creep ductility parameter λ of Gr.122 decreases with increasing test duration to small values less than 5 at 20,000 h to 30,000 h and then increases steeply to about 20 at long times at 650 oC. The RA and total elongation of Gr.122 decrease with increasing test duration to small values but then turn to increase at 625 oC and 650 oC and long times.

Increasing the Spatial Resolution of Visual Field Tests Without Increasing Test Duration: An Evaluation of ARREST.

PurposeThe Australian Reduced Range Extended Spatial Test (ARREST) approach was designed to improve visual field spatial resolution while maintaining a similar test duration to clinically used testing algorithms. ARREST does not completely threshold visual field locations with sensitivity < 17 dB, and uses the presentations saved to test new locations in areas of steep gradient within the visual field. Previous assessments of ARREST's performance have used computer simulation. In this study, we cross-sectionally assessed the performance of ARREST in people with visual field loss.MethodsWe tested 23 people with glaucoma (mean age: 71 ± 8 years) with established visual field loss. Three visual field procedures were performed using the Open Perimetry Interface: cZEST and ARREST on the Octopus 900 perimeter (Haag-Streit AG, Switzerland), and a reference standard (best available estimate [BAE]) on the Compass perimeter (CenterVue SpA, Italy). ARREST was compared against the cZEST and the BAE.ResultsOn average, ARREST added seven new locations (range = 0–15) to a visual field test. There was no significant difference in the number of stimulus presentations between procedures (mean = 259 ± 25 [ARREST] vs. 261 ± 25 [cZEST], P = 0.78). In classifying threshold values < 17 dB, ARREST performed similarly when compared against BAE.ConclusionsThis study provides empirical evidence to support conclusions from previous computer simulations that ARREST can be used to increase spatial sampling in regions of interest without increasing test time.Translational RelevanceARREST is a new approach that augments current visual field testing procedures to provide better spatial description of visual field defects without increasing test duration.

Effect of Duration and Pattern of Hydrographs on Scour Around Pier in Sharp Bend Under Incipient Motion and Live Bed Conditions

In the present study, the effect of peak occurrence time and flood duration on the scour around the bridge pier installed in a sharply bended channel was investigated. For this purpose, several simple single-peaked hydrographs with the same durations and different peak occurrence times were produced in laboratory. In addition, hydrographs having two consecutive peaks with a steady flow discharge at the first peak and an unsteady-flow discharge at the second peak and vice versa were investigated. The flow velocity range began from incipient motion conditions and steeply increased to live bed conditions. In each experiment, the temporal variations of the maximum local scour depth were measured. In single-peaked experiments, by increasing hydrograph duration from 25 to 100 min, the maximum scour depth increased by 20%, and the progression of sediments along the downstream straight path increased by 150%. For hydrographs with two non-equal and the same duration peaks, at a constant discharge for the first peak and a decrease in the second peak discharge from 70 to 60, 50, and 45 (L s−1), the volume of the scour hole around the pier was decreasing 15, 40, and 60%. Its area fell by 10, 40, and 55%, respectively. When the rising and falling limb time of hydrographs were equal, the maximum sedimentation height increased by 2.7, 3.5, and 5 times, respectively by increasing test duration from 25 to 50, 75, and 100 min.

Corrosion and Corrosion Fatigue Properties of Additively Manufactured Magnesium Alloy WE43 in Comparison to Titanium Alloy Ti-6Al-4V in Physiological Environment.

Laser powder bed fusion (L-PBF) of metals enables the manufacturing of highly complex geometries which opens new application fields in the medical sector, especially with regard to personalized implants. In comparison to conventional manufacturing techniques, L-PBF causes different microstructures, and thus, new challenges arise. The main objective of this work is to investigate the influence of different manufacturing parameters of the L-PBF process on the microstructure, process-induced porosity, as well as corrosion fatigue properties of the magnesium alloy WE43 and as a reference on the titanium alloy Ti-6Al-4V. In particular, the investigated magnesium alloy WE43 showed a strong process parameter dependence in terms of porosity (size and distribution), microstructure, corrosion rates, and corrosion fatigue properties. Cyclic tests with increased test duration caused an especially high decrease in fatigue strength for magnesium alloy WE43. It can be demonstrated that, due to high process-induced surface roughness, which supports locally intensified corrosion, multiple crack initiation sites are present, which is one of the main reasons for the drastic decrease in fatigue strength.

The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

The formation of white etching cracks (WECs) in steel rolling element bearings can lead to the premature rolling contact fatigue (RCF) failure mode called white structure flaking. Driving mechanisms are still debated but are proposed to be combinations of mechanical, tribochemical and electrical effects. A number of studies have been conducted to record and map WECs in RCF-tested samples and bearings failed from the field. For the first time, this study uses serial sectioning metallography techniques on non-hydrogen charged test samples over a range of test durations to capture the evolution of WEC formation from their initiation to final flaking. Clear evidence for subsurface initiation at non-metallic inclusions was observed at the early stages of WEC formation, and with increasing test duration the propagation of these cracks from the subsurface region to the contact surface eventually causing flaking. In addition, an increase in the amount of associated microstructural changes adjacent to the cracks is observed, this being indicative of the crack being a prerequisite of the microstructural alteration.

Thermal Desorption Analysis of Hydrogen in Non-hydrogen-Charged Rolling Contact Fatigue-Tested 100Cr6 Steel

Hydrogen diffusion during rolling contact fatigue (RCF) is considered a potential root cause or accelerator of white etching cracks (WECs) in wind turbine gearbox bearing steels. Hydrogen entry into the bearing steel during operation is thought to occur either through the contact surface itself or through cracks that breach the contact surface, in both cases by the decomposition of lubricant through catalytic reactions and/or tribochemical reactions of water. Thermal desorption analysis (TDA) using two experimental set-ups has been used to measure the hydrogen concentration in non-hydrogen-charged bearings over increasing RCF test durations for the first time. TDA on both instruments revealed that hydrogen diffused into the rolling elements, increasing concentrations being measured for longer test durations, with numerous WECs having formed. On the other hand, across all test durations, negligible concentrations of hydrogen were measured in the raceways, and correspondingly no WECs formed. Evidence for a relationship between hydrogen concentration and either the formation or the acceleration of WECs is shown in the rollers, as WECs increased in number and severity with increasing test duration. It is assumed that hydrogen diffusion occurred at wear-induced nascent surfaces or areas of heterogeneous/patchy tribofilm, since most WECs did not breach the contact surface, and those that did only had very small crack volumes for entry of lubricant to have occurred.

Environmentally Relevant Inoculum Concentrations Improve the Reliability of Persistent Assessments in Biodegradation Screening Tests.

Standard OECD biodegradation screening tests (BSTs) have not evolved at the same rate as regulatory concerns, which now place an increased emphasis on environmental persistence. Consequently, many chemicals are falsely assigned as being potentially persistent based on results from BSTs. The present study increased test duration and increased inoculum concentrations to more environmentally relevant levels to assess their impact on biodegradation outcome and intratest replicate variability for chemicals with known environmental persistence. Chemicals were assigned to potential persistence categories based on existing degradation data. These more environmentally relevant BSTs (erBSTs) improved the reliability of persistence assignment by reducing the high variability associated with these tests and the occurrence of failures at low inoculum concentrations due to the exclusion of specific degraders. Environmental fate was determined using a reference set of 14C-labeled compounds with a range of potential environmental persistences, and full mass balance data were collated. The erBST correctly assigned five reference chemicals of known biodegradabilities to their appropriate persistence category in contrast to a standard OECD Ready Biodegradation Test (RBTs, P < 0.05). The erBST was significantly more reproducible than an OECD RBT (ANOVA, P < 0.05), with more consistent rates and extent of biodegradation observed in the erBST.

Determining lower threshold concentrations for synergistic effects

Though only occurring rarely, synergistic interactions between chemicals in mixtures have long been a point of focus. Most studies analyzing synergistic interactions used unrealistically high chemical concentrations. The aim of the present study is to determine the threshold concentration below which proven synergists cease to act as synergists towards the aquatic crustacean Daphnia magna. To do this, we compared several approaches and test-setups to evaluate which approach gives the most conservative estimate for the lower threshold for synergy for three known azole synergists. We focus on synergistic interactions between the pyrethroid insecticide, alpha-cypermethrin, and one of the three azole fungicides prochloraz, propiconazole or epoxiconazole measured on Daphnia magna immobilization. Three different experimental setups were applied: A standard 48h acute toxicity test, an adapted 48h test using passive dosing for constant chemical exposure concentrations, and a 14-day test. Synergy was defined as occuring in mixtures where either EC50 values decreased more than two-fold below what was predicted by concentration addition (horizontal assessment) or as mixtures where the fraction of immobile organisms increased more than two-fold above what was predicted by independent action (vertical assessment). All three tests confirmed the hypothesis of the existence of a lower azole threshold concentration below which no synergistic interaction was observed. The lower threshold concentration, however, decreased with increasing test duration from 0.026±0.013μM (9.794±4.897μgL−1), 0.425±0.089μM (145.435±30.46μgL−1) and 0.757±0.253μM (249.659±83.44μgL−1) for prochloraz, propiconazole and epoxiconazole in standard 48h toxicity tests to 0.015±0.004μM (5.651±1.507μgL−1), 0.145±0.025μM (49.619±8.555μgL−1) and 0.122±0.0417μM (40.236±13.75μgL−1), respectively, in the 14-days tests. Testing synergy in relation to concentration addition provided the most conservative values. The threshold values for the vertical assessments in tests where the two could be compared were in general 1.2 to 4.7 fold higher than the horizontal assessments. Using passive dosing rather than dilution series or spiking did not lower the threshold significantly. Below the threshold for synergy, slight antagony could often be observed. This is most likely due to induction of enzymes active in metabolization of alpha-cypermethrin. The results emphasize the importance of test duration when assessing synergy, but also show that azole concentrations within the typically monitored range of up to 0.5μgL−1 are not likely to cause severe synergy concerning Daphnia magna immobilization.

탄소강의 유동가속부식에 미치는 크롬의 영향

The alloy content of structural materials of nuclear power plants has been recognized an important factor in predicting flow accelerated corrosion (FAC). In particular, many literature data reported that chromium content is one of the most important alloying element and even a small amount of chromium is effective to suppress FAC. This report reviewed and compared chromium models of Ducreux, Bouchacourt, and Kastner which were used in predicting FAC rates. The plant data indicate that Ducreux model may be conservative for the specimen containing 0.15 wt% chromium. The related articles were reviewed as follows. Combined effects of chromium content, pH, temperature, dissolved oxygen (DO), flow velocity, test time, and kinds of amine on the FAC rate were described. 0.1 wt% chromium in steel did not affect the FAC rate with changes in pH. The FAC rates pronounced with higher flow rate and increased with increasing test duration(600 d) for 0.013 wt% chromium. The FAC rates in mixed amine chemistry were higher than in ammonia chemistry, which may be lessened by the addition of chromium to the steel.

Effect of a Variability-Adjusted Algorithm on the Efficiency of Perimetric Testing

Variability in perimetry increases with the amount of damage, making it difficult for testing algorithms to efficiently converge to the true sensitivity. This study describes a variability-adjusted algorithm (VAA), in which step size increases with variability. Contrasts were transformed to a new scale wherein the SD of frequency-of-seeing curves remains 1 unit for any sensitivity. A Bayesian thresholding procedure based on the existing Zippy Estimation by Sequential Testing (ZEST) algorithm was simulated on this new scale, and results converted back to decibels. The root-mean-squared (RMS) error from true sensitivity based on these simulations was compared against that achieved by ZEST using the same number of presentations. The procedure was repeated after limiting sensitivities to 15 dB or higher, the lower limit of reliable sensitivities using standard white-on-white perimetry in glaucoma, for both algorithms. When the true sensitivity was 35 dB, with starting estimate also 35 dB, RMS errors of the algorithms were similar, ranging from 1.39 dB to 1.60 dB. When true sensitivity was instead 20 dB, with starting estimate 35 dB, VAA reduced the RMS error from 7.43 dB to 3.66 dB. Limiting sensitivities at 15 dB or higher reduced RMS errors, except when true sensitivity was near 15 dB. VAA reduces perimetric variability without increasing test duration in cases in which the starting estimate of sensitivity is too high; for example, due to a small scotoma. Limiting the range of possible sensitivities at 15 dB or higher made algorithms more efficient, unless the true sensitivity was near this limit. This framework provides a new family of test algorithms that may benefit patients.

Corrosion of Cr bearing low alloy pipeline steel in CO2 environment at static and flowing conditions

We study the corrosion performance of Cr bearing low alloy pipeline steel (Cr3MoNi) in CO2 saturated formation water, under both static and flowing conditions. Cross-sectional morphologies of corrosion scales at progressively increased test duration are observed by scanning electron microscopy. The characteristic of the corrosion scales are investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. Our results show that the corrosion rate of Cr3MoNi steel at flowing condition is higher than that of static condition, and the degree of Cr enrichment in the scales at flowing condition is also higher. Flow also makes ions distribute evenly in the solution close to the specimen, leading to a uniform distribution of Cr compound in the amorphous corrosion scales. In this way, flow suppresses the presence of the potential pits and also leads to a more flat scale/substrate interface.

Effect of test duration on the visual-evoked potential (VEP) and alpha-wave responses

The purpose of this study was to assess the effect of test duration on the visual-evoked potential (VEP) and related alpha power spectrum measures. Two conditions (eyes-closed and eyes-open) were tested using four different durations: 10, 20, 45, and 60 s. The Diopsys™ NOVA-TR system was used to obtain the visual-evoked potential (VEP) and extracted alpha wave with its related power spectrum. Sixteen visually normal, young-adult subjects (aged 22-25 years) participated in the experiment. The stimulus for the eyes-open condition consisted of a black-and-white, alternating checkerboard pattern with a small central fixation target. All trials were performed during one session. Regarding the VEP parameters, only variability of the VEP amplitude changed significantly with test duration. Sentence should end with a period, not a colon. It decreased with increasing test duration, with the 45- and 60-s trials showing similarly low variability. Regarding the alpha-wave parameters, test duration did not have a significant effect on either the mean alpha power or its variability across trials. The findings demonstrate that forty-five-second test durations are sufficient to minimize intra-session variability of the VEP amplitude and latency measurements, whereas 10-s test durations may be sufficient for accurate measurement of the alpha wave. Optimization of test duration allows for repeatable measures with less total test time. This is especially important for special clinical populations.

Vanadium(III) and vanadium(IV) catalysts in a membrane reactor for benzene hydroxylation to phenol and study of membrane material resistance

Benzene hydroxylation to phenol by using vanadium based catalysts and product recovery were performed in a two-phase membrane reactor. Benzene permeates, through the hydrophobic polypropylene membrane, in the aqueous phase containing the catalyst while phenol permeates back accumulating in the organic phase. The following fundamental aspects have been studied: dose of hydrogen peroxide, initial oxidation states of vanadium catalysts, duration of catalytic tests and lifetime of the membrane in terms of physical and chemical resistance. It was observed that feeding the oxidant by a micro pump, working in the “bulk tube” mode, phenol yield, final phenol concentration in the organic phase, phenol turnover number and system productivity increased, and no tar was formed. Initial oxidation state of vanadium catalysts influenced system performance: indeed improved results in terms of yield (35.2% vs. 25.1%), conversion of hydrogen peroxide to phenol (36.6% vs. 25.9%), productivity (0.97 g gcat−1 h−1 vs. 0.78 g gcat−1 h−1) were obtained by using vanadium(III) chloride compared to vanadium(IV) acetyl acetonate. Higher phenol extraction/recovery in the organic phase (61.1% vs. 46.3%) and then higher selectivity (97.5% vs. 92.8%) were obtained by increasing test duration from 270 to 510min. A weak membrane resistance was observed after 246h of consecutive catalytic runs on the same membrane piece, showing degradation of the membrane material (polypropylene) caused by the OH radical generated in the reacting mixture.

Sliding Wear Behavior of Cast Iron: Influence of MoS2 and Graphite Addition to the Oil Lubricant

The present study discusses sliding wear characteristics of a gray cast iron over a range of applied loads in oil lubricated condition. Effects of MoS2 and graphite addition to the oil lubricant in governing the wear behavior have also been studied. The wear rate increased with load in general with a few exceptions in the case of oil plus 5% MoS2 wherein it had a tendency to show a reverse trend in the intermediate load range. Addition of 5% graphite to the oil brought about a decrease in the wear rate without affecting seizure resistance. Increasing quantity of graphite in the oil from 5 to 10% practically did not affect the wear rate at lower loads. However, it led to significantly lower wear rates at higher loads and also offered higher seizure resistance. In the case of oil plus 5% MoS2 lubricant mixture, the wear rate of the samples was higher than that of the lubricant with 5% graphite when tests were conducted at lower loads while identical response was observed at higher loads in both cases. Seizure resistance of the samples was not affected by the addition of 5% graphite and MoS2 to the oil. The frictional heating also increased with load in general, except in the case of oil containing 5% MoS2 and 10% graphite wherein it remained practically unaffected in the intermediate load range. The presence of 5% graphite and MoS2 in the oil lubricant brought about reduced frictional heating, except in the case of oil plus 5% graphite mixture wherein the trend reversed, and oil plus 5% MoS2 leading to comparable frictional heating during specimen seizure. Increasing test duration caused higher frictional heating. Adhesion was observed to be the principal wear mechanism while microcracking assisted delamination and abrasion also contributed to material loss.

Influence of talc concentration in oil lubricant on the wear response of a bronze journal bearing

This study pertains to the examination of the effects of dispersing talc particles in an oil lubricant towards controlling the sliding wear characteristics of a journal bearing (bush) fabricated using a leaded-tin bronze. Influence of the content of the suspended mass in the oil and applied load on the wear behavior was also investigated. Properties evaluated were wear loss, frictional heating and friction coefficient. Addition of talc particles to the oil lubricant decreased the wear loss, frictional heating and friction coefficient while the applied load produced a reverse effect. Further, increasing content of talc up to 3–5% led to a decrease in the observed properties; the trend reversed at higher concentrations of the suspended mass in the oil. The increasing test duration caused the frictional heating and friction coefficient to increase at a high rate initially. The rate of increase lowered down at longer test durations. The observed wear behavior of the samples has been substantiated through the characteristics of wear surfaces and subsurface regions. The latter also enabled to understand the operating wear mechanisms.