Search results

To improve the wear resistance of the sliding boot, the wear-resistant Fe-21 Wt.% Cr-5 Wt.% B alloy is prepared, and the wear mechanism is studied under dry sliding condition.

The anti-wear Fe-21 Wt.% Cr-5 Wt.% B alloy is prepared by powder metallurgy technique. The tribological behavior of Fe-Cr-B alloy sliding against ASTM 1045 steel pin is studied at 30-60 N and 0.03-0.12 m/s using a reciprocating pin-on-disk tribometer under dry sliding condition. Meanwhile, the ASTM 5140 and 3316 steel are studied as compared samples.

The friction coefficients of tested specimens increase with the increasing normal load. However, this effect is the opposite in case of different sliding speeds. The specific wear rates increase as the sliding speed and normal load increase. The Fe-Cr-B alloy shows the best tribological properties under the dry sliding condition and the wear mechanism is mainly ploughing.

This wear-resistant Fe-21 Wt.% Cr-5 Wt.% B alloy can replace the traditional materials to process the sliding shoes and improve the service life of coal mining machine.

Testing of silicon nitride (Si₃N₄) or silicon carbide (SiC), sliding on itself in water, revealed that hydrodynamic lubrication can be obtained at low‐sliding velocity. The purpose of this paper is to study the performance of Si₃N₄‐metals pairs, sliding in water.

Ball on disc unidirectional sliding tests are run with Si₃N₄ against tool steel, stainless steel and cast iron in water. The friction force is recorded continuously and the wear is evaluated at the end of the run by geometric technique. In addition, SiC sliding on itself in oxidant solution (3 per cent solution of CrO₃ in water) is tested.

The measured friction and wear of water‐lubricated Si₃N₄ against metals are higher compared to Si₃N₄ sliding on itself. At the end of the run‐in SiC, lubricated by the oxidant solution, obtains hydrodynamic lubrication and friction and wear are lower than in water‐lubricated SiC.

The experimental results obtained are valid within the range of load and sliding velocity applied – 1‐10 N, 0.04‐0.33 m/s, respectively. The Si₃N₄ sliding against metals in water over sliding distance of 3,000 m has not shown tendency towards hydrodynamic lubrication.

The paper presents test data on friction and wear properties of Si₃N₄ sliding against metals in water. The low friction and ball wear rate of the SiC, lubricated by the oxidant solution, shows the potential of the 3 per cent distilled water solution of CrO₃ to surpass water as a lubricant for SiC sliding bearings.

For gravity dams built on foundations with directional joint sets, the seepage in the foundation possesses anisotropic characteristics and may have adverse effects on the foundation stability. A methodology for system reliability analysis of gravity dam foundations considering anisotropic seepage and multiple sliding surfaces is proposed in this paper.

Anisotropic seepages in dam foundations are simulated using finite element method (FEM) with the equivalent continuum model (ECM), and their effect on dam foundation stability is involved by uplift pressures acting on the potential sliding surfaces. The system failure probability of the dam foundation is efficiently estimated using Monte Carlo method (MCM) combined with response surface method (RSM).

The case study shows that it is necessary to consider the possibly adverse effect of anisotropic seepage on foundation stability of gravity dams and the deterministic analysis of the foundation stability may be misleading. The system reliability analysis of the dam foundation is justified, as the uncertainties in shear strength parameters of the foundation rocks and joint sets as well as aperture, connectivity and spacing of the joint sets are quantified and the system effect of the multiple potential sliding surfaces on the foundation reliability is reasonably considered.

(1) A methodology is proposed for efficient system reliability analysis of foundation stability of gravity dams considering anisotropic seepage and multiple sliding surfaces (2) The influence of anisotropic seepage on the stability of gravity dam foundation  is revealed (3) The influence of estimation errors of RSMs on the system reliability assessment of dam foundation is investigated.

Sliding wear is a common phenomenon in the iron ore handling industry. Large-scale handling of iron ore bulk-solids causes a high amount of volume loss from the surfaces of bulk-solids-handling equipment. Predicting the sliding wear volume from equipment surfaces is beneficial for efficient maintenance of worn equipment. Recently, the discrete element method (DEM) simulations have been utilised to predict the wear by bulk-solids. However, the sensitivity of wear prediction subjected to DEM parameters has not been systemically investigated at single particle level. To ensure the wear predictions by DEM are accurate and stable, this study aims to conduct the sensitivity analysis at the single particle level.

In this research, pin-on-disc wear tests are modelled to predict the sliding wear by individual iron ore particles. The Hertz–Mindlin (no slip) contact model is implemented to simulate interactions between particle (pin) and geometry (disc). To quantify the wear from geometry surface, a sliding wear equation derived from Archard’s wear model is adopted in the DEM simulations. The accuracy of the pin-on-disc wear test simulation is assessed by comparing the predicted wear volume with that of the theoretical calculation. The stability is evaluated by repetitive tests of a reference case. At the steady-state wear, the sensitivity analysis is done by predicting sliding wear volumes using the parameter values determined by iron ore-handling conditions. This research is carried out using the software EDEM^® 2.7.1.

Numerical errors occur when a particle passes a joint side of geometry meshes. However, this influence is negligible compared to total wear volume of a wear revolution. A reference case study demonstrates that accurate and stable results of sliding wear volume can be achieved. For the sliding wear at steady state, increasing particle density or radius causes more wear, whereas, by contrast, particle Poisson’s ratio, particle shear modulus, geometry mesh size, rotating speed, coefficient of restitution and time step have no impact on wear volume. As expected, increasing indentation force results in a proportional increase. For maintaining wear characteristic and reducing simulation time, the geometry mesh size is recommended. To further reduce simulation time, it is inappropriate using lower particle shear modulus. However, the maximum time step can be increased to 187% T_R without compromising simulation accuracy.

The applied coefficient of sliding wear is determined based on theoretical and experimental studies of a spherical head of iron ore particle. To predict realistic volume loss in the iron ore-handling industry, this coefficient should be experimentally determined by taking into account the non-spherical shapes of iron ore particles.

The effects of DEM parameters on sliding wear are revealed, enabling the selections of adequate values to predict sliding wear in the iron ore-handling industry.

The accuracy and stability to predict sliding wear by using EDEM^® 2.7.1 are verified. Besides, this research accelerates the calibration of sliding wear prediction by DEM.

The purpose of this study is to develop new Al‐based bearing alloys which have better properties than classic commercial bearing materials and to analyze tribologic properties of these alloys under dry sliding conditions experimentally.

Four different aluminium alloys were produced with casting method and tested on pin‐on‐disc wear testing machine. Friction coefficients and weight losses of the samples were determined under various working conditions in consequence of the experiments. Hardness, surface roughness, and surface temperatures of the samples were measured.

The results of the experiment show that friction coefficients vary by surface pressure and sliding speed. Al15Pb3.7Cu1.5Si1.1Fe and Al15Sn5Cu3Si alloys have lower friction coefficient values than other alloys. Al8.5Si3.5Cu alloy has the biggest wear resistance. Al15Pb3.7Cu1.5Si1.1Fe and Al15Sn5Cu3Si alloys are the most worn materials. Al8.5Si3.5Cu alloy has the lowest wear rate.

When the comparison was done between commercial Al alloys and developed Al alloys in this study, it was seen that Al15Sn5Cu3Si and Al15Pb3.7Cu1.5Si1.1Fe alloys have lower friction coefficient values than other commercial alloys.

The effects of the elements except aluminium composing alloys upon tribologic properties were analyzed. Some of the alloy elements were seen to improve tribologic properties whereas some downgrade. When the results are evaluated, Al15Sn5Cu3Si and Al8.5Si3.5Cu alloys containing Si and Sn can be preferred among the aluminium alloys that will work under dry sliding.

This paper reveals new bearing materials. These alloys can be used in journal bearings.

This research aims to describe the influence of weight per cent of graphite (Gr), applied load and sliding speed on the wear behavior of aluminum (Al) alloy A356 reinforced with silicon carbide (SiC) (10 Wt.%) and Gr (1 Wt.% and 5 Wt.%) particles. The objective is to analyze the effect of the aforementioned parameters on a specific wear rate.

These hybrid composites are obtained by means of the compo-casting process. Tribological analyses were conducted on block-on-disc tribometer at three different loads (10, 20 and 30 N) and three different sliding speeds (0.25, 0.5 and 1 m/s), at the sliding distance of 900 m, in dry sliding wear conditions. Optimization of the tribological behavior was conducted via the Taguchi method, and ANOVA was used for the analysis of the specific wear rate. Confirmation tests are used to foresee and check the experimental results. Examined samples were analyzed via a scanning electron microscope (SEM). Regression models for predicting specific wear rate were developed with Taguchi and ANN (artificial neural network) methods.

The biggest impact on value of specific wear rate has the load (43.006%), while the impact of Wt.% Gr (31.514%) was less. After comparison of the results, i.e. regression models, for predicting the specific wear rate, it was observed that ANN was more efficient than the Taguchi method. The specific wear rate of Al alloy A356 with SiC (10 Wt.%) and Gr (1 Wt.% and 5 Wt.%) decreases with a decrease in the load and weight per cent of Gr-reinforcing material, as well as with a decrease in sliding speed.

The results obtained in this paper using the Taguchi method and the ANN method are useful for improving and further investigating the wear behavior of the SiC- and Gr-reinforced Al alloy A356.

This study aims to the optimization using three factors and three-level parameters (sliding speed [rpm], sliding distance [m/s] and load [N]) of design matrix were adapted to Box–Behnken design using design expert v8.0 software. Based on the parameters, to develop the linear regression equation and to find the significant considerable wear process parameters based on output responses like wear loss (WL) and coefficient of friction (COF) value of polymer matrix composites (PMC) specimen of Acrylonitrile-butadiene-styrene (ABS)/cellulose composite (80 wt% of ABS and 20 wt% of cellulose).

The fabrication of the ABS/cellulose composite sample was carried out by the simple hands-on stir process method. As per the American Society for Testing and Materials G99 standard, the sample was made by the molding process. The wear analysis was made by multi tribotester TR25 machine and validated the developed model by using statistical software design expert v.8.0 and numerical tools like analysis of variance. The surface morphology [field emission scanning electron microscopy (FESEM) analysis] of the sample was also observed using the Quanta FEG-250 FESEM instrument.

The parameters like sliding speed, sliding distance and load are independently affected the COF value and WL of the 80% of ABS matrix and 20% cellulose reinforced composite material. The regression equations were generated by the coefficient of friction value and WL, which predicted the minimum WL of 80% of ABS matrix and 20% of cellulose reinforced composite material. The worn surface analysis result exposes the worn path and equal distribution of reinforcement and matrix on the surface of composite material.

The literature survey revealed a small number of studies available regarding wear analysis of ABS matrix and cellulose reinforced composite materials. In the present work, to fabricate and evaluate the wear performance of PMC (80% of ABS and 20% of cellulose) depends on the WL and COF value. The maximum and minimum COF value (µ) of 80% of ABS and 20% of cellulose composite material is 4.71 and 0.28 with the optimized wear process parameter by 1,000 mm of sliding distance, 0.25 (m/s) of sliding speed and 9 N of load.

This paper aims to study the sliding wear and coefficient of friction (COF) using “ball on disc” tribometer. Discs of bearing steel were subjected to different tribological parameters such as heat treatment (through hardening and case hardening), sliding speed, sliding distance and micro-geometry of the functional ball and disc point contact. Results obtained from tribometer were correlated with the preload loss in tapered roller bearing. Preload loss is subjected to wear rate pattern with respect to the internal geometry and micro-geometry of functional surfaces of the tapered roller bearing, caused by internal resistance between roller large ends sliding against cone supporting face. This confirms the optimum geometry and physical/mechanical property of the tapered roller bearing, which makes the use of these bearings under the demanding application in the automotive industry such as differential gears and installation of pinions of differential gears in power transmissions or wheels.

The paper opted for an exploratory study using the design of experiments with full factorial method. The approach was to do ball on disc sliding wear test and correlate that sliding wear with preload loss in tapered roller bearing.

The paper provides the limit of preload loss in tapered roller bearing.

Because of the chosen research approach, the research lacks the effect of environmental conditions such as temperature and relative humidity and lube film thickness effect on wear test. It also lacks the validation part with actual preload loss on tapered roller bearings. Above work is included in future scope of work.

This paper includes the recommendation for surface parameters which can increase the bearing life by reducing the preload loss in tapered roller bearing.

This paper includes the recommendation for surface parameters for bearing manufacturing industries.

This paper provides the relation between sliding wear and preload loss in tapered roller bearing.

The purpose of this paper is to verify, experimentally, the sliding stability of cast polyamide samples under dry sliding in contact with different steel counterface roughnesses. The effect of catalyser (sodium or magnesium) and addition of internal oil or solid lubricants is investigated and a classification for coefficients of friction in relation to the polyamide intrinsic mechanical properties is discussed.

A new tribotester is designed for meso‐scale testing according to the elastic loading region of polymers. The reliability of the tribotester is verified by preliminary determination of the stick‐slip characteristics. Sliding tests for polyamide are done at 1.15‐5.15 N normal load and 0.125‐20 mm/s sliding velocity on steel counterfaces with roughness R_a=4 and 1.6 μm.

Pure polyamides sliding against rough steel show severe stick‐slip. The stick‐slip motion is eliminated in contact with smooth steel counterfaces. Magnesium catalysed polyamide has weaker mechanical properties and shows lower friction with better sliding stability compared to sodium catalysed polyamide. Internal oil lubricant is more efficient in reducing coefficients of friction than internal solid lubricants are. Surface energy measurements are related to coefficients of friction, showing the effect of internal lubrication on adhesion.

Present test results are very specific for the present tribotester configuration and should be further compared to macro‐scale testing. The choice of tribotest conditions strongly affects the sliding performance.

Present tests are done on the meso‐scale, being in between traditional macro‐scale testing and nano‐scale testing. It allows for low contact pressures avoiding the effects of frictional heating and relatively large surfaces areas including the effects of long‐range polymer structure such as internal lubrication.

Since, wear is the one of the most commonly encountered industrial problems leading to frequent replacement of components there is a need to develop metal matrix composites (MMCs) for achieving better wear properties. The purpose of this paper is to fabricate aluminum MMCs to improve the dry sliding wear characteristics. An effective multi-response optimization approach called the principal component analysis (PCA) was used to identify the sets of optimal parameters in dry sliding wear process.

The present work investigates the dry sliding wear behavior of graphite reinforced aluminum composites produced by the molten metal mixing method by means of a pin-on-disc type wear set up. Dry sliding wear tests were carried on graphite reinforced MMCs and its matrix alloy sliding against a steel counter face. Different contact stress, reinforcement percentage, sliding distance and sliding velocity were selected as the control variables and the response selected was wear volume loss (WVL) and coefficient of friction (COF) to evaluate the dry sliding performance. An L25 orthogonal array was employed for the experimental design. Optimization of dry sliding performance of the graphite reinforced MMCs was performed using PCA.

Based on the PCA, the optimum level parameters for overall principal component (PC) of WVL and COF have been identified. Moreover, analysis of variance was performed to know the impact of individual factors on overall PC of WVL and COF. The results indicated that the reinforcement percentage was found to be most effective factor among the other control parameters on dry sliding wear followed by sliding distance, sliding velocity and contact stress. Finally the wear surface morphology of the composites has been investigated using scanning electron microscopy.

Various manufacturing techniques are available for processing of MMCs. Each technique has its own advantages and disadvantages. In particular, some techniques are significantly expensive compared to others. Generally the manufacturer prefers the low cost technique. Therefore stir casting technique which was used in this paper for manufacturing of Aluminum MMCs is the best alternative for processing of MMCs in the present commercial sectors. Since the most important criteria of a dry sliding wear behavior is to provide lower WVL and COF, this study has intended to prove the application of PCA technique for solving multi objective optimization problem in wear applications like piston rings, piston rods, cylinder heads and brake rotors, etc.

Application of multi-response optimization technique for evaluation of tribological characteristics for Aluminum MMCs made up of graphite particulates is a first-of-its-kind approach in literature. Hence PCA method can be successfully used for multi-response optimization of dry sliding wear process.