Wear Rate Of Material Research Articles

Tribological Behavior of CF/PTFE Composite and Anodized Al-Rotor in Traveling Wave Ultrasonic Motors

The tribological behavior of stator friction material and rotor in the traveling wave ultrasonic motor (TWUSM) shows some particularities because of the applied way and the special contact between stator and rotor. In this investigation, the tribological behavior of carbon fiber-reinforced polytetrafluoroethylene composite, which is used as stator friction material, sliding against an anodized aluminum rotor in a TWUSM is reported. The performances of TWUSM were tested, and the surface topography was examined in different stages. The results shown that the speed of USM remained stable at 120 r/min after 60 h of operating and the holding torque and stall torque tended to stabilize after 100 h. Moreover, the fluctuation of roughness of friction material was small, while the surface roughness of rotor decreased 28.8% after 10 h of operating. Both the roughness of friction material and rotor tended to stabilize after 100 h of operating. The wear mechanisms of stator friction material in steady wear stage were found to be adhesive wear and plastic deformation, which was quite different from that of rotor friction material. The wear rate of friction material decreased with time, and wear 1 μm of height required approximately 68 h. The surface topography of rotor changed little, and the wear height after 200 h of operating was less than 2 μm.

Friction and wear behavior of steam-oxidized ferrous PM compacts

This study determines density effect by assessing sintering temperature and graphite content on the dry sliding wear characteristics of steam-treated iron materials using a pin-on-disk wear test. The specimens were prepared from atomized premixed iron base powders and contained 0.1 to 1.0 wt.% carbon compacted at different densities (5.9 g/cc to 6.8 g/cc). The specimens were sintered for 1 h at different sintering temperatures (1090°C to 1130°C), and then subjected to continuous steam treatment at 540°C for 95 min through in situ Powder metallurgy (PM) technique. Steam treatment was proposed to improve the wear performances of the components of PM. Wear tests were conducted using a pin-on-disk-type machine. Load ranged from 20 N to 60 N. Sliding distance and sliding velocity of 312 m and 0.26 m/s, respectively, were adopted for all tests. Scanning electron microscope was used to analyze wear surface. Increased density and graphite content reduced the wear rate of steam-treated materials. Hardness increased with increasing graphite content. Wear mechanism, wear rate map, and wear maps were drawn for the test result data. Wear transition map identified mild, severe, and ultra-severe wear regimes as functions of applied load.

Ultralow wear of gallium nitride

Here, we reveal a remarkable (and surprising) physical property of GaN: it is extremely wear resistant. In fact, we measured the wear rate of GaN is approaching wear rates reported for diamond. Not only does GaN have an ultralow wear rate but also there are quite a few experimental factors that control the magnitude of its wear rate, further contributing to the rich and complex physics of wear of GaN. Here, we discovered several primary controlling factors that will affect the wear rate of III-Nitride materials: crystallographic orientation, sliding environment, and coating composition (GaN, InN and InGaN). Sliding in the ⟨12¯10⟩ is significantly lower wear than ⟨11¯00⟩. Wear increases by 2 orders of magnitude with increasing humidity (from ∼0% to 50% RH). III-Nitride coatings are promising as multifunctional material systems for device design and sliding wear applications.

Modeling Wear of Multimaterial Composite Surfaces

Iterative numerical wear models provide valuable insight into evolving material surfaces under abrasive wear. In this paper, a holistic numerical scheme for predicting the wear of rubbing elements in tribological systems is presented. In order to capture the wear behavior of a multimaterial surface, a finite difference model is developed. The model determines pressure and height loss along a composite surface as it slides against an abrasive compliant countersurface. Using Archard's wear law, the corresponding nodal height loss is found using the appropriate material wear rate, applied pressure, and the incremental sliding distance. This process is iterated until the surface profile reaches a steady-state profile. The steady-state is characterized by the incremental height loss at each node being nearly equivalent to the previous loss in height. Several composite topologies are investigated in order to identify key trends in geometry and material properties on wear performance.

Effect on crystalline structure of AISI M2 steel using tungsten–thorium electrode through MRR, EWR, and surface finish

To investigate on the crystalline structure of AISI M2 steel by using tungsten–thorium electrode in electrical discharge machining (EDM) process was studied. Furthermore, the investigation were carried out for finding the value of material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR) of tool steel material depending upon three variable input process parameters. On the basis of weight loss, the value of MRR and EWR were calculated at optimized process parameter. Subsequently, surface topography of the processed material were examined through different characterization techniques like scanning electron microscopy (SEM), Optical surface profiler (OSP) and Atomic force microscopy (AFM), respectively. In XRD study, broadening of the peak was observed which confirmed the change in material properties due to the homogeneous dispersion of the particles inside the matrix. Lowest surface roughness and MRR of 0.001208mg/min was obtained. Minimum surface roughness was obtained 1.12μm and 2.18427nm by OSP and AFM study, respectively. Also, minimum EWR was found as 0.013986mg/min.

Si3N4 as a biomaterial and its tribo‐characterization under water lubrication

AbstractHip implant wear is recognised as the main cause of hip implant failure therefore has been widely investigated both experimentally and clinically, demonstrating the coexistence of abrasive, adhesive, fatigue and corrosive wear. Many clinical in vivo and bulk material wear rate data from published literature have been presented for non‐oxide ceramic implants. Several studies have shown that the coefficient of friction of self‐mated silicon nitride in water decreases from an initially high value to about 0.002 after a certain run‐in period. Since the worn surfaces become extremely smooth, the low friction is attributed to the initiation of hydrodynamic lubrication by a thin water film at the interface. The possibility of mixed lubrication, i.e. hydrodynamic lubrication by water and boundary lubrication due to the presence of colloidal silica on the wearing surfaces, has also been proposed.Influence of load, speed and surface roughness on the duration of the run‐in period of silicon nitride under water lubrication was investigated in this study. The results confirmed that a low coefficient of friction is obtained following a run‐in period when a wear scar of sufficient size is developed to reduce the contact stress. The run‐in period, during which the coefficient of friction is fairly high, is shorter for smoother surfaces and at higher loads and speeds. The striations that appeared to be associated with the high‐friction spikes can be formed as a result of surface film breakdown. Although the results are consistent with the proposed mechanisms of hydrodynamic lubrication or mixed lubrication, it is proposed that the low‐friction behaviour may also be related to fundamental interactions between two hard and elastically deforming surfaces covered with hydrogen‐terminated oxide films. Copyright © 2016 John Wiley & Sons, Ltd.

Humidity and Water Effect on Wear Characteristics of Disc Braking System

A series of wet braking tests has been performed using two different pad materials. Brake tests were conducted in different operating conditions i.e. dry, humid air and wet environment in which both pad samples were tested against grey cast iron disc at certain sliding speed and contact pressure. Wear analysis was performed to find correlation between presence of water and changes in brake pad wear characteristics. The results revealed that regardless of the frictional behaviour, wear rate for both pad materials tested at humid air and wet braking is significantly lower than in dry results.

A review on particulate slurry erosive wear of industrial materials: In context with pipeline transportation of mineral−slurry

ABSTRACTPipeline transportation of slurry is being carried out all over the world. Slurry pipeline wear is one of the major problems associated with it. The wear rate of the slurry pipeline depends upon factors such as slurry properties, slurry particle properties, flow properties, and pipeline wall properties. Any change in these properties results in change in pipeline wear rate. There is a need to study the effect of individual properties, for predicting the slurry pipeline life span and also to find the methods to minimize the wear rate. In this review paper, an attempt has been made to discuss the parameters which are believed to be the primary factors that affect material wear rate. Several mechanisms and equations suggested by various researchers for the prediction of wear of materials are also reviewed. Most of the models incorporate the effects of only few parameters involved during the wear process. These equations are specific and valid up to limited operating conditions. No general equation have been evolved which can be used under any operating condition, with better accuracy. This can be attributed to lack of data at microscopic level and also to change in the wear mechanisms under various operating conditions.

Tribological and Microstructure Behavior of Quicklime (CaO) Filled Silicon Bronze Alloy for Bearing Material

CaO filled silicon bronze (SiBr) alloy composites have been fabricated by a high temperature vacuum casting technique at five different weight percentages (0 wt%, 2.5 wt%, 5 wt%, 7.5 wt% and 10 wt% of CaO). The void contents, hardness and wear behavior of the CaO filled SiBr alloy composites were studied showing that the addition of particulates in base alloy reduces the void contents from 0.827 % to 0.504 % for 0 wt% to 7.5 wt% of CaO respectively. Similarly, the hardness of CaO filled SiBr alloy composites initially increases from 119.25 Hv to 140.8 Hv on addition of 7.5 % CaO but on further increase in filler content (10 wt%) the hardness decreases to 114.5 HV respectively. The specific wear rate of composite materials for applied load and sliding velocity factors showed surpassing behavior compared to unfilled alloy composites. To get the optimum response of wear behavior of composite materials the Taguchi L25 orthogonal array was applied and the result shows the higher S/N ratio i.e. 106.33 dB. The analysis of variance (ANOVA) result shows that the filler content plays a major effect compared to other factors. The particulate filled composites were examined through scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX) and atomic force microscopy (AFM) in order to understand the wear mechanism and morphology behavior of the composites.

Wear behavior of a low metallic friction material dry sliding against a cast iron disc: Role of the heat-treatment of the disc

In commercial automotive braking systems, consisting of a friction pad dry sliding against a pearlitic cast iron disc, the wear of the disc contributes significantly to the overall wear. In the present work, pin-on-disc sliding tests were carried out for determining the role of conventional heat-treatment conducted on cast iron discs on the friction and wear behavior of the above coupling. Wear rates of both disc and friction materials were reduced by almost one order of magnitude when the disc is preliminarily heat-treated and then ground to remove the surface decarburized layer that forms during the thermal cycle. Heat-treatment and heat-treatment plus grinding resulted also in the decrease of the friction coefficient, which was comparatively lower for the ground samples. The friction and wear behavior along with the contact temperature evolutions were rationalized according to the actual materials characteristics, as resulting from the different treatments.

Mathematical modeling and multi-criteria optimization of rotary electrical discharge machining process

In this paper, mathematical modeling of three performance characteristics namely material removal rate, surface roughness and electrode wear rate in rotary electrical discharge machining RENE80 nickel super alloy is done using regression approach. The parameters considered are peak current, pulse on time, pulse off time and electrode rotational speed. The regression approach is very much effective in mathematical modeling when the performance characteristic is influenced by many variables. The modeling of these characteristics is helpful in predicting the performance under a given set of combination of input process parameters. The adequacy of developed models is tested by correlation coefficient and Analysis of Variance. It is observed that the developed models are adequate in establishing the relationship between input parameters and performance characteristics. Further, multi-criteria optimization of process parameter levels is carried using grey based Taguchi method. The experiments are planned based on Taguchi's L9 orthogonal array. The proposed method employs single grey relational grade as a performance index to obtain optimum levels of parameters. It is found that peak current and electrode rotational speed are influential on these characteristics. Confirmation experiments are conducted to validate optimal parameters and it reveals the improvements in material removal rate, surface roughness and electrode wear rate as 13.84%, 12.91% and 19.42% respectively.

Magnetic Field Assisted Electric Discharge Machining of Cryo-Treated Monel 400 Alloy

Monel alloys are pioneering materials which have exceptional engineering properties such as corrosion resistance, high toughness and show good response to cryogenic treatment. It finds uses in ship building, nuclear aerospace, missile and valve industries. These materials shows strain hardening effect which results in tool wear and in some cases tool breakage when machined by conventional methodshence, unconventional machining such as electrical discharge machining (EDM)discoverspurpose for machining of such materials. Researchers have recognized relation between electrical input process parameters of EDM process and output parameters of EDM process. But researchers have not investigated the influence of external magnetic field and cryo-treatment of work piece on EDM performance measures namely material removal rate (MRR) and tool wear rate (TWR). In vision of this the objective of present work was to study the effect of gap current, external magnetic field and cryogenic treatment of work part on MRR and TWR. Experiments were carried out by creating a 3 mm square hole on Monel400 alloys. Based on experimental results it was found that as gap current increases the MRR and TWR increases for untreated work part. For treated work part MRR increases and TWR decreases with increasein gap current. MRR and TWR increases with constant gap current for untreated work part, as magnetic field increases. For treated work part MRR increases and TWR decreases with increase in magnetic field at constant gap current.

Parametric Analysis of Micro Electrical Discharge Milling Process of Non-Conductive Silicon Carbide

Silicon carbide (SiC) is a high performance ceramic material which is increasingly used in applications which demand for high temperature stable materials. The microstructuring of this material in its sintered state is a challenge for conventional machining methods due to its extraordinary mechanical properties. To overcome these limitations the process of electrical discharge machining (EDM) was modified with a so called assisting electrode (AE) to enable the structuring of non-conductive ceramics such as SiC. This paper presents a parametric analysis of micro electrical discharge milling process of non-conductive SiC for two different tool materials, tungsten carbide (WC) and copper (Cu). A full factorial design with four factors was conducted. The significant factors are shown with main effects plots. Two sets of optimized parameters for maximum material removal rate (MRR) and minimum tool wear rate (TWR) for both tool materials are presented. Hardness and surface roughness are measured and compared to the non-machined material.

Tribological and thermal stability study of nanoporous amorphous boron carbide films prepared by pulsed plasma chemical vapor deposition

In this work, the thermal stability and the oxidation and tribological behavior of nanoporous a-BC:H films are studied and compared with those in conventional diamond-like carbon (DLC) films. a-BC:H films were deposited by pulsed plasma chemical vapor deposition using B(CH3)3 gas as the boron source. A DLC interlayer was used to prevent the a-BC:H film delamination produced by oxidation. Thermal stability of a-BC:H films, with no delamination signs after annealing at 500 °C for 1 h, is better than that of the DLC films, which completely disappeared under the same conditions. Tribological test results indicate that the a-BC:H films, even with lower nanoindentation hardness than the DLC films, show an excellent boundary oil lubricated behavior, with lower friction coefficient and reduce the wear rate of counter materials than those on the DLC film. The good materials properties such as low modulus of elasticity and the formation of micropores from the original nanopores during boundary regimes explain this better performance. Results show that porous a-BC:H films may be an alternative for segmented DLC films in applications where severe tribological conditions and complex shapes exist, so surface patterning is unfeasible.

Twin-disc tests of iron oxides in dry and wet wheel−rail contacts

The wheel−rail contact system is open to the environment; as a result there are various kinds of contaminants present between railway wheels and rails. In addition to water, oil and sand, which are applied intentionally or unintentionally, iron oxides are constantly present on surfaces. A twin-disc rolling-sliding tribometer has been used to study the influence of iron oxides on the adhesion coefficient and wear rates of wheel and rail materials. Iron oxides were created in a climate chamber and tests were performed under both dry and wet conditions. The adhesion coefficient, wear rates and surface roughness were investigated. Results indicate that an increase in slip ratio increases the adhesion coefficient, and the wear rate also increases in the dry condition. In wet conditions, the effect of iron oxides lasts for a long time and greatly influences adhesion and wear. The adhesion curve peaks at a much larger creep with the presence of thin oxides than for thick oxides.

Wear behavior of SiC/PyC composite materials prepared by electromagnetic-field-assisted CVI

Silicon carbide/pyrolytic carbon (SiC/PyC) composite materials with excellent performance of self-lubrication and wear resistance were prepared on SiC substrates by electromagnetic-field-assisted chemical vapor infiltration (CVI). The composition and microstructure of the SiC/PyC materials were investigated in detail by XRD, SEM and EDS, etc. The effects of the deposition temperature on the section features and wear resistance of the SiC/PyC were studied. The results show that the PyC layers were deposited onto SiC substrates spontaneously at a lower deposition temperature. The SiC substrates deposited with PyC can significantly reduce the wear rate of the self-dual composite materials under dry sliding condition. The wear tests suggest that the SiC/PyC composite materials own a better wear resistance property when the deposition temperature is 800 °C, and the wear rate is about 64.6% of that without the deposition of PyC.

COMPUTATIONAL TESTING OF WEAR RATE OF DIFFERENT MATERIAL WITH VARIABLE OPERATING PARAMETERS

In this paper research study has been made on the computational testing of wear rate for different materials (Cu, ss410 and Al) under the different condition of load applied, Speed and time. The set up of pin on disc tribometer has been used to study the wear rate of materials. The experiments has been performed on a group of specimens under different cases of times (5 to 15) minutes, and under different loads (3 to 7) Kg, and different speeds (500 to 1100)rpm the set up is connected with Data Acquisition System which gives wear rate of material computationally. By fixing any two parameters with one variable parameter experiment is performed [2]. Graphical representation of wear rate along with friction force and coefficient of friction is given by WINDUCOM software and the results will show the wear rate relation with (time, speed and load) and the comparisons of one material with other materials

Wear resistance and selection of steels, hardmetals and hardfacings for abrasive wear conditions

Hardness and toughness have a major effect on wear resistance. The material wear rate depends directly on hardness (at sliding wear), as well as on material toughness (at impact wear). The main goal of the present work was to study the abrasive wear behaviour of different wear resistant steels, hardmetals/cermets and hardfacings. The following steels were under the study: a) hardenable boron and non–alloy steel C 45 subjected to different heat treatments; b) hardened steels Hardox 400…600. WC–Co hardmetals and TiC–NiMo cermets and composite metal–matrix coatings were studied. The abrasive wear tests were performed using two methods: a) abrasive rubber–wheel wear; b) abrasive impact wear. The dependence of wear resistance on hardness and toughness of steels is clarified, the wear maps are composed. In combined abrasive/impact wear conditions, composite materials/coatings with multimodal reinforcements show promising results in increasing of abrasive wear resistance of rapidly wearing wear parts.

철도차량용 금속계 소결마찰재의 조성에 따른 트라이볼로지 특성

Graduate School of Railroad, Seoul National University of Science and Technology(Received September 22, 2014; Revised November 10, 2014; Accepted November 17, 2014)Abstract − Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake sys-tems in high energy moving machines that are associated with recently developed 200km/h trains. This has ledto the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigatethe effects of the composition of friction materials on the tribological characteristics of sintered metallic brakepads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressureof 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, wetest and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and thetemperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. Theresults clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a largequantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear ofthe friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, thedisc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, thesurface roughness, and temperature of the friction materials increased, so the average friction coefficientsdecreased. An oxidation layer of Fe

디스크 질량 변화에 따른 철도차량용 제동디스크의 마찰 특성

Low alloy heat resistant brake disk and sintered brake pad are applied to mechanical brake system for the speed-up of urban rapid transit. In this research, we analyzed how the frictional characteristics between brake disk and pad are influenced by the disk mass. At a high disk mass, the friction stability was the lower value as a result of the lack of tribofilm formation at the disk surface. Wear rates of friction materials showed the higher value at a low disk mass and wear rates of 10 mm and 15 mm showed the similar level. Average friction coefficient was the lower value at the 10 mm disk thickness and range of variation of average friction coefficient was also the smaller value at the 10 mm disk thickness. However, there were no significant changes in the friction coefficients under any of test conditions. Surface roughness of a disk showed the highest value at the 5 mm disk and surface roughnesses of 10 mm and 15 mm showed the similar level. As a result, friction characteristics of disk mass influenced the friction stability, as well as the wear rate of friction pad and disk, but not the friction coefficient.