Decrease In Wear Rate Research Articles

Experimental Investigation of CNT Coated Tools for EDM Processes

In EDM process while machine operated on high current and pulse on time values it leads to increase tool wear rate. The aim of this research work was to create a methodology to minimize the tool wear rate at high values of energy related parameters in EDM. The experimental work is investigated comparative study with coated tool electrode and with non coated tool electrode. Copper electrodes are used as tool electrode then it coated with carbon nano tubes for further experimental work. Design of experiment (DOE) is done with Taguchi method and results discussed with ANOVA. The machining results showed that the tool wear rate (TWR) decreases and material removal rate (MRR) increases with coating of CNT on copper electrodes.

Fabrication and Machining Performance of Powder Compacted Alumina Based Cutting Tool

This study focuses on the fabrication of alumina based cutting tool for machining application. Specific weight of alumina powders were pressed in a mold using hydraulic press at 8 tons before compressed through Cold Isostatic Press (CIP) at 30000 psi. Green body then was dried and sintered at 1700 °C at 4 hours sintering time to form solid cutting tools. These cutting tools were then tested in turning operation to machine AISI 1045 with different cutting speeds. The results shows that CIP pressed alumina cutting tool obtained the hardness of 83.2 HRA which is considered adequate to machine AISI 1045 steel. The shrinkage of alumina powders recorded about 7% form green compact to sintered body. In terms of flank wear, the alumina cutting tool demonstrated decreased wear rate as the cutting speed increased from 150 m/min to 225 m/min. Wear area focused at the edge of cutting tool due to small nose radius with the minimum wear rate recorded at 0.0025 mm/s for 225 m/min cutting speed. The newly fabricated cutting tools can be improved if finer or secondary reinforced particles were used.

Friction and Wear Behavior of Single-Phase Fe2B Bulk under Dry Sliding Condition

ABSTRACTThe effects of normal load and velocity on the friction and wear behavior of single-phase Fe2B bulk have been investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Results indicate that the friction coefficient and wear rate both decrease at first and then increase with increasing load and velocity, respectively. Attributed to the formation of a lamellar film on the Fe2B surface, the lowest friction coefficient and wear rate are obtained at a velocity of 0.2 m/s under a load of 12 N. The dynamic friction coefficients under loads of 4 and 12 N are around 0.8 in the initial steady stage and then decrease to about 0.6, whereas the friction coefficient at 20 N shows no obvious change and remains around 0.82. The lubricating film consisting of Fe2O3, B2O3, SiO2, and H3BO3 reduces the friction coefficient at 0.2 m/s under a load of 12 N.

Influence of plasma nitriding temperature on microstructures and mechanical properties of Ti-N/Ti-Al multilayer coatings on the surface of 5083 Al alloys

Novel Ti-N/Ti-Al based compound layers were produced on the surface of 5083 Al alloys by duplex surface treatment. Samples were deposited with pure Ti film by using magnetron sputtering and then plasma nitrided for 8h at 400°C, 430°C, 460°C and 490°C, in a gas mixture of 40% N2+60% H2. The treated samples were characterized by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), microhardness tester and pin-on-disc tribometer. Results showed that the duplex layer was composed of the outer TiN0.3 layer and inner Al18Ti2Mg3 layer. The preferred (002) orientation of TiN0.3 was enhanced with the elevated nitriding temperature. The surface hardness of 5083 Al alloy was remarkably improved by the duplex layer, reaching a maximum value of 900HV0.01, which was about 10 times higher than untreated 5083 Al alloy. Significant decrease in friction coefficient and wear rate also occurred for the nitrided samples. The wear mechanism of nitrided samples is dominated by abrasive wear.

High-quality graphene directly grown on Cu nanoparticles for Cu-graphene nanocomposites

High-quality graphene was directly grown on the surface of Cu nanoparticles (NPs) via chemical vapor deposition (CVD) and then the graphene-covered Cu NPs were consolidated into dense Cu-graphene nanocomposites at different temperature. The surface of Cu NPs is well protected from oxidation due to the coverage of graphene. Nanocomposite consolidated at 650°C (Cu/G-650) exhibits a hardness of 2.53GPa with no distinctive different electrical resistivity compared with pure Cu, 2 orders of magnitude decrease in wear rate and 175% improvement in the coefficient of friction (COF) were reported for the Cu/G-650 nanocomposite as compared with pure Cu. The formation of graphene tribofilm is attributed for the effective protection of the Cu matrix from wear.

Vertically aligned TiO2 nanorods-woven carbon fiber for reinforcement of both mechanical and anti-wear properties in resin composite

A series of TiO2 nanorods were successfully grown on woven carbon fiber by hydrothermal method to reinforce the resin composite. The TiO2 nanorods improved the mechanical interlocking among woven carbon fibers and resin matrix, resulting in better fibers/resin interfacial bonding. Compared with desized-woven carbon fiber, the uniform TiO2 nanorods array resulted in an improvement of 84.3% and 73.9% in the tensile and flexural strength of the composite. However, the disorderly TiO2 nanorods on woven carbon fiber leaded to an insignificant promotion of the mechanical strength. The enhanced performance of well-proportioned TiO2 nanorods-woven carbon fiber was also reflected in the nearly 56% decrease of wear rate, comparing to traditional woven carbon fiber reinforced composite.

Abrasive Wear Characteristics of Silicon Carbide Particle Reinforced Zinc Based Composite

Herein, abrasive wear characteristics of SiCp dispersed zinc-aluminum based composites have been analyzed under high-stress condition. The wear tests were conducted on a Pin-on-Disc machine at a constant linear velocity of 1.57 m/s in the applied load range of 1-7 N while the abrasive platform used is 600 grit emery paper. A matrix alloy was also characterized under identical conditions to assess the influence of the dispersoid (SiC) particle on the wear behaviour. Wear rate, frictional heating and friction coefficient are the focused parameters of the study. The base alloy used has a dendrite structure comprising of α-dendrites surrounded by an α + η eutectoid and metastable e phase in interdendritic regions. The composite shows similar features to those of the base alloy except the additional presence of the reinforcing SiC particles. The wear rate and friction coefficient decrease with increase in abrading distance while a reverse trend was observed in the case of frictional heating which gradually increases with the increase in abrading distance. Incorporation of SiC particles improves the wear resistance of the matrix alloy and increasing the percentage of SiC increases the frictional heating and reduces the friction coefficient of the test material. The wear mechanism has been understood through SEM examination of wear surface, subsurface, debris particles and degraded abrasive grit papers.

Friction and wear characteristics of carbon fiber reinforced silicon carbide ceramic matrix (Cf/SiC) composite and zirconia (ZrO2) ceramic under dry condition

Abstract To investigate the tribological properties of Cf/SiC composite with different fiber orientations and ZrO2 with ground and polished surfaces, running-in tests under dry condition were conducted in a pin-to-disc apparatus. The results show that ground surfaces of ZrO2 ceramic sliding against each fiber orientation exhibit more excellent tribological properties than the polished ones. The average coefficient of friction (COF), pin and disc wear rate decrease about 53.7%–63.3%, 59.4%–80.6% and 69.7%–88.5% respectively among all fiber orientations. Specifically, 90deg fiber orientation sliding against ground ZrO2 surface exhibits the best excellent tribological property. Wear mechanism and the reason leading to the results are researched. The work firstly proposes ground surface scratch is a kind of surface texture which hugely affects material's tribological performance.

Characterization of mechanical properties and three‐body abrasive wear of functionally graded aluminum LM25/titanium carbide metal matrix composite

AbstractSeveral engineering components require location specific performance under operating conditions. A compositional/microstructural gradient can provide the performance required at specific locations and these materials were named as functionally graded materials. Functionally graded aluminium metal matrix composites were generally established for the tribo‐components where high wear resistance was a necessity. Reports on three body abrasive wear behaviour of functionally graded materials was limited to date. In the present work, a new functionally graded system comprising aluminium/titanium carbide (10 wt%) was produced through stir casting route followed by centrifugal casting technique and its three body abrasive wear behaviour was investigated. Hollow cylindrical part with the dimensions of length 150 mm, outer diameter 150 mm and thickness 16 mm was obtained. Microstructural study was performed on outer (1 mm) and inner surface (13 mm) to analyze the compositional gradient across the thickness of the functionally graded composite. Hardness was measured on different surfaces along the radial distance from outer periphery and tensile test was conducted on the outer and inner zone. Abrasive wear test was conducted on different surfaces of the functionally graded composite under various loads and speeds at constant time. The microstructural results revealed that particle segregation was more at the outer surface and less at the inner surface. Wear test results showed that increase in wear rate was obtained with increase of load and decrease in wear rate was obtained with increase of speed. The outer surfaces of the functionally graded composite had greater mechanical properties and better wear resistance compared to other surfaces. Scanning electron microscopy analysis was done on the abraded surfaces and observed wear mechanisms were interpreted.

THE EFFECT OF LOAD ON THE TRIBOLOGICAL PROPERTIES OF MAGNESIUM ALLOY WE54 AFTER PRECIPITATION HARDENING

The paper presents the effect of precipitation hardening on the mechanical and tribological properties of magnesium alloy WE54. Mechanical tests have shown that the hardness and Young’s modulus of the alloy increased as the ageing time became longer. Improvement of the mechanical properties had a direct influence on the tribological properties. Tribological tests were performed on a ball-on-disk tribometer, applying variable loads of 2, 5, and 10 N. In the tests, a more than fourfold decrease in the specific wear rate, a threefold reduction in the linear wear, and a ca. 20% reduction of the friction coefficient were observed. The best results were obtained for ageing time of 24 h. The extension of the heat treatment time to 48h caused overageing of the alloy, which resulted in the deterioration of its mechanical and tribological properties.

Sliding wear of spark plasma sintered CrFeCoNiCu high entropy alloy coatings with MoS2 and WC additions

Using spark plasma sintering (SPS), the coatings of CrFeCoNiCu high entropy alloy (HEA) and its composites with MoS2 and WC additions were sintered on carbon steel substrate, respectively. The dry sliding wear behavior of the HEA coatings was investigated using a ball-on-disk sliding tribometer with a silicon nitride ball. The wear mass loss and the coefficient of friction (COF) increased greatly with the normal load increased. 2 wt.% MoS2 addition is beneficial to decrease the COF as well as the wear rate of HEA coatings. However, adding more MoS2 induce to larger wear rate though the COF decreases continually. On the other hand, adding 50 wt.% WC, the mass loss and COF of this HEA coating decreased obviously. So WC addition is also beneficial to decrease wear rate as well as the COF. The composite coating with 80 wt.% WC has the lowest wear rate 0.7 mg under 30 N normal load, which is more than 16 times lower than that of HEA coating without additions. The worn surface observation for the HEA coatings shows MoS2 addition leads to the wear mechanism evolution from two-body wear to three body wear and delamination wear is the domain wear mechanism of WC/HEA. Therefore, SPS sintered CrFeCoNiCu HEA coating possesses outstanding wear resistance, and the wear rate and COF can be extremely decreased by adding MoS2 and WC.

Effects of La2O3 on the microstructure and tribological properties of plasma-sprayed Cr2O3–TiO2 coatings

Cr2O3–TiO2 coatings with different proportions of La2O3 were deposited by atmospheric plasma spraying. The coatings were evaluated by hardness tester, surface roughness tester, SEM and wear tester. The experiment results showed that the addition of La2O3 could improve the microhardness and decrease porosity, wear rate and surface roughness of the coating. The coating containing 2 wt.% La2O3 had the best tribological properties. The dominant wear mechanism is a mixture of abrasive wear and adhesive wear. The microscopic analysis suggests that the addition of La2O3 could refine the microstructure and promote the formation of solid solution powder, and then affect the properties of coatings.

Development of TiN particulates reinforced SS316 based metal matrix composite by direct metal laser sintering technique and its characterization

The present study describes the fabrication of TiN particulates reinforced SS316 based Metal Matrix Composites (MMCs) in nitrogen and argon atmosphere. The influence of sintering process parameters on microstructure, density, porosity, wear rate and microhardness of the fabricated samples has been analyzed. The input variable process parameters, such as, laser power density (range: 4.13–5.57W/cm2 (× 104)), scanning speed (range: 3500–4500mm/min) and the constant parameters, such as, laser beam diameter (0.4mm), hatching distance (0.2mm) and layer thickness (0.4mm) have been considered in the process. It has been observed from Field Emission Scanning Electron Microscopy (FESEM) analysis that TiN and SS316 powder mixture can be sintered in which chromium acts as a binder. Fine gaps are not found at the interface between TiN and SS316 when the mixture is sintered in nitrogen atmosphere. With an increase in the percentage of TiN, the density and wear rate decreases. However, when the reinforcement is taken beyond 18% by weight, the wear rate starts increasing. The microhardness also increases with an increase in the percentage of TiN. The microstructure, elemental compositions and phase characterization of the developed sintered MMCs have been examined by FESEM, EDX (Energy-dispersive X-ray spectroscopy) and XRD (X-ray diffractometer) analysis, respectively. The results have demonstrated the suitability of the TiN reinforced SS316 MMCs for industrial applications.

Structure and properties of H-beams after accelerated water cooling

The structure and properties of the surface of DP155 H-beams made of 09G2S low-carbon steel are determined on the basis of materials physics, before and after thermomechanical strengthening—that is, accelerated water cooling. Such H-beams are used in monorail tracks. Highly defective structure in the surface layer is created by accelerated cooling of the beam in the line of the 450 bar mill at AO EVRAZ Zapadno-Sibirskii Metallurgicheskii Kombinat, in the following conditions: rolling speed 6 m/s; water pressure in the crosspiece-cooling section 0.22–0.28 MPa; temperature before cooling about 800°C. As a result, the hardness, wear resistance, and scalar dislocation density are higher than in the steel without strengthening. Without thermal strengthening, the microhardness of the samples is 2.70 ± 0.33 GPa, while the Young’s modulus is 269.2 ± 27.1 GPa. Thermomechanical strengthening increases its microhardness to 3.30 ± 0.29 GPa, and decreases the Young’s modulus to 228.2 ± 25.7 GPa. In addition, the microhardness range is increased from 2.20–3.80 GPa to 2.64–4.60 GPa, while the Young’s modulus range is reduced from 208.0–403.0 GPa to 184.1–278.2 GPa on thermomechanical strengthening. It is found that thermomechanical strengthening increases the wear resistance of the steel’s surface layer by a factor of ~1.36 (decrease in wear rate from 5.3 × 10–5 to 2.9 × 10–5 mm3/N m) and increases the frictional coefficient by a factor of 1.36 (from 0.36 to 0.49). Without thermal strengthening, the structure observed is dislocational chaos; the scalar density of the dislocations is (0.9–1.0) × 1010 cm–2. High-temperature rolling and subsequent accelerated cooling of the samples produces dislocational substructure of band type in the ferrite grains and of reticular type in the martensite grains: the mean scalar density of the dislocations in the surface layer is 4.5 × 1010 cm–2. Possible explanations for such behavior are discussed.

Mechanical Properties of Unsaturated Polyester Filled With Silica Fume, Glass Powder and Carbon Black

In this study a polymer matrix composites (PMCs) have been prepared with the aid of ultrasonic wave dispersion method for mixing , using of unsaturated polyester resin with Silica Fume(SF), Glass Powder (GP)and Carbon Black (CB). Moulds were prepared by hand-made from silicon rubber according to the ASTM standard table (4). The fillers added separately with different ratios as (0%,0.5%, 1%, 1.5 %, 2%,2.5% and 3%).The results show increase the hardness and impact strength when added GP, SF, and CB to polymer matrix. Flexural strength and maximum shear stress decrease when added silica fume , but when added glass powder and carbon black led to increase flexural strength and maximum shear stress to certain percent at ( 2%, 1.5% for GP and CB respectively) then dropped when increase weight fraction of GP, CB . Compressive strength decrease when added glass powder and carbon black, while it is increase when added silica fume to polymer matrix. Wear rate decrease when increase weight fraction of carbon black but it increases when added GP and SF.

Investigation of tribological and corrosion properties of CuTi–alumina nanocomposite fabricated by mechanical alloying

AbstractThis study examined the effects of addition of alumina nanoparticles on the microstructure, tribological and corrosion properties of CuTi alloy. Mechanical alloying was performed employing satellite ball milling. X-ray diffraction revealed that CuTi solid solution was formed after 40 h of mechanical alloying. Mechanically alloyed powder was cold-pressed and sintered at 850 °C. Alumina nanoparticles were uniformly dispersed in the CuTi alloy matrix. Tribological properties of the samples were evaluated by pin-on-disk wear testing. The results showed a decrease in wear rate by 30 % owing to the presence of nanoparticles in the nanocomposite. The corrosion properties of samples were assessed employing potentiodynamic polarization and immersion methods in a 3.5 wt.% NaCl solution. The corrosion current density of CuTi alloy decreased from 125.9 to 6.3 μA · cm−2 following the addition of alumina nanoparticles.

Tribological behavior of copper-molybdenum disulfide composites

The dry sliding friction and wear behavior of Cu-MoS2 composite pins against bearing steel (AISI 52100) discs were investigated in order to determine the optimal additive content. The MoS2 content ranged from 0–40vol%. The microstructure and composition of the worn surface, wear debris and transfer layer were observed and analyzed in detail to reveal the dominant friction and wear mechanisms. It is confirmed that MoS2 is an effective lubricant for copper matrix composites against steel because the friction coefficient decreased from 0.67 to 0.18 when adding 20vol% of the MoS2. The wear rates of the composites tended first to increase then decrease as the MoS2 content increased. The high wear rates of Cu-5vol% MoS2 and Cu-10vol% MoS2 composites are mainly attributed to the cracks associated with the MoS2 particles, and the decrease of wear rate for composites with MoS2 above 20vol% is derived from the formation of a nearly continuous lubricating film on the worn surface. The formation mechanism for MoS2 lubricating film has been clarified by observing its microstructure and characterizing its distribution in the worn surface.

Effect of B4C/Fly Ash Addition on Wear and Mechanical Properties of Al-Cu-Mg Alloy

This research studied the effect of adding fly ash and boron carbide (B4C) particulates reinforcement on the mechanical properties and wear resistance of Al- 4.5% Cu- 1.18% Mg matrix alloy. Stir casting method has been used to fabricate the alloy and hybrid composite samples containing 2wt% of B4C and 5, 10, 15،20 wt % fly ash. The x-ray inspection revealed the dispersion of intermetallic compounds (Al2Cu,MgO and SiO2) Also, the mechanical properties have been evaluated, the results showed an increase in the tensile and yield properties with the increase of weight percentage of fly ash content up to 15 wt%, but the elongation decreased, while the hardness increased. Wear rate examination has been concluded by using pin on disc apparatus under different loads of (5, 10, 15) N, sliding velocities (1.413, 2.827, 4.241) mm/sec, and different times of (5, 10, 15) min. The results showed decrease in wear rate at 20% fly ash composite sample when compared with other composites samples and base alloy.

Characteristics optimization of powder mixed electric discharge machining using titanium powder for die steel materials

In the present study, four quality characteristics of the electrical discharge are simultaneously presented and optimized using titanium powder mixed electric discharge machining. The Taguchi method and the grey relational analysis are applied to the processing parameters to investigate the following: workpiece material, tool material, polarity, pulse-on time, current, pulse-off time, and powder concentration. The combination of the Taguchi method and grey relational analysis is applied to optimize simultaneously four quality characteristics of powder mixed electric discharge machining, including material removal rate, tool wear rate, surface roughness, and microhardness surface. Optimal results by the Taguchi–grey relational analysis show that both surface roughness and tool wear rate decrease, while both material removal rate and microhardness surface increase, respectively. This approach proves effective in terms of improving the processing efficiency of the study parameters. The results from both optimization calculations and experimentation demonstrate high accuracy and efficiency. Furthermore, powder mixed electric discharge machining has improved significantly. The concentration of titanium powder is the processing parameter with the strongest influence on the efficiency of powder mixed electric discharge machining.

Tribological Behavior of TiAl–Multilayer Graphene–Ag Composites at Different Temperatures and Sliding Speeds

Tribological behavior of TiAl–multilayer graphene–Ag composites (TMACs) prepared by spark plasma sintering against a Si3N4 ball was investigated on a ball-on-disk high-temperature tribometer at different test temperatures and sliding speeds in this study. The test results showed that TMACs had the lower friction coefficient and less wear rate at 450 °C–0.25 m/s, which was attributed to the formation of the high-strength and intact tribofilms on worn surface. At 450 °C–0.25 m/s, during the sliding process, multilayer graphene (MLG) was ground out to form the high-strength skeletons on the worn surface of TMACs. Ag was migrated from the worn surface and combined with the MLG skeleton to form the high-strength and intact tribofilms. The high-strength and intact tribofilms were beneficial to lowering the friction coefficient for the lubricating effect of Ag and decreasing wear rate for the enhancing effect of MLG skeleton.