Carbon Nanotubes Improves the Tribological Properties of Ni60/Al<sub>2</sub>O<sub>3</sub> Coatings

Tribological application of carbon nanotubes in a metal-based composite coating and composites

<div class="section abstract"><div class="htmlview paragraph">The material demands for advanced technologies have led to development of new generation, light-weight, and multi-functional materials. Aluminum matrix composites (AMCs) have captured considerable attention in aviation, space and automotive industries in recent years. Carbon nanotubes (CNT) are one of the most promising candidate of reinforcements used to improve mechanical strength and hardness of metal matrix composites (MMCs). In this study, dry sliding wear behavior of aluminum (Al) matrix (MMCs) reinforced with different amounts (0, 0.5, 1 and 2 wt%) of CNTs were prepared through ball milling, the process was followed by compaction at room temperature and pressureless sintering at 630 °C under argon atmosphere for 1hr. Wear tests were performed on a pin-on-disk tribometer against SAE 1040 steel counter body under constant load and sliding speed at room temperature. Worn surfaces of composites were characterized by scanning electron microscopy (SEM) technique in order to identify dominant wear mechanism of the as-produced composite materials. Preliminary result of this study showed that the composite displayed lower wear rate and friction coefficient under mild wear conditions comparing to aluminum alloy without reinforcement.</div></div>

Tribological Behaviour of Aluminium Hybrid Metal Matrix Composite

ABSTRACTA favorable hardness ratio (Hdisk/Hpin = Hd/Hp) could lead to a transition to mild wear during sliding contact. To determine a more appropriate Hd/Hp value for the sliding wear, the dry sliding pin-on-disk wear tests of Ni3Al matrix composites (NMCs) with multilayer graphene (MLG) are undertaken at Hd/Hp values of 0.99, 0.83, 0.42, and 0.35 at sliding speeds of 0.1, 0.3, 0.5, and 0.7 m/s. It is found that the tribological properties of NMCs are strongly affected by the various hardness ratios. At 0.1 m/s, the friction coefficient decreases with a decrease in Hd/Hp value. The low friction coefficient is 0.14 and the wear rate is 0.9 × 10−5 mm3 N−1m−1 under the ceramic counterpart with Hd/Hp of 0.35. At 0.7 m/s, the tribological properties show the opposite trend with a decrease in Hd/Hp. At an Hd/Hp of 0.35, the smooth compact layer on the worn surface could decrease the friction at 0.1 m/s, and the improved hardness in the subsurface by strain hardening would play an important role in the improvement of wear resistance. Under the metal counterpart with Hd/Hp of 0.99, plastic deformation only occurs on the contact surface and the MLG could suppress further shear deformation in the subsurface, leading to a low wear rate (2.4 × 10−5 mm3 N−1m−1) and friction coefficient (0.15) at 0.7 m/s.

In the present work we report the development of carbon nanotube having multi-walls reinforced copper nanocomposites. The carbon nanotubes were used in both uncoated and nickel coated conditions to reinforce copper matrix. The nanocomposites with different carbon nanotubes (0.25 to 1.0) weight percentage were developed using a combination of ultrasonication, ball milling, sintering and upsetting forging processes. The developed nanocomposites were subjected to microstructural characterization using scanning and transmission electron microscopes to observe the dispersion of carbon nanotubes. The effect of carbon nanotubes on friction and wear properties of copper nanocomposites were studied using pin on disc testing rig as per ASTM G99 standard. The coefficient of friction of both 1 wt% uncoated and nickel coated carbon nanotubes reinforced nanocomposites was found to drop by 60.41% and 70.83% respectively when compared to copper. Similarly the wear rate of nanocomposites were found to decrease with the incoporation of carbon nanotubes. The low coefficient of friction and wear rate were attributed to uniform dispersion of carbon nanotubes and formation of carbonaceous layer on the surface of nanocomposites during dry sliding wear.

This paper investigated the influence of heat treatment (T6) on the dry sliding wear behavior of SiCp/Al-5Si-1Cu-0.5Mg composite that was fabricated by electromagnetic stirring method. The wear rates and friction coefficients were measured using a pin-on-disc tribometer under loads of 15–90 N at dry sliding speeds of 100 r/min, 200 r/min, and 300 r/min, over a sliding time of 15 min. The worn surfaces and debris were examined using a scanning electron microscope and was analyzed with an energy dispersive spectrometer. The experimental results revealed that SiCp/Al-5Si-1Cu-0.5Mg alloy treated with T6 exhibited lower wear rate and friction coefficient than the other investigated alloys. As the applied load increased, the wear rate and friction coefficient increased. While, the wear rate and friction coefficient decreased with the sliding speed increasing. The morphology of the eutectic silicon was spheroidal after the T6 heat treatment. SiCp particles and Al2Cu phase can be considered as the main raisons for improving the wear behavior. Abrasion and oxidation were the wear mechanisms at low load levels. However, the wear mechanisms at high load levels were plastic deformation and delamination.

This study investigates the tribological behaviour of Cr2O3-TiO2 composite coatings deposited on aluminium 6061 alloy. Cr2O3-TiO2 composite coatings were deposited by high velocity oxyfuel (HVOF) technique. Developed coatings were subjected to microstructure studies, microhardness test (ASTM E92), friction and wear test (ASTM G99). Pin-on-disc machine was used to evaluate friction and wear characteristics of Cr2O3-TiO2 coatings. Effect of sliding velocity (0.314 m/s-1.26 m/s) and load (20 N-100 N) on friction and wear characteristics of Cr2O3-TiO2 coatings were studied and compared with uncoated aluminium alloy. Results showed 54% improvement in hardness of Cr2O3-TiO2 coatings in comparison with aluminium alloy. Coefficient of friction and wear rate decreases by 12% and 48% respectively when evaluated with uncoated aluminium alloy. Coefficient of friction (COF) and wear rate increases with increase in load and sliding velocity for both coatings and substrate. However, Cr2O3-TiO2 coatings showed lower wear rate and COF at all the loads and sliding velocities studied when compared with uncoated aluminium alloy. Worn out surfaces of uncoated and Cr2O3-TiO2 coated surfaces were subjected to SEM analysis to understand the wear mechanisms in composite coatings.

Effects of sliding velocity and normal load on tribological behavior of aged Al-Sn-Cu alloy

This investigation has evaluated the wear properties of Carbon fiber-epoxy/GNP (Graphene Nanoplatelets) composites. In this research, carbon fiber and Graphene nanoplatelets (GNP) of different weight percentages of GNP (0, 0.1,0.3, and 0.5 wt.%) reinforced hybrid composites were fabricated via compression molding assist hand layup technique. An abrasive wear test has been performed using the Design of experiments. Analysis of variance (ANOVA) tables has been used to understand the effect of control parameters (wt.% of filler, normal load, and sliding distance) on response parameters (specific wear rate and friction coefficient). The control variables such as normal loads of 5, 10, 15, and 20 N and sliding distances (150, 200, 250, and 300 m) are selected for this study. It has been discovered that adding GNPs reduces the particular wear rate and friction coefficient. Scanning electron microscopy (SEM) was used to examine composites' worn surfaces. The composites with GNPs had lower weight loss, friction coefficient, and wear rate as compared to plain carbon fiber-reinforced epoxy, and these metrics decreased as the percentage of GNPs increased. The analysis concluded that experimental results are closer to optimum results.

Tribology of SiCp reinforced Al-12Si matrix composite coatings in water

Sliding wear behavior of E-glass-epoxy/MWCNT composites: An experimental assessment

Effect of multi-walled carbon nanotubes as reinforced fibres on tribological behaviour of Ni–P electroless coatings

Carbon nanotubes (CNTs) have shown tremendous progress during the past two decades due to their extraordinary properties. With CNTs added as an alloying element, various engineering materials exhibit better mechanical properties. Multi-walled carbon nanotubes (MWCNT) were synthesized in-house by chemical vapor deposition process. Carbon nanotube-reinforced aluminum composites were prepared by cold pressing (or compaction) and sintering using different fractions (0.5, 1.0, 1.5, and 2.0 weight percent) of MWCNTs. The Al-CNT composites consists of tin (Sn) at 1.0 wt. % in each composition. Tin promotes the sintering of aluminum matrix composite. The effect of CNT on the density, hardness, and wear behavior of the composites were studied. Wear tests were performed to determine friction and wear under dry, wet, and hot conditions under varying loads from 5 N to 20 N. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques were used for the characterization. This investigation shows that increased CNT content significantly improves the hardness and wear resistance of the composites. The friction and wear were found to increase with operating temperature. A significant reduction in coefficient of friction and wear rate was observed with the application of oil during the wear test.

Wear and friction behavior of Al6061 alloy reinforced with carbon nanotubes

Microstructural characterization and wear behaviour of High Velocity Oxy-Fuel sprayed Cr3C2-25NiCr coating