Mechanical and tribological properties of LM13/TiO2/MoS2 hybrid metal matrix composite synthesized by stir casting

This paper involves the fabrication of LM13/TiO₂ (12?wt%)/MoS₂ (3?wt%) hybrid metal matrix composite and unreinforced alloy using liquid metallurgy route and evaluation of mechanical properties and adhesive wear characteristics. Microstructural investigation revealed homogeneous distribution of reinforcements in matrix. Hardness and tensile properties revealed that the composite had attained an improvement of 16.5 and 35%, respectively, over alloy. Wear characteristics were analyzed using pin-on-disk tribometer by varying load (10–40?N), sliding velocity (1–4?m/s), and sliding distance (500–2000?m). Statistical analysis was performed using response surface methodology to obtain the optimum wear process parameters for achieving maximum wear resistance. Results revealed that, with increasing load and sliding velocity, an increment in wear rate was observed for both alloy and composite, while a decline was observed with increasing sliding distance for composite and vice versa for alloy. Worn surface analysis revealed that load plays a prominent role in deciding wear rate, followed by sliding velocity. Sliding distance had less effect on wear rate of composite while it had significance on alloy. This hybrid composite can replace the conventional material used in automotive applications involving tribological importance.     

Tribological properties of powder metallurgy – Processed aluminium self lubricating hybrid composites with SiC additions

In this experimental study, aluminium (Al)-based graphite (Gr) and silicon carbide (SiC) particle-reinforced, self-lubricating hybrid composite materials were manufactured by powder metallurgy. The tribological and mechanical properties of these composite materials were investigated under dry sliding conditions. The results of the tests revealed that the SiC-reinforced hybrid composites exhibited a lower wear loss compared to the unreinforced alloy and Al–Gr composites. It was found that with an increase in the SiC content, the wear resistance increased monotonically with hardness. The hybridisation of the two reinforcements also improved the wear resistance of the composites, especially under high sliding speeds. Additionally, the wear loss of the hybrid composites decreased with increasing applied load and sliding distance, and a low friction coefficient and low wear loss were achieved at high sliding speeds. The composite with 5 wt.% Gr and 20 wt.% SiC showed the greatest improvement in tribological performance. The wear mechanism was studied through worn surface and wear debris analysis as well as microscopic examination of the wear tracks. This study revealed that the addition of both a hard reinforcement (e.g., SiC) and soft reinforcement (e.g., graphite) significantly improves the wear resistance of aluminium composites. On the whole, these results indicate that the hybrid aluminium composites can be considered as an outstanding material where high strength and wear-resistant components are of major importance, predominantly in the aerospace and automotive engineering sectors.     

Influence of redmud particle hybridization in banana/sisal and sisal/glass composites

A novel hybrid composite is developed by adding redmud as the secondary reinforcing filler with banana/sisal and sisal/glass fiber reinforced polyester composites. The composites are prepared by the hand layup technique followed by compression molding. The tensile, flexural, and impact strength of the composites are investigated by varying the parameters such as particle size (4 and 13?µm) and weight percentage (2, 4, 6, and 8?wt%) of redmud particle addition. The experimental result shows that the addition of redmud enhances the mechanical property of the hybrid composite. The maximum increase of 33% in tensile strength and 54% in flexural strength is observed for the sisal/glass composite and 25% increase in impact strength for the banana/sisal composite. The linear regression analysis is also introduced to predict the errors in the scatter plot. Furthermore, the Scanning Electron Microscopy (SEM) is used to study the effect of redmud on the interfacial bonding in the banana/sisal and sisal/glass fiber reinforced polyester composites.     

Effect of addition of graphite particulates on the wear behaviour in aluminium–silicon carbide–graphite composites

Aluminium matrix composites with multiple reinforcements (hybrid AMCs) are finding increased applications because of improved mechanical and tribological properties and hence are better substitutes for single reinforced composites. Few investigations have been reported on the tribological behaviour of these composites with % reinforcement above 10%. The present study focuses on the influence of addition of graphite (Gr) particulates as a second reinforcement on the tribological behaviour of aluminium matrix composites reinforced with silicon carbide (SiC) particulates. Dry sliding wear tests have been performed to study the influence of Gr particulates, load, sliding speed and sliding distance on the wear of hybrid composite specimens with combined % reinforcement of 2.5%, 5%, 7.5% and 10% with equal weight % of SiC and Gr particulates. Experiments are also conducted on composites with % reinforcement of SiC similar to hybrid composites for the sake of comparison. Parametric studies based on design of experiments (DOE) techniques indicate that the wear of hybrid composites decreases from 0.0234 g to 0.0221 g as the % reinforcement increases from 3% to 7.5%. But the wear has a tendency to increase beyond % reinforcement of 7.5% as its value is 0.0225 g at.% reinforcement of 10%. This trend is absent in case of composites reinforced with SiC alone. The values of wear of these composites are 0.0323 g, 0.0252 g and 0.0223 g, respectively, at.% reinforcement of 3%, 7.5% and 10% clearly indicating that hybrid composites exhibit better wear characteristics compared to composites reinforced with SiC alone. Load and sliding distance show a positive influence on wear implying increase of wear with increase of either load or sliding distance or both. Whereas speed shows a negative influence on wear indicating decrease of wear with increase of speed. Interactions among load, sliding speed and sliding distance are noticed in hybrid composites and this may be attributed to the addition of Gr particulates. Such interactions are not present in composite reinforced with SiC alone. Mathematical models are formulated to predict the wear of the composites.     

PPESK树脂基复合材料的摩擦磨损性能

以含二氮杂萘酮结构的聚醚砚酮（ＰＰＥＳＫ）树脂为基体,填加固体润滑剂和短炭纤维（ＣＦ）制备了新型耐热脂基复合材料,研究了摩擦条件下（如载荷,行程等）和ＣＦ含量对复合材料的摩擦磨损性能的影响,分析了ＰＰＥＳK树脂及复合材料的磨损机理,结果表明,短ＣＦ和固体润滑剂的加入可有效改善ＰＰＥＳＫ的摩擦磨损性能,当ＣＦ含量为１０％时,复合材料的摩擦系数与聚西四氟乙烯（ＰＴＦＥ）相当,但比磨损率降低２个数量级,与纯树脂相比,磨擦系数减小为原来的二分之一,而复合材料的磨损特性主要表现为粘着磨损,ＰＰＥＳＫ树脂基复合材料批基体,聚四氟乙烯（ＰＴＦＥ）具有更好的耐磨性和自润滑性。     

Comparative analysis of wear behavior of garnet and fly ash reinforced Al7075 hybrid composite

Al7075 hybrid composites reinforced with varying weight percentage (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%) of each of garnet and fly ash were fabricated and characterized for their comparative wear assessment. The sliding wear test was conducted on a reciprocating tribometer in dry medium under the working conditions of applied normal load (2 N, 4 N, 6 N, 8 N), sliding velocities (0.04 m/s, 0.08 m/s, 0.12 m/s, 0.16 m/s), sliding distance (20 m, 40 m, 60 m, 80 m) and working temperature (25 °C, 50 °C, 75 °C, 100 °C). The experiments were performed as per steady‐state condition and Taguchi (L₂₅) orthogonal array design to evaluate specific wear rate of the Al7075 hybrid composites. The finding of results indicated that the wear rate was decreased with the increase in the filler content in both the case of garnet and fly ash reinforced Al7075 hybrid composites. The results from Taguchi experiments suggested that the filler content and load were the most significant factors affecting wear behavior of composites while temperature and sliding distance are the least significant factors. Also, the garnet reinforced Al7075 hybrid composite indicated less specific wear rate as compared to that of fly ash reinforced Al7075 hybrid composite.     

Prediction of mechanical properties and modeling on sliding wear behavior of LM25/TiC composite using response surface methodology

Aluminum LM25/TiC (10?wt%) metal matrix composite was developed using the liquid metallurgy route. The microstructural examination and the mechanical properties such as hardness and tensile strength were investigated on the composite specimens. The tribological behavior of the composite was studied using central composite design (CCD) based on response surface methodology (RSM) under the influence of wear process parameters such as applied load, sliding velocity and sliding distance. Pin-on-disc tribometer was utilized for conducting the experimental runs and the model was constructed based on the obtained wear rates. Confirmation experiments and analysis of variance were performed to ensure the adequacy of the constructed model. Microstructural examination reveals that uniform dispersion was attained in the composite, which enhances the hardness and the tensile strength. The wear results showed that the wear rate increased with increase in load, decreases with increase in velocity and varies nonlinearly with sliding distance. Scanning electron microscopic (SEM) analysis was performed to examine the worn surface morphologies and the worn surfaces revealed that TiC reinforcement protects the matrix from more material removal at all conditions. The developed composite can be utilized for the tribological applications like engine block, cylinder liners and pistons.     

空心微珠-碳纤维共混改性聚酰亚胺复合材料的摩擦学性能

通过模压成型制备了碳纤维与空心微珠共混改性的聚酰亚胺复合材料, 采用MRH-3型摩擦磨损试验机研究了空心微珠含量、滑动速度及载荷对复合材料摩擦学性能的影响, 并对其磨损形貌及机制进行了分析。结果表明: 空心微珠-碳纤维/聚酰亚胺复合材料摩擦学性能优于其单独填充的聚酰亚胺基复合材料; 空心微珠含量对共混改性的复合材料摩擦系数影响不大, 但其磨损率随着空心微珠含量的增加先减小后增大; 15%空心微珠-10%碳纤维(质量分数)共混增强的复合材料的减摩耐磨性能最佳; 随着滑动速度提高, 空心微珠-碳纤维/聚酰亚胺复合材料的摩擦系数下降, 磨损率增大; 空心微珠-碳纤维/聚酰亚胺复合材料摩擦系数随着载荷增加先下降后上升, 而磨损率则随着载荷增加而增大; 空心微珠-碳纤维/聚酰亚胺的主要磨损机制在较低载荷时为磨粒磨损, 在较高载荷时为粘着磨损和磨粒磨损。     

Optimization of tribological parameters in abrasive wear mode of carbon-epoxy hybrid composites

Abrasive wear performance of fabric reinforced composites filled with functional fillers is influenced by the properties of the constituents. This work is focused on identifying the factors such as filler type, filler loading, grit size of SiC paper, normal applied load and sliding distance on two-body abrasive wear behaviour of the hybrid composites. Abrasive wear tests were carried on carbon fabric reinforced epoxy composite (C-E) filled with filler alumina (Al₂O₃) and molybdenum disulphide (MoS₂) separately in different proportions, using pin-on-disc apparatus. The experiments were planned according to Taguchi L18 orthogonal array by considering five factors, one at two levels and the remaining at three levels, affecting the abrasion process. Grey relational analysis (GRA) was employed to optimize the tribological parameters having multiple-response. Analysis of variance (ANOVA) was employed to determine the significance of factors influencing wear. Also, the comparative specific wear rates of all the composites under dry sliding and two-body abrasive wear were discussed. The analysis showed that the filler loading, grit size and filler type are the most significant factors in controlling the specific wear rate of the C-E composite. Optimal combination of the process parameters for multi performance characteristics of the composite under study is the set with filler type as MoS₂, filler loading of 10 wt.%, grit size 320, load of 15 N and sliding distance of 30 m. Further, the optimal parameter setting for minimum specific wear rate, coefficient of friction and maximum hardness were corroborated with the help of scanning electron micrographs.     

Investigation on mechanical properties and tribological behaviour of stir cast LM13 aluminium alloy based particulate hybrid composites

LM13 aluminium alloy with boron carbide (0 wt.%–7.5 wt.%) and fly ash (2.5 wt.%) reinforced particulate hybrid composites were fabricated using liquid metallurgy route. Microstructure and mechanical properties viz., hardness, ultimate tensile strength and ductility were investigated. Wear behaviour of composites was tested by varying sliding distance and load. Fracture surface and worn surface of composites were examined using field emission scanning electron microscope. Microstructure of hybrid composites revealed uniform dispersion of particles in LM13 aluminium alloy. Hardness and tensile strength of composites increased with increasing wt.% of boron carbide and fly ash particles. Wear test results showed that addition of particles significantly decreased the weight loss and coefficient of friction. Also cumulative weight loss decreased up to 47.2 % for 10 wt.% of hybrid composites as compared to LM13 aluminium alloy. Fracture surface of composites showed dimples with particle cracking on the surface. Worn surface of LM13 aluminium alloy showed continuous grooves due to ploughing with delamination. However, worn surface of composites showed fine grooves due to the presence of hard reinforcements on the surface. Boron carbide and fly ash reinforced LM13 aluminium hybrid composites exhibited superior mechanical properties with excellent wear resistance as compared to LM13 aluminium alloy.     

纳米TiO2填充聚醚砜酮复合材料的摩擦学性能

采用热压成型的方法制备了纳米TiO2填充聚醚砜酮(PPESK)复合材料，在MM—2000摩擦磨损试验机上考察了干摩擦条件下纳米TiO2含量以及试验载荷对复合材料摩擦磨损性能的影响，并利用扫描电子显微镜(SEM)观察分析PPESK及纳米TiO2／PPESK复合材料磨损表面形貌及磨损机理。结果表明，添加少量纳米TiO2即可以明显提高PPESK的耐磨性，当纳米TiO2含量超过2．5％(体积)时，其耐磨性随填料含量变化不明显，载荷对纳米TiO2填充PPESK复合材料磨损率的影响不大。在低含量时(＜2．5％)，纳米TiO2具有减摩效果，高含量时反而比未填充时大；随量载荷的增加，填充PPESK的摩擦系数显著降低。     

Influence of lubricant filling on the dry sliding wear behaviors of hybrid PTFE/Nomex fabric composite

To improve the antiwear property and load carrying capacity of hybrid PTFE/Nomex fabric/phenolic composites, graphene and graphene oxide (GO) had been synthesized and were employed as fillers, together with graphite. Sliding wear tests show that the wear rates of filler-reinforced PTFE/Nomex fabric composites were reduced greatly when compared to unfilled fabric composite. Besides, it was found that the 2 wt% GO filled PTFE/Nomex fabric composites exhibited the optimal tribological properties. It was proposed that the self-lubrication of GO, the favorable interface stability of the composite, and the uniform transfer film on the counterpart pin contributed together to the reinforced tribological property of GO filled PTFE/Nomex fabric composite. We also investigated the influence of filler content, applied load, sliding speed, and tensile and bonding strength on the tribological properties of PTFE/Nomex fabric composites.     

碳纤维及石墨填充聚四氟乙烯复合材料的摩擦学性能研究

利用M-200型环-块摩擦磨损试验机对石墨(Gr.)及碳纤维(CF)填充聚四氟乙烯(PTFE)复合材料的摩擦磨损性能进行了研究,探讨了石墨及碳纤维的协同润滑效应.认为碳纤维的加入大大提高了复合材料的承载能力,石墨的加入减小了碳纤维表面与对偶的摩擦系数,从而降低了碳纤维的脱落趋势,提高了复合材料的耐磨性.利用扫描电子显微镜(SEM)对PTFE复合材料的摩擦面及对偶转移膜进行了观察.结果表明,本实验中20%的石墨和10%碳纤维填充PTFE复合材料的摩擦磨损性能最好,且在高载荷下的摩擦磨损性能尤为突出,具有一定的应用价值.     

Tribological behavior of ZA27/Al2O3/graphite hybrid nanocomposites

ZA27 alloy composites reinforced with alumina and graphite nanoparticles are a unique class of advanced engineered materials that have been developed to use in tribological applications. In this study, dry sliding wear behavior of ZA27 alloy matrix hybrid nanocomposites has been investigated. Mechanical alloying and hot pressing methods have been used for the fabrication of these composite materials. Sliding wear tests were conducted using a block-on-disc type sliding wear testing apparatus under unlubricated conditions. Scanning electron microscopy analyses have been carried out to examine the wear surfaces. The results showed that the increase of alumina nanoparticle content can positively influence improvement of the tribological behavior of the hybrid nanocomposites.     

Wear characteristics of hybrid aluminium matrix composites reinforced with graphite and silicon carbide particulates

This investigation studies the dry sliding wear behaviour of Al matrix composites reinforced with Gr and SiC particulate up to 10%, to study the effect of % reinforcement, load, sliding speed and sliding distance on stir cast Al–SiC–Gr hybrid composites, Al–Gr and Al–SiC composites. Parametric studies indicate that the wear of hybrid composites has a tendency to increase beyond% reinforcement of 7.5% as its values are 0.0242 g, 0.0228 g and 0.0234 g respectively at 3%, 7.5% and 10% reinforcement. The corresponding values are 0.0254 g, 0.0240 g and 0.0242 g in Al–Gr composites and 0.0307 g, 0.0254 g and 0.0221 g in Al–SiC composites, clearly indicating that hybrid composites exhibit better wear characteristics. Increase of speed reduces wear and increase of either load or sliding distance or both increases wear. Statistical analysis has revealed interactions among load, sliding speed and sliding distance in composites with Gr particulates.     

梯度自润滑复合材料在不同滑动摩擦下的摩擦学特性

梯度自润滑复合材料是一种新型润滑材料,利用粉末冶金工艺设计和制备了该材料,考察了其在不同摩擦条件下的摩擦学特性,并对其摩擦磨损机理进行了分析和研究.结果表明:梯度自润滑复合材料随着复合固体润滑剂含量的增多,摩擦学性能明显改善,但润滑剂含量过高将导致材料表面硬度过低;该材料适用于高载倚下的润滑部件;脂润滑条件下,复合固体润滑剂与润滑脂结合在摩擦面上形成的膏状润滑膜使梯度自润滑复合材料的摩擦学性能显著改善;在脂润滑高载荷条件下,梯度自润滑复合材料的磨损主要发生在磨损初期,之后磨损极小,摩擦系数也趋于减小.     

Study on the friction and wear behavior of basalt fabric composites filled with graphite and nano-SiO2

To improve the friction and wear behavior of basalt fabric reinforced phenolic composites, single graphite or nano-SiO₂ and both of them were incorporated. The tribological properties of the resulting composites under different sliding conditions were investigated systematically on a model ring-on-block test rig. The friction and wear mechanisms of the composites were studied through analyzing the worn surfaces and transfer films by a scanning electron microscopy (SEM). Experimental results showed that graphite (Gr) was more beneficial than nano-SiO₂ in improving the tribological properties of basalt fabric composites (BFC) when they were singly incorporated. It is well worth noting that the friction and wear behavior of the filled composites was improved further when nano-SiO₂ and graphite were added together, indicating that there was a synergistic effect between them. Tribological tests under different sliding conditions revealed that the BFC/Gr/SiO₂ composites seemed to be more suitable for tribological applications under higher sliding speed and load.     

Hybrid effect of nanoparticles with carbon fibers on the mechanical and wear properties of polymer composites

Polyetheretherketone (PEEK) composites reinforced with carbon fibers (CFs) and nano-ZrO₂ particles were prepared by incorporating nanoparticles into PEEK/CF composites via twin-screw extrusion. The effects of nanoparticles on the mechanical and wear properties of the PEEK/CF composites were studied. The results showed that the incorporation of nano-ZrO₂ particles with carbon fiber could effectively enhance the tensile properties of the composites. The tensile strength and Young’s modulus of the composites increased with the increasing nano-ZrO₂ content. The enhancement effect of the particle was more significant in the hybrid reinforced composites. The compounding of the two fillers also remarkably improved the wear resistance of the composites under water condition especially under high pressures. It was revealed that the excellent wear resistance of the PEEK/CF/ZrO₂ composites was due to a synergy effect between the nano-ZrO₂ particles and CF. CF carried the majority of load during sliding process and prevented severe wear to the matrix. The incorporation of nano-ZrO₂ effectively inhibited the CF failures through reducing the stress concentration on the carbon fibers interface and the shear stress between two sliding surfaces. It was also indicated that the wear rates of the hybrid composites decreased with the increasing applied load and sliding distance under water lubrication. And low friction coefficient and low wear rate could be achieved at high sliding velocity.     

The friction and wear properties of carbon nanotubes/graphite/carbon fabric reinforced phenolic polymer composites

In this paper, either graphite (Gr) or carbon nanotubes (CNTs), or both of them were incorporated into carbon fabric reinforced phenolic (CFRP) composites, preparing by a dip-coating and heat molding process, the tribological properties of the resulting composites were investigated using a block-on-ring arrangement. The worn surfaces were observed by scanning electron microscope to understand the mechanism. Experimental results showed that the optimal Gr was more beneficial than CNTs in improving the tribological properties of the CFRP composites when they were singly incorporated. It is well worth noting that the friction and wear behavior of the CNTs-filled CFRP composites were improved further when Gr was added, indicating that there is a synergistic effect between them. Tribological tests under different sliding conditions revealed that the Gr and CNTs-filled CFRP composites seemed to be the most suitable for tribological applications under higher sliding speed and load, and oil lubrication.