Tribological Applications of Composite Materials

Non-oxide ceramics have been widely used in many tribological applications under a wide range of operating conditions over many decades. Nevertheless, a comprehensive review of tribomechanical characteristics of such potential ceramics relating to modern trends is not articulated anywhere before. Therefore, this chapter reviews studies regarding the tribological and mechanical performance of non-oxide based ceramic matrix composites (CMCs) carried out by various researchers. This work concerns only the tribological investigation of the ceramic composite in dry sliding/erosive condition and hence the characteristics under liquid lubricant or any other liquid medium is beyond the scope of this writing. Widely used boride, carbide and nitride based ceramics are considered as the matrix phase for these ceramic composites. The tribological and mechanical effects of reinforcements and dopants, such as hard or soft nano-micro particles (SiC, ZrC, B₄C, WC, hBN, graphene etc.), nanowire/nanotube/fibre (SiC/CNTs/C_f etc.) and some rare earth compounds (Sm₂O₃, Y₂O₃, La₂O₃, Nd₂O₃, Yb₂O₃, Lu₂O₃ etc.) into the non-oxide based ceramic composites are described under sliding conditions from room temperature to elevated temperature. In addition to this, the key applications of such composites in a wide range of operating conditions are discussed. This chapter also highlights the advantages and disadvantages of this class of ceramic matrix composites.

The advanced technology of composite and its allied tribological properties is now gaining importance in many industries. However, composite materials encounter few problems during the tribological testing, such as the concentration of filler particles, type of particle, compatibility of counterpart material, and running conditions. With this viewpoint, the present study provides insightful information about different composites for tribological applications. In this work, composite tribological performance of polymer, ceramic, metal-matrix composite, and the coating is studied. Among the tested composites, carbon fillers have provided better tribological properties in terms of contact friction and wear. The microstructure of graphene composites contains a single-layer graphene film, which functionalizes the polymer composite surface. The effect of particle filler orientation in normal and parallel direction is described for the ceramic composites. The friction data of ceramic composites with carbon/carbon–silicon carbide filler is less fluctuating in the parallel direction. In metal-matrix composite, the infusion of graphene particles reduces the wear rate and friction coefficient values at high-applied loads. Further, zirconium-based metal-matrix composites are tested at low, medium, and high break energy densities. The wear behavior of cubic-zirconium dioxide is found to be low at all the break energy density due to its crystalline structure. Tribological properties of polymer-based liquid/solid filler composites for coating application with their significant parameters are studied. The result shows that the wear life improves by using an equal concentration of two particles. At last, the cost associated with tribological losses and its mitigation measures is discussed.

Nowadays, the use of lubricants in the industrial sector is rapidly increasing, particularly in applications that are subject to high loads and high speeds. Lubricant is a material, generally synthetic, applied to reduce friction between surfaces in reciprocal interaction, which essentially decreases the heat generated by moving surfaces. It may also function as transporting foreign particle or carry any debris to prevent clogging. The solid lubricant is present as a thin film, paste or powder that serves as a friction reducer and also avoids wear on both surfaces in order to reduce the scar on the side. Solid lubricant is a crucial technology for increasing the efficiency of jet and car engines, including engine running at significantly higher temperatures, and for improving the durability of spacecraft. Solid lubricants act as a special application to minimize harm in situations where the use of liquid lubricants is inefficient or insufficient, for example in space technology, automotive or also in vacuum areas. There are a few types of solid lubricants such as transition metal dichalcogenide compounds, carbon-based materials; soft metals and polymers. They can be divided into two specific groups for convenience: soft (hardness < 10 GPa) and hard (hardness > 10 GPa) solid lubricants. Many research has been done in solid-liquid lubricant and mostly of the solid-liquid lubricant is not capable lubricate properly without any modification or additives. In this chapter the different modification, additives and also tribology testing is been reviewed and discussed to get better understanding in solid-liquid lubricants in composite material.

This chapter presents a brief account of the current state-of-the-art in the area of the tribology of fiber reinforced polymer composites. The important factors which determine the friction and wear properties of fibers from the surface modification are mentioned here. Tribological trends for fiber reinforced polymer composites, both traditional and nanocomposites, are presented using data currently available in the literature. Variation in fiber length, fiber orientation, type of treatments and physical characteristics are significantly influence the tribological properties. Finally, based on our current understanding of this field, we have speculated upon some future trends and directions in the area of polymer tribology.

In the fast-developing world, the environmental pollution, preservation of renewable and biodegradable resources has motivated researchers to develop novel eco-friendly materials and products based on sustainability principles. In this work, natural sources such as inner banana trunk polymer matrix composites (IBTPMC) and eggshell polymer matrix composites (ESPMC) are prepared by injection molding (IM) and vacuum assisted resin transfer molding (VARTM). The objective is to evaluate feasibility of the materials using IM and VARTM techniques. The specimens were subjected to the mechanical testing for its strength. The tensile modulus for ESPMC composites is 897 MPa compared to IBTPMC only 561 MPa. In izod impact test, IBTPMC shows the highest impact strength of 0.362 J, which is superior then in ESPMC or pure polypropylene (PP). The flexural strength of the pure PP is 58 MPa while for IBTPMC and ESTPMC, both are 42 MPa and 53 MPa respectively. Wear rate for ESPCM has reduced by 64–66% by increasing the load. Wear rate for IBTPCM shows increased by 13 times the initial wear as loading increases and reduced from 1–1.3 times as sliding distance increases. It shows that the IBTPMC fibre ruptured easily leading to higher wear in comparison to ESPCM structure due to fibre wetting properties and distribution of fibre in the matric interface. Coefficient of friction (COF) for IBTPMC shows increment from 0.38 to 0.55. While the COF for ESPCM increased from 0.28 to 0.35. Finally, Scanning Electron Microscope (SEM) to analyze the structure of the fractured surfaces was carried out.

Biomedical applications are important aspects in mankind. The word “Biomedical” is recently been used in the researches where the materials are made or synthesized from biological sources or these materials are used for various treatment of living beings. Recently in biomedical applications, polymers have paved their way in various applications such as implants, grafts, connective tissues etc. and hence, understanding the tribological properties of these polymers becomes an important factor to estimate their performance index. Polymethyl methacrylate (PMMA), poly ether ether ketone (PEEK) and Ultra-high-molecular-weight polyethylene (UHMWPE) has been extensively used for biomedical applications but polyoxymethylene (POM) has not been explored in depth till date. This chapter focusses on investigating the tribological properties of nano hydroxy apatite (nHAp) added polyoxymethylene (POM) composites using a pin on disc tribometer. nHAp prepared from egg shells by wet-precipitation method, were added in various weight percentages (1%, 2%, 3%, 4%, and 5%) to POM. Several pins made of POM reinforced with nHAPwere used to investigate the tribological properties using a pin on disc tribometer. A 316L stainless steel disc was used as counter surface to these pins during the tribo test. The shore hardness of the POM composites were measured which exhibited an increase in hardness with the increase in concentration of nHAp in POM. The tribo tests results exhibited a decrease in the coefficient of friction (CoF) up to a certain concentration of nHAp (4% this case), beyond which the coefficient of friction increased. In case of wear rate, the lower concentrations of nHAp showed less wear rate but the wear rate increased with the increase in concentration of nHAp. 1–4% nHAp included POM pins exhibited as low as 77% wear rate compared to POM compsite which did not contain any nHAp particles. The presented results indicates that POM can be a good choice for several biotribo pairs, however the biocompatibility of POM is to be explored. The present work will be helpful in making various composites for implants once the biocompatibility of POM is established.

Friction of elastomer materials, apart their volume composition and structure, should be also considered from a point of view of their surface layer. Similarly, to the migration of low molecular weight components in rubber mixes, the surface segregation also takes place in polymer blends. The produced surface layer can either be of an amorphous or a crystalline character, lubricating the tribological contact or making it stiffer adequately, in the both cases acting to reduce friction. The surface hardness gradient of rubber vulcanizates is the result of the surface profile of their crosslink density and structure. It can be modified either by some changes to the composition of a curing system or by the application of an appropriate post-treatment, realized by various chemical and physical modifications (halogenation, plasma, laser or ion beam), very often accompanied by the changes to the surface microroughness and energy. Studies on the surface composition, structure and morphology and the related changes to hardness, microroughness and the surface energy of elastomer composites revealed a great potential to modify and/or to control their friction, what was discussed on some examples. The research methodology included an equilibrium swelling and a thiol-amine analysis, infra-red-, Raman-, X-rays photoelectron-, secondary ion mass- and Rutherford Back Scattering spectroscopies, atomic force-, scanning electron- and optical microscopies, a micro indentation, the surface profilometry and the contact angle determinations. The experimental results were correlated to the friction of various elastomer composites determined with a block-on-ring tribometer. The relations observed can be used for a knowledge-based designing of elastomer materials, their processing, modification and exploitation, enabling for tailoring friction of these materials.

Titanium (Ti) and titanium based alloy (Ti6Al4V) are known for its high strength, high stiffness, resistance to corrosion and biocompatibility. The mechanical properties as well as bio-compatibility of titanium lead to wide variety of applications in biomedical, environmental, aerospace, automotive and marine applications. The titanium based composites are widely preferred at present to enhance the wear, friction and corrosion behavior based on applications where it is used. Moreover, titanium based bio-composites are widely preferred in biomedical applications because of its improved friction and wear resistance properties. The present chapter emphasizes more on tribological study of titanium based composites in general and also titanium based bio-composites in hip joint replacement on biomedical applications. At the same time, the focus is also given to classify various coating techniques used to produce the titanium composites and parameters used to analyze the tribological behavior of titanium composites. This chapter also deals with approaches used to test with and without bio-lubricant, tribological and corrosion properties of titanium composites.

Recent advances in the sphere of materials engineering have seen the advent of a new generation of composite materials that have become a replacement for the traditional materials used in different industries over the years. The proven potential of composite technology to deliver in line with critical global trends in the aerospace, automobile, and marine industries has placed it on top of other materials in the market. As composite materials can be lightweight and durable, they score very highly on efficiency measures with desired engineering properties required. A careful and wise combination of matrices, reinforcements, and additives can be tailored for specific applications of the end product. Traditionally, most of the fillers were considered as additives, limiting their contribution to a composite only on reducing their cost. However, the diversity of applications and a broad spectrum of their usage has led to high demand for incorporating fillers in composite technology. In this perspective, the objective of this chapter is to explore the works of literature for providing information about the fillers concerning processing, functions, mechanical and tribological characteristics, environmental impact. Moreover, the recent advances and challenges in employing different types of fillers in different classes of composites have been briefly discussed.

Molybdenum disulphide (MoS₂) is widely used in various applications because of its lubricating properties. However, its performance needs to further improve. In the present work Molybdenum disulphide (MoS₂) based composite coating with addition of TiO₂ (having different particle size and weight% addition) were developed and coated on AISI52100 steel substrate. The substrate specimens were pre-treated using phosphating to improve the porosity which helps to enhance the bond strength between the coating and steel substrate. A tribological study of this developed composite coating was carried out at different contact pressures and sliding speeds using the pin-on-disc test rig. It was observed that particle size of TiO₂ and its different wt% significantly affects the tribological properties of the developed composite coating. In case of all considered operating conditions with developed samples of composite MoS₂-TiO₂ coating, the sample C (63.3 nm particle size with 15 wt% addition) of TiO₂ depicts about 31% lower coefficient of friction and 39% lower wear rate compared to pure MoS₂ coating.

The chapter presents studies regarding the tribological performance of composite materials and multilayer composite coated tools in manufacturing processes carried out by the authors. Two manufacturing processes were investigated—metal forming and metal cutting. In metal forming, the study aimed to explore lubricant-free forming utilizing multilayer DLC composite hard coating as the potential tool coating. The experimental studies on the coating include characterization of the coating, and tribological analysis of the coating using commercially available pin-on-disk, laboratory tribology simulative test and industrial ironing of stainless steel. In order to examine the influence of temperature and contact pressure along the tool/workpiece interface on friction, Finite Element analysis was performed. Meanwhile, in metal cutting, two environmentally benign machining techniques were investigated to determine their potentials in delaying tool wear progression. First, sustainable machining by coupling multilayer ceramic composite coated-tool with cryogenic coolant as the cutting fluid. Second, the machining of Carbon Fibre Composite and Titanium alloys stacks using Ultrasonic Assisted Drilling (UAD) technique. Both techniques include investigations on machining conditions with varied cutting tool speeds. The examinations on the experimental results were focused on temperature, tool wear, surface integrity and metallurgical structure of near-surface region.

In the recent years, several studies have been carried out the feasibility of the application of polymer composite spur gears in tribological applications. Due to the heterogeneous nature of composite materials, its wear property behaves differently during meshing of gears. Hence, the present chapter studied different types of polymers and polymer composites and their wear behaviours and wear test in spur gear application. It also provides the importance of fillers in polymer in wear related application. This is an attempt to present a review on tribological performance of polymer and its composites. Tribological analysis is an important role to decide the friction and wear behaviour of polymer spur gear during the meshing of gears. The process parameters like temperature, applied torque, stress and speed affect the friction and wear property of polymer spur gear. The failure of polymer spur gear is widely affected by these parameters generated on tooth. The optimum value of all these parameters reduces the wear and improves the life of gear. Further, the addition of proper functional fillers on polymer are also able to improve the wear property. It is a novel technique to add fillers in neat polymer which is not only a cost effective but also a method to modify the various property of the polymers.

The use of lubricant during the machining process plays an important role to reduce friction and wear. Mineral-based oil is the most widely used lubricant that provided high-quality lubrication properties. However, mineral-based oil has poor biodegradability and causes long-term pollution to the environment and harmful to human. Implementation of environmental-friendly lubricant was encouraged to achieve sustainable manufacturing practices. The inherent biodegradability of vegetable-based oil with solid particle offers greater benefit to the environment and lubrication performance. The study aims to evaluate the influence of green solid particle (hexagonal boron nitride, hBN) enriched in the modified jatropha oil (MJO) through tribology testing using four-ball tribotester machine. hBN particle was added in MJO at various concentration ratio; 0.05 wt% and 0.5 wt%. The MJO samples were compared with the crude jatropha oil and commercial synthetic ester. The tribology testing was conducted according to ASTM D4712. The value of coefficient of friction, wear scar diameter, worn surface analysis and surface roughness were evaluated. The lowest concentration of hBN particles in MJO (MJO + 0.05 wt% hBN) has reduced the coefficient of friction with smaller wear scar diameter and better surface roughness quality. The worn surface analysis from the ball lubricate by MJO + 0.05 wt% hBN had light and shallow grooves. The study proved that MJO + 0.05 wt% hBN exhibits better lubrication ability and suitable as an alternative for the environmental-friendly lubricant especially for minimum quantity lubrication (MQL) oil.

In this chapter, authors aim to highlight the prospect of natural fiber reinforced polymer composites (NFRPC) as tribo-materials for different engineering system. Incorporation of fibers originate from plants in polymer composite is not new as they provide environmental friendly lighter composite demanded by automative sectors where the conservation of energy is concerned. First two section gives a brief understanding on treatment of fiber surface for efficient compatibility with polymer matrix and their arrangement in composites and followed by composite fabrication for thermoset and thermoplastic composites using natural fibers. Later authors compile some published research works in order to interprete the tribo properties based on the different test parameters and composite systems impregnated by different types fibers various arrangements. Finally prospect of using hybrid polymeric composite incorporated with natural fiber and synthetic micro and Nano fillers as tribo materials is highlighted.

The objective of this chapter is to review the recent progress on the tribological properties of natural fiber reinforced composites (NFRC). Specific emphasis is given to plant based fibers as they are abundantly available and share major portion of natural fibers than other natural fibers extracted from animal and mineral sources. The various factors affecting the friction and wear properties under dry and wet medium conditions of NFRC materials are discussed. An outline of the tribological test in NFRC materials are discussed with emphasis on test methods, NFRC materials and types of fibers. A general trend on the tribological properties with influencing parameters is represented in graphical format for readers to understand the interplay of various effects. The wear mechanism of NFRC and nanoparticle treated (such as nanocellulose and nanoclays) materials with respect to transfer film forming capabilities and measurement techniques were discussed. Commonly used theoretical analysis such as artificial neural networks (ANN) models for predicting frictional properties of NFRC were discussed. Overall, this chapter provides the reader a conscience and succinct information about friction and wear properties of NFRC materials that are studied in last two decades.