Automotive Tribology

Tribology is existed at the interface of two materials which are in relative motion and this causes friction at the interface. Due to friction, heat is generated between two meting surfaces which causes wear on surfaces either one or both the materials. To reduce friction and wear at interface, a lubricant is supplied. This lubricant may be either solid lubricant such as graphite, graphene etc. or liquid lubricant such as base oil, mineral oil etc. or semisolid lubricant such as grease. In this chapter, the detailed description of friction, wear and lubrication is given. Furthermore, a number of examples are also presented where tribology is very important such as bearings, gears, engines, orthopaedic joints and micro-machines. At last, the brief introduction of important applications are also discussed along with brief prescription about book chapters.

There is tremendous requirement for development of compact and fuel efficient automotive engines with reduced emissions. From tribological point of view, automotive engine components such as piston assembly, bearings and valve trains are lubricated and their surface behaviors have been extensively studied. In this chapter, current and future trends of automotive lubrication and requirements from automotive lubricants are discussed in detail. American Society for Testing and Materials (ASTM) standards are used for selection of automotive lubricants. The lubrication of light weight materials (Al, Mg) was studied, which was used to replace heavier cast iron blocks used presently. In this chapter, future trends of light weighted tribological materials to be used in near future as well as nano tribology are discussed. New trends of tribology in automotive engines were explained and also selections of new lubricant used in advance engines were discussed. The overall studies of tribology of engines components enhance the engine performance.

Poor quality leads to poor efficiency. As the research progresses, the development in the sustainable material are also progresses. This change leads to enhancement in the efficiency of the product. Novel sustainable material is the need of the hour for the future development. Natural composite fits the best alternative to deal with environment problem. In the past decade natural fibers applications has been increasing as never before. These applications are aerospace, infrastructure, thermal etc. Metal like steel, aluminum, cast iron are some of the materials which have been dominating the industries before the introduction polymer composite. These metals have been dominating the market but for a long time but lacking in the environmental issues. Natural fibers have successfully filling that gap. Being biodegradable, it is nature friendly and easy to dispose off. Decreased weight, nature friendly and easy availability are the attractive characteristics that influences various industries towards natural fiber composite. The current segment deals with the various natural fiber composites and their applications in the industries.

With the growing industrial development and reliance on fossil fuels, green house gas emission has become a major problem. Transportation plays a massive role in producing CO₂ gas emission with personal vehicles producing the largest share. Light weighting is a possible solution of reducing the CO₂ gas emissions. On an average, 100 kg of mass reduction achieved on a passenger car saves about 9 g of CO₂ per km at the car exhaust. Some lightweight materials are already being used in automobile sector such as aluminum, magnesium, their alloys, composite materials, etc. A novel category is metal foams, which are one of the metal matrix composites, having uniformly distributed gaseous pores as reinforcement embedded in the metal matrix. A high porosity in metal foams makes them potential candidates to absorb the large amount of mechanical energy, damping vibrations and ability of sound absorption which can be well exploited in automotive industry. As per requirement in different sectors, metal foam of different metals has been developed like Al, Mg, Fe, etc. Based on the porosity of metal foams, they have found their applications in the functional and structural field. This book chapter emphasizes on the recent development in the field of metal foams, mechanical properties, which can be exploited in the automotive industry, processing method and also gives the overview of existing and as well as the potential field where these novel material can be utilized.

Research on composite materials has got much attention for the development of social and economic growth. The Polymer composite is a material which is highly advantageous in the area of construction, packaging and automotive application due to its high strength to the weight ratio, self-lubrication properties, improved fatigue resistance, higher resistance to thermal expansion, wear, and corrosion resistance. Tribo-performance of polymer composite indicates the behaviour of friction and wear of polymer composite which is basically decided by amount and types of polymer matrix and reinforcement. In the past decade, a large number of studies have been carried out the feasibility of the application of polymer composite in tribological applications. However, a very few study has been conducted on the tribological performance of composite material in an automotive application. Here attempts have been to provide a review on tribological performance of polymer and its composites which deals with the application of polymer composite in automotive application and recent developments of polymer composite in tribo-performance. It also deals with the effects of different process and material parameters on tribological properties of the polymer composite.

The thermosetting and thermoplastic materials reinforced with natural fiber are widely used in the automotive sector. Variety of natural fibers like jute, kenaf, hemp, banana, sisal, etc. are used in FRP composite due to lightweight, eco-friendly, easy availability and low cost. In addition, FRP composite also meets the structural and robustness demands of interior and exterior components of the vehicles. However, the erosion behavior of the FRP composites is a critical parameter in the dusty environment. In this work, needle punched nonwoven fiber composite is prepared using vacuum assisted resin transfer molding (VARTM) process with variation in filler size (10, 25 and 50 μm). The composites are prepared using 4 layers of needle punched jute fiber of 250 × 250 mm and mill scale is added 10 wt% of epoxy. Tensile and flexural properties are evaluated. The erosion tests are carried out using irregular silica sand at different impingement angles, impact velocities and environment temperatures. It is observed that the composite C1 with 10 μm filler size shows the maximum tensile and flexural strength 45.564 ± 0.72 MPa and 73.16 ± 1.34 MPa respectively. It is also observed that the composite C1 (10 μm) exhibited lower erosion rate of 216.67 mg/kg at 30° impingement angle compared to C2 (25 μm) and C3 (50 μm).

The automotive industry is experiencing a radical change where the metallic components are replaced with the light weight fiber reinforced composite materials. Fiber reinforced polymer (FRP) components are an effective alternate offering improved properties such as reduced weight, good mechanical strength, corrosion resistance etc. Carbon fiber reinforced polymer (CFRP) is lighter than aluminum and stronger than iron and exhibits higher elasticity than titanium. In the present study, the carbon fiber and Silicon Nitride (Si₃Ni₄) filler is used to fabricate FRP composite. Carbon fiber has high strength to volume ratio, high chemical resistance, low weight, high stiffness and high tensile strength whereas Si₃Ni₄ is an abrasion resistant and thermally conductive material. Carbon fiber reinforced epoxy matrix composite is fabricated using vacuum assisted resin transfer molding (VARTM) technique with different weight percent of silicon nitride (0, 10, 20 and 30 wt%). 10 layers of carbon fiber are stacked in the glass mould for the fabrication of the composite. The erosion test is performed with varying impingement angle from 45–90°, impact velocity from 30 to 60 m/s and filler content from 0 to 30 wt%. It is found from the Taguchi design of experiment that the impact velocity is most significant factor and the filler content is the least significant factor. However, increase in the filler content increase the wear resistance of the fabricated composite.

This segment encompasses the tribological changes usher by the addition of various reinforcements to the aluminium metal matrix composite. Aluminium matrix composites (AMCs) are being successfully tailored to achieve certain mechanical properties for specific applications. AMCs can be called as advance engineering materials with excellent properties. High hardness, high thermal conductivity, good yielding strength, strength to weight ratio, low coefficient of thermal expansion and excellent wear resistance are some of the attractive properties which AMCs possess. Applications like automobile, aerospace and several other industrial applications are being attracted towards AMCs due to its qualities. Various reinforcements are available in the market which can be added to aluminium metal to further enhance its properties. Particularly, in the field of tribology, these reinforcements have proved their worth in AMCs. To examine the effects of various reinforcements, a comprehensive study has been reported in the field of tribology for AMCs.

The traditional greases are composed of mineral or synthetic oil, thickening agent, additives and fillers. Thickeners having fibrous matrix are generally made of fatty acid soaps (calcium, lithium, aluminum, sodium) and non-soaps (clay, PTFE, polyurea, silica). The tribological performance of the grease is depends upon the viscosity of the base oil, type and its concentration of thickening agent. A variety of additives and fillers were added to the grease to obtain the desired properties of the grease. Lubricating greases are widely used in numerous automotive applications such as gears, cams, ball and roller bearings. A significant amount of power is lost due to the friction (i.e. friction in brakes, engine, tires, and transmission) in the automotive components. By reducing the frictional losses, the significant amount of power can be saved and this will improve the efficiency of the parts. The lubrication by the grease help in separation of the contacting surfaces to achieve low friction, wear, and long life. In the last decades, the researchers have contributed for enhancing the tribological performance of the grease with different fillers. In recent time the nano-additives is gaining importance for improving the tribological performance of the mating surface. Further, due to environmental concern, bio-based greases are explored in the formulation of the lubricating grease. This chapter enumerates the recent developments in the formulation of grease and their important aspect for improvising the tribological performance of automotive components.

In the automotive industry, losses results from friction and wear processes are huge, and every year almost thirty percent of the economy is consumed due to tribological losses. Recent advancement in technologies now permits the tribologist to design suitable lubrication techniques that were unachievable in the past. Recently, vapor film deposition or adding a thin layer of lubricants with improved physical and chemical properties is enormous. However, the suitability of such type of techniques is still in developing stage. To control the contact mechanism of sliding/rolling elements in the automotive industry, this work reports the importance of solid/liquid particles in lubrication. The friction and wear behavior of nanoparticles based on thin film coating and liquid lubrication technique is studied with traditional lubrication concept of vapor deposition and fluid film lubrication. Both techniques are necessary for designing lubricating film at the nanometer scale to control the surface properties of materials at nano/micro scales. Further, nanoparticles of self-lubricious materials are also used to prepare laboratory grease and are compared with traditional industrial grease. The obtained results are discussed by the intrinsic mechanism of sliding/rolling, theories of friction, wear, and involved parameters in the tribological tests. The potential application of prepared vapor deposition films/nanolubricants is loaded gears, bearings, piston cylinder, etc. The work can also be suitable in other industries where failure occurrence is repeated continuously due to resulting frictional losses.

Lubricants are used as anti-friction and heat absorbing media and therefore lead to smooth and reliable functions/operations, and therefore reduces the risks of frequent failures and thus enhance the durability/life-cycle of vehicle. At present, due to worldwide concern in protecting the environment from pollution and the increased prices and depletion of reserve crude oil, there has been growing interest to formulate and apply an alternative solution with the research and development in environment-friendly bio-lubricants from natural resources. A bio-lubricant is renewable and sustainable lubricants which is biodegradable, non-toxic, and emits net zero greenhouse gas. This chapter deals the potential of vegetable oil-based bio-lubricant for automotive application. In this chapter, the source, properties, as well as advantages and disadvantages of the bio-lubricant has been detailed. Further, the future prospects and challenges of bio-lubricants as potential alternative of conventional lubricants has been elucidated.

The chapter highlights the investigations on the friction reduction capability of a pre-determined sized hemispherical dimples of 3 mm diameter, taking into consideration the fact of easy availability of the tool (ball nose end mill) for industrial applications. The dimples were created using CNC milling machines on EN 31 disc. A pin-on-disc tribometer was used to investigate the tribological behavior of the various textured density surface (7.5, 15 and 22.5%) against EN 8 steel under various loading conditions (120, 140, and 160 N) and very harsh lubricating conditions: dry, partial lubrication (lubricant supplied 54 mL dropwise at a flowrate 1 mL/s) and starved lubrication (10 mL lubricant spread over the disc before the experiment). A significant decrease of 12% reduction of coefficient of friction (COF) was observed with 15% texture density under 120 N while the COF increased by 40–60% at texture density of 22.5% and high loads. In dry condition there was no significant change in COF but the specific wear rate decreased by 64.69% in 22.5% texture density. In the present set of experiments carried out at lighter load (120 N), both 7.5 and 15% texture densities exhibited better results as compared to 22.5% texture densities (under partial lubrication). Surface characterizations by optical microscopy revealed that the friction reduction of the dimpled surface was primarily due to the lubricant retaining capability by the dimples which acted as oil reservoirs, but high texture densities intensified the friction.

The chapter deals smart fluid i.e. Magneto Rheological fluid which is gaining interest of researcher as the range of application is vast. This book chapter starts with introduction of MR fluid, constituents of MR fluid and detailed study of each constituent. Also, discussing about the present necessity of MR fluid technology we discuss the operational modes of MR fluid. MR devices function basically on three operational modes of MR fluid i.e. flow mode, shear mode and squeeze mode. Every mode possess its own characteristics in high performance application system. Further Mathematical modelling of various rheological parameters and MR fluid is carried out, there after the detailed synthesis process and characterization of MR fluid is discussed. At last overview of MR fluid application is discussed and in detailed progress in MR brakes and clutch system is discussed.

Effect of shot peening on high stress abrasive wear behavior of medium carbon steel (AISI 6150 steel) at varying applied load and abrasive size has been studied. The shot peening leads to sub-surface work hardening and surface denting. The extent of work hardening and denting increases with increase in shot peening intensity. The experiments are performed on shot peening machine under two conditions of applied load, abrasive size and shot peening intensity as 7 N, 90 µm and 0.486 mm Almen “A” and 1 N, 30 µm and 0.117 mm Almen “A”, respectively. The wear rate decreases by 20–30% due to shot peening to a level of 0.117 mm Almen “A” from the un-peened state. Further increase in peening intensity does not lead to any significant improvement in wear resistance. The wear rate decreases with increase in sliding distance due to work hardening and degradation of abrasive media.

Presently, worldwide research is focused on energy efficiency to meet the requirement of greenhouse gas emission and economic reasons. The substantial amount of energy is consumed mainly in industrial, transportation and power generation sectors. The leading source of energy consumption is friction. Friction causes wear of the machine components and their replacement. Therefore, to minimize energy consumption the friction reduction is a foremost objective. Potential mechanisms for the reduction of friction are modified lubricants, coatings, and surface texture. In comparison with other mechanisms, surface texturing is a feasible, promising and well-established technique to improve the tribological performance of machine components for more than two decades. Surface texture decreases an area of contact, act as a reservoir and improves hydrodynamic effect in dry, mixed and hydrodynamic lubrication regime respectively. All of this contributes to reducing the friction coefficient. In addition to this, the surface texture improves the load capacity, dynamic stability and noise intensity of the bearings. It develops additional hydrodynamic effect and minimizing fluid leakage in oil and gas seals. Also, in automobile components such as piston rings, cylinder liner and wet clutch, the texture geometry is considered to be micro-pocket. Lubricant retained in the micro-pocket can be released to surrounding areas of texture to improve the tribological performance. This article outlines the recent advancement in texture design for different automotive components, their mechanisms, key findings and future roadmap. Also, the challenges in the fabrication of surface texture for automotive components are discussed in detail.

The improvement of engine efficiency has been of utmost necessity for automobile industries in order to control the increasing climate change and greenhouse emissions. Hence, the fuel efficiency may be increased by minimizing the energy losses from the engine. In spite of wide applications of reciprocating internal combustion (IC) engines in most of the ground and sea transport vehicles and electrical power generations, they have several shortcomings. The IC engines possess low thermal and mechanical efficiencies due to increased loss of fuel energy as heat and friction. They also release a substantial amount of particulate and NO_x (nitrogen oxide) emissions that gives rise to greenhouse effect. Amongst the various approaches of improving engine efficiency, the tribologists and lubrication engineers focused mainly on reduced engine friction as a vital and economic method. The achievement of efficient lubrication of moving engine components with least or no unfavorable effect on the environment is important to lessen friction and wear. The improvements in different tribological engine components and additives may lead to reduced fuel consumption, exhaust emissions and maintenance along with increased engine power outputs and durability. The tribological performance of an engine can be improved by employing materials of superior tribological properties for manufacturing different mechanical parts, improved surface coatings as well as developed lubrication technologies. This chapter presents the details of various components of reciprocating IC engines as well as the lubricants used and the remedial measures to reduce the engine wear and friction.

This book chapter focuses on the development in replacement of first generation brake materials (asbestos) by organic fiber based polymer composites. This replacement is necessary as the asbestos brake pads causes hazardous effects to the human being and environment. Many researchers report the several organic alternatives for asbestos in different journals. In this chapter, some of the best performed and eco-friendly compositions for brake materials are discussed. The uses of organic fibers and fillers such as flax, basalt, coconut, palm kernel shell, periwinkle shell, and pineapple leaf etc. are studied as an alternative to the asbestos based materials for braking pads. Different combinations of organic fibers with different binders like phenolic resin, polyester, and epoxy etc. are also studied and its influence on the behavior of brake pads is reviewed. Moreover, wear and friction coefficient are the two significant factors to be considered for suitability of any friction materials for braking pad application. Moreover, the influential rules and mechanism of braking conditions like pressure, velocity, and temperature on the friction and wear behaviors of organic reinforcing friction materials are summarized.