Metal matrix composites (MMCs) are an important class of engineering materials that are increasin... more Metal matrix composites (MMCs) are an important class of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, marine, and sports industries due to their lightweight and superior mechanical properties. In MMCs, nonmetallic materials are embedded into the metals or the alloys as reinforcements to obtain a novel material with attractive engineering properties, such as improved ultimate tensile strength, ductility, toughness, and tribological behavior. In this chapter, an attempt has been made to summarize the tribological performance of various MMCs as a function of several relevant parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and the environment). In general, it was shown that the wear resistance and friction coefficient of MMCs are improved by increasing the volume fraction of the reinforcements. As the normal load and sliding speed increase, the wear rate of the composites increases and the friction coefficient of the composites decreases. The wear rate and friction coefficient decrease with increasing temperature up to a critical temperature, and thereafter both wear rate and friction coefficient increase with increasing temperature. The nano-composites showed best friction and wear performance when compared to micro-composites.
Self-lubricating metal matrix composites (SLMMCs) are an important category of engineering materi... more Self-lubricating metal matrix composites (SLMMCs) are an important category of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, and marine industries due to superior tribological properties. Implementing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum-based lubricants at sliding contacts in a way to help the environment and to reduce energy dissipation in industrial components for strategies toward energy efficiency and sustainability. In SLMMCs, solid lubricant materials including carbonous materials, molybdenum disulfide (MoS2), and hexagonal boron nitride (h-BN) are embedded into the metal matrices as reinforcements to manufacture a novel material with an attractive self-lubricating properties. Due to their lubricious nature, these solid lubricant materials have attracted researchers to synthesize lightweight self-lubricating metal matrix composites with superior tribological properties. This chapter focuses on the recent development in tribological behavior of self-lubricating metal matrix (aluminum, copper, magnesium, and nickel) composites. It is important to note that the tribological parameters, such as normal load, sliding speed, and temperature vary on a wide range and also the counterface materials differ in different experimental tests, comparing the results of tribological behavior of different self-lubricating composites is extremely difficult. In this chapter, attempts have been made to summarize the tribological performance of various SLMMCs as a function of several tribological parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and environment). The mechanisms involved for the improved mechanical and tribological performances are discussed.
In the present investigation, aluminum matrix nanocomposites reinforced by graphene nanoplatelets... more In the present investigation, aluminum matrix nanocomposites reinforced by graphene nanoplatelets were synthesized by powder metallurgy method. The microstructure of the Al-Graphene nanoplatelets sample was investigated by TEM. The hardness measurements of these samples were investigated using a Rockwell hardness tester. To investigate the tribological behavior of aluminum matrix composites reinforced by graphene nanoplatelets and pure aluminum, pin-on-disk experiments were conducted on the prepared samples. In the experiments, the influence of reinforcement, volume fraction, normal load, and sliding velocity on the tribological performance was investigated. Results showed that the wear rate of Al-1wt.% GNP is increased with increasing normal loads. However, the coefficient of friction (COF) of the Al-1wt.% GNP decreased with increasing normal loads. Formation of graphene film on the worn surface of Al-1wt.% GNP sample and morphology of the worn surfaces of aluminum and composite samples were analyzed by Optical Microscope (OM) and Scanning Electron Microscope (SEM). It was found that the graphene nanoplatelets reinforced nano-composites showed superior tribological properties and demonstrated the ability of the self-lubricating nature of the composite during tribological conditions.
Aluminum/Graphite (Al/Gr) composites have been used as self-lubricating materials due to the supe... more Aluminum/Graphite (Al/Gr) composites have been used as self-lubricating materials due to the superior lubricating effect of graphite during sliding. This paper summarizes various tribological aspects of self-lubricating aluminum composites. The influence of various factors such as (a) material factors – graphite size and volume fraction, and (b) mechanical factors – applied load and sliding speed on the tribological properties of self-lubricating aluminum composites are discussed. Furthermore, the tribological properties of self-lubricating composites as a function of these parameters and the active wear mechanism involved in various systems are discussed. Bringing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum based lubricants in sliding contacts in a way to help the environment and reduce energy dissipation in industrial components for strategies toward sustainability and energy efficiency.
Polymer composites reinforced with fibrous materials are used in several tribological and mechani... more Polymer composites reinforced with fibrous materials are used in several tribological and mechanical applications. In this study, the effect of carbon fiber as a reinforcement on the mechanical and tribological properties of a bio-based epoxy composite was investigated. The level of cure was investigated using DSC and the tribo-surfaces were studied using SEM micrographs. Use of carbon fibers with epoxy composites expectedly enhanced the bending strength and modulus of the composite. More importantly, the use of carbon fibers improved the tribological properties. Taguchi technique was employed in order to extract the data in a controlled situation in the experiments. Through the regression analysis equations, it was possible to predict the COF and volume loss as a function of these parameters.
Rapid innovation in nanotechnology in recent years enabled development of advanced metal matrix n... more Rapid innovation in nanotechnology in recent years enabled development of advanced metal matrix nanocomposites for structural engineering and functional devices. Carbonous materials, such as graphite, carbon nanotubes (CNT’s), and graphene possess unique electrical, mechanical, and thermal properties. Owe to their lubricious nature, these carbonous materials have attracted researchers to synthesize lightweight self-lubricating metal matrix nanocomposites with superior mechanical and tribological properties for several applications in automotive and aerospace industries. This review focuses on the recent development in mechanical and tribological behavior of self-lubricating metallic nanocomposites reinforced by carbonous nanomaterials such as CNT and graphene. The review includes development of self-lubricating nanocomposites, related issues in their processing, their characterization, and investigation of their tribological behavior. The results reveal that adding CNT and graphene to metals decreases both coefficient of friction and wear rate as well as increases the tensile strength. The mechanisms involved for the improved mechanical and tribological behavior is discussed.
Many different types of advanced metal matrix composites are now available, some of which possess... more Many different types of advanced metal matrix composites are now available, some of which possess functional properties. Recent work on particle-reinforced, self-lubricating and self-healing metals and metal matrix nanocomposites (MMNCs) synthesized by solidification synthesis is reviewed. Particle-based MMNCs have been developed by several modern processing tools based on either solid- or liquid-phase synthesis techniques that are claimed to exhibit exciting mechanical properties including improvements of modulus, yield strength, and ultimate tensile strength. This article presents a brief and objective review of the work done over the last decade to identify the challenges and future opportunities in the area of functional nanocomposites. Increasing interest in lightweight materials has resulted in studies on hollow particle-filled metal matrix syntactic foams. Syntactic foams seem especially suitable for development with functional properties such as self-healing and self-lubrication. The metal matrix micro and nanocomposites, and syntactic foams having combinations of ultrahigh strength and wear resistance, self-lubricating, and/or self-healing properties can lead to increased energy efficiency, reliability, comfort of operation, reparability, and safety of vehicles. The focus of the present review is aluminum and magnesium matrix functional materials.
Many different types of advanced metal matrix composites are now available, some of which possess... more Many different types of advanced metal matrix composites are now available, some of which possess functional properties. Recent work on particle-reinforced, self-lubricating and self-healing metals and metal matrix nanocomposites (MMNCs) synthesized by solidification synthesis is reviewed. Particlebased MMNCs have been developed by several modern processing tools based on either solid-or liquid-phase synthesis techniques that are claimed to exhibit exciting mechanical properties including improvements of modulus, yield strength, and ultimate tensile strength. This article presents a brief and objective review of the work done over the last decade to identify the challenges and future opportunities in the area of functional nanocomposites. Increasing interest in lightweight materials has resulted in studies on hollow particle-filled metal matrix syntactic foams. Syntactic foams seem especially suitable for development with functional properties such as self-healing and self-lubrication. The metal matrix micro and nanocomposites, and syntactic foams having combinations of ultrahigh strength and wear resistance, selflubricating, and/or self-healing properties can lead to increased energy efficiency, reliability, comfort of operation, reparability, and safety of vehicles. The focus of the present review is aluminum and magnesium matrix functional materials.
Metal matrix composites (MMCs) are an important class of engineering materials that are increasin... more Metal matrix composites (MMCs) are an important class of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, marine, and sports industries due to their lightweight and superior mechanical properties. In MMCs, nonmetallic materials are embedded into the metals or the alloys as reinforcements to obtain a novel material with attractive engineering properties, such as improved ultimate tensile strength, ductility, toughness, and tribological behavior. In this chapter, an attempt has been made to summarize the tribological performance of various MMCs as a function of several relevant parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and the environment). In general, it was shown that the wear resistance and friction coefficient of MMCs are improved by increasing the volume fraction of the reinforcements. As the normal load and sliding speed increase, the wear rate of the composites increases and the friction coefficient of the composites decreases. The wear rate and friction coefficient decrease with increasing temperature up to a critical temperature, and thereafter both wear rate and friction coefficient increase with increasing temperature. The nano-composites showed best friction and wear performance when compared to micro-composites.
Over the last decades, numerous investigations have been conducted on Nitinol properties. However... more Over the last decades, numerous investigations have been conducted on Nitinol properties. However, the effects of alloying elements on Ni-rich NiTi alloys have been considered less. In this research, different effects of homogenization time and cooling rate on the behaviors of Ni-42.5wt%Ti-3wt%Cu alloy were evaluated. The mentioned alloy was fabricated by vacuum arc melting method. Three different homogenization times (half, one and two hours) and three cooling media (water, air and furnace) were selected. The microstructure and hardness were examined by means of optical and scanning electron microscope (SEM) equipped with an energy dispersive Xray (EDX) analysis and hardness test, respectively. According to the microscopic investigations, no significant changes were observed after half an hour. However, results indicate that increasing time of homogenization leads to finer precipitations and a uniform distribution of them. The various cooling environments result in the formation of two types of precipitation phases. It was seen that in the high cooling rate, the majority of precipitations consisted of Ti 2 (Ni,Cu) while by decreasing cooling rate NiTiCu precipitates appeared too, which affect the hardness.
The present paper deals with different effects of homogenization time and cooling environment on ... more The present paper deals with different effects of homogenization time and cooling environment on Ni-42.5wt%Ti-7.5wt%Cu alloy. The alloy was prepared by vacuum arc melting. Afterwards, three homogenization times (half, one and two hour) and three cooling environments (water, air and furnace) at 1373 K were selected. Optical and Scanning Electron Microscopic methods, EDX, DSC and hardness tests have been used to evaluate the microstructure, transformation temperatures and hardness. Results indicate that specimens that were cooled in air are super-saturated. Also, the microstructure from furnace cooling has many disparities with the other cooling environments' microstructure and two types of precipitates exhibit in the matrix, but in other cooling environments, only one phase can be seen. Particles of the Ti 2 (Ni,Cu) phase are distributed in the matrix in all of the microstructures irrespective of cooling rate. Observations show that increasing the time of homogenization results in finer precipitates and uniform distribution in the matrix. In addition, alteration of cooling rate and time of homogenization affect the martensitic transformation temperatures. On the other hand, the hardness varies slightly for different homogenization times but declines extremely with decreasing cooling rate. Moreover homogenization time and the cooling environment affect the transformation temperatures on furnace cooled samples.
Metal matrix composites (MMCs) are an important class of engineering materials that are increasin... more Metal matrix composites (MMCs) are an important class of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, marine, and sports industries due to their lightweight and superior mechanical properties. In MMCs, nonmetallic materials are embedded into the metals or the alloys as reinforcements to obtain a novel material with attractive engineering properties, such as improved ultimate tensile strength, ductility, toughness, and tribological behavior. In this chapter, an attempt has been made to summarize the tribological performance of various MMCs as a function of several relevant parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and the environment). In general, it was shown that the wear resistance and friction coefficient of MMCs are improved by increasing the volume fraction of the reinforcements. As the normal load and sliding speed increase, the wear rate of the composites increases and the friction coefficient of the composites decreases. The wear rate and friction coefficient decrease with increasing temperature up to a critical temperature, and thereafter both wear rate and friction coefficient increase with increasing temperature. The nano-composites showed best friction and wear performance when compared to micro-composites.
Self-lubricating metal matrix composites (SLMMCs) are an important category of engineering materi... more Self-lubricating metal matrix composites (SLMMCs) are an important category of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, and marine industries due to superior tribological properties. Implementing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum-based lubricants at sliding contacts in a way to help the environment and to reduce energy dissipation in industrial components for strategies toward energy efficiency and sustainability. In SLMMCs, solid lubricant materials including carbonous materials, molybdenum disulfide (MoS2), and hexagonal boron nitride (h-BN) are embedded into the metal matrices as reinforcements to manufacture a novel material with an attractive self-lubricating properties. Due to their lubricious nature, these solid lubricant materials have attracted researchers to synthesize lightweight self-lubricating metal matrix composites with superior tribological properties. This chapter focuses on the recent development in tribological behavior of self-lubricating metal matrix (aluminum, copper, magnesium, and nickel) composites. It is important to note that the tribological parameters, such as normal load, sliding speed, and temperature vary on a wide range and also the counterface materials differ in different experimental tests, comparing the results of tribological behavior of different self-lubricating composites is extremely difficult. In this chapter, attempts have been made to summarize the tribological performance of various SLMMCs as a function of several tribological parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and environment). The mechanisms involved for the improved mechanical and tribological performances are discussed.
In the present investigation, aluminum matrix nanocomposites reinforced by graphene nanoplatelets... more In the present investigation, aluminum matrix nanocomposites reinforced by graphene nanoplatelets were synthesized by powder metallurgy method. The microstructure of the Al-Graphene nanoplatelets sample was investigated by TEM. The hardness measurements of these samples were investigated using a Rockwell hardness tester. To investigate the tribological behavior of aluminum matrix composites reinforced by graphene nanoplatelets and pure aluminum, pin-on-disk experiments were conducted on the prepared samples. In the experiments, the influence of reinforcement, volume fraction, normal load, and sliding velocity on the tribological performance was investigated. Results showed that the wear rate of Al-1wt.% GNP is increased with increasing normal loads. However, the coefficient of friction (COF) of the Al-1wt.% GNP decreased with increasing normal loads. Formation of graphene film on the worn surface of Al-1wt.% GNP sample and morphology of the worn surfaces of aluminum and composite samples were analyzed by Optical Microscope (OM) and Scanning Electron Microscope (SEM). It was found that the graphene nanoplatelets reinforced nano-composites showed superior tribological properties and demonstrated the ability of the self-lubricating nature of the composite during tribological conditions.
Aluminum/Graphite (Al/Gr) composites have been used as self-lubricating materials due to the supe... more Aluminum/Graphite (Al/Gr) composites have been used as self-lubricating materials due to the superior lubricating effect of graphite during sliding. This paper summarizes various tribological aspects of self-lubricating aluminum composites. The influence of various factors such as (a) material factors – graphite size and volume fraction, and (b) mechanical factors – applied load and sliding speed on the tribological properties of self-lubricating aluminum composites are discussed. Furthermore, the tribological properties of self-lubricating composites as a function of these parameters and the active wear mechanism involved in various systems are discussed. Bringing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum based lubricants in sliding contacts in a way to help the environment and reduce energy dissipation in industrial components for strategies toward sustainability and energy efficiency.
Polymer composites reinforced with fibrous materials are used in several tribological and mechani... more Polymer composites reinforced with fibrous materials are used in several tribological and mechanical applications. In this study, the effect of carbon fiber as a reinforcement on the mechanical and tribological properties of a bio-based epoxy composite was investigated. The level of cure was investigated using DSC and the tribo-surfaces were studied using SEM micrographs. Use of carbon fibers with epoxy composites expectedly enhanced the bending strength and modulus of the composite. More importantly, the use of carbon fibers improved the tribological properties. Taguchi technique was employed in order to extract the data in a controlled situation in the experiments. Through the regression analysis equations, it was possible to predict the COF and volume loss as a function of these parameters.
Rapid innovation in nanotechnology in recent years enabled development of advanced metal matrix n... more Rapid innovation in nanotechnology in recent years enabled development of advanced metal matrix nanocomposites for structural engineering and functional devices. Carbonous materials, such as graphite, carbon nanotubes (CNT’s), and graphene possess unique electrical, mechanical, and thermal properties. Owe to their lubricious nature, these carbonous materials have attracted researchers to synthesize lightweight self-lubricating metal matrix nanocomposites with superior mechanical and tribological properties for several applications in automotive and aerospace industries. This review focuses on the recent development in mechanical and tribological behavior of self-lubricating metallic nanocomposites reinforced by carbonous nanomaterials such as CNT and graphene. The review includes development of self-lubricating nanocomposites, related issues in their processing, their characterization, and investigation of their tribological behavior. The results reveal that adding CNT and graphene to metals decreases both coefficient of friction and wear rate as well as increases the tensile strength. The mechanisms involved for the improved mechanical and tribological behavior is discussed.
Many different types of advanced metal matrix composites are now available, some of which possess... more Many different types of advanced metal matrix composites are now available, some of which possess functional properties. Recent work on particle-reinforced, self-lubricating and self-healing metals and metal matrix nanocomposites (MMNCs) synthesized by solidification synthesis is reviewed. Particle-based MMNCs have been developed by several modern processing tools based on either solid- or liquid-phase synthesis techniques that are claimed to exhibit exciting mechanical properties including improvements of modulus, yield strength, and ultimate tensile strength. This article presents a brief and objective review of the work done over the last decade to identify the challenges and future opportunities in the area of functional nanocomposites. Increasing interest in lightweight materials has resulted in studies on hollow particle-filled metal matrix syntactic foams. Syntactic foams seem especially suitable for development with functional properties such as self-healing and self-lubrication. The metal matrix micro and nanocomposites, and syntactic foams having combinations of ultrahigh strength and wear resistance, self-lubricating, and/or self-healing properties can lead to increased energy efficiency, reliability, comfort of operation, reparability, and safety of vehicles. The focus of the present review is aluminum and magnesium matrix functional materials.
Many different types of advanced metal matrix composites are now available, some of which possess... more Many different types of advanced metal matrix composites are now available, some of which possess functional properties. Recent work on particle-reinforced, self-lubricating and self-healing metals and metal matrix nanocomposites (MMNCs) synthesized by solidification synthesis is reviewed. Particlebased MMNCs have been developed by several modern processing tools based on either solid-or liquid-phase synthesis techniques that are claimed to exhibit exciting mechanical properties including improvements of modulus, yield strength, and ultimate tensile strength. This article presents a brief and objective review of the work done over the last decade to identify the challenges and future opportunities in the area of functional nanocomposites. Increasing interest in lightweight materials has resulted in studies on hollow particle-filled metal matrix syntactic foams. Syntactic foams seem especially suitable for development with functional properties such as self-healing and self-lubrication. The metal matrix micro and nanocomposites, and syntactic foams having combinations of ultrahigh strength and wear resistance, selflubricating, and/or self-healing properties can lead to increased energy efficiency, reliability, comfort of operation, reparability, and safety of vehicles. The focus of the present review is aluminum and magnesium matrix functional materials.
Metal matrix composites (MMCs) are an important class of engineering materials that are increasin... more Metal matrix composites (MMCs) are an important class of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, marine, and sports industries due to their lightweight and superior mechanical properties. In MMCs, nonmetallic materials are embedded into the metals or the alloys as reinforcements to obtain a novel material with attractive engineering properties, such as improved ultimate tensile strength, ductility, toughness, and tribological behavior. In this chapter, an attempt has been made to summarize the tribological performance of various MMCs as a function of several relevant parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and the environment). In general, it was shown that the wear resistance and friction coefficient of MMCs are improved by increasing the volume fraction of the reinforcements. As the normal load and sliding speed increase, the wear rate of the composites increases and the friction coefficient of the composites decreases. The wear rate and friction coefficient decrease with increasing temperature up to a critical temperature, and thereafter both wear rate and friction coefficient increase with increasing temperature. The nano-composites showed best friction and wear performance when compared to micro-composites.
Over the last decades, numerous investigations have been conducted on Nitinol properties. However... more Over the last decades, numerous investigations have been conducted on Nitinol properties. However, the effects of alloying elements on Ni-rich NiTi alloys have been considered less. In this research, different effects of homogenization time and cooling rate on the behaviors of Ni-42.5wt%Ti-3wt%Cu alloy were evaluated. The mentioned alloy was fabricated by vacuum arc melting method. Three different homogenization times (half, one and two hours) and three cooling media (water, air and furnace) were selected. The microstructure and hardness were examined by means of optical and scanning electron microscope (SEM) equipped with an energy dispersive Xray (EDX) analysis and hardness test, respectively. According to the microscopic investigations, no significant changes were observed after half an hour. However, results indicate that increasing time of homogenization leads to finer precipitations and a uniform distribution of them. The various cooling environments result in the formation of two types of precipitation phases. It was seen that in the high cooling rate, the majority of precipitations consisted of Ti 2 (Ni,Cu) while by decreasing cooling rate NiTiCu precipitates appeared too, which affect the hardness.
The present paper deals with different effects of homogenization time and cooling environment on ... more The present paper deals with different effects of homogenization time and cooling environment on Ni-42.5wt%Ti-7.5wt%Cu alloy. The alloy was prepared by vacuum arc melting. Afterwards, three homogenization times (half, one and two hour) and three cooling environments (water, air and furnace) at 1373 K were selected. Optical and Scanning Electron Microscopic methods, EDX, DSC and hardness tests have been used to evaluate the microstructure, transformation temperatures and hardness. Results indicate that specimens that were cooled in air are super-saturated. Also, the microstructure from furnace cooling has many disparities with the other cooling environments' microstructure and two types of precipitates exhibit in the matrix, but in other cooling environments, only one phase can be seen. Particles of the Ti 2 (Ni,Cu) phase are distributed in the matrix in all of the microstructures irrespective of cooling rate. Observations show that increasing the time of homogenization results in finer precipitates and uniform distribution in the matrix. In addition, alteration of cooling rate and time of homogenization affect the martensitic transformation temperatures. On the other hand, the hardness varies slightly for different homogenization times but declines extremely with decreasing cooling rate. Moreover homogenization time and the cooling environment affect the transformation temperatures on furnace cooled samples.
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