Iron Matrix Composites Research Articles

Effect of MWCNT Content on the Structure and Properties of Spark Plasma-Sintered Iron-MWCNT Composites Synthesized by High-Energy Ball Milling

The effect of multiwall carbon nanotube (MWCNT) content on the physical and mechanical properties of Fe-MWCNT composites has been studied. High-energy ball milling (HEBM) is employed to produce the composite powder; following this, spark plasma sintering (SPS) process has been adopted for powder consolidation. The composite powder and the sintered products were subjected to structural characterization by XRD. Microstructural studies were carried out by optical, field-emission scanning and high-resolution transmission electron microscopy. While Fourier transform infrared spectroscopic study of composites was done to understand the bonding characteristics, Raman spectroscopy was employed to assess the structural damage of MWCNT after HEBM. The effects of processing on the behavior of C-C, C-O and Fe-O bonds are studied by x-ray photoelectron spectroscopy. Microhardness and compressive strength of composites are also determined. Finally, magnetic and electrical properties of the composites were characterized. It was observed that optimized ball milling conditions help to preserve the structural identity of MWCNT. Consolidation by SPS insured good interfacial bonding. The microhardness and compression strength are significantly improved in MWCNT-reinforced iron matrix composite. MWCNT has appreciably improved the electrical conductivity of the composites. Tethering of MWCNT by iron oxide has led to appreciable improvement in saturation magnetization till 3 wt.% MWCNT.

Simulation of stress distribution and evolution in SiC particle reinforced iron matrix composites

An Eshelby particle-compounded model was employed to investigate the stress distribution in the SiCp/Fe composites during straining in order to predict the stress-strain curves of the composites. Effect of the SiC volume content and aspect ratios on yield strength of the SiCp/Fe composites was studied by the simulation. The modeling results indicate that the stress in the iron matrix is much smaller than that in SiC particles as straining the composites, which means the strengthening mechanisms of the SiCp/Fe composites is determined by the load transfer mechanisms. The aspect ratios of the particles play a significant role in yield strength of the SiCp/Fe composites especially as the particle volume content is large. The stress in SiC particles has a stronger dependence on the aspect ratios of the particles only if the reinforcement volume content is small.

Wettability and interaction mechanism for Ni-modified ZTA particles reinforced iron matrix composites

The wetting behaviors of bare and Ni-modified zirconia toughened alumina (ZTA) with molten iron matrix have been explored by sessile drop technique and gathered to compare their wettability. Experimental results show that the wetting angles of molten 65Mn steel and high chromium cast iron (HCCI) matrix on bare ZTA substrates are 104.1° and 102.3°, respectively, whereas it is decreased to 83.6° and 88.2° on Ni-modified ZTA substrates. The wetting angle of HCCI matrix on Ni plate is just 1.5° in 1 min. At high casting temperature, element Ni originated from Ni coating can diffuse into molten Fe and keep constant basically. Small amount of element Ni can react with Al2O3 on ZTA/Fe interface to form Al2NiO4. A schematic illustration of the cast-infiltration process is put forward, which indicates that Ni-modified ZTA can be wetted with molten iron through Ni diffusion and reactive wetting. A ZTA/Al2NiO4/Fe interface layer is formed by mechanical bonding, interdiffusion and small amount of chemical reactions, to achieve composites with tight interfacial bonding strength. Besides, Ni-modified ZTA particles are prepared through electroless plating assisted with Ethaline additive and used as precursor to reinforce 65Mn steel matrix composite by nonpressure casting infiltration method.

The influence of titanium addition on wettability of high-chromium white cast iron-matrix composites

The mining industry exerts ever increasing demand for components with high wear resistance to the extent that plain ferrous alloys are falling short. Innovative metal-matrix composites non-ferrous metals have been widely researched and used. Casting composites based on ferrous alloys pose monumental challenges in casting. First, the density differential results in large buoyant forces on the ceramic such that unless a rigid structure is configured, the less dense ceramic floats on the metal stream. Second, the poor wetting properties between metal and ceramic will result in inferior bonding of the matrix, hence separation of solids in service. The paper attempts to improve the bonding characteristics of zirconia and alumina through wettability studies. High-chromium white cast iron was used as a substrate. The wetting behavior of molten iron on the substrates of zirconia and alumina was investigated. The study shows that alumina is poorly wetted with copper and nickel; the wetting angles were higher than 90°. Thus, the envisaged coating of alumina with copper or nickel prior to casting of ferrous melts will not significantly alter or improve wettability of alumina. Between copper and nickel, nickel has better bonding with alumina than copper. Titanium in high-chromium white cast iron was found to improve the wetting characteristics on alumina. The wetting angle decreased with increased titanium content.

Dry sliding wear investigation on tungsten carbide particles reinforced iron matrix composites

WC particles reinforced Fe-based metal matrix composites were synthesized by powder metallurgy process. The microstructure and composition of the specimens were analyzed and the wear-resistant properties against WC and alumina balls were comparatively investigated by SEM/EDS analyses. The wear rates of specimens were evaluated by optical profilometry. Microstructure exhibited austenite Fe-FCC dendrites, eutectic (iron austenite + carbides) and primary carbides. Two wear mechanisms have been identified from SEM as main mechanisms during dry sliding wear of Tungsten carbides reinforced iron matrix, namely oxidation and abrasion. The overall wear performance, which is obtained by considering the wear loss of the substrates, indicated less resistance against Alumina compared to WC ball contact.

Effects of Deep Cryogenic Treatment on the Microstructures and Tribological Properties of Iron Matrix Self-Lubricating Composites

The effects of deep cryogenic treatment on the microstructures and tribological properties of the self-lubricating iron matrix composites are investigated. The self-lubricating composites are deeply cryogenically treated at about −196 °C. The results show that with deep cryogenic treatment, the martensite phase transformation occurred from phase γ to α′, and the fine particle carbides precipitated between martensites with the extension of cryogenic treatment time, measured by X-ray diffractometry (XRD) and scanning electron microscope (SEM). Compared with the as-sintered specimen, the maximum hardness of the specimens processed by cryogenic treatment increases by 172.8% from 253.2 HV to 690.7 HV. The materials with deep cryogenic treatment for 8 h show the best tribological properties, i.e., the average friction coefficient decreases by 75% from 0.36 to 0.09, and the wear coefficient decreases by 63% from 341 to 126 × 10−6 mm3/Nm at 150 N and 8 mm/s. The improvement of the tribological property can be primarily attributed to the martensite phase transformation from γ to α′ and the precipitation of fine particles carbides between the martensites, which increase the hardness and the wear resistance after the cryogenic treatment.

Influence of Thermal Fatigue on the Wear Behavior of Brake Discs Sliding against Organic and Semimetallic Friction Materials

ABSTRACTIn this article, brake discs are exposed to high thermal stress, causing thermal fatigue damage. The aim of this work is to study the evolution of the wear behavior of brake disc materials, such as cast iron, chromium steel, and metal matrix composites, under the influence of thermal fatigue. The brake disc specimens are heated and then cooled rapidly. Then, wear tests are carried out using a pin-on-disc-type tribometer. Organic and semimetallic friction materials are used for all wear tests. The results show that thermal fatigue affects the structure of the contact surfaces of all of the disc specimens by increasing their roughness. Furthermore, the wear rate of the friction materials increased, except a reduction of the wear rate is noted for the semimetallic friction material rubbing against cast iron. Moreover, thermal fatigue has no significant influence on the coefficient of friction. The worn surface of the metal matrix composite sliding against semimetallic friction material is characterized by abrasive and adhesive wear mechanisms.

Effect of Electroless Nickel Plating on Properties of Iron Matrix Composites

Iron matrix composites are a kind of high-performance, low-cost metal matrix composites. They are the most promising metal matrix composites. In order to overcome the problem of reinforced particles and molten iron not infiltrating, the application of electroless nickel plating can solve it successfully. Based on the principle of electroless nickel plating, this paper studies the erosion and wear resistance of iron matrix reinforced composite. The experimental results show that the electroless nickel plating on the surface of the reinforced particles can achieve better bonding with the iron matrix and improve the infiltration of the matrix. Different particle volume fractions and different particle sizes have a greater influence on the erosion wear resistance of iron matrix composites. The larger the volume fraction of particles, the greater the volume wear, and when the particle volume fraction is the same, the erosion wear of the iron matrix composites increases with particle size.

Effect of WC content on properties of iron matrix composite

Fe-2Cu-2Ni-1Mo-1C matrix composite with WC content of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% were prepared. Pore morphology, density, hardness and bending strength of materials were studied. Results show, for Fe matrix composite reinforced by WC particles prepared via conventional powder metallurgy process, WC content needs to be well controlled to be 2%, which benefits the properties of the composite (hardness of HRB101.6 and strength of 945.1MPa); WC particles can effectively reduce the quantity of tiny pores, but may easily agglomerates, and excess WC particles may cut apart the matrix material and degrade the performance.

The Particle Shape of WC Governing the Fracture Mechanism of Particle Reinforced Iron Matrix Composites.

In this work, tungsten carbide particles (WCp, spherical and irregular particles)-reinforced iron matrix composites were manufactured utilizing a liquid sintering technique. The mechanical properties and the fracture mechanism of WCp/iron matrix composites were investigated theoretically and experimentally. The crack schematic diagram and fracture simulation diagram of WCp/iron matrix composites were summarized, indicating that the micro-crack was initiated both from the interface for spherical and irregular WCp/iron matrix composites. However, irregular WCp had a tendency to form spherical WCp. The micro-cracks then expanded to a wide macro-crack at the interface, leading to a final failure of the composites. In comparison with the spherical WCp, the irregular WCp were prone to break due to the stress concentration resulting in being prone to generating brittle cracking. The study on the fracture mechanisms of WCp/iron matrix composites might provide a theoretical guidance for the design and engineering application of particle reinforced composites.

Interaction of Edge Dislocations with Graphene Nanosheets in Graphene/Fe Composites

Graphene is an ideal reinforcement material for metal-matrix composites owing to its exceptional mechanical properties. However, as a 2D layered material, graphene shows highly anisotropic behavior, which greatly affects the mechanical properties of graphene-based composites. In this study, the interaction between an edge dislocation (b = 1/2 (111)) and a pair of graphene nanosheets (GNSs) in GNS reinforced iron matrix composite (GNS/Fe) was investigated using molecular dynamic simulations under simple shearing conditions. We studied the cases wherein the GNS pair was parallel to the (1 1 ¯ 0), (11 2 ¯ ), and (111) planes, respectively. The results showed that the GNS reinforcement can effectively hinder dislocation motion, which improves the yield strength. The interaction between the edge dislocation and the GNS pair parallel to the (11 2 ¯ ) plane showed the strongest effect of blocking dislocations among the three cases, resulting in increases in the shear modulus and yield stress of 107% and 1400%, respectively. This remarkable enhancement was attributed to the Orowan “by-passing” strengthening mechanism, whereas cross-slip of dislocation segments was observed during looping around GNSs. Our results might contribute to the development of high-strength iron matrix composites.

Preparation of nickel coating on ZTA particles by electroless plating

With the aim to effectively improve the interface between ZrO2 toughened Al2O3 (ZTA) particles and metal matrix, nickel was deposited on the surface of ZTA particles by electroless plating method. Formation mechanism of nickel coating and effects of the solution pH, loading capacity of ZTA particles and temperature on the nickel deposition were investigated. Microstructures, thickness and element distributions of nickel coating were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the nickel was successfully deposited on the surface of ZTA particles by electroless plating without noticeable defects. The process of electroless nickel plating could be explained by combination of atomic hydrogen and electrochemistry theories. The interfacial nucleation of nickel is easier to form than spontaneous nucleation in the solution. Deposited Nickel has priority on the surface of ZTA particles comparing to that in solution. The optimal conditions to coat nickel on the surface of ZTA particles are: solution pH 4.7–4.8, loading capacity 15–20 g/L, and electroless plating temperature 85 °C. The ZTA particle reinforced iron matrix composites prepared by powder metallurgy could have better interfacial bonding between ZTA particle and iron matrix because of the nickel coating on the surface of ZTA particle. Nickel diffuses into the iron matrix during the sintering preparation of composite materials. The interface between ZTA particle and iron matrix presents the evidence of non-chemical bonding.

Characterization of interfacial layer of ZTA ceramic particles reinforced iron matrix composites

Experimental evidence is first provided for the reaction product in the interfacial layer of ZTA (zirconia toughened alumina) ceramic particles reinforced HCCI (high chromium cast iron). Phases formed in the interfacial layer during solidification were identified by TEM and HRTEM. It is confirmed that they were the amorphous Na4SiO4 phases. The diffusion of Al is faster than that of other elements in the interfacial layer. The hardness and modulus of interfacial layer were 1877.5 HV and 299.8 Gpa, respectively. The phase transformation (t-ZrO2→m-ZrO2 and θ-Al2O3→α-Al2O3) occurred during the composite preparation.

Effects of Different Matrix on Interface and Compression Fracture Behavior of WC Particles Reinforced Iron Matrix Composites

The WC particles reinforced iron matrix composites were prepared by utilizing energy ball milling powder mixed and vacuum powder sintering method in this paper. The effects of two kinds of matrix on the micro-structure, interface and fracture mechanism of the composites were studied emphatically, and it provided a theoretical guidance for the design and engineering application of particle reinforced metal matrix composites. The results show that: in the two kinds of matrix composites, WC particles and interface had different degree of melting, WC particles and the matrix were metallurgical combination; ferritic matrix composites had better compressibility than pearlite matrix composites (1089Mpa); the fracture mode of ferrite matrix composites was quasi-cleavage fracture and pearlite matrix composites was pure cleavage fracture; the compressive micro-cracks of the two matrix composites generated at the interface and expand at the interface to a broad macroscopic crack, which eventually the material fails.

A review on properties of conventional and metal matrix composite materials in manufacturing of disc brake

Brake is the most important element in automobile which keeps safety and comfortable. This paper reviews on different braking methods and procedures used in the study of automotive braking system. It covers types of braking systems, material properties and different types of materials used in the manufacturing of especially disc brakes. The advantages and limitations of each type of braking approach were examined from the previous research papers. This study will be helpful for understanding the improvement and performance of the braking system, to increase the fuel consumption and reduction of weight in automobiles. And also discusses the materials used from past studies and use of different conventional materials like cast iron and Metal Matrix Composites (MMCs) material. From the past two decades a lot of improvement in MMCs is observed in a big way, primarily because of their superior physical, mechanical and tribological properties when compared to monolithic materials. The principal advantage of MMCs over other materials lies in the improved in strength, hardness and reduction of weight. .It is found that the analysis are still in approach favored by the automobile sector.

Study on reaction mechanisms of iron matrix compositesreinforced with in situ Al2O3 particles reacted byAl-Fe2O3-Fe system

Iron matrix composites reinforced with Al2O3 particles were fabricated in situ through exothermic dispersive (XD) reaction from a powder mix of pure elements Fe, Al and Fe2O3. The fabrication and reaction mechanisms were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC) analysis. The reaction between Al and Fe2O3 was found to occur in three steps. Their activation energies are 203.8 kJ/mol, 1100.9 kJ/mol and 380 kJ/mol, respectively. DSC analysis shows that the reaction peak shifts to a higher temperature with an increase in the heating rate. When the heating rate is 10 K/min, the rates of the three reactions exhibit a similar trend, i.e., the reaction rate is very slow at the start, and then it increases rapidly, finally it becomes slow again. Their reaction times are 456, 672 and 650 s, respectively.

Microstructure Characteristics of Fe-Matrix Composites Reinforced by In-Situ Carbide Particulates

Carbide particulates reinforced iron-matrix composites were prepared by in-situ synthesis reaction between Ti, V and C on liquid alloys surface. The microstructure of the composite was characterized by SEM, TEM and OM. The results showed that the main phases were α-Fe, carbide particulate; besides, there were small amounts of γ-Fe and graphite (G) in the composite. The carbides were TiVC2 and VC in the shape of short bar and graininess. The matrix consisted of martensite and small amounts of retained austenite.

Integral method of preparation and fabrication of metal matrix composite: Selective laser melting of in-situ nano/submicro-sized carbides reinforced iron matrix composites

This paper presents a study on the formation, microstructure and mechanical property of Cr3C2/Fe nanocomposites using selective laser melting (SLM). Scanning electron microscope (SEM), transmission electron microscope (TEM) and tensile tests were conducted to investigate the influence of Cr3C2 particulates on the microstructure and mechanical properties. It was found that the porosity decreased when volumetric energy density increased from 27 to 37J/mm3, then rose to 55J/mm3. The results showed that the Cr3C2 particulates decomposed completely during SLM process and interacted with Fe matrix to form (α-Fe, Cr) solid solution and M(Fe, Cr)23C6 carbides. In addition, due to the characteristic of rapid solidification, very fine grains were obtained throughout the composites. The tensile tests showed that the ultimate tensile strength could reach up to 1158MPa.

Preparation and Properties of High Chromium Cast Iron Matrix Composites Reinforced by Zirconium Corundum Particles

In this paper, the zirconia corundum ceramic particles reinforced high chromium cast iron matrix wear resistant composite material was produced by vacuum infiltration casting. The experimental results show that the nickel plating on the surface of the ceramic was beneficial to the infiltration of the molten metal. The interface of the composite was dense without defects and uniform particle distribution in the composite. Based on the dynamic analysis of the infiltration process, the mechanism of casting infiltration was expounded detailedly. The friction and wear experiments show that the wear resistance of the composites is 1.93 times of high chromium cast iron and the life was greatly improved. The morphology analysis results show that the wear resistance of the composites was low stress abrasive wear, so the wear mechanism was micro cutting of abrasive grains.

Synthesis, mechanical properties and corrosion behavior of powder metallurgy processed Fe/Mg2Si composites for biodegradable implant applications

Recently, Fe and Fe-based alloys have shown their potential as degradable materials for biomedical applications. Nevertheless, the slow corrosion rate limits their performance in certain situations. The shift to iron matrix composites represents a possible approach, not only to improve the mechanical properties, but also to accelerate and tune the corrosion rate in a physiological environment.In this work, Fe-based composites reinforced by Mg2Si particles were proposed. The initial powders were prepared by different combinations of mixing and milling processes, and finally consolidated by hot rolling. The influence of the microstructure on mechanical properties and corrosion behavior of Fe/Mg2Si was investigated. Scanning electron microscopy and X-ray diffraction were used for the assessment of the composite structure. Tensile and hardness tests were performed to characterize the mechanical properties. Potentiodynamic and static corrosion tests were carried out to investigate the corrosion behavior in a pseudo-physiological environment. Samples with smaller Mg2Si particles showed a more homogenous distribution of the reinforcement. Yield and ultimate tensile strength increased when compared to those of pure Fe (from 400MPa and 416MPa to 523MPa and 630MPa, respectively). Electrochemical measurements and immersion tests indicated that the addition of Mg2Si could increase the corrosion rate of Fe even twice (from 0.14 to 0.28mm·year−1). It was found that the preparation method of the initial composite powders played a major role in the corrosion process as well as in the corrosion mechanism of the final composite.