TiC Reinforcement Research Articles

The Effects of TiC Reinforcement on Thermal, Electrical and Dry Sliding Wear Behaviour of Aluminium Matrix Nanocomposites

The Effects of TiC Reinforcement on Thermal, Electrical and Dry Sliding Wear Behaviour of Aluminium Matrix Nanocomposites

The influences of melting degree of TiC reinforcements on microstructure and mechanical properties of laser direct deposited Ti6Al4V-TiC composites

This study is concerned with the influences of melting degree of embedded TiC reinforcements on microstructure and mechanical properties of laser direct deposited Ti6Al4V-TiC composites and a functionally graded material. The melting degree of embedded TiC was controlled by the input laser energy density and the added TiC content. The formation of detrimental primary dendritic TiC grains was successfully avoided by properly adjusting the deposition conditions and the particle size range of TiC reinforcements. The resultant compression test revealed the ultimate strength increasing from 1381±19MPa to 1636±23MPa as the premixed TiC content increased from 0 to 15vol% while a true strain of 0.141±0.002 was still retained for 15vol% TiC. The primary strengthening mechanism for composites with the most melting control of TiC is the solid solution strengthening induced by carbon, while that for the least melting control is dominated by the unmelted TiC particulates and the refined microstructure resulting from the resolidified carbides. The defect-free functionally graded Ti6Al4V-TiC with 0 to 40vol% TiC achieved an increased hardness from HRC ~39 to HRC ~65.

Brazing SiO2f/SiO2 with TC4 alloy with the help of coating graphene

The joining of SiO2f/SiO2 to TC4 alloys suffers from the problems of poor wettability with AgCuTi, excessive Ti dissolving from TC4 and emergence of high residual stress among the joint. To solve these problems, an effective method by coating graphene on the SiO2f/SiO2 is developed. Wetting experiments confirm that contact angle notably reduces from 131° to 42.8° after coating rGO. Further, rGO react with Ti element from the brazing alloy and TC4 alloy, inhibiting the formation of excessive brittle reaction layer and in situ forming TiC reinforcement. The highest shear strength of SiO2f/SiO2-TC4 brazed joints was up to 39.2 MPa.

Microstructure growth behavior and its evolution mechanism during laser additive manufacture of in-situ reinforced (TiB+TiC)/Ti composite

The in-situ (TiB + TiC) reinforced Ti matrix composites with novel microstructures were successfully prepared by laser additive manufacture in this paper. The phase identification, surface morphologies, microstructure growth and its evolution mechanism, and microhardness of B4C/Ti composite under variable laser power were systematically analyzed. The results revealed that the in-situ TiC+TiB reinforcements generated surrounding the incorporated B4C particles and the pro-eutectic TiB phases precipitated from the molten liquid. Under the activities of a large laser power penetrated into powder-bed, the top surface morphology appeared to be smooth, due to the sufficient convections within pool and neighboring tracks. The laser power significantly influenced the microstructure growth within molten pool. As increasing the laser power, the in-situ whisker-like TiB and granular TiC phases were evidently grew and coarsened, ascribed to the sufficient energy and considerable diffusion of B and C elements. The high microhardness of approximate 577.1 HV0.2 was obtained at a relatively low laser power, attributing to the enhancement of fine TiB and TiC reinforcements. Furthermore, the evolution mechanism of microstructure within molten pool was concluded, as well.

Tribological Behavior of TiAl Metal Matrix Composite Brake Disk with TiC Reinforcement Under Dry Sliding Conditions

In this investigation, the effect of TiC particulate reinforcement and sintering parameters on tribological behavior of TiAl metal matrix composite (TMMC) has been studied and compared with commercially conventional gray cast iron to evaluate the use of TMMC as brake disk material in an automobile. Three sample disks of TMMC containing TiC particulate reinforcement (D1-5 wt.%, D2 and D3-10 wt.%) were produced by the spark plasma sintering process. D3 compared with D2 was sintered at a higher temperature to evaluate the effect of SPS parameters on the wear characteristics of TMMC. All experiments were performed on pin-on-disk tribotester under a dry sliding condition with different loads (10-11.5 N) and sliding velocities (0.2-0.9 m/s). It is found that higher content of TiC increased TMMC hardness and density. XRD technique has been used to analyze the phase composition. Owing to the high sintering temperature, α-2 Ti3Al phase was formed which further enhanced the matrix anti-wear capability. Scanning electron microscope (SEM) was used to capture the wear track and observe wear mechanism. Energy-dispersive spectroscopy (EDS) has been used to analyze the tribofilm and wear debris. The results showed that the tribofilm for TMMC was mainly composed of metal oxides. Oxidation of Al and Ti due to frictional heat provides wear-resistant protective layer. Under almost all sliding conditions, TMMC, especially disk D3, exhibited minimum wear rate and stable friction coefficient, whereas gray cast iron exhibited lower and unstable friction coefficient as well as higher wear rate. TMMC has shown superior tribological characteristics over gray cast iron in terms of low wear rate along with stable and adequate friction coefficient which is necessary for braking operation and life of brake disk. However, further investigation on full-scale automobile conditions is needed for its practical application.

Wear behavior of in-situ TiC particles reinforced aluminum matrix composite

The microstructure, tensile property and wear resistance of 7075 aluminum matrix composite reinforced with TiC particles prepared by in-situ reaction casting were investigated. The effect of TiC reinforcement on wear behavior was analyzed. The wear mechanism was also discussed. A micro-mechanism model of reaction kinetics for synthesis of TiC was acquired. Results show that TiC could increase the tensile and yield strength, but decrease the elongation. Besides, TiC particles improve the property of wear resistance of 7075 aluminum alloy. The wear mechanisms include abrasive wear and adhesive wear in wear test process.

The formation mechanism of TiC reinforcement and improved tensile strength in additive manufactured Ti matrix nanocomposite

The nanoscale TiC reinforced Ti matrix nanocomposites with nearly full density of 98.2% were fabricated by selective laser melting. Owing to the unique metallurgical action of SLM, the TiC exhibited two typical morphologies: nanoscale lamellar and submicron strip structures, and showed a uniform network distribution. The formation mechanism of TiC was investigated in detail. The SLM-processed Ti matrix nanocomposite possessed a significantly enhanced tensile strength of 914 MPa due to the formation and uniform dispersion of nanoscale TiC.

Microstructure Evolution of TiC Particles In Situ, Synthesized by Laser Cladding.

In this paper, a TiC reinforcement metal matrix composite coating is produced using nickel and graphite mixing powder on the surface ofTi-6Al-4V alloy by laser radiation. The microstructure of the coatings is investigated by XRD, SEM and EDS. Results show that most of the TiC phase is granular, with a size of several micrometers, and a few of the TiC phases are petals or flakes. At the cross-section of the coatings, a few special TiC patterns are found and these TiC patterns do not always occur at the observed cross-section. The even distribution of the TiC phase in the coatings confirms that the convection of the laser-melted pool leads to the homogenization of titanium atoms from the molten substrate, and carbon atoms from the preplace powder layer, by the mass transfer. The characteristics of the TiC pattern confirm that the morphology and distribution of the primary TiC phase could be influenced by convection. Two main reasons for this are that the density of the TiC phase is lower than the liquid melt, and that the primary TiC phase precipitates from the pool with a high convection speed at high temperature.

Accelerated Short-Term Techniques to Evaluate Corrosion in TiC Reinforced AA6063 Composites

AA6063-TiC composites have several weight percentages up to 9 wt. % were fabricated by using stir casting route method. The effects of the weight percentage of TiC particles on the microstructures and corrosion behavior of AA6063-TiC composites were studied. The results revealed that the AA6063-TiC composites exhibited higher density than the AA6063 matrix. The accelerated corrosion tests of AA6063-TiC composites in 3.5 wt. % NaCl aqueous solution at room temperature, the AA6063-TiC composites have better corrosion resistance than the AA6063 matrix. Increasing the weight percentage of the TiC particles to reduces the corrosion rate of the AA6063-TiC composites. In this process corrosion rate of 0.4402 mm/year for AA6063 matrix, 0.3891 mm/year for 3 wt. % , 0.3568 mm/year for 6 wt. % and 0.3062 mm/year for 9 wt. % of TiC particles respectively. The poor corrosion resistance of the composites can be attributed to the galvanic effects between the AA6063 matrix and TiC reinforcement.

Strengthening effects of TiC particles and microstructure refinement in in situ TiC-reinforced Ti matrix composites

TiC-reinforced Ti matrix composites of various TiC volume fractions were prepared via an in situ synthesis method. The microstructure of the composites was refined by thermo-mechanical processing yielding Widmanstätten and bimodal microstructures. The strengthening effects exerted by TiC reinforcement and microstructure refinement in the composite were evaluated via tensile tests at 873K, and the strengthening mechanisms were investigated by transmission electron microscopy and mechanical models. The addition of carbon increased the beta transfus temperature of the composite significantly. The strengthening effect exerted by the solid solution carbon and dislocation hindering by the TiC particles played important roles in determining the strength of the prepared composites. In composites that featured Widmanstätten and bimodal microstructures with no precipitated silicides, the size of the α colonies was an important factor that determined the composite strength. In contrast, in composites wherein silicide precipitation had occur, the size of the α plates was a contributing factor owing to the dislocation hindering effect exerted by the silicides.

Synthesis of Ti matrix composites reinforced with TiC particles: thermodynamic equilibrium and change in microstructure

The evolution of TiC reinforcement during the high-temperature consolidation step of a particulate-reinforced Ti matrix composite has been studied. A four-step scenario has been highlighted starting with the dissolution of the smallest particles to reach C saturation of the Ti matrix, followed by a change in the TiC stoichiometry from the initial TiC0.96 composition to the equilibrium composition (TiC0.57). This change in composition induces an increase in both the total mass fraction of reinforcement and the particle diameter. The diameter increase promotes contact between individual particles in the most reinforced domains and initiates an aggregation phenomenon that is responsible for the observed high growth rate of particles for heat treatment times shorter than 1 h. Finally Ostwald ripening is responsible for the growth of particles for longer heat treatment times.

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

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

TiC Reinforcement Composite Coating Produced Using Graphite of the Cast Iron by Laser Cladding.

In this study, a TiC-reinforced composite coating was produced to improve the wear resistance of a pearlite matrix grey iron using a pre-placed Ti powder by laser cladding. Results of scanning electron microscopy (SEM), X-ray diffractometer (XRD), and energy dispersive X-ray spectroscopy (EDS) confirmed that the coating was composed of TiC particles and two kinds of α-Fe phase. The fine TiC particles were only a few microns in size and uniformly distributed on the matrix phase in the composite coating. The microstructure characteristic of the composite coating resulted in the microhardness rising to about 1000 HV0.3 (China GB/T 4342-1991) and the wear resistance significantly increased relative to the substrate. In addition, the fine and homogeneous solidification microstructure without graphite phase in the transition zone led to a good metallurgical bonding and transition between the coating and the substrate. It was of great significance for the cast iron to modify the surface and repair surface defects or surface damage.

Mechanical activation-assisted combustion synthesis of in situ aluminum matrix hybrid (TiC/Al2O3) nanocomposite

The aim of this study is the synthesis of aluminum-based metal matrix nanocomposites reinforced with in situ TiC and Al2O3 hybrid reinforcements by the mechanically activated combustion synthesis. The composites were fabricated from the powder blends consisting of aluminum, rutile and graphite with an excess amount of aluminum following the 14Al–3TiO2−3C system and milled up to 30h. Phase evolutions and structural changes during ball milling and combustion synthesis were studied by X-ray diffraction technique, field-emission gun scanning electron microscopy and transmission electron microscopy. The results showed that even after 10h of milling, no new phases were formed. The increasing of milling time caused the broadening of all the peaks indicating a decrease in the crystallite size and an increase in the lattice strain. These results showed that Al, C and TiO2 nanocrystallites could be obtained during the ball-milling process. The result of combustion synthesis of un-milled powders confirmed that no new phases were found. In comparison with un-milled powder mixture, the 10h milled powder could be easily ignited and XRD, HRSEM and TEM results confirmed that Al/TiC–Al2O3 nanocomposite was successfully synthesized through combustion method from the mechanical activated powder mixture. Mechanical activation via high energy ball-milling provided to the initial powder mixture extra energy, which is needed to increase the reactivity of powder mixture and to make possible the ignition and the sustaining of combustion.

Effect of solid carburization on surface microstructure and hardness of Ti-6Al-4V alloy and (TiB+La2O3)/Ti-6Al-4V composite

Solid carburization was employed to improve the hardness of Ti-6Al-4V alloy and (TiB+La2O3)/Ti composite. The samples wrapped in graphite powder were placed in sealed quartz tubes, followed by solid carburization at 1227 K for 24 h. Microstructure and phase analysis indicated that TiC reinforcements and Ti-C solid solutions were introduced after solid carburization. Moreover, the volume fraction of equiaxed α-Ti phase in diffusion layer decreased obviously with increasing sample depth. Hardness testing results indicated that both the carburized surfaces performed significant improvement of about 100% in micro-hardness compared with untreated materials. The variation of carbon contents with increasing sample depth resulted in a hardened layer of 300 μm in the carburized samples. Meanwhile, slight influence on the internal microstructure and hardness indicated that solid carburization was an effective method in strengthening the surface of titanium alloy and titanium matrix composite.

A study on kerf characteristics of hybrid aluminium 7075 metal matrix composites machined using abrasive water jet machining technology

Metal matrix composites are difficult to machine in traditional machining methods. Abrasive water jet machining is a state-of-the art technology which enables machining of practically all engineering materials. This article deals with the investigation on optimization of process parameters of abrasive water jet machining of hybrid aluminium 7075 metal matrix composites with 5%, 10% and 15% of TiC and B4C (equal amount of each) reinforcement. The kerf characteristics such as kerf top width, kerf angle and surface roughness were studied against the abrasive water jet machining process parameters, namely, water jet pressure, jet traverse speed and standoff distance. Contribution of these parameters on responses was determined by analysis of variance. Regression models were obtained for kerf characteristics. Contribution of traverse speed was found to be more than other parameters in affecting top kerf width. Water jet pressure influenced more in affecting kerf angle and surface finish. The microstructures of machined surfaces were also analysed by scanning electron microscopy. The scanning electron microscopy investigations exposed the plastic deformation cutting of hybrid 7075 aluminium metal matrix composite. X-ray diffraction analysis results proved the non-entrapment of abrasive particle on the machined surface.

Performance of Sn–3.0Ag–0.5Cu composite solder with TiC reinforcement: Physical properties, solderability and microstructural evolution under isothermal ageing

This paper is focused on the effect of TiC nano-reinforcement that was successfully introduced into a SAC305 lead-free solder alloy with different weight fractions (0, 0.05, 0.1 and 0.2 wt%) through a powder-metallurgy route. Actual retained ratios of TiC reinforcement in composite solder billets and solder joints were quantitatively analysed. The obtained SAC/TiC solders were also studied extensively with regard to their coefficient of thermal expansion (CTE), wettability and thermal properties. In addition, evolution of interfacial intermetallic compounds (IMCs) and corresponding changes in mechanical properties under thermal ageing were investigated. Only about 10%–30% of initial TiC nanoparticles added were found retained in the final composite solder joints. With an appropriate addition amount of TiC nanoparticles, the composite solders exhibited an improvement in their wettability. A negligible change in their melting point and a widened melting range were found in composite solders containing TiC reinforcement. Also, the CTE of composite solder alloys was effectively decreased when compared with the plain SAC solder alloy. In addition, a growth of interfacial IMCs in composite solder joints was notably suppressed under isothermal ageing condition, while their corresponding mechanical properties of composite solder joints significantly outperformed those of non-reinforced solder joints throughout the ageing period.

Effect of extrusion dies angle on the microstructure and properties of (TiB+TiC)/Ti6Al4V in situ titanium matrix composite

Forged 5vol% (TiB+TiC)/Ti6Al4V titanium matrix composite billets with a heterogeneous reinforced structure was successfully hot indirect extruded with different dies angle (θ=45°, 60° and 75°) at 1303K. The dies angle was found to work as one key factor to change the microstructures and mechanical properties. Detail investigation on the microstructural evolution revealed that the significant grain refinement was obtained after extrusion due to dynamic recrystallization, the fully dynamic recrystallization takes place during indirect extrusion at dies angle 75°. In situ TiB and TiC reinforcements were also significantly refined by the indirect extrusion process, while highly developed preferred orientation of TiB short fibers along extrusion direction. Meanwhile, the mechanical properties showed that the ultimate tensile strength, yield strength and elongation exhibited a simultaneous increase after the indirect extrusion, especially on the ductility of the materials. The strength was slightly improved but not too much by hot extrusion. However, both tensile strength and elongation to fracture were reduced as the extrusion dies angle enlarged from 45° to 75°. Higher strength and elongation were obtained with optimal dies angle 45°, confirmed by matrix refinement, dynamical recrystallization and the optimal aspect ratio of TiB short fibers. Therefore, the optimal hot extrusion with the extrusion dies angle should be controlled less than 60°.

Fabrication and properties of the TiC reinforced high-strength steel matrix composite

The composite of 35CrMo high-strength steel matrix reinforced with TiC reinforcement (50wt.%) has been produced by conventional powder metallurgy (PM). The sintering temperature and process for heating treatment were discussed. The scanning electron microscopy (SEM) revealed the morphology and distribution of the reinforcement phase. Density, hardness, and transverse rupture strength (TRS) of the samples were analyzed. The results showed that the optimal sintering process for the composite is sintering at 1430°C for 1h and heat treatment process is annealing at 850°C/30min, quenching at 880°C/30min and then tempering at 560°C/60min. The composite after heat treatment has excellent mechanical properties with a relative density of 99.7%, hardness of 65 HRC, TRS of 1850±20MPa, respectively, and will be used as refractory moulds, cold work moulds and some gaskets, etc.

Mechanical properties and microstructure characterization of spark plasma and conventional sintering of Al–SiC–TiC composites

This work presents fabrication and characterization of Al–SiC–TiC composite materials containing 15 wt% SiC and 5 wt% TiC as reinforcing phases. The spark plasma and conventional sintering were done at 440 °C for 25 min and 600 °C for 60 min, respectively. The results indicate that the mechanical properties obtained by sprak plasma process are much higher than conventional sintering. The 99.2 ± 0.4% and 90.4 ± 0.7% of theoretical density were measured for samples sintered by SPS and conventionally, respectively. XRD analyses indicate no decomposition of SiC and TiC reinforcements. SEM investigations demonstrate uniform distribution of reinforcement particles in aluminum matrix and also fine microstructure of the SPS samples.