Influence of SiAlON ceramic reinforcement on Ti6Al4V alloy matrix via spark plasma sintering technique

Abstract : The titanium-based composite was fabricated by strengthening Ti6Al4V alloy with addition of SiAlON ceramics utilizing spark plasma sintering technique. Ti6Al4V and SiAlON powders were mixed in a T2F Turbula mixer with different propor- tions (5, 10, 15 and 20 vol%) and the admixed powders were consolidated using spark plasma sintering to produce titanium matrix composites. The characterization of the sintered composites was performed using X-ray diffraction, optical microscopy and scanning electron microscopy. The influence of SiAlON additions on densification, microstructure, microhardness and fracture morphology were investigated on the sintered composites. The experimental results revealed that the densification of the sintered titanium matrix composites was in the range of 95%–98%, which decreased with an increase in SiAlON addition. However, an increase in microhardness values ranging from 363 to 574 HV0.1 was achieved. The microstructure shows that the SiAlON ceramic particle was uniformly distributed within the titanium matrix composites which comprises of a mixture of lamellar colonies with β grain boundaries. The fracture features of all composites exhibit mixed fracture of both intergranular and transgranular fracture mechanism

Spark plasma sintering of nanoceramics dispersion strengthened titanium aluminium vanadium alloy

Abstract: Please refer to full text to view abstract.Ph.D

Synthesis and characterization of commercial pure titanium-nickel alloy behavior reinforced with titanium diboride

Abstract: Commercial pure titanium alloy with Ni-TiB2 ceramic additions (5, 10, 15 and 20 vol.%) were synthesized through the spark plasma sintering approach with sintering temperature of 1000 oC, the heating rate of 100 oC/min, holding time of 5 min at a constant pressure of 50 MPa. The study investigated the effect of Ni-TiB2 on the densification, phase change, microhardness, microstructure, and wear properties of the sintered titanium-based composites. Results showed that Ti-Ni-TiB2 composites relative density ranges from 97 to 99 %, while microhardness values increase with addition of nickel and titanium diboride from 228 to 587 HV0.1. The microstructural evolution shows that pure titanium transformed from lamellar phase to equiaxed alpha phase upon addition of nickel alloy and further get refined with a distinct grain boundary comprises of titanium diboride around the boundaries. The average coefficient of friction for the titanium-based composite was higher for commercially pure titanium (0.73) while the addition of TiB2 exhibit (0.66, 0.63, 0.58, 0.55 and 0.46 respectively) improvement in the wear behavior

Densification, microstructural characterization, and the electrochemical behaviour of spark-plasma sintered Ti6Al4V-5Cr-TiB2 composites

The impacts of Cr-TiB2 addition on densification, hardness, microstructure, phase transformation, and corrosion were examined. The results indicated an even and uniform dispersion of TiB2 particles in the titanium matrix, with no noticeable interfaces throughout the sintering process. The relative density of the sintered titanium-based composites dropped, with an increase in TiB2 percentage. The microhardness result indicated that Ti6Al4V has 326 HV0.5, while the maximum hardness was 598 HV0.5, produced from 20 wt.% TiB2 ceramic particles. The Ti6Al4V alloy depicts α-phase forms parallel plates in the prior β-grain borders and expands into the β-grain to create α-colonies, while the addition of 5–20 wt.% Cr-TiB2 resulted in a microstructural transformation characterized by equiaxed α-precipitates embedded within the β-phase matrix, for all samples. The electrochemical behaviour revealed that the Ecorr decreased as TiB2 increased, while the icorr was higher. However, samples containing 5Cr and 5Cr-5TiB2 moved to a more positive Ecorr region, whereas the icorr altered to a more negative area. This meant that the presence of ceramic reinforcements increased the corrosion resistance of the alloys and that higher concentrations of titanium diboride provided less protection against ion attack in a chloride environment.Peer reviewe

Synthesis and characterization of spark plasma sintered zirconia and ferrotitanium reinforced hybrid aluminium composite

This research reports on the microstructural characterization and nanomechanical evaluation of hybrid aluminium-based composite, fabricated by reinforcing pure aluminium matrix with zirconia (ZrO2) and ferrotitanium (TiFe) particles. The composites were consolidated using the spark plasma sintering technique, and the properties of the reinforced composites were examined and compared with pure aluminium samples fabricated using the same sintering parameters. The formation of new phases in the hybrid composites was ascertained using the X-ray diffraction technique, while the morphologies of the starting powders and as-sintered specimens were analysed using optical and scanning electron microscopes. Mechanical tests such as Vickers microhardness and frictional coefficient were determined to ascertain the respective strength and tribological performance. Nanoindentation test was also carried out to evaluate the nanomechanical properties such as penetration depth, elastic modulus, work indentation, and indentationcreep. The results from this study revealed that mixing and sintering the admixed powders at sufficiently high temperature resulted in the formation of new phases which contributed to improved mechanical performance of the hybrid composites. The absence of pinning effect in loading and unloading curves from the nanoindentation test conducted confirmed the homogeneous dispersion of the reinforcement particles. Overall, the sample reinforced with 5% TiFe and 5% ZrO2 exhibited the most improved mechanical properties, while the unreinforced aluminium sample recorded the least mechanical and nanomechanical performance.Peer reviewe

Densification characteristics, microstructure and wear behaviour of spark plasma sintering processed titanium-niobium pentoxide (Ti-Nb2O5) based composites

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Optimization of process parameters for spark plasma sintering of nano structured SAF 2205 composite

This research optimized spark plasma sintering (SPS) process parameters in terms of sintering temperature, holding time and heating rate for the development of a nano-structured duplex stainless steel (SAF 2205 grade) reinforced with titanium nitride (TiN). The mixed powders were sintered using an automated spark plasma sintering machine (model HHPD-25, FCT GmbH, Germany). Characterization was performed using X-ray diffraction and scanning electron microscopy. Density and hardness of the composites were investigated. The XRD result showed the formation of FeN0.068. SEM/EDS revealed the presence of nano ranged particles of TiN segregated at the grain boundaries of the duplex matrix. A decrease in hardness and densification was observed when sintering temperature and heating rate were 1200 °C and 150 °C/min respectively. The optimum properties were obtained in composites sintered at 1150 °C for 15 min and 100 °C/min. The composite grades irrespective of the process parameters exhibited similar shrinkage behavior, which is characterized by three distinctive peaks, which is an indication of good densification phenomena. Keywords: Spark plasma sintering, Duplex stainless steel (SAF 2205), Titanium nitride (TiN), Microstructure, Density, Hardnes

Erosion wear behavior of spark plasma-sintered Ti-6Al-4V reinforced with TiN nanoparticles

The extensive application of titanium alloys is delimited as their erosion wear properties deteriorate when exposed to erosive and harsh environments. The present research investigates the effects of TiN additions (2, 4, and 6 vol.%) on the Ti-6Al-4V alloy prepared by spark plasma sintering technique. Erosion wear behaviour of the composites was investigated by high-velocity solid particle erosion test and tribometer pin-on-disc friction module method. The duration of the test was 10 min, while the mass loss of the sample was recorded after 2-min interval. The surface analysis and phase identifications of the sintered composites were examined by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Microstructural analysis revealed a transformation from lamellar with β grain boundaries in Ti-6Al-4V alloy to bimodal structures upon addition of TiN nanoparticles. XRD patterns of the alloy indicated an increase in diffraction peaks from lower intensity to high intensity with an increase in TiN nanoparticle content. Erosion is visible in Ti-6Al-4V alloy, 4 and 6 vol.% TiN, but less severe with 2 vol.% TiN addition for all the test times. However, this is due to grain detachment of the hard phase regions between the matrix and the reinforcing phase of the composites. The results showed the presence of micro-voids on the eroded surfaces. It was found that Ti-6Al-4V alloy with TiN nanoparticle addition was resistant to erosion wear, while the recorded steady-state friction coefficients for all the samples range from 0.2 to 0.4. However, an increase in microhardness values ranges from 342 to 513 HV0.1.Fil: Kganakga, Mokgoba Glodean. Universidad de Johannesburgo; NoruegaFil: Prieto, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Falodun, Oluwasegun Eso. Universidad de Johannesburgo; NoruegaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Obadele, Babatunde Abiodun. Botswana International University of Science and Technology; BotsuanaFil: Ajibola, Olarewaju Olawale. Federal University; NigeriaFil: Olubambi, Peter Apata. Universidad de Johannesburgo; Norueg

Mechanical properties of ultrafine graphite –Ti (C0.9, N0.1) solid solutions fabricated via spark plasma sintering

Abstract : Spark plasma sintering technique was used to consolidate solid solution of graphite–Ti (C0.9, N0.1) using ultrafine size of graphite and titanium carbonitride powder with carbon to nitrogen composition of 90:10 at 2000 oC for 5 mins. The densification of the sintered graphite (0-1 wt. %) –Ti (C0.9, N0.1) was 98-99% at 2000 oC in the matrix. The carbide rich and Ti rich were the two distinct solid solution phases observed, although Graphite –Ti (C0.9, N0.1) solid solution as a solitary phase was attained at 2000 oC. This could be attributed to changes in the parameters with in the lattice site due to excess heat and causing the solid solutions phases to favour the carbide and titanium phases, respectively. The graphite–Ti (C0.9, N0.1) solid solution upon the application of different load the value of the hardness decreases as the load increases for unreinforced and reinforced Ti (C0.9, N0.1). Furthermore, the fracture toughness (KIC ) was within the range of (1.04 – 7.99) in MPa m1/2