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

Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze

Abstract: In this study, nickel aluminium bronze alloys (NAB) with appreciable densification and improved microhardness was consolidated via spark plasma sintering technique. The NAB alloy was synthesized from starting elemental powders comprised nickel (4 wt.%), aluminium (6, 8 & 10 wt.%) and copper using dry milling technique. Starting powders were homogeneously milled using gentle ball mill for 8 h at a speed of 150 rpm and a BPR of 10:1. Subsequently, the milled powders were consolidated using the spark plasma sintering technique at 750 °C under a compressive pressure of 50MPa and rate of heating (100 °C/min). Furthermore, the powders and sintered alloys were characterized using SEM and XRD to ascertain the microstructural and phase evolutions during the synthesis of the NAB. The density and microhardness of the alloys were further investigated to ascertain the integrity of the sintered alloys. The results indicated that the increase in aluminium content resulted in the formation of intermetallic and beta phases on the alloy after sintering and the microhardness of the alloys improved with the increase in aluminium content

Nanoindentation studies and analysis of the mechanical properties of Ti-Nb2O5 based composites

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Corrosion behaviour of thermal cycled aluminium hybrid composites reinforced with rice husk ash and silicon carbide

The corrosion behaviour of aluminium hybrid composites reinforced with rice husk ash and silicon carbide subjected to thermal cycling has been investigated. Aluminium hybrid composites having 10 wt% reinforcement consisting of silicon carbide (SiC) and rice husk ash (RHA) in weight ratios of 1:0, 3:1, 1:1, 1:3, and 0:1 respectively were produced. The composites were subjected to varying thermal cycles of 6, 12 and 18 from room temperature to 200 °C repeatedly. Potentiodynamic polarization measurements were used to study the corrosion behaviour of the produced composites. The results show that the composites displayed similar polarization curves and passivity characteristics irrespective of the number of thermal cycles both in H2SO4 and NaCl solutions. No consistent trend of corrosion current density changes with increase in thermal cycling was established for composite grades 3:1, 1:1 in H2SO4 and 1:0, 0:1 and 3:1 in NaCl solutions. The hybrid composite grades with a higher RHA content generally exhibited a lower tendency to corrode compared to the other composite grades. Generally, the composites seemed to be structurally stable as they maintained their corrosion resistance levels even after exposure to thermal cycling. Keywords: Aluminium hybrid composites, Corrosion, Potentiodynamic electrochemical measurements, Rice husk ash, Structural stability, Thermal cyclin

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

Sustainable Naturally Derived Plantain Fibers/Epoxy Based Composites for Structural Applications

This study investigated the comparative influence of different compositions (3 wt. %, 6 wt. %, 9 wt. %, 12 wt.%, and 15 wt. %) of treated plantain stem fiber (PSF) and plantain leaf fiber (PLF) on selected properties of the epoxy-based composite. These plantain fibers and epoxy resin were mixed based on predetermined compositions and stirred using a stirrer at an ambient temperature for 3 minutes before pouring into a mold using a hand layup process. The composites were allowed to cure within 2–3 hours. Mechanical (tensile, flexural, impact, and hardness), wear, thermal conductivity and water absorption properties, and surface morphologies of the developed composites were investigated. The study revealed that the optimum properties were attained at 9 wt.% and 12 wt.% PSF and PLF except for wear and water absorption that occurred at 15 wt.%. The PSF gave more enhancement in all the properties except for impact strength. Hence, from the combination of properties obtained, these bio-based fibers can be used to improve the conductivity of eco-friendly and biodegradable polymer-based composites for electrical/electronics, biomedical, automobile, and building applications

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

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