The role of graphite addition on spark plasma sintered titanium nitride
- Authors: Akinribide, O. J. , Obadele, B. A. , Ayeleru, O. O. , Akinwamide, S. O. , Nomoto, K. , Eizadjou, M. , Ringer, S. P. , Olubambi, P. A.
- Date: 2020
- Subjects: TiN , Graphite , Spark plasma sintering
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/451622 , uj:39803 , Citation: Akinribide, O.J. et al. 2020. The role of graphite addition on spark plasma sintered titanium nitride. , DOI: https://doi.org/10.1016/j.jmrt.2020.03.040
- Description: Abstract: tComposites of titanium nitride reinforced with graphite were synthesized using sparkplasma sintering at 2000◦C. The effects of graphite addition on the microstructure, relativedensity, and mechanical properties of TiN ceramics matrix were examined. The investiga-tion was performed on TiN powder with varying graphite content (1–5 wt.%) for 8 h using anenergy ball milling equipment. Results show that TiN without and with graphite (TiN + 1 wt.%graphite) sintered at 2000◦C recorded sintered relative density of 96.7% and 97% respec-tively. Additionally, TiN with 3 wt.% graphite had a relative density of 98%. However, theshrinkage of TiN + 3 wt.% graphite was observed to be the lowest compared to other com-posites at the same sintering conditions. Microstructural analysis indicates that the grainof titanium nitride in the composite was very fine and continuous. Subsequently, a bimodalparticle sizes were observed when 5 wt.% graphite was dispersed in TiN. The highest Vickersmicrohardness of 23.5 GPa and fracture toughness of 6.5 MPa m1/2were achieved with com-posites reinforced with 3 wt.% graphite at milling period of 8 h. The combination of TEM/EDSand HRTEM/FFT show a single pattern of diffraction and consistency in interplanar distanceobtained from X-ray diffractometry of the milled sample. There is a clear coherence interfacebetween the phases.
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Processing of pure titanium containing titanium-based reinforcing ceramics additives using spark plasma sintering
- Authors: Diouf, Saliou , Durowoju, Mondiu Olayinka , Shongwe, Mxolisi Brendon , Olubambi, Peter Apata
- Date: 2017
- Subjects: Spark plasma sintering , Titanium matrix composites , Ceramics
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/240416 , uj:24730 , Citation: Diouf, S. 2017. Processing of pure titanium containing titanium-based reinforcing ceramics additives using spark plasma sintering. Leonardo Electronic Journal of Practices and Technologies. 269-286. , ISSN: 1583-1078
- Description: Abstract: The densification behaviour, microstructural changes and hardness characteristics during spark plasma sintering of CP-Ti reinforced with TiC, TiN, TiCN and TiB2 were investigated. Commercially pure Ti powders were dry mixed with varied amounts (2.5 and 5 wt. %) of the ceramic additives using a T2F Turbula mixer for 5 h and at a speed of 49 rpm. The blended composite powders were then sintered using spark plasma sintering system (model HHPD-25 from FCT Germany) at a heating rate of 100oC min-1, dwell time of 5 min and sintering temperature of 950ºC. The sintering of CP-Ti was used as a base study to select the proper spark plasma sintering temperature for full density. Densification was monitored through analysis of the recorded punch displacement and the measured density of the sintered samples using Archimedes method. High densities ranging from 97.8% for 5% TiB2 addition to 99.6% for 5% TiCN addition were achieved at a relatively low temperature of 950°C...
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Microstructural and electrochemical studies of spark plasma sintered multiwall carbon nanotubes reinforced TiO2eMnO2 based composite
- Authors: Lephuthing, Senzeni Sipho , Okoro, Avwerosuoghene Moses , Ige, Oladeji Oluremi , Olunambi, Peter Apata
- Date: 2020
- Subjects: Microstructure , Spark plasma sintering , Electrochemical study
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/480894 , uj:43549 , Citation: Lephuting, S.S., Okoro, A.M., Ige, O.O., Olunambi, P.A. 2020. Microstructural and electrochemical studies of spark plasma sintered multiwall carbon nanotubes reinforced TiO2eMnO2 based composite. DOI:
- Description: Abstract: An electrochemical study was conducted to investigate the suitability of TiO2, TiO2- MWCNTs and (5,10 and 15 wt.%) of MnO2 in TiO2-MWCNTs composites as dimensional stable electrodes which were developed via conventional powder processing and spark plasma sintering. The following electrochemical tests were carried out including open circuit potential, galvanostatic chronoamperometry and cyclic voltammetry measurements. The results showed that an increase on MnO2 content in the composites did not only lower the potentials but enhanced the stability of the composites. The degradation which translates to corrosion susceptibility was favorable on composite samples with lower MnO2 content. Also, the presence of MWCNTs in the composites improved the electrocatalytic capacity of the material. Furthermore, the anodic layers formed on the composites during polarization was analyzed using SEM, XRD and cyclic voltammetry. The results showed that the formation of anodic layer during 24 h of polarization increased with the addition of MnO2 content and 15 MnO2eTiO2-MWCNT composite grade showed minimal pores after polarization which translates to higher protection.
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Influence of nanocrystalline nickel powder on oxidation resistance of spark plasma sintered Ni-17Cr6.5Co1.2Mo6Al4W7.6Ta alloy
- Authors: Babalola, Bukola Joseph , Maledi, Nthabiseng , Shongwe, Mxolisi Brendon , Bodunrin, Michael Oluwatosin , Obadele, Babatunde Abiodun , Olubambi, Peter Apata
- Date: 2020
- Subjects: Nickel based superalloy , Nanostructured , Spark plasma sintering
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/453453 , uj:40033 , Citation: Babalola, B.J. et al. 2020. Influence of nanocrystalline nickel powder on oxidation resistance of spark plasma sintered Ni-17Cr6.5Co1.2Mo6Al4W7.6Ta alloy. , DOI: https:// doi.org/10.1016/j.jksues.2019.01.002
- Description: Abstract: An investigation was carried out to evaluate the isothermal oxidation behavior of nickel based superal- loys at 1100 °C for 120 h. The alloys which were microstructured and nanostructured were developed by spark plasma sintering system. The oxidation test was carried out at a temperature of 1100 °C in air at different exposure time up to 120 h. The nanostructured nickel based alloy possessed better oxidation resistance with the formation of continuous adherent alumina, chromia scales, and spinel on the alloy surface and with no significant internal oxides. The oxidation rate of NiO was observed to be lower in the nanostructured nickel superalloy due to low diffusion rate of Nickel. The oxidation kinetics followed a parabolic oxidation law.
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Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze
- Authors: Okoro, Avwerosuoghene Moses , Lephuthing, Senzeni Sipho , Oke, Samuel Ranti , Olubambi, Peter Apata
- Date: 2021
- Subjects: Spark plasma sintering , Nickel aluminium bronze , Microstructure
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/480910 , uj:43551 , Citation: Okoro, A.M. et al. 2021. Influence of aluminium content on the microstructure and densification of spark plasma sintered nickel aluminium bronze. DOI: https://doi.org/10.1051/mfreview/2021006
- Description: 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.
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High temperature oxidation resistance of Ni22Cr11Al bond coat produced by spark plasma sintering as thermal barrier coatings
- Authors: Omoniyi, F.I.S. , Olubambi, P.A. , Sadiku, E.R.
- Date: 2016
- Subjects: High temperature , Oxidation , Spark plasma sintering
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/214305 , uj:21264 , Citation: Omoniyi, F.I.S., Olubambi, P.A & Sadiku, E.R. 2016. High temperature oxidation resistance of Ni22Cr11Al bond coat produced by spark plasma sintering as thermal barrier coatings.
- Description: Abstract: Thermal barrier coating (TBC) system is used in both aero engines and other gas turbines offer oxidation protection to super alloy substrate component. In the present work, it shows the ability of a new fabrication technique to develop rapidly new coating composition and microstructure. The compact powder were prepared by powder metallurgy method involving powder mixing and the bond coat was synthesized through the application of spark plasma sintering (SPS) at 1100°C, 1050°C and 1100°C to produce a fully dense 94%) Ni22Cr11Al bulk samples. The influence of sintering temperature on hardness of Ni22Cr11Al done by micro vickers hardness tester was investigated. And oxidation test were carried out at 1100°C for 20 hr, 40 hr and 100 hr. The resulting coat was characterised with Optical microscopy, Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Micro XRD analysis after the oxidation test revealed the formation of protective oxides and non-protective oxides.
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Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering
- Authors: Obadele, Babatunde Abiodun , Ige, Oladeji Oluremi , Olubambi, Peter Apata
- Date: 2017
- Subjects: Spark plasma sintering , Zirconia , Titanium
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/225471 , uj:22773 , Citation: Obadele, B.A., Ige, O.O. & Olubambi, P.A. 2017. Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering.
- Description: Abstract: Ti–Ni–ZrO2 composites were prepared by spark plasma sintering (SPS). The effect of ZrO2 content on the densification, microstructure and microhardness properties of the composites were investigated. Samples were characterized by SEM, EDS and XRD analyses. Noticeably, SPS process under the sintering conditions was achieved at a sintering temperature of 950 ºC, for 10 min holding time, at 100 °C/min of heating rate and at an applied pressure of 50 MPa. This resulted in maximum densification of the powder compact and the formation of a distinguishable spherical globules rich in Ni surrounding the retained Ti. Gradient composition distribution of ZrO2 at the grain boundaries resulted into pinning effect of the grain growth. As the ZrO2 content increased from 5 to 10 vol.%, it was accompanied by a significant increase in hardness values of the sintered composites from 480 to 713 HV.
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Evaluation of microstructural and nanomechanical performance of spark plasma sintered TiFe-SiC reinforced aluminium matrix composites
- Authors: Akinwamide, Samuel Olukayode , Lesufi, Miltia , Akinribide, Ojo Jeremiah , Mpolo, Peggy , Olubam, Peter Apata
- Date: 2020
- Subjects: Spark plasma sintering , Aluminium , Silicon carbide
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/444284 , uj:38831 , Citation: Akinwamide, S.O. et al. 2020. Evaluation of microstructural and nanomechanical performance of spark plasma sintered TiFe-SiC reinforced aluminium matrix composites.
- Description: Abstract: tDue to the increasing demand for lighter materials with enhanced properties, the upgrade oftechniques to improve the production of high-performance composite materials is of greatinterest in modern technology. The microstructural and mechanical properties of sparkplasma sintered aluminium based composites with ferrotitanium (TiFe) and silicon carbide(SiC) reinforcements were investigated. High energy ball milling technique was adopted toeffectively disperse the particles SiC and TiFe reinforcements into the matrix of aluminium,and the admixed powders were compacted using spark plasma sintering technique. Thespecimens sectioned from the sintered compacts were analysed using an X-ray diffractome-ter (XRD), optical microscope (OM), and field emission scanning electron microscope (FESEM)to understand the microstructural features and phase evolution of the sintered compos-ites. The mechanical properties of the composites were also investigated through hardness,nanomechanical and tribology tests. Results from the microstructural examinations con-ducted shows that the reinforcement particles were evenly dispersed within the aluminiummatrix, as a result of the milling process. Furthermore, all the sintered composites hadtheir microstructural features enhanced, but properties such as hardness, frictional coeffi-cient, and elastic modulus were more enhanced in specimen reinforced with 2%SiC+2%TiFeparticles. The reduced crystallite size recorded by the sintered specimens confirmed theeffectiveness of the milling process, and powder metallurgy route adopted for fabrication.
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Effects of ternary metal additions on corrosion of spark plasma sintered Ni-Fe alloys in H2SO4 and NaCl
- Authors: Shongwe, Mxolisi Brendon , Makena, Isaac Moraka , Ajibola, Olawale Olarewaju , Olubambi, Peter Apata , Adams, Feyisayo Victoria
- Date: 2018
- Subjects: Spark plasma sintering , Corrosion , Ni-Fe based alloy
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/279685 , uj:30039 , Citation: Shongwe, M.B. et al. 2018. Effects of ternary metal additions on corrosion of spark plasma sintered Ni-Fe alloys in H2SO4 and NaCl. Bulletin of the Chemical Society of Ethiopia, 32(2), 337-349. DOI: https://dx.doi.org/10.4314/bcse.v32i2.12 , ISSN 1011-3924
- Description: Abstract: Effect of ternary additions on electrochemical behavior of Ni-Fe binary alloys developed by Spark Plasma Sintering (SPS) were investigated and reported. All specimens revealed common passivity behavior in H2SO4. Both binary and ternary alloys did not reveal passivity region under saline conditions. The alloys have lower corrosion rates in NaCl than in H2SO4. Binary Ni50Fe50 alloy is characterized by large pits in H2SO4 and homogeneous corrosion on surface in NaCl. Ni50Fe40Ta10 shows better passivity in 1 M H2SO4 and Ni50Fe40Al10 has the lowest corrosion rate in 3.5 wt.% NaCl.
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Data on assessment and exploratory statistical correlation data analysis of sintered Nd :YAG laser welded 2507 duplex stainless steel
- Authors: Olanipekun, Ayorinde Tayo , Mashinini, Peter Madindwa , Maledi, Nthabiseng Beauty
- Date: 2020
- Subjects: Spark plasma sintering , Welding , Microhardness
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/433562 , uj:37493 , Citation: Olanipekun, A.T., Mashinini, P.M. & Maledi, N.B. 2020. Data on assessment and exploratory statistical correlation data analysis of sintered Nd: YAG laser welded 2507 duplex stainless steel. Data in Brief 32 (2020) 106201. https://doi.org/10.1016/j.dib.2020.106201
- Description: Abstract: The effect Spark Plasma Sintering (SPS) parameters and Nd:YAG laser welding parameters such as sintering tempera- ture, sintering time, welding power, welding speed, on Vick- ers hardness mechanical properties of the Weld Zone(WZ) was statistically investigated. Rectangular plates of 2507 Du- plex Stainless Steel (DSS) fabricated by SPS were joined by Nd: YAG laser welding process. Linear regression analysis was performed on the data, followed by Pearson correlation anal- ysis to relate hardness with other predicting variables and show their statistical significance to hardness value of the weld zone.The evaluated R 2 which is 49%% was used to mea- sure the closeness of the data to the regression fitted line.
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A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy
- Authors: Shongwe, Mxolisi Brendon , Diouf, Saliou , Durowoju, Mondiu Olayinka , Olubambi, Peter Apata , Ramakokovhu, Munyadziwa Mercy , Obadele, Babatunde Abiodun
- Date: 2016
- Subjects: Tungsten heavy alloys , Spark plasma sintering , Microstructure
- Type: Article
- Identifier: http://hdl.handle.net/10210/123454 , uj:20793 , Citation: Shongwe, M.B. et al. 2016. A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy.
- Description: Abstract: Mixed 93W-4.9Ni-2.1Fe powders were sintered via the spark plasma sintering (SPS) and hybrid spark plasma sintering (HSPS) techniques with 30 mm and 60 mm samples in both conditions. After SPS and HSPS, the 30 mm and 60 mm alloys (except 60mm-SPS) had a relative density (>99.2%) close to the theoretical density. Phase, microstructure and mechanical properties evolution of W-Ni-Fe alloy during SPS and HSPS were studied. The microstructural evolution of the 60 mm alloys varied from the edge of the sample to the core of the sample. Results show that the grain size and the hardness vary considerable from the edge to the core of sintered sample of 60 mm sintered using conventional SPS compared to hybrid SPS. Similarly, the hardness also increased from the edge to the core. The 60 mm-HSPS alloy exhibit improved bending strength than the 60 mm-SPS, 1115 MPa and 920 MPa respectively, former being similar to the 30 mm-SPS and HSPS alloys. The intergranular fracture along the W/W grain boundary is the main fracture modes of W-Ni-Fe, however in the 60 mm-SPS alloy peeling of the grains was also observed which diminished the properties. The mechanical properties of SPS and HSPS 93W-4.9Ni-2.1Fe heavy alloys are dependent on the microstructural parameters such as tungsten grain size and overall homogeneity.
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