Sintering, Mechanical, Electrical and Oxidation Properties of Ceramic Intermetallic TiC-Ti 3 Al Composites from Nano-TiC Particles (original) (raw)
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Ceramics International, 2016
The paper discusses the development of a new material system for interconnect application in Solid Oxide Fuel Cells (SOFC) based on TiC-Ti 3 Al. Nano-sized TiC powders utilized in this research were synthesized using carbon coated TiO 2 precursors from a patented process. The pressureless sintering of TiC-Ti 3 Al in a vacuum was applied at temperatures between 1100-1500 o C and content of Ti 3 Al was varied in the range of 10-40 wt. %. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used for phase evaluation and sintering behavior. Relative density increased markedly with increasing sintering temperature because of grain growth and formation of the Ti 3 AlC 2 secondary phase. Dense products (>95% TD) were prepared from nanosized TiC powders with 10 and 20 wt. % Ti 3 Al, but with about 8 to 10% porosity for 30 and 40 wt. % Ti 3 Al. The mechanical properties were determined from Vickers hardness and fracture toughness calculations. Vickers hardness decreased and fracture toughness increased with increasing Ti 3 Al content. The electrical conductivity and oxidation behavior of TiC-Ti 3 Al composites were investigated to evaluate the feasibility for SOFC interconnect application. The electrical conductivity measurements in the air at 800ºC for 100 hours were made using the Kelvin 4wire method.
INVESTIGATION OF NOVEL ALLOY TiC-Ni-Ni3Al FOR SOLID OXIDE FUEL CELL INTERCONNECT APPLICATIONS
2005
Solid oxide fuel cell interconnect materials must meet stringent requirements. Such interconnects must operate at temperatures approaching 800°C while resisting oxidation and reduction, which can occur from the anode and cathode materials and the operating environment. They also must retain their electrical conductivity under these conditions and possess compatible coefficients of thermal expansion as the anode and cathode. Results are presented in this report for fuel cell interconnect candidate materials currently under investigation based upon nano-size titanium carbide (TiC) powders. The TiC is liquid phase sintered with either nickel (Ni) or nickel-aluminide (Ni 3 Al) in varying concentrations. The oxidation resistance of the submicron grain TiC-metal materials is presented as a function weight change versus time at 700 o C and 800°C for varying content of metal/intermetallic in the system. Electrical conductivity at 800°C as a function of time is also presented for TiC-Ni to demonstrate the vitality of these materials for interconnect applications. TGA studies showed that the weight gain was 0.8 mg/cm 2 for TiC(30)-Ni(30wt.%) after 100 hours in wet air at 800 o C and the weight gain was calculated to be 0.5205 mg/cm 2 for TiC(30)-Ni(10 wt.%) after 100 hours at 700 o C and 100 hours at 800 o C. At room temperature the electrical conductivity was measured to be 2444 1/[ohm.cm] for TiC-Ni compositions. The electrical conductivities at 800 o C in air was recorded to be 19 1/[ohm.cm] after 125 hours. Two identical samples were supplied to PNNL (Dr. Jeff Stevenson) for ASR testing during the pre-decision period and currently they are being tested there. Fabrication, oxidation resistance and electrical conductivity studies indicate that TiC-Ni-Ni 3 Al ternary appears to be a very important system for the development of interconnect composition for solid oxide fuel cells.
The Effect of TiC Additives on Mechanical and Electrical Properties of Al2O3 Ceramic
Applied Sciences
In this study the influence of TiC content on the mechanical and electrical properties of Al2O3-TiC composites containing 30 and 40 vol.% TiC were investigated. The Vickers hardness and fracture toughness of the composites increased with the addition of TiC phase. The composite with 40 vol.% TiC showed the highest flexural strength (687 ± 39 MPa), fracture toughness (7.8 ± 0.4 MPa·m1/2) and hardness (22.3 ± 0.3 GPa) with a homogeneous distribution of the second phase within the ceramic matrix. Besides enhanced mechanical properties, it was found that ceramic composites with more than 30 vol.% TiC fabricated by the spark plasma sintering possess sufficient electrical conductivity for electrical discharge machining as well. Therefore, they do not limit the flexibility of the shape, and any intricate parts can be easily made with these composites which can be recommended for the production of cutting inserts in the tools for machining of superhard hardened steels, hard-to-machine mater...
Beneficial role of carbon black on the properties of TiC ceramics
Ceramics International, 2020
This investigation aimed to study the influence of carbon black on the qualifications of TiC-based materials. For this objective, two samples, namely monolithic TiC and TiC-5 wt% carbon black were sintered by spark plasma sintering (SPS) method at 1900°C. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to characterize the as-sintered samples. Introducing carbon black enhanced the relative density of TiC significantly, reaching a near fully dense substance. Phase analysis and microstructural studies manifested the formation of non-stoichiometric TiC x in both ceramics. Although the introduction of carbonaceous additive considerably increased the thermal conductivity and flexural strength of TiC, standing at 25.1 W/ mK and 658 MPa, respectively, its influence on the Vickers hardness was trivial (both~3200 HV 0.1 kg). Finally, the composite specimen presented a lower coefficient of friction (~0.31) on average compared to the undoped TiC (~0.34).
Study on the Ti-C/nano-ceramic additives reaction due to sintering of elemental powders
ZANCO JOURNAL OF PURE AND APPLIED SCIENCES, 2019
The goal is to contribute towards well understanding the solid state reaction between TiC base ceramic and nano additives. A mixture of elemental powders of Ti and Graphite doped with a range of ceramic nano additives of each Al 2 O 3 and CuO was pressed and heated up to 1100 °C. Phase evolution was then investigated using X-ray diffraction (XRD) and Differential thermal analysis (DTA). TiC is identified to be the most dominant phase through the reaction between Ti and Graphite at 1100 °C. TiO 2 is the most detected oxide due to the reaction of Ti-C/ nano Al 2 O 3 and also for Ti-C/ nano CuO reaction. No evidence of both elemental Al and Cu was found due to structural analysis in the final products. On the other hand, energy dispersive X-ray spectroscopy (EDS) results confirm the appearance of Al and Cu in the produced microstructure. Further investigation may generate belief that Al and Cu ingress within TiC structure causing a fluctuation in its measured lattice constant.
Manufacturing of high volume fraction of nanolayered Ti3AlC2 metallic ceramics
Manufacturing of high volume fraction (vf) nano-laminated Ti 3 AlC 2 /Ti 2 AlC ternary carbides product through mechanical milling (MM) of Ti, Al and C consolidated by hot pressing process (HP) was investigated. The microstruc-tures of milled powders and sintered samples were characterized using SEM, TEM and XRD. High energy milling of Ti, Al and C using steel media resulted in the formation of nanocrystalline amorphous-like microstructure of TiC phases and Ti/Al/Fe elements. A fully dense product involves high content of Ti 3 AlC 2-Ti 2 AlC (TAC) metallic ceramics and a small amount of Ti/Al/Fe interlayer was developed through liquid phase sintering (LPS). Mechanisms of anisotropic nano-multilayered morphology microstructure and translaminar fracture phenomena were discussed.
International Journal of Mechanical and Production Engineering Research and Development, 2020
Aluminium matrix infused with titanium carbide (TiC) particles was prepared by means of powder metallurgy process. The effect of TiC addition on microstructure, hardness and electrical conductivity of as-sintered Al-TiC with 2 µm and ≤ 200 nm reinforcement were investigated. Microstructure studies reveal the even distribution of TiC particles in the aluminium matrix. With increasing addition of TiC, the hardness of composites increased after the 10% and suddenly reduced because the composites reduce its resistance and create more sites for crack initiation. Hardness and electrical conductivity of composites have been varied based on particle size variation of TiC.
Thermal Stability and Mechanical Characteristics of Densified Ti3AlC2-Based Material
Solid State Phenomena, 2015
The mechanical properties and temperature stability in air and hydrogen of the highly dense (ρ=4.27 g/cm 3 , porosity 1 %) material based on nanolaminated MAX phase Ti 3 AlC 2 (89 % Ti 3 AlC 2 , 6 % TiC, 5 % Al 2 O 3 ) manufactured by hot pressing (at 30 MPa) have been investigated. At room temperature the samples exhibited microhardness H V = 4.6 GPa (at 5 N), hardness HV50 = 630 MPa (at 50 N ) and HRA=70 (at 600 N), Young modulus was 140 ± 29 GPa, fracture toughness K 1C =10.2 MPa·m 0.5 compression strength 700 MPa and bending strength 500 MPa. After 1000 hours of exposition at 600 °C the oxide film (containing mainly Al 2 O 3 and TiO 2 ) formed on the surface and material demonstrated a higher oxidation resistance than chromium ferrite steels. Due to the surface oxidation the defects self-healing took place and the bending strength of the porous Ti 3 AlC 2 (22% porosity) after exposition for 3 h at 600 o C in air slightly (for 3%) increased as compared to that at 20 o C. Besides, the porous Ti 3 AlC 2 material resisted to high-temperature creep and after being kept in H 2 at 600 °C for 3h its bending strength reduced by 5 %.
Materials Today: Proceedings, 2020
In this work, Ti-TiC composite have been prepared by powder metallurgy technique using recycled titanium chips and graphite powder. From the Ti chips obtained from the machining of Ti bar, at first Ti powder was prepared by ball milling method. Then the prepared Ti powder was mixed with graphite (C) powder at 48:12 (wt.) ratio and compacted at different compaction pressure (400-700 MPa) and subsequently sintered at 1200°C temperature. The sintered pellets were characterized by X-ray diffraction (XRD) technique, scanning electron microscopy (SEM). The density of the composite pellets was measured by Archimedes principle. The hardness value of the produced TiC-Ti composite was assessed by Vickers micro-indentation method, and the wear behaviour was evaluated by sliding wear test using ball on disc wear tester. The experimental results revealed that by combined ball milling and sintering route Ti-TiC composite can be prepared from the waste Ti chips, and the compaction pressure has a significant effect on the properties of the prepared composite.