Synthesis of Nano-Crystalline TiC Powder from Active Impure Ti Chips via Self Propagating High-Temperature Synthesis and the Effect of Al on the Synthesis Temperature

In this research, the possibility of production of TiC powder from inexpensive raw materials via simple methods has been investigated. Impure Ti chips, carbon black and Al powder were activated by a highenergy ball mill. Then they were synthesized by the method of self propagating high-temperature synthesis (SHS) at various temperatures. XRD study indicated that TiC within 1000 °C to 1300 °C temperature range has been synthesized where the temperature in a sample containing Al was less than 1000 °C. From the broadening of the diffraction lines in the XRD patterns, it was concluded that the TiC crystallites were nanosized and the lattice parameter had deviated slightly from the standard size. The existence of Al increased the lattice parameter of TiC and the strain in the process

Modelling crack propagation in RC beam-column joints

Accurate modelling is required to estimate crack propagation in a beam–column joint. In this study, a numerical method is developed to model crack propagation and failure loading in a beam–column joint under static load. To realize this objective, a four-node, thin-layer interface element is produced to model the fracture process zone and crack propagation. Moreover, the fracture criterion for determining the growth of a crack based on the release rate of strain energy is established. To validate the present model, ABAQUS software is used to simulate crack propagation by conventional cohesive elements. The numerical results obtained are extremely close to the experimental results within an accuracy level ranging from 4.3% to 6.7%. Meanwhile, the ABAQUS software data and the experimental data are predicted at a margin of error ranging from 12.4% to 16%

Structural and morphological analysis of zinc incorporated non-stoichiometric hydroxyapatite nano powders

In this study, Zn incorporated non-stoichiometric hydroxyapatite (nHAp) was synthesized via precipitation method and effect of the incorporation of Zn (fraction: 2, 4, 6 and 8 mol-%) on the microstructure of nHAp was studied by XRD, FTIR analysis and SEM-EDS techniques. The formation of nHAp was confirmed by XRD and FTIR those showed that no secondary phase was formed through the Zn incorporation. The SEM studies also revealed that particles were formed in nano-metric size (30-60 nm). It was found that crystallite and particle size of Zn incorporated nHAp gradually decreased up to 6 mol-%, and started to increase while the Zn fraction reached up to the 8 mol-% and hence the morphology of the aggregated products was also changed. It can be concluded that the incorporation of Zn cations cause to form nHAp phase. Furthermore, the nHAp microstructure has deviated from stoichiometric condition by incorporation of more Zn cations.Keywords: Microstructure; Nanopowder; Non-Stoichiometric Hydroxyapatite; Zn Incorporatio

Structural and morphological analysis of zinc incorporated non-stoichiometric hydroxyapatite nano powders

ABSTRACT In this study, Zn incorporated non-stoichiometric hydroxyapatite (nHAp) was synthesized via precipitation method and effect of the incorporation of Zn (fraction: 2, 4, 6 and 8 mol-%) on the microstructure of nHAp was studied by XRD, FTIR analysis and SEM-EDS techniques. The formation of nHAp was confirmed by XRD and FTIR those showed that no secondary phase was formed through the Zn incorporation. The SEM studies also revealed that particles were formed in nano-metric size (30-60 nm). It was found that crystallite and particle size of Zn incorporated nHAp gradually decreased up to 6 mol-%, and started to increase while the Zn fraction reached up to the 8 mol-% and hence the morphology of the aggregated products was also changed. It can be concluded that the incorporation of Zn cations cause to form nHAp phase. Furthermore, the nHAp microstructure has deviated from stoichiometric condition by incorporation of more Zn cations

Production of Al2O3–SiC nano-composites by spark plasma sintering

In this paper, Al2O3–SiC composites were produced by SPS at temperatures of 1600 °C for 10 min under vacuum atmosphere. For preparing samples, Al2O3 with the second phase including of micro and nano-sized SiC powder were milled for 5 h. The milled powders were sintered in a SPS machine. After sintering process, phase studies, densification and mechanical properties of Al2O3–SiC composites were examined. Results showed that the specimens containing micro-sized SiC have an important effect on bulk density, hardness and strength. The highest relative density, hardness and strength were 99.7%, 324.6 HV and 2329 MPa, respectively, in Al2O3–20 wt% SiCmicro composite. Due to short time sintering, the growth was limited and grains still remained in nano-meter scale

Effect of milling time on XRD phases and microstructure of a novel Al67Cu20Fe10B3 quasicrystalline alloy

The quasicrystalline materials represent a new materials group with definite crystallite structural characteristics, in which the AlCuFe(B) quasicrystalline alloys have been widely studied owing to its various technological advantages such as easily accessible in nature, thermal stability, affordability as well as not having toxic constituent elements. Although these materials can be achieved by different procedures, the synthesis of more extensive amounts of AlCuFeB quasicrystalline single-phase powders is more complicated. In this study, the Al _67 Cu _20 Fe _10 B _3 quasicrystalline alloys were synthesized through the mechanical alloying process and afterward consolidated to the bulk specimens by cold isostatic pressing (CIP) technique. The structural and microstructural evolutions, as well as the morphology of as-milled powders and phase transformations, were studied during the ball milling process using field-emission scanning electron microscopy (FESEM) and x-ray diffractometry (XRD), while the thermal behavior was investigated using differential thermal analysis (DTA). The most fascinated result revealed that the stable AlCuFeB single quasicrystalline phase could be directly synthesized in short milling times (around ∼4 h) by a high-energy planetary ball milling. It was appreciated that the icosahedral phase is stable up to 300 °C, which is misplaced stability at superior temperatures and transforms into crystalline phases. The microhardness of consolidated ball-milled powders at various milling times was determined and it was figured out that the icosahedral phase has an extreme microhardness as much as 10.73 GPa