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Mechanical Strengthening and Microstructural Evolutions of Ni-B Based Hardfacing Alloys Influenced by Titanium Additions
Zeblon Meshack Ebimobowei,
Ajenifuja Emmanuel,
Ajao John Adegbindin
Issue:
Volume 8, Issue 2, June 2019
Pages:
41-47
Received:
31 January 2019
Accepted:
11 March 2019
Published:
13 April 2019
Abstract: The microstructure and mechanical behaviour of Ni-B binary alloys have been enhanced in this study by varied titanium additions. The alloys investigated were chosen from the nickel-rich region of the Ni-B-Ti system. The microstructure of the alloys was examined using Optical Microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Analyzer (EDXA). The addition of titanium led to the formation of various complex phases and a ternary phase τ was observed in the study. The addition of titanium to the Ni-B alloys was found to enhance the mechanical properties of the ternary alloys. Microhardness value of the alloys was observed to increase from 216.2 HV with zero Ti in Ni-B alloys to 1530.7 HV in alloys with 11 wt. % Ti. The stiffness of the alloys was also found to increase as deduced from elastic modulus value of 513.77 to 1046.51 N/m2 in Alloys C. Remarkable improvement in physical properties of the Ni-based ternary alloys is due to the formation of various hard boride phases and grain size reduction occasioned by the increase in titanium content.
Abstract: The microstructure and mechanical behaviour of Ni-B binary alloys have been enhanced in this study by varied titanium additions. The alloys investigated were chosen from the nickel-rich region of the Ni-B-Ti system. The microstructure of the alloys was examined using Optical Microscope (OM) and Scanning Electron Microscope (SEM) equipped with Energ...
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Evaluation of the Effect of Polystyrene on the Performance of Asphalt Mixes
Aftab Akbar,
Kashif Akbar,
Naveed Khan,
Afaq Ali,
Abdul Karim,
Fayaz-ur-rehman
Issue:
Volume 8, Issue 2, June 2019
Pages:
48-55
Received:
7 November 2018
Accepted:
28 December 2018
Published:
26 April 2019
Abstract: Asphalt, sometimes known as Bitumen is a sticky, black and highly viscous liquid or semi-solid form of petroleum. It is mainly found in natural deposits or may be a refined product. The primary use (70%) of asphalt/bitumen is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. The reason for its extensive use is that asphalt is exceptionally rigid and durable; it flings sufficient flexibility to fit defect in underlying surfaces. Replacement/reprocessing and removal of damaged asphalt is a simple and comparatively easy operation. The asphalt is also a hundred percent recyclable product. Ordinary asphalt pavement has a limited amount of stress bearing capacity. Asphalt pavements are also affected by the surroundings and climate. The usual pavement distresses include: cracking; disintegration, distortion, skidding hazards; and surface treatment distresses. In this modern age, civil engineering constructions have their own structural and durability requirements, every structure has its own intended purpose and hence to meet this purpose, modification in traditional asphalt has become mandatory. It has been found that different types of additives added in specific percentage to asphalt improves the physical properties i.e. resistance of cracking and strengthening of asphalt. In this project, we have carried out test on asphalt with Polystyrene as an additive to check the influence of these additives on strength of Asphalt. According to various research papers, it has been found that addition of Polystyrene gives strength to asphalt. Hence, in this project we were interested in finding out the optimum quantity of polystyrene required achieving the maximum strength. From the exhaustive and extensive experimental work it was found that with increase in Polystyrene content in asphalt mix up to a limit, there was a tremendous increase in strength. At 5% Polystyrene content maximum stability achieved was 10.41 KN and flow was 3.46 mm, but as the percentage of Polystyrene increased, a decrease in the strength occurs. Hence the optimum amount of Polystyrene is 5%.
Abstract: Asphalt, sometimes known as Bitumen is a sticky, black and highly viscous liquid or semi-solid form of petroleum. It is mainly found in natural deposits or may be a refined product. The primary use (70%) of asphalt/bitumen is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. The ...
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The First Principles Study on Two Alloys of Cr2ZnAl and Cr2AgAl
Dongmei Zhang,
Lijun Li,
Bo Hou,
Zhiming Li,
Chaofan Sun,
Lei Feng
Issue:
Volume 8, Issue 2, June 2019
Pages:
56-60
Received:
6 March 2019
Accepted:
11 April 2019
Published:
9 May 2019
Abstract: The Heusler alloy is with a ordered structure, in which the atoms are in specific location, and the alloy usually shows special character. The Co Mn Ni based Heusler alloys are all studied in many literature, but there is little study of the Cr based Heusler alloys. In order to find new Heusler alloys, Cr2AgAl and Cr2ZnAl are studied by first principles. Using the CALYPSO software, the crystal structure of Cr2AgAl is found to be F-43m, the lattice parameter is a=6.1100 Å, it is a Heusler alloy, and the density of states and the bands structure have been studied, showing it is a metal conductor and not a magnet. The X-ray diffraction result of the alloy was also obtained by calculating, the two peaks at 25 degree and 29 degree, represent the (111) and (200), and the existence of these two peaks implies an ordered atom structure formed. This X-ray result can be used to guide the experimental synthesis of this alloy material.The crystal structure of Cr2ZnAl is P4mm, the lattice parameter is a=b=2.97300 Å, c= 6.02320 Å, it is not a Heusler alloy, and it is also a metal conductor and not a magnet from the results of its density of states and the bands structure.
Abstract: The Heusler alloy is with a ordered structure, in which the atoms are in specific location, and the alloy usually shows special character. The Co Mn Ni based Heusler alloys are all studied in many literature, but there is little study of the Cr based Heusler alloys. In order to find new Heusler alloys, Cr2AgAl and Cr2ZnAl are studied by first princ...
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Surface Energy of Diamond Cubic Crystals and Anisotropy Analysis Revealed by Empirical Electron Surface Models
Issue:
Volume 8, Issue 2, June 2019
Pages:
61-69
Received:
2 April 2019
Accepted:
9 May 2019
Published:
10 June 2019
Abstract: A detailed knowledge of structure and energy of surface contributes to the understanding of many surface phenomena. In this work, the surface energies of 48 surfaces for diamond cubic crystals, including diamond (C), silicon (Si), germanium (Ge), and tin (Sn), have been studied by using the empirical electron surface models (EESM), extended from empirical electron theory (EET). Under the first-order approximation, the calculated results are in agreement with experimental and other theoretical values. It is also found that the surface energies show a strong anisotropy. The surface energy of close-packed plane (111) is the lowest one among all index surfaces. For the low-index planes, the order of the surface energies is γ(111) < γ(110) < γ(001). And surface energy variation of the (hk0) and (hhl) planes with the change of the included angle has also been analyzed. EESM provides a good basis for the surface research, and it also can be extended to more material systems. Such extensive results from the same theoretical model should be useful to understand various surface processes for theorists and experimentalists.
Abstract: A detailed knowledge of structure and energy of surface contributes to the understanding of many surface phenomena. In this work, the surface energies of 48 surfaces for diamond cubic crystals, including diamond (C), silicon (Si), germanium (Ge), and tin (Sn), have been studied by using the empirical electron surface models (EESM), extended from em...
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Effects of Zn Substitution on Structure Factors, Debye-Waller Factors and Related Structural Properties of the Mg1-xZnxFeNiO4 Spinels
Kadhim Ahmed Khalaf,
Ahmed Al-Rawas,
Abbasher Gismelseed,
Majid Al-Ruqeishi,
Salwan Al-Ani,
Ahmad Al-Jubouri,
Khamis Al-Ryami,
Bushra Al-Jaddedi
Issue:
Volume 8, Issue 2, June 2019
Pages:
70-93
Received:
7 January 2019
Accepted:
24 May 2019
Published:
10 June 2019
Abstract: The effects of Zn2+ ions substitutions on the Debye-Waller Factors, structure factor and other related structural properties of the Mg1-xZnxNiFeO4 (where 0.0≤x≤1.0) spinels have been investigated using the XRD, TEM, SEM and FT-IR tools. The Mg1-xZnxNiFeO4 samples were prepared using the conventional ceramic solid state sintering techniques at temperatures around 1100°C. The Mg1-xZnxNiFeO4 spinels have predominantly inverse type structure with inversion factor, λ in the range 0.69 to 0.36. The X-ray diffraction (XRD) patterns of all compositions showed the formation of cubic spinel structure. The lattice constant “a” increases from 8.3397Å for MgFeNiO4 to 8.3855Å for ZnFeNiO4 spinels. The increases in lattice parameters have been attributed to the replacement of small Mg2+ ions (0.66 Å) with the Zn2+ (0.74 Å) ions of a larger ionic radius. The IR spectra confirm the existence of two main absorption bands υ1 and υ2 in the frequency range of (400–1000 cm-1), arising due to the tetrahedral (A) and octahedral (B) stretching vibrations respectively. Values of both υ1 and υ2 decrease as Zn content increases. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed aggregates of stacked grains. The normalized XRD intensities of the main (hkl) planes were used in the estimation of the Debye-Waller factor. Values of the Debye-Waller factors were estimated to be in the range (0.77-1.44A2). The calculated and observed relative intensities and areas of the most related plains to cation distributions (i.e.: the (220), (311), (222), (400), (422), (511) and (440) plains) were obtained by normalizing with respect to the most intensive reflection from the (311) plane. An inverse relation between the ordering, Q and inversion, λ factors exists in these partially inverse spinels. Both Q and λ decrease as Zn content (x) increases in the sample. The cation distributions indicate that the sample, MgFeNiO4 with x=0, λ=2/3 and maximum configurational entropy Sc(=15.876 J/mol, K) should represents the sample of the complete randomness of cation distributions in these spinels and can be written as (Mg1/3Fe2/3)[Mg2/3Fe1/3Ni3/3)O4. In general the variation of the different structural parameters with Zn content lie on two different regions, the first region for x values (0.0-0.6) the “highly normal” and the second region for x values (0.6-1.0) the “highly inverse” type structure.
Abstract: The effects of Zn2+ ions substitutions on the Debye-Waller Factors, structure factor and other related structural properties of the Mg1-xZnxNiFeO4 (where 0.0≤x≤1.0) spinels have been investigated using the XRD, TEM, SEM and FT-IR tools. The Mg1-xZnxNiFeO4 samples were prepared using the conventional ceramic solid state sintering techniques at tempe...
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Curability, Workability and Stability Investigation on a Novel Pure Liquid One Component Thermal Curable Epoxy Adhesive
Chunfu Chen,
Bin Li,
Masao Kanari,
Daoqiang Lu
Issue:
Volume 8, Issue 2, June 2019
Pages:
94-99
Received:
3 April 2019
Accepted:
23 May 2019
Published:
29 June 2019
Abstract: A novel one component thermal curable epoxy adhesive composed of all liquid reactive ingredients was developed recently. Its thermal cure behavior was measured and analyzed with differential scanning calorimetry isothermal method. Workability and pot life at room temperature as well as storage stability and shelf life under chilled, frozen conditions were measured and analyzed by monitoring its viscosity change during the storage period. The measurement results confirmed that the novel one component epoxy adhesive can cure well at relatively low temperature and its pot life is much longer than conventional two component epoxy adhesives with similar curability and adhesion performance. The novel one component epoxy adhesive was also confirmed to be very stable and its shelf life can be several years long under suitable frozen storage. Based on cure behavior measurement results, cure kinetics of the novel one component epoxy adhesive was investigated. Arrhenius equation obtained from kinetics plot curve was applied to predict pot life and shelf life and it was found that the predicted pot life and shelf life correlate very well with actual measured results. Crystallization temperature of the novel epoxy adhesive was also measured and found to have close relationship with storage stability. This study verified that differential scanning calorimetry isothermal method can be used to predict shelf life of one component epoxy products. In addition, crystallization temperature measurement can be utilized for better stable epoxy adhesive development and suitable storage temperature determination.
Abstract: A novel one component thermal curable epoxy adhesive composed of all liquid reactive ingredients was developed recently. Its thermal cure behavior was measured and analyzed with differential scanning calorimetry isothermal method. Workability and pot life at room temperature as well as storage stability and shelf life under chilled, frozen conditio...
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