Diameter-Controlled Growth of Carbon Nanotubes Through Pyrolysis of Acetylene Using Rare Earth Alloy as Catalyst in Hydrogen

Carbonnanotubes[1] (CNTs)havenovelquasione dimensionhollowstructurewithsmalldensity ,largeratioofsurfacetovolume ,highmechanicalstrength ,goodconductivityandchemicalstability .CNTshavepotentialapplicationsinmakingcatalystcarrier ,fabricatingnanoelectronics ,manufacturinghigh densityenergystoragematerial ,constructinghigh strengthcompositematerial ,andpreparingelec tromagneticwaveabsorptionmaterial[2～ 8] .InordertostudytheperformanceandapplicationofCNTs ,itisimportanttofindouthowtosynthesiz…     

The Effect of Carbon Nanotubes Based Nanolubricant on Stick–Slip Behavior

In this article, stick–slip behavior of a metal–metal interface is investigated in presence of a lubricant mixed with multiwalled carbon nanotubes (MWCNTs). The friction experiments are carried out to determine the critical pulling velocity at which stick–slip motion disappears and steady sliding follows thereafter. The sliding experiments show that the critical velocity decreases with increase in concentration of MWCNTs in the lubricant up to 1.6% (wt./vol.), but further addition of the nanoparticles in the lubricant leads to increase in the critical velocity. Also, the critical velocity is found to be nearly independent of normal stress at the optimal concentration of the nanoparticles. Moreover, amplitude of stick–slip motion decreases with increase in concentration of MWCNTs up to the optimal value at a fixed velocity but the same begin to increase after the optimal concentration. The results are explained in light of the rolling-sliding mechanism of the spherical or cylindrical nanoparticles reported in literature. The present study reveals that the stick–slip instability can also be eliminated by using an optimal concentration of the nanoparticles in the lubricant.     

Kinetics of Reduction of NiO–WO3 Mixtures by Hydrogen

The kinetics of reduction of the oxide mixtures of Ni-W with different Ni/(Ni-W) molar ratios within the range of 923 K to 1173 K in flowing hydrogen gas was investigated by means of thermogravimetric analysis under isothermal conditions. The products were examined by X-ray diffraction, scanning electron microscope (SEM), and electron dispersion spectroscopy (EDS) analyses. Five different oxide mixtures apart from the pure oxides were studied in the present work. The results indicate that the reduction reaction proceeds through three consecutive steps that are as follows: $$ {\text{NiO-}} {\text{WO}}_{ 3} \to {\text{Ni-}}{\text{WO}}_{ 3} \to {\text{Ni-}}{\text{WO}}_{ 2} \to {\text{Ni-}}{\text{W}} $$ From the experimental results, the Arrhenius activation energies of the three steps were evaluated for all of the studied compositions. The activation energy for the first step was calculated to be approximately 18 kJ/mol. For the second and third stages, the activation energy values varied from 62 to 38 kJ/mol for the second stage and 51 to 34 kJ/mol for the third stage depending on the Ni/(Ni + W) molar ratio in the precursors; the activation energy increased with increasing ratios. SEM images showed that the grain size of the final product was dependent on the Ni/(Ni + W) molar ratio; smaller grains were formed at higher nickel contents.     

Study on the Interaction between Rare Earth and Carbon in High Carbon Steel

ＳｔｕｄｙｏｎｔｈｅＩｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎＲａｒｅＥａｒｔｈａｎｄＣａｒｂｏｎｉｎＨｉｇｈＣａｒｂｏｎＳｔｅｅｌ￥ＬｉｎＱｉｎ（林勤），ＦｕＴｉｎｇｌｉｎｇ（付廷灵），ＹｕＺｏｎｇｓｅｎ（余宗森），ＹｅＷｅｎ（叶文）（Ｕｎｉｖｅｒｓｉｔ...     

Influence of RE Addition on the Synthesis Mechanism of Si_3N_4from Silica Reduction by Carbon in Nitrogen Atmosphere

ＩｎｆｌｕｅｎｃｅｏｆＲＥＡｄｄｉｔｉｏｎｏｎｔｈｅＳｙｎｔｈｅｓｉｓＭｅｃｈａｎｉｓｍｏｆＳｉ_３Ｎ_４ｆｒｏｍＳｉｌｉｃａＲｅｄｕｃｔｉｏｎｂｙＣａｒｂｏｎｉｎＮｉｔｒｏｇｅｎ　ＡｔｍｏｓｐｈｅｒｅＬｉＷｅｎｃｈａｏ（李文超）；ＺｈｕａｎｇＹｏｕｑ...     

Processing of Cu–Al–Ni Alloy by Spray Atomization and Deposition Process

The present work describes a new route for the preparation of Cu–Al–Ni alloy strips via spray atomization and deposition route. The route consists of atomizing liquid Cu–Al–Ni alloy with a jet of argon gas in a closed chamber, at a pressure of 1 MPa. The semi-solid Cu–Al–Ni droplets are subsequently collected on the steel substrate placed vertically below the liquid metal stream in the atomization chamber to form a three-dimensional preform. The deposit produced on the substrate contains ~?5% porosity. The microstructural details of the spray deposited Cu–Al–Ni strips explains particularly the presence of porosity, formation of splats during the flight of spray casting and the associated microstructural evolution in Cu–Al–Ni spray deposit are explained.     

Synthesis of the ZrN–ZrB2 Composite by Spark Plasma Sintering

Powder Metallurgy and Metal Ceramics - Reactive spark plasma sintering of ZrH2, BN, and B powder mixtures in the temperature range 1500–1900°C was used to produce a ZrN–ZrB2...     

Composition and Structure of the Diamond–Low Carbon Steel Transition Zone Obtained by Contact Heating in Vacuum at the Eutectic Temperature of Fe–C

Russian Journal of Non-Ferrous Metals - This study covers the structure, elemental, and phase composition of products formed in the contact interaction between diamond and low-carbon steel in...     

Development of the γ′ Stability in Co–Al–W Alloys at 800 °C by Alloying with Carbon

Metallurgical and Materials Transactions A - The microstructures and hardnesses of Co–10Al–9W–1C, Co–7Al–5W–1C, and Co–7Al–5W (at. pct) alloys are...     

Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅱ. Hydrogenation of Benzene Catalyzed by MlNi_5

Ｂｅｎｚｅｎｅｈｙｄｒｏｇｅｎａｔｉｏｎｉｓｏｆｉｎｄｕｓｔｒｉａｌｉｍ ｐｏｒｔａｎｃｅｂｅｃａｕｓｅｉｔｓｒｅａｃｔｉｏｎｐｒｏｄｕｃｔ ,ｃｙｃｌｏ ｈｅｘａｎｅｉｓａｎｉｍｐｏｒｔａｎｔｉｎｄｕｓｔｒｉａｌｉｎｔｅｒｍｅｄｉａｔｅｕｓｅｄｉｎｔｈｅｐｒｏｄｕｃｔｉｏｎｏｆＮｙｌｏｎ 6ａｎｄＮｙｌｏｎ 6 6 [1] .Ｂｅｎｚｅｎｅｈｙｄｒｏｇｅｎａｔｉｏｎｏｆｂｏｔｈｔｈｅｌｉｑ ｕｉｄｐｈａｓｅａｎｄｇａｓｐｈａｓｅｕｎｄｅｒｄｉｆｆｅｒｅｎｔｃａｔａｌｙ ｓｉｓｗｅｒｅｒｅｐｏｒｔｅｄ[2 ,3 ] .Ｒ…     

Peculiarities of the Synthesis of High-Temperature TaSi2–SiC Ceramics Reinforced in situ by Discrete Silicon Carbide Nanofibers

Russian Journal of Non-Ferrous Metals - The possibility of increasing the mechanical properties of the ceramic material of the TaSi2–SiC system by reinforcing it with silicon carbide...     

Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries Ⅰ. Absorption of Hydrogen by Hydrogen Storage Alloy MlNi_5 Suspended in Benzene

Ｈｙｄｒｏｇｅｎｓｔｏｒａｇｅａｌｌｏｙｈａｖｅａｔｔｒａｃｔｅｄｍｕｃｈａｔｔｅｎｔｉｏｎｂｅｃａｕｓｅｏｆｔｈｅｉｒｌａｒｇｅｃａｐａｃｉｔｙｆｏｒｈｙｄｒｏｇｅｎｓｔｏｒａｇｅｃｏｕｐｌｅｄｗｉｔｈｔｈｅｉｒｒｅａｄｙｒｅｌｅａｓｅｏｆｈｙｄｒｏｇｅｎａｔｍｏｄｅｒａｔｅｔｅｍｐｅｒａｔｕｒｅｓａｎｄｐｒｅｓｓｕｒｅｓａｎｄｔｈｅｉｒａｂｉｌｉｔｙｔｏｕｎｄｅｒｇｏｍａｎｙｃｙｃｌｅｓｏｆａｂｓｏｒｐｔｉｏｎａｎｄｄｅｓｏｒｐｔｉｏｎｗｉｔｈｌｉｔｔｌｅｄｅｃｒｅａｓｅｉｎｃａｐａｃｉｔｙ…     

Study on Kinetics of Hydrogen Absorption by Metal Hydride Slurries I .Absorption of Hydrogen by Hydrogen Storage Alloy MlNi5 Suspended in Benzene

The absorption of hydrogen was studied in metal hydride slurry, which is formed by benzene and hydrogen storage alloy powder. The influence of temperature on the rate of absorption was discussed using three-phase mass transfer model. It is also concluded that the suitable absorption temperature is 313 K.     

Molecular Dynamics Calculation of the Self-Diffusion Coefficients in Molten LiF–RbBr and LiF–CsBr Mixtures

Classical molecular dynamics simulation is used to calculate the self-diffusion coefficients of the ions that make up reciprocal molten LiF–RbBr and LiF–CsBr mixtures at a temperature of 1420 K over the entire concentration range. The microscopic motion of the fluoride ion is shown to change qualitatively as a function of the nature of the cation forming the nearest environment. For example, the nearest environment of the fluoride ion in a reciprocal LiF–RbBr mixture at a low rubidium bromide concentration favors an increase in its self-diffusion coefficient despite the fact that the system density increases in this case.     

Electrochemical Corrosion of Composite Ceramics and Thermal Spray Coatings in the ZrB2–SiC–AlN System

Powder Metallurgy and Metal Ceramics - Polarization studies of the ZrB2–SiC–AlN compact ceramic material and thermal spray coatings of the same composition were conducted in a 3% NaCl...     

Formation of Titanium Boride in the Surface Layer of an Iron–Carbon Alloy Casting

The main stages of titanium boride formation in alloyed surface layers on iron–carbon alloy castings are considered. Surface alloying was performed by self-propagating high-temperature synthesis in alloying compositions during lost-foam casting. Titanium and ferrotitanium are used in alloying compositions to ensure synthesis, which is initiated by the melt thermal energy during casting formation. The thermal effects of the main reactions of titanium boride formation in various alloying compositions are compared. The microstructure, the phase composition, and the hardness of the alloyed surface layers are studied.     

Interdiffusion Study in the Fe–Nb System

The diffusion characteristics of the Fe–Nb system were investigated using the diffusion couple technique. The average interdiffusion coefficient was calculated for the Fe₂Nb Laves and the FeNb μ phases. The possible diffusion mechanism was predicted by using the calculated values of the activation energy for diffusion. Kirkendall marker experiments were conducted to determine the relative mobilities of the species. Fe was found to have a faster diffusion rate than Nb in both phases.