scholarly journals Discrete One-Stage Mechanochemical Synthesis of Titanium-Nitride in a High-Energy Mill

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1743
Author(s):  
Oleg Lapshin ◽  
Olga Shkoda ◽  
Oksana Ivanova ◽  
Sergey Zelepugin
Keyword(s):  
Mathematical Model ◽  
Titanium Nitride ◽  
Mechanochemical Synthesis ◽  
Chemical Conversion ◽  
High Heat ◽  
High Energy ◽  
Structural Defects ◽  
Theoretical Evaluation ◽  
Interfacial Areas ◽  
Two Factors

Discrete (discontinuous) mechanochemical synthesis of titanium nitride was experimentally investigated. The experimental results show that mechanical activation intensifies the chemical conversion in the Ti-N system, and the discrete synthesis of the final product is conducted under “soft” controlled conditions without high heat release. The new theory of mechanochemical synthesis and the mathematical model based on it were used for theoretical evaluation of the dynamics of titanium activation in the nitrogen medium. It was found that the discrete mode of synthesis includes two factors accelerating mechanochemical reactions in the Ti-N synthesis: structural (grinding of metallic reagent and formation of interfacial areas) and kinetic (accumulation of excess energy stored in the formed structural defects in metallic reagent). The kinetic constants of the process were found using experimental data and the inverse problem method. The diagrams defining the controlled modes of obtaining titanium nitride particles with the given characteristics were constructed. A mathematical model for theoretical estimation of the dynamics of activation of titanium powder in the nitrogen medium was developed using a new macrokinetic theory of mechanochemical synthesis.

scholarly journals Mechanochemical Synthesis and Nitrogenation of the Nd1.1Fe10CoTi Alloy for Permanent Magnet

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3854
Author(s):  
Hugo Martínez Sánchez ◽  
George Hadjipanayis ◽  
Germán Antonio Pérez Alcázar ◽  
Ligia Edith Zamora Alfonso ◽  
Juan Sebastián Trujillo Hernández
Keyword(s):  
Mechanochemical Synthesis ◽  
Applied Field ◽  
Volume Fraction ◽  
Synthesis Method ◽  
High Energy ◽  
Direction Parallel ◽  
Best Value ◽  
Heat Treated ◽  
Bcc Phase ◽  
First Time

In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd1.1Fe10CoTi compound from Nd2O3, Fe2O3, Co and TiO2. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn12-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N2. The magnetic properties Mr, µ0Hc, and (BH)max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were Mr = 75 Am2 kg–1, µ0Hc = 0.500 T and (BH)max = 58 kJ·m–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)max~114 kJ·m–3 was obtained for 3 h and the highest µ0Hc = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.

scholarly journals Mechanochemical Synthesis and Rapid Consolidation of Nanocrystalline 3NiAl-Al2O3Composites

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
In-Jin Shon ◽  
In-Yong Ko ◽  
Seung-Hoon Jo ◽  
Jung-Mann Doh ◽  
Jin-Kook Yoon ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Mechanochemical Synthesis ◽  
High Frequency ◽  
Nanocrystalline Materials ◽  
Physical And Mechanical Properties ◽  
High Energy ◽  
Reinforced Composite ◽  
Energy Ball ◽  
High Frequency Induction

Nanopowders of 3NiAl and Al2O3were synthesized from 3NiO and 5Al powders by high-energy ball milling. Nanocrystalline Al2O3reinforced composite was consolidated by high-frequency induction-heated sintering within 3 minutes from mechanochemically synthesized powders of Al2O3and 3NiAl. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition grain growth. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. The relative density of the composite was 97%. The average Vickers hardness and fracture toughness values obtained were 804 kg/mm2and 7.5 MPa⋅m1/2, respectively.

scholarly journals Influences of environment on the development and lifetime reproductive performance in domestic rabbit females

2019 ◽  
Vol 27 (3) ◽  
pp. 123 ◽  
Author(s):  
D. Savietto ◽  
E. Martínez-Paredes ◽  
J.J. Pascual
Keyword(s):  
Reproductive Performance ◽  
Average Daily Gain ◽  
Adult Life ◽  
High Energy ◽  
Body Development ◽  
Rabbit Haemorrhagic Disease ◽  
Two Factors ◽  
Haemorrhagic Disease ◽  
Access To Food ◽  
Daily Gain

<p class="MDPI18keywords">Environmental insults of different nature and intensity, such as fluctuation in the air temperature, which can affect access to food, its quality and diseases, are a reality in any livestock system. This is much more important when the insults occur in early life, conditioning the development and adult life of animals. In ecology, for instance, it is widely accepted that high quality offspring are more reactive against predators, occupy better territories and find more mates, resulting in longer lives and greater fitness. It is also a given that adults exposed to famine or disease as juveniles have shorter lives and produce fewer offspring. To determine whether the environment influences the development and lifetime reproductive performance of rabbit females, we designed an experiment combining two factors: nest and pubescent development. Nest development was measured by recording the average daily gain of 864 females during suckling and during their pubescent life (63 to 184 d old), and body development was conditioned by providing animals a high-energy control (C) or a fibre-rich (F) diet. However, in the course of the study, 191 of the 864 pubescent females were exposed to rabbit haemorrhagic disease (RHD). This unexpected environmental insult was considered as a third experimental factor influencing the reproductive performance of rabbit females. Contrary to expectation, fast suckling gain impairs reproductive lifespan, resulting in fewer newborn kits produced in a female lifetime. Although females on diet F lived 37 d longer than females on diet C, this difference was only perceived in their pubescent life. In addition, the exposure to RHD interacted with suckling gain (SG). Exposed females with a fast SG produced more kits as adults, but in the absence of the virus, high SG females produced fewer newborn kits. These results open new insights into the management of future breeders during nesting and pubescent life.</p>

The Influence of Diamond Surface Perfection on the Preferential Nucleation of SP2 Carbon During Methane Pyrolysis

1992 ◽  
Vol 280 ◽  
Author(s):  
B. Y. Lin ◽  
C. P. Beetz ◽  
D. W. Brown ◽  
B. A. Lincoln
Keyword(s):  
Natural Diamond ◽  
High Energy ◽  
Diamond Surface ◽  
Structural Defects ◽  
High Energy Electron ◽  
Diamond Surfaces ◽  
Preferential Nucleation ◽  
Cvd Diamond Film ◽  
Surface Morphologies ◽  
Methane Pyrolysis

ABSTRACTWe report a set of CH4 pyrolysis experiments in a UHV system on diamond surfaces having varying degrees of surface roughness or perfection. Scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and reflection high energy electron diffraction (RHEED) were used to examine the formation of graphite and the resulting surface morphologies. A (100) type Ha natural diamond having 3 sputtered craters on the surface was used as the substrate, sp2 carbon was formed preferentially on the structurally defective crater surfaces after ∼3×1010 L of CH4 exposure at 900°C, whereas essentially no sp2 carbon was found on the flat portions of the diamond surface. Similar experiments were also carried out on a polycrystalline CVD diamond film and sp2 carbon was formed on that surface afte ∼4×109 L of CH4 exposure at 900°C. These results indicate that structural defects on diamond surfaces are a crucial factor in the preferential nucleation of sp2 carbon during CH4 pyrolysis.

Thickness Deformation of Constrained Layer Damping: An Experimental and Theoretical Evaluation

2000 ◽  
Vol 123 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Peter Y. H. Huang ◽  
Per G. Reinhall ◽  
I. Y. Shen ◽  
Jessica M. Yellin
Keyword(s):  
Mathematical Model ◽  
Transfer Functions ◽  
Viscoelastic Layer ◽  
Experimental Setup ◽  
Experimental Measurements ◽  
Constrained Layer Damping ◽  
Response Functions ◽  
Theoretical Evaluation ◽  
Calculated Frequency ◽  
Direct Measurements

This paper presents a study of thickness deformation of the viscoelastic material in constrained layer damping (CLD) treatments. The first goal of the study is to demonstrate the feasibility of using direct measurement to investigate thickness deformation in CLD treatments. The experimental setup consisted of a constrained layer beam cantilevered to a shaker, an accelerometer mounted at the cantilevered end, and two laser vibrometers that simultaneously measured the responses of the base beam and the constraining layer, respectively, at the free end. A spectrum analyzer calculated frequency response functions (FRFs) between the accelerometer inputs and the vibrometer outputs. Measured FRFs of the base beam and the constraining layer were compared to detect thickness deformation. Experimental results showed that direct measurements can detect thickness deformation as low as 0.5 percent. The second goal is to evaluate the accuracy of a mathematical model developed by Miles and Reinhall [7] that accounts for thickness deformation. FRFs were calculated by using the method of distributed transfer functions by Yang and Tan [13]. Comparison of the numerical results with the experimental measurements indicated that consideration of thickness deformation can improve the accuracy of existing constrained layer damping models when the viscoelastic layer is thick.

scholarly journals Forecasting Solar Energetic Particle Events and Associated False Alarms

2017 ◽  
Vol 13 (S335) ◽  
pp. 324-327
Author(s):  
Bill Swalwell ◽  
Silvia Dalla ◽  
Robert Walsh
Keyword(s):  
Energetic Particle ◽  
Solar Energetic Particle ◽  
High Energy ◽  
False Alarms ◽  
Solar Event ◽  
Solar Energetic Particle Events ◽  
Two Factors ◽  
Very High Energy ◽  
Solar Events ◽  
Very High

AbstractBecause of the significant dangers they pose, accurate forecasting of Solar Energetic Particle (SEP) events is vital. Whilst it has long been known that SEP-production is associated with high-energy solar events, forecasting algorithms based upon the observation of these types of solar event suffer from high false alarm rates. Here we analyse the parameters of 4 very high energy solar events which were false alarms, with a view to reaching an understanding as to why SEPs were not detected at Earth. We find that in each case at least two factors were present which have been shown to be detrimental to SEP production.

Mathematical Model of the Grinding and Mixing of Powder Binary Solids in a High-Energy Mill

2019 ◽  
Vol 93 (8) ◽  
pp. 1592-1597 ◽  
Author(s):  
O. V. Lapshin ◽  
V. V. Boldyrev ◽  
E. V. Boldyreva
Keyword(s):  
Mathematical Model ◽  
High Energy
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