-
The Use of Coatings to Obtain the Diffusion Layer on the Walls of Molds
Gerasimova Alla,
Radyuk Aleksandr Germanovich
Issue:
Volume 5, Issue 1, January 2016
Pages:
1-4
Received:
25 November 2015
Accepted:
10 December 2015
Published:
15 January 2016
Abstract: In this work diffusion layers on narrow walls of crystallizers removed from service were created by aluminium spraying on M1 copper and МН2, 5КоКрХ copper alloy with subsequent heat treatment for increasing of life time of crystallizers in continuous casting machines. Layer thickness and microhardness have been assumed as basic measure of serviceability. To clarify the reasons of reducing the thickness of the diffusion layer on the copper alloy МН2, 5КоКрХ were conducted metallographic and microengineering research. The coating was applied on the wall alloy МН2, 5КоКрХ, the diffusion layer microhardness was measured on microthermometry PMT-3. The analysis found that increasing the thickness of the deposited coating and the temperature rise of the heat treatment, as a rule, lead to an increase in the thickness of the diffusion layer; change the security environment with 95%N2+5%H2 100%H2 does not change the thickness of the diffusion layer; a diffusion layer microhardness of 2-6 times higher than the microhardness of copper and is 1140-3880 MPa against 460-590 MPa on copper base. It is reasonable to spray aluminium thermal coating on narrow crystallizer walls with subsequent heat treatment in protective atmosphere using adjusted modes and proofing of a crystallizer in a continuous casting machine for estimation of wall state during exploitation and change of cast metal quality.
Abstract: In this work diffusion layers on narrow walls of crystallizers removed from service were created by aluminium spraying on M1 copper and МН2, 5КоКрХ copper alloy with subsequent heat treatment for increasing of life time of crystallizers in continuous casting machines. Layer thickness and microhardness have been assumed as basic measure of serviceab...
Show More
-
Gaseous Metal Hydrides MBeH3 and M2BeH4 (M = Li, Na): Quantum Chemical Study of Structure, Vibrational Spectra and Thermodynamic Properties
Awadhi Shomari,
Tatiana P. Pogrebnaya,
Alexander M. Pogrebnoi
Issue:
Volume 5, Issue 1, January 2016
Pages:
5-17
Received:
22 December 2015
Accepted:
5 January 2016
Published:
21 January 2016
Abstract: The theoretical study of complex hydrides MBeH3 and M2BeH4 (M = Li, Na) have been carried out using DFT MP2 methods with basis set 6-311++G (d, p). The optimized geometrical parameters, vibrational spectra and thermodynamic properties of the hydrides and subunits MH, M2H+, M2H2, BeH2, BeH3− have been determined. Two geometrical configurations, cyclic (C2v) and linear (C∞v), were found for pentaatomic MBeH3 molecules, the cyclic isomer being predominant. Three isomers of M2BeH4 molecules were revealed of the following shapes: two-cycled (D2d), polyhedral (C2v) and hexagonal (C2v). Among these structures polyhedral isomer was found to have the lowest energy. The relative abundance of the M2BeH4 isomers in saturated vapour was analyzed. The enthalpies of formation ∆fH(0) of complex hydrides in gaseous phase were determined (in kJmol1): 105 ± 26 (LiBeH3), 63 ± 37 (Li2BeH4), 121 ± 27 (NaBeH3), and 117 ± 39 (Na2BeH4). The thermodynamic stability of the hydrides was examined through Gibbs free energies for heterophase decomposition.
Abstract: The theoretical study of complex hydrides MBeH3 and M2BeH4 (M = Li, Na) have been carried out using DFT MP2 methods with basis set 6-311++G (d, p). The optimized geometrical parameters, vibrational spectra and thermodynamic properties of the hydrides and subunits MH, M2H+, M2H2, BeH2, BeH3− have been determined. Two geometrical configurations, cycl...
Show More
-
Controllable Synthesis and Catalytic Property of Novel Copper Oxides (CuO and Cu2O) Nanostructures
Wenxian Wei,
Bin Xu,
Qingli Huang
Issue:
Volume 5, Issue 1, January 2016
Pages:
18-22
Received:
26 January 2016
Accepted:
Published:
27 January 2016
Abstract: Copper oxides (CuO and Cu2O) semiconductor micro- and nanostructures have been selectively synthesized using cupric nitrate trihydrate (Cu(NO3)2•3H2O), potassium biphthalate (KHC8H4O4) and sodium hydroxide (NaOH) as starting materials in water solution by a simple hydrothermal method. The phase and morphology of the products could be controlled by changing the amount of sodium hydroxide and sodium potassium biphthalate. X-ray diffraction (XRD), field scanning electron microscopy (SEM) and Raman spectra (Raman) were used to characterize the products. It was found that oval-shaped CuO, CuO nanoplates and octahedral Cu2O were prepared by adjusting the molar of the NaOH and KH C8H4O4, meaning that NaOH and KH C8H4O4 played an important role in the morphology and phase of the samples. The catalytic application in accelerating catalytic decomposition of ammonium perchlorate (AP) of the as-prepared samples was also investigated by means of differential scanning calorimetry (DSC). Compared with CuO (oval-shaped or plates), octahedral Cu2O exhibited better catalysis on thermal decomposition of AP. The present work can afford some guidance for the rationally controllable synthesis of other catalytic materials.
Abstract: Copper oxides (CuO and Cu2O) semiconductor micro- and nanostructures have been selectively synthesized using cupric nitrate trihydrate (Cu(NO3)2•3H2O), potassium biphthalate (KHC8H4O4) and sodium hydroxide (NaOH) as starting materials in water solution by a simple hydrothermal method. The phase and morphology of the products could be controlled by ...
Show More
-
Gray’s Paradox and Wave Solutions in Explaining Anomalously Low Friction and Wear in Tribology
V. M. Stadnichenko,
O. M. Troshin
Issue:
Volume 5, Issue 1, January 2016
Pages:
23-30
Received:
12 January 2016
Accepted:
20 January 2016
Published:
17 February 2016
Abstract: The results of theoretical and experimental studies of the anomalously low friction are presented in this paper from the standpoint of thermodynamics of non-equilibrium processes, arising under conditions of elastic interaction of micro-relief of tribosystem elements. The dependences of acoustic emission parameters which correspond to the alteration of energy dissipation mechanism of friction pairs superficial layers are obtained. In addition to molecular and mechanical components of the force of friction at anomalously low wear a wave component appears, and in this case the effect of this component prevails.
Abstract: The results of theoretical and experimental studies of the anomalously low friction are presented in this paper from the standpoint of thermodynamics of non-equilibrium processes, arising under conditions of elastic interaction of micro-relief of tribosystem elements. The dependences of acoustic emission parameters which correspond to the alteratio...
Show More
-
Experimental Study on Fracture Behaviors of Concrete Beams Strengthened with FRP Sheet of Different Width
Juanxia Zhang,
Zhonghui Chen,
Xianzhang Guo,
Wencheng Ma
Issue:
Volume 5, Issue 1, January 2016
Pages:
31-35
Received:
31 January 2016
Accepted:
15 February 2016
Published:
26 February 2016
Abstract: A total of six beams have been tested to investigate the influence of FRP sheet on the mechanical behavior of concrete beam with different FRP sheet width. In addition, the failure mode of the concrete beam and FRP reinforced concrete beams were also studied by numerical simulation method named Realistic Failure Process Analysis (RFPA). The results indicate that, the loading capacity is increased and maximum deflection of the concrete beam is also increased with the increasing of the FRP sheet width. Moreover, the interfacial debonding easily propagates along the interfacial concrete layer at a load that is below the estimated maximum strength of the FRP-strengthened structure. The maximum strength of the FRP sheet in the experiment was not achieved due to the adhesive layer between the concrete and FRP sheet was not strong enough compared with the numerical simulation result. It showed that the FRP sheet width was considered to be an important factor influence the failure mode and load capacity. So does the interface between the concrete and FRP plate.
Abstract: A total of six beams have been tested to investigate the influence of FRP sheet on the mechanical behavior of concrete beam with different FRP sheet width. In addition, the failure mode of the concrete beam and FRP reinforced concrete beams were also studied by numerical simulation method named Realistic Failure Process Analysis (RFPA). The results...
Show More
