Search1995 Vol. 2, No. 2
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1995, vol. 2, no. 2, pp.
71-78.
Abstract:
Hot corrosion(HC) of the APS(atomospheric plasma spraying)CoNiCrAlTaSiY coating on a nickel-base superalloy GH864 has been studied. The effect of laser-treatment on hot corrosion resistance was also examined.It was shown that CoNiCrAlTaSiY coating had superior properties in resistance to hot corrosion due to the readiness of the formation of a protective Cr2O3 scale on the coating surface.A model for the mechanism of hot corrosion of this coating has been suggested. Hot corrosion resistance of this coating was significantly increased by the laser treatment simply because the surface of the as sprayed coating was densified by the high power laser beam.
Hot corrosion(HC) of the APS(atomospheric plasma spraying)CoNiCrAlTaSiY coating on a nickel-base superalloy GH864 has been studied. The effect of laser-treatment on hot corrosion resistance was also examined.It was shown that CoNiCrAlTaSiY coating had superior properties in resistance to hot corrosion due to the readiness of the formation of a protective Cr2O3 scale on the coating surface.A model for the mechanism of hot corrosion of this coating has been suggested. Hot corrosion resistance of this coating was significantly increased by the laser treatment simply because the surface of the as sprayed coating was densified by the high power laser beam.
1995, vol. 2, no. 2, pp.
79-83.
Abstract:
Low-temperature deposition of diamond thin films in the range of 280~445℃ has been successfully carried out by microwave plasma-assisted CVD method.At lower deposition temperatures (280~445℃),the large increase in the nucleation density and great improvement in the average surfae roughness of the diamond were observed. Results of low temperature deposition and characterization of diamond thin films obtained are presented.
Low-temperature deposition of diamond thin films in the range of 280~445℃ has been successfully carried out by microwave plasma-assisted CVD method.At lower deposition temperatures (280~445℃),the large increase in the nucleation density and great improvement in the average surfae roughness of the diamond were observed. Results of low temperature deposition and characterization of diamond thin films obtained are presented.
1995, vol. 2, no. 2, pp.
84-91,108.
Abstract:
This paper used EAM and static relaxation method to simulate the grain boundary segregation behavior of Mg in Ni-based superalloys. The results offer a better understanding in the strengthening mechanism of Mg addition in superalloys. The segregation of Mg increases the grain boundary cohesive bond and the vacancy formation energy, and decreases the mobility of grain boundary dislocation. It results in the retardation of creep voids initiation and growth.
This paper used EAM and static relaxation method to simulate the grain boundary segregation behavior of Mg in Ni-based superalloys. The results offer a better understanding in the strengthening mechanism of Mg addition in superalloys. The segregation of Mg increases the grain boundary cohesive bond and the vacancy formation energy, and decreases the mobility of grain boundary dislocation. It results in the retardation of creep voids initiation and growth.
1995, vol. 2, no. 2, pp.
92-96.
Abstract:
According to the Cd-Sb alloy phase diagram, resistivity, heat capacity, partial molar entropy and viscosity,the structural units of this alloy melt have been determined as Cd and Sb atoms as well as Cd3Sb2, Cd4Sb3 and CdSb compounds.Based on these structural units and the coexistence theory of metallic melt structure involing compound formation,a calculating model of mass action concentrations has been deduced.The calculated mass action concentrations NCd are in good agreement with measured activities aCd. The Gibbs standard free energy of formatioin for above three compunds have been obtained too.
According to the Cd-Sb alloy phase diagram, resistivity, heat capacity, partial molar entropy and viscosity,the structural units of this alloy melt have been determined as Cd and Sb atoms as well as Cd3Sb2, Cd4Sb3 and CdSb compounds.Based on these structural units and the coexistence theory of metallic melt structure involing compound formation,a calculating model of mass action concentrations has been deduced.The calculated mass action concentrations NCd are in good agreement with measured activities aCd. The Gibbs standard free energy of formatioin for above three compunds have been obtained too.
1995, vol. 2, no. 2, pp.
97-103.
Abstract:
151Eu Mossbauer spectra of BaFBr:Eu phosphor are reported for the first time.The results show that f(Eu2+)<f(Eu3+) or <x2>Fu2+><x2>Fu3+,which indicates that the attraction between phonons and Eu2+ is stronger than that between phonons and Eu3+,this may cause a faster increase of f(Eu2+) vs f(Eu3+) when temperature decreases as observed in the experiments.It is also found from Mossbauer investigation that when temperature decreases,the relative content of Eu2+ decreases, while that of Eu3+ increases.The temperature dependent Mossbauer spectra provide evidence for electron exchange or hopping between Eu2+ or Eu3+ sites in BaFBr lattice. The Mossbauer results are discussed and compared with the results of XPS and Photoluminescence studies.
151Eu Mossbauer spectra of BaFBr:Eu phosphor are reported for the first time.The results show that f(Eu2+)<f(Eu3+) or <x2>Fu2+><x2>Fu3+,which indicates that the attraction between phonons and Eu2+ is stronger than that between phonons and Eu3+,this may cause a faster increase of f(Eu2+) vs f(Eu3+) when temperature decreases as observed in the experiments.It is also found from Mossbauer investigation that when temperature decreases,the relative content of Eu2+ decreases, while that of Eu3+ increases.The temperature dependent Mossbauer spectra provide evidence for electron exchange or hopping between Eu2+ or Eu3+ sites in BaFBr lattice. The Mossbauer results are discussed and compared with the results of XPS and Photoluminescence studies.
1995, vol. 2, no. 2, pp.
104-108.
Abstract:
A uniform, dense and defect free Cr2O3 thin film, which is amorphous at ambient temperature, was applied on the surface of intermetallic Fe3Al by electrodeposition reaction sintering, and the effect of this film on the oxidation of Fe3Al at 900℃ in air was studied. The films and the oxide scales were analyzed by TEM, EDAX,SEM and XRD.It is proved that, by surface applied Cr2O3 thin film,a continuous, protective,fine grained α-Al2O3 scale was formed on Fe3Al. As a result, the adherence of the scale and oxidation resistance of Fe3Al were improved.
A uniform, dense and defect free Cr2O3 thin film, which is amorphous at ambient temperature, was applied on the surface of intermetallic Fe3Al by electrodeposition reaction sintering, and the effect of this film on the oxidation of Fe3Al at 900℃ in air was studied. The films and the oxide scales were analyzed by TEM, EDAX,SEM and XRD.It is proved that, by surface applied Cr2O3 thin film,a continuous, protective,fine grained α-Al2O3 scale was formed on Fe3Al. As a result, the adherence of the scale and oxidation resistance of Fe3Al were improved.
1995, vol. 2, no. 2, pp.
109-113.
Abstract:
An effective Dynamic Moire method was presented to determine the critical time of crack instable propagation in rock dynamic fracture. Two pieces of grating were installed near the notch of Short Rod specimen to form the Moire fringes, then the COD versus time could be monitored from the movement of the Moire fringes, and finally the critical time could be determined from the velocity of COD. This method was also compared with another one.It could be concluded that the critical time determined by Dynamic Moire method corresponds with that of the Transmitted Wave method at the loading rates from 103 to 104 MPa·m1/2·S-1.
An effective Dynamic Moire method was presented to determine the critical time of crack instable propagation in rock dynamic fracture. Two pieces of grating were installed near the notch of Short Rod specimen to form the Moire fringes, then the COD versus time could be monitored from the movement of the Moire fringes, and finally the critical time could be determined from the velocity of COD. This method was also compared with another one.It could be concluded that the critical time determined by Dynamic Moire method corresponds with that of the Transmitted Wave method at the loading rates from 103 to 104 MPa·m1/2·S-1.
1995, vol. 2, no. 2, pp.
114-123.
Abstract:
A new branch of hypergraph theory-directed hyperaph theory and a kind of new methods-dicomposition contraction(DCP, PDCP and GDC) methods are presented for solving hypernetwork problems.lts computing time is lower than that of ECP method in several order of magnitude.
A new branch of hypergraph theory-directed hyperaph theory and a kind of new methods-dicomposition contraction(DCP, PDCP and GDC) methods are presented for solving hypernetwork problems.lts computing time is lower than that of ECP method in several order of magnitude.
1995, vol. 2, no. 2, pp.
124-130.
Abstract:
The research on tundish metallurgy has focused mainly on taking countermeasures to avoid and remove inclusions and the recent developments on tundish metallurgy were surveyed.The authers'advices for future development of tundish metallurgy were given in summary section.
The research on tundish metallurgy has focused mainly on taking countermeasures to avoid and remove inclusions and the recent developments on tundish metallurgy were surveyed.The authers'advices for future development of tundish metallurgy were given in summary section.
1995, vol. 2, no. 2, pp.
131-135.
Abstract:
The kinetics of the deposition of lithium on aluminium electrode has been studied by cyclic voltammetry.The deposition of lithium on aluminium electrode was found to be controlled by the diffusion of lithium within the β-LiAl alloy probably through the vacancy mechanism. The limiting operating potential and current for prepanng the lithium aluminium electrodes were given.
The kinetics of the deposition of lithium on aluminium electrode has been studied by cyclic voltammetry.The deposition of lithium on aluminium electrode was found to be controlled by the diffusion of lithium within the β-LiAl alloy probably through the vacancy mechanism. The limiting operating potential and current for prepanng the lithium aluminium electrodes were given.
1995, vol. 2, no. 2, pp.
136-140.
Abstract:
A mathematical formulation is developed to represent the magneticfield intensity, the current density, the velocity field, the temperature field in the DC arc furnace bath.The governing equations are solved numerically to describe the magnetic field intensity profiles, the current density profiles, Lorentz force profiles, streamline profiles, the velocity profiles and temperature profiles in the 30t DC-EAF bath. The theoretical predictions of temperature field are in good agreement with measurement in the 30t DC-EAF bath, and the recirculation rate of flow is also in good agreement with published estimation.
A mathematical formulation is developed to represent the magneticfield intensity, the current density, the velocity field, the temperature field in the DC arc furnace bath.The governing equations are solved numerically to describe the magnetic field intensity profiles, the current density profiles, Lorentz force profiles, streamline profiles, the velocity profiles and temperature profiles in the 30t DC-EAF bath. The theoretical predictions of temperature field are in good agreement with measurement in the 30t DC-EAF bath, and the recirculation rate of flow is also in good agreement with published estimation.
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