Search1997 Vol. 4, No. 2
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1997, vol. 4, no. 2, pp.
1-15.
Abstract:
The discoveries of so-called quasicrystals have broken through the theoretic foundation set up by the classical crystallographic group theory since 1891 and proposed new topics for study of solid structures. Electron diffraction patterns (EDP's) and high-resolution microscopic (HREM) images have proved invaluable tools of studying the structures of crystals. The recognition and determination of EDP's and HREM images of a real-structure play a key role for understanding the structure. This paper will introduce some new developments about crystallographic group theory and new image processing methods on EDP's and HREM images. Contrary to popular beliefs, the research shows that quasicrystals can be understood (perturbed) complex periodic structures.
The discoveries of so-called quasicrystals have broken through the theoretic foundation set up by the classical crystallographic group theory since 1891 and proposed new topics for study of solid structures. Electron diffraction patterns (EDP's) and high-resolution microscopic (HREM) images have proved invaluable tools of studying the structures of crystals. The recognition and determination of EDP's and HREM images of a real-structure play a key role for understanding the structure. This paper will introduce some new developments about crystallographic group theory and new image processing methods on EDP's and HREM images. Contrary to popular beliefs, the research shows that quasicrystals can be understood (perturbed) complex periodic structures.
1997, vol. 4, no. 2, pp.
16-20.
Abstract:
The effect of some additives on the microstructure and properties of andalusite-cordierite refractory is concerned with. A study has been made on Al2O3, Cr2O3 and SiC powders, which are selected as additives and added respectively to the standard formulation in varying amounts as extra content (2%, 4%, or 6%). As the results indicate, Al2O3 (best at 4%) and SiC (best at 2%) can improve the microstructure and the properties of the material.But Cr2O3 shows the effect to the contrary.
The effect of some additives on the microstructure and properties of andalusite-cordierite refractory is concerned with. A study has been made on Al2O3, Cr2O3 and SiC powders, which are selected as additives and added respectively to the standard formulation in varying amounts as extra content (2%, 4%, or 6%). As the results indicate, Al2O3 (best at 4%) and SiC (best at 2%) can improve the microstructure and the properties of the material.But Cr2O3 shows the effect to the contrary.
1997, vol. 4, no. 2, pp.
21-25.
Abstract:
Hot ductility of the Nb- and Ti-containing line-pipe steel CC slab specimens were measured under the sirain rate of 1 × 10-3/s. Three types of precipitates were found in the fractured specimens. One was the block-shaped coarse TiN particles precipitated at high temperature. Another type was the fine dynamic precipitation products precipitated at 950~900℃ which caused remarkable ductility reduction of the steel. The third type was the co-existed precipitates formed by fine Nb precipitates nucleating and growing on TiN paricles. Compared with Nb-containing steel which contains no Ti, there was no ductility drop for Nb- and Ti-containing steel at temperature between 850℃ and Ar3 and, the γ→α transformation inside the grain matrixes proceeded faster, which both improved the ductility of the steel in the low ductility temperature Region Ⅲ.
Hot ductility of the Nb- and Ti-containing line-pipe steel CC slab specimens were measured under the sirain rate of 1 × 10-3/s. Three types of precipitates were found in the fractured specimens. One was the block-shaped coarse TiN particles precipitated at high temperature. Another type was the fine dynamic precipitation products precipitated at 950~900℃ which caused remarkable ductility reduction of the steel. The third type was the co-existed precipitates formed by fine Nb precipitates nucleating and growing on TiN paricles. Compared with Nb-containing steel which contains no Ti, there was no ductility drop for Nb- and Ti-containing steel at temperature between 850℃ and Ar3 and, the γ→α transformation inside the grain matrixes proceeded faster, which both improved the ductility of the steel in the low ductility temperature Region Ⅲ.
1997, vol. 4, no. 2, pp.
26-30.
Abstract:
Three dimensional velocity distribution and turbulence energy dissipation of the steel in tundish are calculated. Then, the mathematical model of collision removal and flotation removal is established. In this collision mode,the rate constants of all types of collision are concluded, the change rate of inclusion number density is obtained.The quantitative calculation shows that it is violent turbulence at the inlet area of tundish and that collision is the main removal type to those inclusions with radius from 0 to 25μm.The collision of inclusions has two effect: one is to decrease the number of small inclusions, the other is to increase the number of big inclusions.To calculate the removal of inclusions, both collision and flotation should be considered. At last, the result of industrial experiment proves the collisien model is true.
Three dimensional velocity distribution and turbulence energy dissipation of the steel in tundish are calculated. Then, the mathematical model of collision removal and flotation removal is established. In this collision mode,the rate constants of all types of collision are concluded, the change rate of inclusion number density is obtained.The quantitative calculation shows that it is violent turbulence at the inlet area of tundish and that collision is the main removal type to those inclusions with radius from 0 to 25μm.The collision of inclusions has two effect: one is to decrease the number of small inclusions, the other is to increase the number of big inclusions.To calculate the removal of inclusions, both collision and flotation should be considered. At last, the result of industrial experiment proves the collisien model is true.
1997, vol. 4, no. 2, pp.
30-30.
Abstract:
The experiments on the foaminess of the CaO-MgO-Al2O3-SiO2-CaF2 refining slag system have been carried out. The obtained results are as followst (1) relative foaming height linearly increases with the increasing of the flowrate of blowing gas; (2) the proper content of MgO is about 11% when slag basicity B<2.5 and it should lower when slag basicity will be higher; (3) the better content of Al2O3, (MgO)+(Al2O3 ) is 15% and 20%~26% respectively at the range of lower basicities; (4) the effect of slag basicity on the foaminess is complex and its optimizing vaiue is 1.9 at the specific contents of MgO, Al2O3 and CaF2.
The experiments on the foaminess of the CaO-MgO-Al2O3-SiO2-CaF2 refining slag system have been carried out. The obtained results are as followst (1) relative foaming height linearly increases with the increasing of the flowrate of blowing gas; (2) the proper content of MgO is about 11% when slag basicity B<2.5 and it should lower when slag basicity will be higher; (3) the better content of Al2O3, (MgO)+(Al2O3 ) is 15% and 20%~26% respectively at the range of lower basicities; (4) the effect of slag basicity on the foaminess is complex and its optimizing vaiue is 1.9 at the specific contents of MgO, Al2O3 and CaF2.
1997, vol. 4, no. 2, pp.
30-30.
Abstract:
The study on direct reduction process of pellet containing carbon with the addition of Zn-Pb-bearing iron and steel plant dust shows that the reduction time and pellet basicity have obvious effect on the evaporation of lead and final metallization degree of pellet.The reduction temperature has significantl influences on the lead and zinc evaporation ratios and on final metallization degree of pellet. The optimum process parameters obtained are reduction temperature of 1 250 ℃,reduction time of 25 min and pellet basicity of 0.9.
The study on direct reduction process of pellet containing carbon with the addition of Zn-Pb-bearing iron and steel plant dust shows that the reduction time and pellet basicity have obvious effect on the evaporation of lead and final metallization degree of pellet.The reduction temperature has significantl influences on the lead and zinc evaporation ratios and on final metallization degree of pellet. The optimum process parameters obtained are reduction temperature of 1 250 ℃,reduction time of 25 min and pellet basicity of 0.9.
1997, vol. 4, no. 2, pp.
31-33.
Abstract:
The stresses in laser cladding of Ni3Al-WC composite coating co and in heat affect zone (HAZ) σh have been induced based on considering the influences of laser processing parameters power P and beam traverse speed v.According to the calculated results, certain limits of P and v are necessary in order to obtain crack free coatings. It agrees well with the experimental results.
The stresses in laser cladding of Ni3Al-WC composite coating co and in heat affect zone (HAZ) σh have been induced based on considering the influences of laser processing parameters power P and beam traverse speed v.According to the calculated results, certain limits of P and v are necessary in order to obtain crack free coatings. It agrees well with the experimental results.
1997, vol. 4, no. 2, pp.
33-33.
Abstract:
A two-dimensional heat transfer model was developed to calculate the mould wall temperature field under normal operations condition and to determine its changing behavior when breakout occured. On the numerical simulation of sticking type breakout process and the breakout related wall temperature evolution, parameters of prediction were suggested.
A two-dimensional heat transfer model was developed to calculate the mould wall temperature field under normal operations condition and to determine its changing behavior when breakout occured. On the numerical simulation of sticking type breakout process and the breakout related wall temperature evolution, parameters of prediction were suggested.
1997, vol. 4, no. 2, pp.
34-37.
Abstract:
Hydrogenation kinetics of MLNi3.8(Co,Mn,Al)1.2 and MLNi3.7(Co,Mn,Al)1.2Cu0.1 alloy in α + β phase at the temperature range of 30~70 ℃ has been studied. The kinetic mechanism of hydrogen absorption is not affected by initial hydrogen pressure. Temperature does not influence the rate of hydrogen absorption obviously. In the prior and later period of hydrogen absorption the rate-controlling step is chemical reaction and hydrogen diffusion in the hydride phase respectively for MLNi3.8(Co,Mn,Al)1.2 alloy. Adding Cu, the rate-controlling step changes from chemical reaction to the nucleation and growth of β phase in the prior period and the process of hydrogen absorption still controlled by diffusion in the later period.
Hydrogenation kinetics of MLNi3.8(Co,Mn,Al)1.2 and MLNi3.7(Co,Mn,Al)1.2Cu0.1 alloy in α + β phase at the temperature range of 30~70 ℃ has been studied. The kinetic mechanism of hydrogen absorption is not affected by initial hydrogen pressure. Temperature does not influence the rate of hydrogen absorption obviously. In the prior and later period of hydrogen absorption the rate-controlling step is chemical reaction and hydrogen diffusion in the hydride phase respectively for MLNi3.8(Co,Mn,Al)1.2 alloy. Adding Cu, the rate-controlling step changes from chemical reaction to the nucleation and growth of β phase in the prior period and the process of hydrogen absorption still controlled by diffusion in the later period.
1997, vol. 4, no. 2, pp.
37-37.
Abstract:
The strain-induced microstructural changes of Fe3Al-based alloys during room temperature deformation and high temperature creep were investigated. The results illustrated the strain-induced disor dering occured during room temperature deformation. Creep strain could induced two opposite processes, which are strain-induced disordering and creep recovery-induced reordering. These two opposite creep induced processes during creep result in reducing the influence of primary microstructure on the rupture life.
The strain-induced microstructural changes of Fe3Al-based alloys during room temperature deformation and high temperature creep were investigated. The results illustrated the strain-induced disor dering occured during room temperature deformation. Creep strain could induced two opposite processes, which are strain-induced disordering and creep recovery-induced reordering. These two opposite creep induced processes during creep result in reducing the influence of primary microstructure on the rupture life.
1997, vol. 4, no. 2, pp.
37-37.
Abstract:
The creep curves of heat resistant steel 12Cr1MoV was investigated. by constant stress creep tests. The creep curves of constant stress creep are quite different from that of constant load creep. The original θ-Concept Project procedure can be validated to successfully describe the constant stress creep curves but not constant load creep. A modified θ procedure was developed. This approach can successfully described both constant stress creep and constant load creep curves. The new approach leads to a great improvement in accuracy of long term prediction of extrapolation due to validation of a great number of existing constant load creep data.
The creep curves of heat resistant steel 12Cr1MoV was investigated. by constant stress creep tests. The creep curves of constant stress creep are quite different from that of constant load creep. The original θ-Concept Project procedure can be validated to successfully describe the constant stress creep curves but not constant load creep. A modified θ procedure was developed. This approach can successfully described both constant stress creep and constant load creep curves. The new approach leads to a great improvement in accuracy of long term prediction of extrapolation due to validation of a great number of existing constant load creep data.
1997, vol. 4, no. 2, pp.
38-42.
Abstract:
The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shiny black surface on mirrors was the product of the soil corrosion of the bronze mirrors. It is formed by reaction between the alloy and the humic acid in soil, and leaching of copper and lead oxides through a long period of time when the mirrors were buried under the ground. A dense cormsion-resistallt layer on the bronze mirrors consisted predominantly of stannic oxide.
The formation of black patina caused by soil humic acid under different conditions has been studied,and the black, grey and brown shiny surfaces prepared in laboratory have been analysed. The formation of tin-rich shiny black surface on mirrors was the product of the soil corrosion of the bronze mirrors. It is formed by reaction between the alloy and the humic acid in soil, and leaching of copper and lead oxides through a long period of time when the mirrors were buried under the ground. A dense cormsion-resistallt layer on the bronze mirrors consisted predominantly of stannic oxide.
1997, vol. 4, no. 2, pp.
43-46.
Abstract:
Hot solution of hydroquinone is oxidized by air forming quinone and quinhydrone, both of which have weak oxidizeability, enabling to oxidize metals on the surface of bronze mirror samples forming black and brilliant patina. SEM and electron micro probe analysis show that Cu content is lower than that of the original alloy due to Cu loss; Sn content is higher than the original alloy in patina. This indicates that humic acid is not the substance resulting in making black patina on the bronze mirror surface, but the black patina which produced from hydroquinone solution absence of Si, Al and Mg.
Hot solution of hydroquinone is oxidized by air forming quinone and quinhydrone, both of which have weak oxidizeability, enabling to oxidize metals on the surface of bronze mirror samples forming black and brilliant patina. SEM and electron micro probe analysis show that Cu content is lower than that of the original alloy due to Cu loss; Sn content is higher than the original alloy in patina. This indicates that humic acid is not the substance resulting in making black patina on the bronze mirror surface, but the black patina which produced from hydroquinone solution absence of Si, Al and Mg.
1997, vol. 4, no. 2, pp.
46-46.
Abstract:
An intelligent control plan for the secondary cooling of continuous casting of slab was put forward. An off-line simulation of the system by using neural networks combined with fuzzy logic control is provided. The results show that the intelligent control system can not only control the surface temperature of the bloom of the secondary cooling but also has a good ability of self-adaptation and self-learning.
An intelligent control plan for the secondary cooling of continuous casting of slab was put forward. An off-line simulation of the system by using neural networks combined with fuzzy logic control is provided. The results show that the intelligent control system can not only control the surface temperature of the bloom of the secondary cooling but also has a good ability of self-adaptation and self-learning.
1997, vol. 4, no. 2, pp.
47-50.
Abstract:
The oxidation resistance of isotropic pitch-based carbon fibers are sudied by thermogravimetric analysis,scanning electron microscope and mechanical propefties measure. The change of weight loss,microtextule and mechanical properties on condition of thermostatical oxidation and nonisothermal oxidation are separately mainly discussed.The results during isothermic oxidation at 316℃ showed that the weight loss of isotropic pitch-based carbon fiber increased and the strength, module rapidly decreased with prolongation of time, but the surface of carbon fiber is smoother and has not surface such as etching pits etc. The weight of isotropic pitch-based carbon fiber decreased more rapidly during the experiment of thermo-variable weight loss after 500℃ than before 500℃.
The oxidation resistance of isotropic pitch-based carbon fibers are sudied by thermogravimetric analysis,scanning electron microscope and mechanical propefties measure. The change of weight loss,microtextule and mechanical properties on condition of thermostatical oxidation and nonisothermal oxidation are separately mainly discussed.The results during isothermic oxidation at 316℃ showed that the weight loss of isotropic pitch-based carbon fiber increased and the strength, module rapidly decreased with prolongation of time, but the surface of carbon fiber is smoother and has not surface such as etching pits etc. The weight of isotropic pitch-based carbon fiber decreased more rapidly during the experiment of thermo-variable weight loss after 500℃ than before 500℃.
1997, vol. 4, no. 2, pp.
50-50.
Abstract:
Fine grain cast IN718 compressor blade form abroad has been analyzed. There is no columnar grain, uniform equiaxed grain, less segregation and no porosity cast defect in essence in the section of blade body with fine grain, in which grain size is about ASTM 2~4. Its microstructure is approachable to that of forging. It is hopeful to achieve the goal of replacing forging by casting.
Fine grain cast IN718 compressor blade form abroad has been analyzed. There is no columnar grain, uniform equiaxed grain, less segregation and no porosity cast defect in essence in the section of blade body with fine grain, in which grain size is about ASTM 2~4. Its microstructure is approachable to that of forging. It is hopeful to achieve the goal of replacing forging by casting.
1997, vol. 4, no. 2, pp.
50-50.
Abstract:
Based on the principle of BP neural networks, the rolling force model is established after thoroughly analyzing and reprocessing the data of 1 350 mm aluminium foil mill. It states that the difference between the output of artificial neural networks rolling force model and the real value is in the order of 3 percent. The model reflects the real feature of process.
Based on the principle of BP neural networks, the rolling force model is established after thoroughly analyzing and reprocessing the data of 1 350 mm aluminium foil mill. It states that the difference between the output of artificial neural networks rolling force model and the real value is in the order of 3 percent. The model reflects the real feature of process.
1997, vol. 4, no. 2, pp.
51-54.
Abstract:
A coprecipitation method was used for preparation of 0.95Pb[(Mg0.8Zn0.2)1/3Nb2/3]O3-0.05PbTiO3(PMZN-PT),dielectric ceramic powder. X-ray powder diffraction and electron probe energy dispersive, X-ray analyzer revealed that the powder calcinated at 800℃ for 2 h is the PMZN-PT with 100% single perovskite phase, and the order of magnitude of atomic proportion of Mg to Zn reaches approximately 10:1. In addition, the influence of Zn and Ti content on the perovskite phase and pyrochlore phase formation namely: 0.95Pb[(Mg1-xZnx)1/3Nb2/3]O3-0.05PbTiO3, (1-y)Pb[(Mg0.7Zn0.3)1/3Nb2/3]O3-yPbTiO3 was also analysed.
A coprecipitation method was used for preparation of 0.95Pb[(Mg0.8Zn0.2)1/3Nb2/3]O3-0.05PbTiO3(PMZN-PT),dielectric ceramic powder. X-ray powder diffraction and electron probe energy dispersive, X-ray analyzer revealed that the powder calcinated at 800℃ for 2 h is the PMZN-PT with 100% single perovskite phase, and the order of magnitude of atomic proportion of Mg to Zn reaches approximately 10:1. In addition, the influence of Zn and Ti content on the perovskite phase and pyrochlore phase formation namely: 0.95Pb[(Mg1-xZnx)1/3Nb2/3]O3-0.05PbTiO3, (1-y)Pb[(Mg0.7Zn0.3)1/3Nb2/3]O3-yPbTiO3 was also analysed.
1997, vol. 4, no. 2, pp.
55-56.
Abstract:
TiO2 thin film was deposited on Na-Ca-Si glass substrate by sol-gel process. TEM observation showed that the film is compactly joined to the substrate. TEM-EDX analyses of the film, film-substrate interface, and substrate revealed that the diffusion of Na+ from the substrate to the film is negative diffusion.
TiO2 thin film was deposited on Na-Ca-Si glass substrate by sol-gel process. TEM observation showed that the film is compactly joined to the substrate. TEM-EDX analyses of the film, film-substrate interface, and substrate revealed that the diffusion of Na+ from the substrate to the film is negative diffusion.
1997, vol. 4, no. 2, pp.
57-59.
Abstract:
Explores the generalization error of fuzzy neural network, analyzes the reason for occurrence and presents the equation of calculating error by the confidence interval approach. In addition, a generalization error transfering(GET) method of improving the generalization error is proposed. The simulation experimental results of heating furnance show that the GET scheme is efficient.
Explores the generalization error of fuzzy neural network, analyzes the reason for occurrence and presents the equation of calculating error by the confidence interval approach. In addition, a generalization error transfering(GET) method of improving the generalization error is proposed. The simulation experimental results of heating furnance show that the GET scheme is efficient.
1997, vol. 4, no. 2, pp.
60-62.
Abstract:
By means of this approach, a constructive method of pandiagonal magic squares is proposed. Pandiagonalmagic squares of order mn can be generated via two ones which are orders m and n, respectively.
By means of this approach, a constructive method of pandiagonal magic squares is proposed. Pandiagonalmagic squares of order mn can be generated via two ones which are orders m and n, respectively.
1997, vol. 4, no. 2, pp.
62-62.
Abstract:
The dissolution equilibrium of Bi vapor in liquid iron and the interaction effect of third element were conducted in a sealed Mo reaction chamber by vapor pressure method. The relationship between the standard solution Gibbs free energy of Bi in liquid iron and temperature obtained can be expressed. The interaction coefficients of third elements on Bismuth in liquid iron at 1 873 K can be deduced.
The dissolution equilibrium of Bi vapor in liquid iron and the interaction effect of third element were conducted in a sealed Mo reaction chamber by vapor pressure method. The relationship between the standard solution Gibbs free energy of Bi in liquid iron and temperature obtained can be expressed. The interaction coefficients of third elements on Bismuth in liquid iron at 1 873 K can be deduced.
1997, vol. 4, no. 2, pp.
62-62.
Abstract:
The determination of CaO content in columbite and steel cinder with flame atomic absorption spectrometry is studied. EDTA+TEA is used to eliminate the interferences, in HCI media,with La as releaser. The methods of sample treatment and the CaO in remainder undissolved in acids have been conducted. The result of the determination and recovery of CaO shows that the rate of recovery is 100%~102%, R.S.D<2%.
The determination of CaO content in columbite and steel cinder with flame atomic absorption spectrometry is studied. EDTA+TEA is used to eliminate the interferences, in HCI media,with La as releaser. The methods of sample treatment and the CaO in remainder undissolved in acids have been conducted. The result of the determination and recovery of CaO shows that the rate of recovery is 100%~102%, R.S.D<2%.
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