Search2007 Vol. 14, No. 4
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2007, vol. 14, no. 4, pp.
291-296.
https://doi.org/10.1016/S1005-8850(07)60057-7
Abstract:
To study the mechanism of separating pyrite and dolomite by flotation, the acting mechanisms of WHL depressor and both the minerals were studied by means of thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrareddiffuse reflection spectroscopy (PTIR-DRS), and X-ray photoelectron spectroscopy (XPS). The results indicated that WHL formed metal salts with metal ions dissolved in water from dolomite and pyrite, which then deposited on their surfaces. Both of the minerals could be depressed by WHL. In the process of flotation, sulfur was created besides the WIlL being absorbed on the surface of the sulfur concentrate, and its recovery rate was slightly affected.
To study the mechanism of separating pyrite and dolomite by flotation, the acting mechanisms of WHL depressor and both the minerals were studied by means of thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrareddiffuse reflection spectroscopy (PTIR-DRS), and X-ray photoelectron spectroscopy (XPS). The results indicated that WHL formed metal salts with metal ions dissolved in water from dolomite and pyrite, which then deposited on their surfaces. Both of the minerals could be depressed by WHL. In the process of flotation, sulfur was created besides the WIlL being absorbed on the surface of the sulfur concentrate, and its recovery rate was slightly affected.
2007, vol. 14, no. 4, pp.
297-301.
https://doi.org/10.1016/S1005-8850(07)60058-9
Abstract:
Ground granulated blast furnace slag (GGBFS) and steelmaking slag have been used as a raw material for cement production or as an aggregate to make concrete, which contribute aluminum, calcium, iron, and silicon oxides. The suitability of the slag for a particular application depends on its reactivity, cost, availability, and its influence on the properties of the resulting concrete. For the interest of durability studying of concrete in the presence of slag, the accelerated carbonation products and leaching behavior of the slag and Portland cement (PC) were studied. The experimental results confirmed that the slag was more resistant to carbonation compared to PC. The carbonation degree of GGBFS reduced by 17.74%; and the carbonation degrees of steelmaking slags reduced by 9.51%-11.94%. Carbonation neutralized the alkaline nature of the hydrated pastes and gave rise to the redox potential of the leachate slightly (30-77 mV). The carbonation also increased the release of most of the elements presented, except for calcium, to the aqueous environment. It is concluded that blend cements (PC plus slag) have economical advantages and better durability compared to PC,
Ground granulated blast furnace slag (GGBFS) and steelmaking slag have been used as a raw material for cement production or as an aggregate to make concrete, which contribute aluminum, calcium, iron, and silicon oxides. The suitability of the slag for a particular application depends on its reactivity, cost, availability, and its influence on the properties of the resulting concrete. For the interest of durability studying of concrete in the presence of slag, the accelerated carbonation products and leaching behavior of the slag and Portland cement (PC) were studied. The experimental results confirmed that the slag was more resistant to carbonation compared to PC. The carbonation degree of GGBFS reduced by 17.74%; and the carbonation degrees of steelmaking slags reduced by 9.51%-11.94%. Carbonation neutralized the alkaline nature of the hydrated pastes and gave rise to the redox potential of the leachate slightly (30-77 mV). The carbonation also increased the release of most of the elements presented, except for calcium, to the aqueous environment. It is concluded that blend cements (PC plus slag) have economical advantages and better durability compared to PC,
2007, vol. 14, no. 4, pp.
302-306.
https://doi.org/10.1016/S1005-8850(07)60059-0
Abstract:
The principle and technological design of electroslag continuous casting (ESCC), including bifilar mode, T-shaped mould, and metal level detecting system, are detailed. Remelting was carded out for 1Crl8Ni9Ti stainless steel with ESCC. The surface finish, chemical composition, macroand microstructures, and inclusions of the remelted billets were characterized. ESCC reduces the cost and increases the productivity in comparison to traditional ESR, while achieves comparably excellent products.
The principle and technological design of electroslag continuous casting (ESCC), including bifilar mode, T-shaped mould, and metal level detecting system, are detailed. Remelting was carded out for 1Crl8Ni9Ti stainless steel with ESCC. The surface finish, chemical composition, macroand microstructures, and inclusions of the remelted billets were characterized. ESCC reduces the cost and increases the productivity in comparison to traditional ESR, while achieves comparably excellent products.
2007, vol. 14, no. 4, pp.
307-311.
https://doi.org/10.1016/S1005-8850(07)60060-7
Abstract:
A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace (TTRHF) in compact strip production (CSP). To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI'RI-IF was provided.
A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace (TTRHF) in compact strip production (CSP). To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI'RI-IF was provided.
2007, vol. 14, no. 4, pp.
312-316.
https://doi.org/10.1016/S1005-8850(07)60061-9
Abstract:
On the basis of the effect of carbon precipitation on the microstructure and properties of steel products below A1 temperature, a new thermal treatment method (temper-rapid cooling process) was studied. By the temper-rapid cooling process, the yield strengths of the high strength low carbon (HSLC) steel ZJ330 and SPA-H produced using the compact strip production (CSP) process increased from 340 to about 410 MPa and from 410 to about 450 MPa, respectively. The results indirectly indicated that there existed nanoscaled iron-carbon precipitates that have obvious precipitation effect on low carbon steel produced by CSP. The prospect of application is discussed.
On the basis of the effect of carbon precipitation on the microstructure and properties of steel products below A1 temperature, a new thermal treatment method (temper-rapid cooling process) was studied. By the temper-rapid cooling process, the yield strengths of the high strength low carbon (HSLC) steel ZJ330 and SPA-H produced using the compact strip production (CSP) process increased from 340 to about 410 MPa and from 410 to about 450 MPa, respectively. The results indirectly indicated that there existed nanoscaled iron-carbon precipitates that have obvious precipitation effect on low carbon steel produced by CSP. The prospect of application is discussed.
2007, vol. 14, no. 4, pp.
317-320.
https://doi.org/10.1016/S1005-8850(07)60062-0
Abstract:
The effect of electropulse on the solidification structure of commercially pure aluminium was studied. The orthogonal array L9 was used to determine the effect of three process parameters of electropulse modification (EPM), which were pulse current intensity, pulse frequency, and treating time. For each factor, three levels were chosen to cover the experimental region. According to the experimental results, the solidification structure of commercially pure aluminium was modified from large grains with columnar crystals to finer grains with equiaxed crystals, by allowing the electropulse to act on liquid aluminium. However, the solidification structures could be refined differently at different EPM parameters. Certain EPM parameters should be selected to get the optimum solidification structure. Among the three parameters, pulse frequency was the most important factor influencing the solidification structure, the secondary factor was current intensity, and treating time was the third one. The optimum parameters were the pulse frequency of 5 Hz, the current intensity of 68 A, and the treating time of 10 s.
The effect of electropulse on the solidification structure of commercially pure aluminium was studied. The orthogonal array L9 was used to determine the effect of three process parameters of electropulse modification (EPM), which were pulse current intensity, pulse frequency, and treating time. For each factor, three levels were chosen to cover the experimental region. According to the experimental results, the solidification structure of commercially pure aluminium was modified from large grains with columnar crystals to finer grains with equiaxed crystals, by allowing the electropulse to act on liquid aluminium. However, the solidification structures could be refined differently at different EPM parameters. Certain EPM parameters should be selected to get the optimum solidification structure. Among the three parameters, pulse frequency was the most important factor influencing the solidification structure, the secondary factor was current intensity, and treating time was the third one. The optimum parameters were the pulse frequency of 5 Hz, the current intensity of 68 A, and the treating time of 10 s.
2007, vol. 14, no. 4, pp.
321-326.
https://doi.org/10.1016/S1005-8850(07)60063-2
Abstract:
A pulsed Nd:YAG (yttrium aluminum garnet) laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), with associated energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The microhardness was also measured along the depth direction of the specimens, A crack- and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized single-track and multi-track laser cladding. The phases of the coating are a-Fe, T-Fe, and FeSi. The high microhardness of the lasercladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt% in the single-track cladding and 6.5wt% in the multi-track cladding, respectively.
A pulsed Nd:YAG (yttrium aluminum garnet) laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), with associated energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The microhardness was also measured along the depth direction of the specimens, A crack- and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized single-track and multi-track laser cladding. The phases of the coating are a-Fe, T-Fe, and FeSi. The high microhardness of the lasercladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt% in the single-track cladding and 6.5wt% in the multi-track cladding, respectively.
2007, vol. 14, no. 4, pp.
327-330.
https://doi.org/10.1016/S1005-8850(07)60064-4
Abstract:
The effect of austenitization heat treatment on magnetic properties was examined by means of Mössbauer spectroscopy on an Fe-40wt%Ni-2wt%Mn alloy. The morphology of the alloy was obtained by using scanning electron microscopy (SEM) under different heat treatment conditions. The magnetic behavior of the non heat-treated alloy is ferromagnetic. A mixed magnetic structure including both paramagnetic and ferromagnetic states was obtained at 800℃ after 6 and 12 h heat treatments. In addition, the magnetic structure of the heat-treated alloy at 1150℃ for 12 h was ferromagnetic. With the volume fraction changing, the effective hyperfine field of the ferromagnetic austenite phase and isomery shift values were also determined by Mtssbauer spectroscopy.
The effect of austenitization heat treatment on magnetic properties was examined by means of Mössbauer spectroscopy on an Fe-40wt%Ni-2wt%Mn alloy. The morphology of the alloy was obtained by using scanning electron microscopy (SEM) under different heat treatment conditions. The magnetic behavior of the non heat-treated alloy is ferromagnetic. A mixed magnetic structure including both paramagnetic and ferromagnetic states was obtained at 800℃ after 6 and 12 h heat treatments. In addition, the magnetic structure of the heat-treated alloy at 1150℃ for 12 h was ferromagnetic. With the volume fraction changing, the effective hyperfine field of the ferromagnetic austenite phase and isomery shift values were also determined by Mtssbauer spectroscopy.
2007, vol. 14, no. 4, pp.
331-334.
https://doi.org/10.1016/S1005-8850(07)60065-6
Abstract:
The Fe3Al-based intermetallics were prepared by mechanical alloying and spark plasma sintering (SPS), and the influence of milling time on the properties of materials was investigated. The phase identification was investigated by X-ray, and the surface morphology and fractography were observed by scanning electron microscope (SEM). The mechanical properties such as bending strength, strain, and microhardness were tested. The results show that Fe reacts with Al completely to form Fe3Al during short SPS processing time. The relative densities of the sintered samples were nearly 100%. The mechanical properties of the sintered samples can be improved along with the milling time. The representative values are the bend strength of 1327 MPa and the microhardness of 434.
The Fe3Al-based intermetallics were prepared by mechanical alloying and spark plasma sintering (SPS), and the influence of milling time on the properties of materials was investigated. The phase identification was investigated by X-ray, and the surface morphology and fractography were observed by scanning electron microscope (SEM). The mechanical properties such as bending strength, strain, and microhardness were tested. The results show that Fe reacts with Al completely to form Fe3Al during short SPS processing time. The relative densities of the sintered samples were nearly 100%. The mechanical properties of the sintered samples can be improved along with the milling time. The representative values are the bend strength of 1327 MPa and the microhardness of 434.
2007, vol. 14, no. 4, pp.
335-340.
https://doi.org/10.1016/S1005-8850(07)60066-8
Abstract:
The development of microstructure during the aging of Ti-10V-2Fe-3A1 alloy in the 13 and (α+β) solution-treated and quenched conditions was investigated. The results showed that the isothermal holding below 400℃ yielded homogeneously distributed, spherical ω-phase particles. Fine α aggregates are formed uniformly within 13 grains by nucleating at at particles or β/ω interfaces. At higher temperatures, thin martensite plates decomposed in water-quenched condition. The formation of ω phase was avoided and coarse coarse α-phase plates directly precipitated from the 13 matrix. The highest hardness values were found when the alloys were aged at 400℃ for 8 h. The significance of the observations was discussed in terms of the effect of aging on the precipitations and property.
The development of microstructure during the aging of Ti-10V-2Fe-3A1 alloy in the 13 and (α+β) solution-treated and quenched conditions was investigated. The results showed that the isothermal holding below 400℃ yielded homogeneously distributed, spherical ω-phase particles. Fine α aggregates are formed uniformly within 13 grains by nucleating at at particles or β/ω interfaces. At higher temperatures, thin martensite plates decomposed in water-quenched condition. The formation of ω phase was avoided and coarse coarse α-phase plates directly precipitated from the 13 matrix. The highest hardness values were found when the alloys were aged at 400℃ for 8 h. The significance of the observations was discussed in terms of the effect of aging on the precipitations and property.
2007, vol. 14, no. 4, pp.
341-344.
https://doi.org/10.1016/S1005-8850(07)60067-X
Abstract:
The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires (QWR) superlattices (SLS) was studied. The transmission electron microscopy (TEM) results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers (MLs) InAs deposition. In addition, the zig-zag features along the extending direction and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carders between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.
The influence of InAs deposition thickness on the structural and optical properties of InAs/InA1As quantum wires (QWR) superlattices (SLS) was studied. The transmission electron microscopy (TEM) results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers (MLs) InAs deposition. In addition, the zig-zag features along the extending direction and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carders between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.
2007, vol. 14, no. 4, pp.
345-349.
https://doi.org/10.1016/S1005-8850(07)60068-1
Abstract:
SnSb alloy powders for the anode of Li-ion batteries were synthesized by two kinds of reduction precipitation methods: solution titration and rapid mixing. Two kinds of SnSb alloy powders showed different phase compositions and particle morphologies although the same starting materials were used. The SnSb alloy electrode synthesized by titration exhibits high reversible specific capacity and good cycling stability, whereas the rapid-mixing sample shows high irreversible capacity and fast capacity fade. The broad particle size distribution of SnSb powders synthesized by titration is considered to be responsible for the improvement of cycling stability. The initial charge-discharge efficiency exceeding 80% has been obtained for the titration sample. The electrochemical reaction process of two kinds of synthesized SnSb composite electrodes was characterized by cyclic voltammetry and AC impedance techniques.
SnSb alloy powders for the anode of Li-ion batteries were synthesized by two kinds of reduction precipitation methods: solution titration and rapid mixing. Two kinds of SnSb alloy powders showed different phase compositions and particle morphologies although the same starting materials were used. The SnSb alloy electrode synthesized by titration exhibits high reversible specific capacity and good cycling stability, whereas the rapid-mixing sample shows high irreversible capacity and fast capacity fade. The broad particle size distribution of SnSb powders synthesized by titration is considered to be responsible for the improvement of cycling stability. The initial charge-discharge efficiency exceeding 80% has been obtained for the titration sample. The electrochemical reaction process of two kinds of synthesized SnSb composite electrodes was characterized by cyclic voltammetry and AC impedance techniques.
2007, vol. 14, no. 4, pp.
350-355.
https://doi.org/10.1016/S1005-8850(07)60069-3
Abstract:
The effect of sliding duration on the tribological behaviors of spot patterned coatings was investigated. Two patterns based on physical vapor deposition (PVD) TiN coatings were used, such as, in-lined (IN) and staggered (ST) spots. The tribological behaviors were evaluated by using a Cameron-Plint wear test rig. The M2 steel discs deposited TiN coatings with IN and ST patterns slid against the ASSAB 17 tool steel pins at a speed of 0.23 m/s, in Shell Tellus T32 lubricant and were loaded with 900 N. The testing results on disc specimens with two types of PVD TiN spot patterns, all coated with a bias voltage of -180 V and slid for 4, 8 and 11 h respectively, were presented. The results revealed that the in-lined coatings possessed relatively better wear behaviors than the staggered pattern coatings. Mechanisms for such superiority and for the cause of peeling were discussed. A relevant design approach was suggested for the application of such patterned coatings.
The effect of sliding duration on the tribological behaviors of spot patterned coatings was investigated. Two patterns based on physical vapor deposition (PVD) TiN coatings were used, such as, in-lined (IN) and staggered (ST) spots. The tribological behaviors were evaluated by using a Cameron-Plint wear test rig. The M2 steel discs deposited TiN coatings with IN and ST patterns slid against the ASSAB 17 tool steel pins at a speed of 0.23 m/s, in Shell Tellus T32 lubricant and were loaded with 900 N. The testing results on disc specimens with two types of PVD TiN spot patterns, all coated with a bias voltage of -180 V and slid for 4, 8 and 11 h respectively, were presented. The results revealed that the in-lined coatings possessed relatively better wear behaviors than the staggered pattern coatings. Mechanisms for such superiority and for the cause of peeling were discussed. A relevant design approach was suggested for the application of such patterned coatings.
2007, vol. 14, no. 4, pp.
356-360.
https://doi.org/10.1016/S1005-8850(07)60070-X
Abstract:
The glass-transition behavior of Pd40Cu30Ni10P20 bulk metallic glass was investigated by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The effect of pressure on the crystallization behavior of Pd40Cu30Ni10P20 bulk glass was studied by in situ high-pressure and high-temperature X-ray powder diffraction using synchrotron radiation. Phase analyses show at least six crystalline phases in the crystallized sample, namely, monoclinic, tetragonal CuaPd-like, rhombohedral, fcc-Ni2Pd2P, fcc-(Ni, Pd) solid solution, and body-centered tetragonal (bct) NiaP-like phases. The onset crystallization temperature increases with pressure having a slope of 1 1 K/GPa in the range of 0 to 4 GPa. The results are attributed to the competing process between the thermodynamic potential barrier and the diffusion activation energy under pressure.
The glass-transition behavior of Pd40Cu30Ni10P20 bulk metallic glass was investigated by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The effect of pressure on the crystallization behavior of Pd40Cu30Ni10P20 bulk glass was studied by in situ high-pressure and high-temperature X-ray powder diffraction using synchrotron radiation. Phase analyses show at least six crystalline phases in the crystallized sample, namely, monoclinic, tetragonal CuaPd-like, rhombohedral, fcc-Ni2Pd2P, fcc-(Ni, Pd) solid solution, and body-centered tetragonal (bct) NiaP-like phases. The onset crystallization temperature increases with pressure having a slope of 1 1 K/GPa in the range of 0 to 4 GPa. The results are attributed to the competing process between the thermodynamic potential barrier and the diffusion activation energy under pressure.
2007, vol. 14, no. 4, pp.
361-364.
https://doi.org/10.1016/S1005-8850(07)60071-1
Abstract:
The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells: one using MgZr4(PO4)6 (MZP) as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively: △$G_Ⅰ^{{\rm{\rlap{-} o}}}$ = -3579-15 T (J/mol) and △$G_Ⅱ^{{\rm{\rlap{-} o}}}$ =6258-24.3 T (J/mol). The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao's and Tretjakov's data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows: △$G_{Ⅰ\;{\rm{Formation}}}^{{\rm{\rlap{-} o}}}$ =-1427394+360.5 T (J/mol) and △$G_{Ⅱ\;{\rm{Formation}}}^{{\rm{\rlap{-} o}}}$ =-1417557+351.2 T (J/mol).
The standard Gibbs free energy of formation of magnesium ferrite was determined by means of two types of solid state electrochemical cells: one using MgZr4(PO4)6 (MZP) as the solid electrolyte and the other using CaF2 as the solid electrolyte. The first cell was operated in the range of 950 to 1100 K. The second cell was operated in the range of 1125 to 1200 K. The reversibility of the cell EMFs was confirmed by microcoulometric titration. The Gibbs energy changes of magnesium ferrite relative to component oxides were calculated based on EMF measurements and are given by following expressions, respectively: △$G_Ⅰ^{{\rm{\rlap{-} o}}}$ = -3579-15 T (J/mol) and △$G_Ⅱ^{{\rm{\rlap{-} o}}}$ =6258-24.3 T (J/mol). The results obtained from two different cells are consistent with each other. The results also are in agreement with Rao's and Tretjakov's data in the measured temperature range. When the Gibbs free energies of formation of MgO and Fe203 were substituted in the reaction, the Gibbs free energies of formation of MgFe204 was obtained in two temperature ranges and the for mations are shown as follows: △$G_{Ⅰ\;{\rm{Formation}}}^{{\rm{\rlap{-} o}}}$ =-1427394+360.5 T (J/mol) and △$G_{Ⅱ\;{\rm{Formation}}}^{{\rm{\rlap{-} o}}}$ =-1417557+351.2 T (J/mol).
2007, vol. 14, no. 4, pp.
365-368.
https://doi.org/10.1016/S1005-8850(07)60072-3
Abstract:
Optical emission spectroscopy (OES) was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition (CVD). C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments (DOE). An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination, or are consumed on the substrate surface where chemical reactions occur.
Optical emission spectroscopy (OES) was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition (CVD). C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments (DOE). An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination, or are consumed on the substrate surface where chemical reactions occur.
2007, vol. 14, no. 4, pp.
369-372.
https://doi.org/10.1016/S1005-8850(07)60073-5
Abstract:
Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol (PEG). The obtained materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermo gravimetric analyzer and differential scanning calorimetry (TG-DSC), nitrogen adsorption-desorption measurements, and X-ray diffraction (XRD). The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cma/g, a BET specific surface area of 361.55 m2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.
Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol (PEG). The obtained materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermo gravimetric analyzer and differential scanning calorimetry (TG-DSC), nitrogen adsorption-desorption measurements, and X-ray diffraction (XRD). The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cma/g, a BET specific surface area of 361.55 m2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.
2007, vol. 14, no. 4, pp.
373-377.
https://doi.org/10.1016/S1005-8850(07)60074-7
Abstract:
Three kinds of fluorinated Schiff's base esters, 4-allyloxy-2-X-6-X-benzoic acid 4-[(2, 3, 4-trifluorophenylimino)methyl]phenyl ester, where X=H or F, were synthesized and characterized. Their chemical structures were identified by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR). Their mesomorphic properties were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). It was found that all the three compounds exhibited enantiotropic nematic phases only. And their cleating point temperature and thermal range of mesophase decreased with the number of fluorine atoms on the rigid core of the compounds; while their melting point temperature showed no distinct regularity.
Three kinds of fluorinated Schiff's base esters, 4-allyloxy-2-X-6-X-benzoic acid 4-[(2, 3, 4-trifluorophenylimino)methyl]phenyl ester, where X=H or F, were synthesized and characterized. Their chemical structures were identified by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR). Their mesomorphic properties were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). It was found that all the three compounds exhibited enantiotropic nematic phases only. And their cleating point temperature and thermal range of mesophase decreased with the number of fluorine atoms on the rigid core of the compounds; while their melting point temperature showed no distinct regularity.
2007, vol. 14, no. 4, pp.
378-380.
https://doi.org/10.1016/S1005-8850(07)60075-9
Abstract:
Mathematical analysis of continuous variable crown (CVC) roll contour used in CSP production line was conducted and the roll contour function of CVC roll was obtained. The validation with actual CVC roll contour shows that the calculation values of the roll contour function and the actual roll contour parameters given by equipment provider are the same, which proves that the roll contour function of CVC rolls given in this article is correct. The nonlinear relationship between the roll crown of CVC rolls and roll shift amounts was deduced. The concept of crown extremum was given.
Mathematical analysis of continuous variable crown (CVC) roll contour used in CSP production line was conducted and the roll contour function of CVC roll was obtained. The validation with actual CVC roll contour shows that the calculation values of the roll contour function and the actual roll contour parameters given by equipment provider are the same, which proves that the roll contour function of CVC rolls given in this article is correct. The nonlinear relationship between the roll crown of CVC rolls and roll shift amounts was deduced. The concept of crown extremum was given.
2007, vol. 14, no. 4, pp.
381-386.
https://doi.org/10.1016/S1005-8850(07)60076-0
Abstract:
The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.
The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.
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