Search2007 Vol. 14, No. 3
Display Method:
2007, vol. 14, no. 3, pp.
195-199.
https://doi.org/10.1016/S1005-8850(07)60038-3
Abstract:
The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instrumented drilling system as a ground investigation tool in the detection of other lithology formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system (DPM) for drilling in an intricate decomposed granite site. In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confidence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.
The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instrumented drilling system as a ground investigation tool in the detection of other lithology formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system (DPM) for drilling in an intricate decomposed granite site. In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confidence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.
2007, vol. 14, no. 3, pp.
200-203.
https://doi.org/10.1016/S1005-8850(07)60039-5
Abstract:
The separation of rutile from apatite by flotation and the mechanism of depressing the apatite of sodium hexametaphosphate were studied. The results showed that rutile and apatite could be separated by using alkyl-imino-bismethylene phosphoric acid and sodium hexametaphosphate as a collector and a regulator, respectively. Sodium hexametaphosphate could selectively dissolve calcium ions on the apatite surface, and make calcium ions break away from lattice binding through combining.
The separation of rutile from apatite by flotation and the mechanism of depressing the apatite of sodium hexametaphosphate were studied. The results showed that rutile and apatite could be separated by using alkyl-imino-bismethylene phosphoric acid and sodium hexametaphosphate as a collector and a regulator, respectively. Sodium hexametaphosphate could selectively dissolve calcium ions on the apatite surface, and make calcium ions break away from lattice binding through combining.
2007, vol. 14, no. 3, pp.
204-211.
https://doi.org/10.1016/S1005-8850(07)60040-1
Abstract:
The calculating models of mass action concentrations for electrolyte aqueous solutions NaBr-H2O, LiNO3-H2O, HNO3-H2O, and KF-H2O have been developed at 298.15 K and their molalities ranging from 0.1 mol/kg to saturation according to the ion and molecule coexistence theory as well as mass action law. The calculated mass action concentration is based on pure species as the standard state and the mole fraction as the concentration unit, and the reported activities are usually based on infinite dilution as the standard state and molality as the concentration unit. Hence, the calculated mass action concentration must be transformed to the same standard state and concentration unit. The transformation coefficients between calculated mass action concentrations and reported activities of the same component fluctuate in a very narrow range. Thus, the transformed mass action concentrations not only agree well with reported activities, but also strictly obey mass action law. The calculated results show that the new developed models can embody the intrinsic structure of investigated four electrolyte aqueous solutions. The results also indicate that mass action law has its widespread applicability to electrolyte binary aqueous solutions.
The calculating models of mass action concentrations for electrolyte aqueous solutions NaBr-H2O, LiNO3-H2O, HNO3-H2O, and KF-H2O have been developed at 298.15 K and their molalities ranging from 0.1 mol/kg to saturation according to the ion and molecule coexistence theory as well as mass action law. The calculated mass action concentration is based on pure species as the standard state and the mole fraction as the concentration unit, and the reported activities are usually based on infinite dilution as the standard state and molality as the concentration unit. Hence, the calculated mass action concentration must be transformed to the same standard state and concentration unit. The transformation coefficients between calculated mass action concentrations and reported activities of the same component fluctuate in a very narrow range. Thus, the transformed mass action concentrations not only agree well with reported activities, but also strictly obey mass action law. The calculated results show that the new developed models can embody the intrinsic structure of investigated four electrolyte aqueous solutions. The results also indicate that mass action law has its widespread applicability to electrolyte binary aqueous solutions.
2007, vol. 14, no. 3, pp.
212-218.
https://doi.org/10.1016/S1005-8850(07)60041-3
Abstract:
The chemical composition in a cross section of a high grade pipeline slab was measured point by point (in a scale of 1 μm) using original position statistic distribution analysis (OPA). The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab.
The chemical composition in a cross section of a high grade pipeline slab was measured point by point (in a scale of 1 μm) using original position statistic distribution analysis (OPA). The result indicated that negative segregation strips of Si, Mn, Mo, Ni, Cr, Nb, Cu, Ti, and V exist in the two sides 24 mm away from the central line, with a width of 8-12 mm, Negative segregation inside the central line is more severe than that outside the central line, and the highest positive segregation of the elements appears closely by the inner sides of the negative segregation strips. No obvious negative segregation strip of S and P is found. Segregation of the elements in the central area is higher than that in the outer and inner arc areas. The segregation of C, Ti, S, and P is high and that of Cr, Cu, Si, and Mn is low in the slab.
2007, vol. 14, no. 3, pp.
219-224.
https://doi.org/10.1016/S1005-8850(07)60042-5
Abstract:
Mold fluxes having adaptable properties were developed in the laboratory to solve quality defects, such as depressions and longitudinal cracks when casting hypo-peritectic steel at high casting speed. Firstly, the effect of components on the high basicity mold flux properties was first studied using the orthogonal method. In the scope of the studied content, Li2O has the largest effect on the melting temperature, and the least effect on the viscosity; CaF2 has the largest effect on the viscosity, and the least effect on the melting temperature; Na2O and CaO/SiO2 have no obvious influence on the melting temperature and viscosity. Secondly, two powders (Z1 and Z6) have reasonable viscosity-temperature curves, higher solidification temperatures, and porous structure after solidification, but the crystal property of Z6 is worse than that of Z1, and thus Z1 is more suitable for continuous casting hypo-peritectic steel at high casting speed. Thirdly, a higher basicity of powder, a less free enthalpy of crystal compound, and a lower baffle energy are good for a higher tendentiousness of crystal.
Mold fluxes having adaptable properties were developed in the laboratory to solve quality defects, such as depressions and longitudinal cracks when casting hypo-peritectic steel at high casting speed. Firstly, the effect of components on the high basicity mold flux properties was first studied using the orthogonal method. In the scope of the studied content, Li2O has the largest effect on the melting temperature, and the least effect on the viscosity; CaF2 has the largest effect on the viscosity, and the least effect on the melting temperature; Na2O and CaO/SiO2 have no obvious influence on the melting temperature and viscosity. Secondly, two powders (Z1 and Z6) have reasonable viscosity-temperature curves, higher solidification temperatures, and porous structure after solidification, but the crystal property of Z6 is worse than that of Z1, and thus Z1 is more suitable for continuous casting hypo-peritectic steel at high casting speed. Thirdly, a higher basicity of powder, a less free enthalpy of crystal compound, and a lower baffle energy are good for a higher tendentiousness of crystal.
2007, vol. 14, no. 3, pp.
225-230.
https://doi.org/10.1016/S1005-8850(07)60043-7
Abstract:
A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed. The preparation technology includes the following steps: (1) calcining the hydromagnesite at 700-750℃ for 1.5-2 h; (2) hydrating the calcined hydromagnesite to be slurry containing the solid-liquid ratio of 15-20 g·L-1; (3) acquiring Mg(HCO3)2 solution by carbonating the slurry, the carbonation temperature, CO2 pressure, and end point PH value of carbonation are less than 40℃, 0.4-0.6 MPa, and 7 respectively during the carbonation process; (4) preparing precipitated basic magnesium carbonate by thermally decomposing the Mg(HCO3)2 solution at 90-100℃; (5) obtaining the MgO product by calcining the precipitated basic magnesium carbonate at 850-950℃ for 30-60 min, and adopting flowing nitrogen during the cooling process. By using this technology, more than 80wt% magnesium in hydromagnesite mineral can be extracted, and high-performance MgO products used in special silicon steel can be obtained.
A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed. The preparation technology includes the following steps: (1) calcining the hydromagnesite at 700-750℃ for 1.5-2 h; (2) hydrating the calcined hydromagnesite to be slurry containing the solid-liquid ratio of 15-20 g·L-1; (3) acquiring Mg(HCO3)2 solution by carbonating the slurry, the carbonation temperature, CO2 pressure, and end point PH value of carbonation are less than 40℃, 0.4-0.6 MPa, and 7 respectively during the carbonation process; (4) preparing precipitated basic magnesium carbonate by thermally decomposing the Mg(HCO3)2 solution at 90-100℃; (5) obtaining the MgO product by calcining the precipitated basic magnesium carbonate at 850-950℃ for 30-60 min, and adopting flowing nitrogen during the cooling process. By using this technology, more than 80wt% magnesium in hydromagnesite mineral can be extracted, and high-performance MgO products used in special silicon steel can be obtained.
2007, vol. 14, no. 3, pp.
231-235.
https://doi.org/10.1016/S1005-8850(07)60044-9
Abstract:
The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope (OM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy (Fe, Cr)23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and (Cr, V)2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular (Fe, Cr)23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.
The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope (OM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy (Fe, Cr)23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and (Cr, V)2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular (Fe, Cr)23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.
2007, vol. 14, no. 3, pp.
236-239.
https://doi.org/10.1016/S1005-8850(07)60045-0
Abstract:
The variation in altitude density function (ADF) of the surface topography of mild steel during electrochemical polishing (ECP) was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distributions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.
The variation in altitude density function (ADF) of the surface topography of mild steel during electrochemical polishing (ECP) was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distributions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.
2007, vol. 14, no. 3, pp.
240-245.
https://doi.org/10.1016/S1005-8850(07)60046-2
Abstract:
The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the accuracy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates (percent of shape index satisfying requirement) of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.
The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the accuracy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates (percent of shape index satisfying requirement) of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.
2007, vol. 14, no. 3, pp.
246-250.
https://doi.org/10.1016/S1005-8850(07)60047-4
Abstract:
The ageing behavior of a pre-stretched thick plate of Al-Zn-Mg-Cu alloy was systemically studied including one-step ageing, two-step ageing, and retrogression and reageing treatment (RRA). One-step ageing of the alloy resulted in peak ultimate tensile strengths of 595 and 575 MPa after 22 and 6 h at 120 and 135℃, respectively. The strengthening phase in peak aged (T6 temper) alloy contained GP zones and the η' phase predominantly. After two-step ageing, the electrical conductivity was increased markedly, but the pre-stretched thick plate sacrificed a great loss of strength. RRA treatment provided a method for maintaining the strength close to that obtained by T6 temper and for obtaining the high electrical conductivity close to that obtained by T7 temper; the ultimate tensile strength and electrical conductivity were 583 MPa and 21.0 MS/m, respectively. TEM analysis of T7 and RRA specimens revealed two types of precipitates that contributed to age strengthening i.e. the η' and η phases.
The ageing behavior of a pre-stretched thick plate of Al-Zn-Mg-Cu alloy was systemically studied including one-step ageing, two-step ageing, and retrogression and reageing treatment (RRA). One-step ageing of the alloy resulted in peak ultimate tensile strengths of 595 and 575 MPa after 22 and 6 h at 120 and 135℃, respectively. The strengthening phase in peak aged (T6 temper) alloy contained GP zones and the η' phase predominantly. After two-step ageing, the electrical conductivity was increased markedly, but the pre-stretched thick plate sacrificed a great loss of strength. RRA treatment provided a method for maintaining the strength close to that obtained by T6 temper and for obtaining the high electrical conductivity close to that obtained by T7 temper; the ultimate tensile strength and electrical conductivity were 583 MPa and 21.0 MS/m, respectively. TEM analysis of T7 and RRA specimens revealed two types of precipitates that contributed to age strengthening i.e. the η' and η phases.
2007, vol. 14, no. 3, pp.
251-255.
https://doi.org/10.1016/S1005-8850(07)60048-6
Abstract:
Densification behavior of high Nb containing TiAl alloys through reactive hot pressing was investigated. The results showed that the density of the sample hot pressed at 1400℃ could reach a near full density of 98.37%. However, the densification abnormality was observed at 1500℃. The diffusion of elemental Nb during microstructural evolution is an important aspect affecting densification, which will form pore nests. With the increase of hot pressing temperature, the diffusion of Nb becomes more adequate. HIP (Hot isostatic pressing) treatment can only decrease porosity to some extent, but cannot eliminate it completely.
Densification behavior of high Nb containing TiAl alloys through reactive hot pressing was investigated. The results showed that the density of the sample hot pressed at 1400℃ could reach a near full density of 98.37%. However, the densification abnormality was observed at 1500℃. The diffusion of elemental Nb during microstructural evolution is an important aspect affecting densification, which will form pore nests. With the increase of hot pressing temperature, the diffusion of Nb becomes more adequate. HIP (Hot isostatic pressing) treatment can only decrease porosity to some extent, but cannot eliminate it completely.
2007, vol. 14, no. 3, pp.
256-260.
https://doi.org/10.1016/S1005-8850(07)60049-8
Abstract:
Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and -196℃ were performed to investigate the effects of Al addition substituting Ni on the phase transformation behaviors, the mechanical properties, and the shape memory effects of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys. It is found that 1at% Al addition dramatically decreases the martensitic start transformation temperature and expands the transformation temperature range of R-phase for TiNiFeAl alloys. The results of tensile test indicate that 1at% Al improves the yield strength of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys by 40% and 64%, but decreases the plasticity to 11% and 12% from 26% and 27% respectively. Moreover, excellent shape memory effect of 6.6% and 7.5% were found in Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys, which results from the stress-induced martensite transformation from the R-phase.
Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and -196℃ were performed to investigate the effects of Al addition substituting Ni on the phase transformation behaviors, the mechanical properties, and the shape memory effects of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys. It is found that 1at% Al addition dramatically decreases the martensitic start transformation temperature and expands the transformation temperature range of R-phase for TiNiFeAl alloys. The results of tensile test indicate that 1at% Al improves the yield strength of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys by 40% and 64%, but decreases the plasticity to 11% and 12% from 26% and 27% respectively. Moreover, excellent shape memory effect of 6.6% and 7.5% were found in Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys, which results from the stress-induced martensite transformation from the R-phase.
2007, vol. 14, no. 3, pp.
261-265.
https://doi.org/10.1016/S1005-8850(07)60050-4
Abstract:
A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynamic process of the Al-CrO3-NaF-Al2O3-N2-O2 new material system by the combustion synthesis method was discussed based on the observation results by SEM, EDS, and XRD in combination with the combustion front quenching method (CFQM) and the relation curves between reaction free enthalpies and the corresponding temperatures. The combustion synthesis mechanism and the formation reasons of the phase in the combustion product were analyzed.
A new material with heat-resistant and adiabatic characteristics and high strength was prepared using the combustion synthesis method by mixed powders of CrO3, Al, Al2O3, and NaF in atmospheric gas. The reaction dynamic process of the Al-CrO3-NaF-Al2O3-N2-O2 new material system by the combustion synthesis method was discussed based on the observation results by SEM, EDS, and XRD in combination with the combustion front quenching method (CFQM) and the relation curves between reaction free enthalpies and the corresponding temperatures. The combustion synthesis mechanism and the formation reasons of the phase in the combustion product were analyzed.
2007, vol. 14, no. 3, pp.
266-270.
https://doi.org/10.1016/S1005-8850(07)60051-6
Abstract:
Y2O3-doped ZnO-based varistor ceramics were prepared using high-energy ball milling (HEBM) and low-temperature sintering technique, with voltage-gradient of 1934-2197 V/mm, non-linear coefficients of 20.8-21.8, leakage currents of 0.59-1.04 μA, and densities of 5.46-5.57 g/cm3. With increasing Y2O3 content, the voltage-gradient increases because of the decrease of ZnO grain size; the non-linear coefficient and the leakage current improve but the density decreases because of more porosity; the donor concentration and density of interface states decrease, whereas the barrier height and width increase because of the acceptor effect of Y2O3 in varistor ceramics.
Y2O3-doped ZnO-based varistor ceramics were prepared using high-energy ball milling (HEBM) and low-temperature sintering technique, with voltage-gradient of 1934-2197 V/mm, non-linear coefficients of 20.8-21.8, leakage currents of 0.59-1.04 μA, and densities of 5.46-5.57 g/cm3. With increasing Y2O3 content, the voltage-gradient increases because of the decrease of ZnO grain size; the non-linear coefficient and the leakage current improve but the density decreases because of more porosity; the donor concentration and density of interface states decrease, whereas the barrier height and width increase because of the acceptor effect of Y2O3 in varistor ceramics.
2007, vol. 14, no. 3, pp.
271-275.
https://doi.org/10.1016/S1005-8850(07)60052-8
Abstract:
β-Si3N4 powders prepared by self-propagating high-temperature synthesis (SHS) with additions of Y2O3 and Al2O3 were sintered by spark plasma sintering (SPS). The densification, microstructure, and mechanical properties of Si3N4 ceramics prepared using this method were compared with those obtained by hot pressing process. Well densified Si3N4 ceramics with finer and homogeneous microstructure and better mechanical properties were obtained in the case of the SPS technique at 200℃ lower than that of hot pressing. The microhardness is 15.72 GPa, the bending strength is 716.46 MPa, and the fracture toughness is 7.03 MPa·m1/2.
β-Si3N4 powders prepared by self-propagating high-temperature synthesis (SHS) with additions of Y2O3 and Al2O3 were sintered by spark plasma sintering (SPS). The densification, microstructure, and mechanical properties of Si3N4 ceramics prepared using this method were compared with those obtained by hot pressing process. Well densified Si3N4 ceramics with finer and homogeneous microstructure and better mechanical properties were obtained in the case of the SPS technique at 200℃ lower than that of hot pressing. The microhardness is 15.72 GPa, the bending strength is 716.46 MPa, and the fracture toughness is 7.03 MPa·m1/2.
2007, vol. 14, no. 3, pp.
276-279.
https://doi.org/10.1016/S1005-8850(07)60053-X
Abstract:
A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al(SO4)2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.
A γ-Al2O3 particles reinforced Al-Si alloy matrix composite was fabricated by adding NH4Al(SO4)2 to molten aluminum alloy. TEM observation shows that in-situ γ-Al2O3 particles are generally spherical and uniformly distributed in the matrix. The results of dry sliding wear tests show that the wear resistance of the composites increases with increasing mass fraction, and the volume loss is considerably lesser than that of the matrix and is lesser than that of the composites by adding γ-Al2O3 particles directly.
2007, vol. 14, no. 3, pp.
280-285.
https://doi.org/10.1016/S1005-8850(07)60054-1
Abstract:
The scattering of elastic waves by a spherical particle with imperfect interface and the nondestructive detection of interfacial damage were studied. First, the scattering of elastic waves by a spherical particle with imperfect interface, i.e. spring interface model, was studied. Then, multiple scattering by random distributed particles was investigated and the equations to evaluate the velocity and attenuation of effective waves defined by statistic averaging were given. Furthermore, on the basis of the established relation between the velocity and interfacial constants, a method to evaluate the interfacial damage nondestructively from the ultrasonic data was proposed. Numerical simulation was performed for the SiC-Al composites. The velocities of the effective waves were computed to show the influence of the interface constants. Using the genetic algorithm, the interfacial damage was evaluated from the synthetic experimental data with various noise levels. The numerical results showed the feasibility of the method proposed.
The scattering of elastic waves by a spherical particle with imperfect interface and the nondestructive detection of interfacial damage were studied. First, the scattering of elastic waves by a spherical particle with imperfect interface, i.e. spring interface model, was studied. Then, multiple scattering by random distributed particles was investigated and the equations to evaluate the velocity and attenuation of effective waves defined by statistic averaging were given. Furthermore, on the basis of the established relation between the velocity and interfacial constants, a method to evaluate the interfacial damage nondestructively from the ultrasonic data was proposed. Numerical simulation was performed for the SiC-Al composites. The velocities of the effective waves were computed to show the influence of the interface constants. Using the genetic algorithm, the interfacial damage was evaluated from the synthetic experimental data with various noise levels. The numerical results showed the feasibility of the method proposed.
2007, vol. 14, no. 3, pp.
286-289.
https://doi.org/10.1016/S1005-8850(07)60055-3
Abstract:
The acrylonitrile-butadiene-styrene (ABS) surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results showed that with the increase of Pd concentration in the etching solution the ABS surface roughness reduced. The ratio of O to C increases and forms a large amount of O=C-O functional groups by dipping into Pd contained etching solution, thus the amount of colloids palladium adsorption increases. The carboxyl group acts as the adsorption site for the Pd/Sn catalyst.
The acrylonitrile-butadiene-styrene (ABS) surface was etched by dipping it into chromic acid-sulfuric acid containing a trace amount of palladium. The surface roughness, activity, and valence bond were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results showed that with the increase of Pd concentration in the etching solution the ABS surface roughness reduced. The ratio of O to C increases and forms a large amount of O=C-O functional groups by dipping into Pd contained etching solution, thus the amount of colloids palladium adsorption increases. The carboxyl group acts as the adsorption site for the Pd/Sn catalyst.
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