Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfur...Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.展开更多
Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)score...Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)scores.Methods:A total of 80 periodontitis patients who received implant restoration in our hospital from May 2023 to May 2025 were selected as research subjects.They were randomly divided into an observation group and a control group using a random number table method,with 40 cases in each group.The observation group used the digital intraoral scanning impression technique to obtain impressions,while the control group used the traditional silicone rubber impression technique.The impression-taking time,the number of prostheses try-ins,implant survival rate,periodontal health indicators(probing depth,gingival index,bleeding index),and VAS scores(pain during treatment and comfort after restoration)were compared between the two groups.Results:The observation group was superior to the control group in terms of impression-taking time,the number of prostheses try-ins,and implant survival rate(p<0.05).Six months after restoration,the improvement in periodontal health indicators in the observation group was significantly better than that in the control group(p<0.05).In addition,the pain VAS score of the observation group during treatment was lower than that of the control group,and the comfort VAS score after restoration was higher than that of the control group(p<0.05).Conclusion:Digital intraoral scanning impression technology can effectively enhance the efficiency and success rate of implant restoration in periodontitis patients,improve periodontal health,alleviate patients’discomfort during treatment,and increase post-restoration comfort,demonstrating high clinical application value.展开更多
Background: The distribution of forest vegetation within urban environments is critically important as it influences urban environmental conditions and the energy exchange through the absorption of solar radiation and...Background: The distribution of forest vegetation within urban environments is critically important as it influences urban environmental conditions and the energy exchange through the absorption of solar radiation and modulation of evapotranspiration. It also plays an important role filtering urban water systems and reducing storm water runoff.Methods: We investigate the capacity of ALS data to individually detect, map and characterize large(taller than15 m) trees within the City of Vancouver. Large trees are critical for the function and character of Vancouver’s urban forest. We used an object-based approach for individual tree detection and segmentation to determine tree locations(position of the stem), to delineate the shape of the crowns and to categorize the latter either as coniferous or deciduous.Results: Results indicate a detection rate of 76.6% for trees > 15 m with a positioning error of 2.11 m(stem location). Extracted tree heights possessed a RMSE of 2.60 m and a bias of-1.87 m, whereas crown diameter was derived with a RMSE of 3.85 m and a bias of-2.06 m. Missed trees are principally a result of undetected treetops occurring in dense, overlapping canopies with more accurate detection and delineation of trees in open areas.Conclusion: By identifying key structural trees across Vancouver’s urban forests, we can better understand their role in providing ecosystem goods and services for city residents.展开更多
Background： Forests are a key component of the global carbon cycle, and research is needed into the effects of human-driven and natural processes on their carbon pools. Airborne laser scanning （ALS） produces detail...Background： Forests are a key component of the global carbon cycle, and research is needed into the effects of human-driven and natural processes on their carbon pools. Airborne laser scanning （ALS） produces detailed 3D maps of forest canopy structure from which aboveground carbon density can be estimated. Working with a ALS dataset collected over the 8049-km2 Wellington Region of New Zealand we create maps of indigenous forest carbon and evaluate the influence of wind by examining how carbon storage varies with aspect. Storms flowing from the west are a common cause of disturbance in this region, and we hypothesised that west-facing forests exposed to these winds would be shorter than those in sheltered east-facing sites. Methods： The aboveground carbon density of 31 forest inventory plots located within the ALS survey region were used to develop estimation models relating carbon density to ALS information. Power-law models using rasters of top-of-the-canopy height were compared with models using tree-level information extracted from the ALS dataset. A forest carbon map with spatial resolution of 25 m was generated from ALS maps of forest height and the estimation models. The map was used to evaluate the influences of wind on forests. Results： Power-law models were slightly less accurate than tree-centric models （RMSE 35% vs 32%） but were selected for map generation for computational efficiency. The carbon map comprised 4.5 million natural forest pixels within which canopy height had been measured by ALS, providing an unprecedented dataset with which to examine drivers of carbon density. Forests facing in the direction of westerly storms stored less carbon, as hypothesised. They had much greater above-ground carbon density for a given height than any of 14 tropical forests previously analysed by the same approach, and had exceptionally high basal areas for their height. We speculate that strong winds have kept forests short without impeding basal area growth. Conclusion： Simple estimation models based on top-of-the canopy height are almost as accurate as state-of-the-art tree-centric approaches, which require more computing power. High-resolution carbon maps produced by ALS provide powerful datasets for evaluating the environmental drivers of forest structure, such as wind.展开更多
In order to develop new reference materials for microanalytical nuclear techniques, scanning proton microprobe (SPM) technique was used to determine homogeneity level within 100×200 μm 2 micro area on the small ...In order to develop new reference materials for microanalytical nuclear techniques, scanning proton microprobe (SPM) technique was used to determine homogeneity level within 100×200 μm 2 micro area on the small pieces of IAEA urban dust reference materials. The experimental methods were described in detail. The results show that IAEA 396A/M Vienna urban dust is homogeneous enough for small sample analysis of standard reference material (SRM).展开更多
Advances in imaging have led to the development of several new types of microscopes such as serial block face scanning electron microscopy (SBF-SEM),lightsheet microscopy,as well as X-ray micro-computed tomography (mi...Advances in imaging have led to the development of several new types of microscopes such as serial block face scanning electron microscopy (SBF-SEM),lightsheet microscopy,as well as X-ray micro-computed tomography (micro-CT),which enables the study of samples in fundamentally different ways.展开更多
The aim of this study was to observe the morphological changes of muscle in the process of rigor mortis. The quadriceps of 40 rats at various postmortem intervals were observed under the...The aim of this study was to observe the morphological changes of muscle in the process of rigor mortis. The quadriceps of 40 rats at various postmortem intervals were observed under the scanning electron microscope(SEM) and the light microscope by phosphotungstic acid haematoxylin(PTAH) stain. The results showed that the striations of muscle were blurred within 4 h, but they became apparent from 6 h to 24 h after death. The authors suggest that this phenomenon be associated with the increased resistance of muscle against the postmortal changes. The observations by scanning electron microscopy and light microscopy have revealed that the muscles do contract in the process of rigor mortis because the distance between two Z lines shortens and the I band narrows, compared with those in anaesthetised animals. The basic biochemical process for the formation of rigor mortis is the same as that of muscle contraction except that the former happens postmortem and the latter antemortem.展开更多
In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique ...In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique (EMI) which is based onthe use of piezoelectric Lead Zirconate Titanate (PZT) patches and Scanning LaserDoppler Vibrometry (SLDV) for damage detection purposes of concrete structures andearly age monitoring. Typically the EMI technique utilizes the direct and inversepiezoelectric effect of a PZT patch attached to a host structure via an impedance analyzerthat is used for both the actuation and sensing the response of the PZT-Host structuresystem. In the proposed technique the attached PZTs are actuated via a function generatorand the PZT-Host structure response is obtained by a Scanning Laser DopplerVibrometer. Spectrums of oscillation velocity of the surface of the attached PZTs verticalto the laser beam versus frequency are obtained and are evaluated for SHM purposes.This damage detection approach also includes the use of a damage index denoted asECAR (Ellipse to Circle Area Ratio) based on 2-D error statistics and is compared to theRoot Mean Square Deviation (RMSD) damage index commonly used in SHMapplications. Experimental results include ascending uniaxial compressive load ofconcrete cubic specimens, ascending three point bending of reinforced concrete beamspecimens and early age monitoring of concrete. Results illustrate the efficiency of theproposed technique in damage detection as well as early age monitoring as, in the firstcase, both severity and location of damage can be determined by examining the values ofdamage indices for each damaged state and in the early age monitoring case damageindices follow the strength gain curve.展开更多
The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are revi...The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.展开更多
The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution ki...The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.展开更多
The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods fo...The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.展开更多
The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on t...The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on the butt surface of Q235 steel via laser.The interaction behavior between the short fibers and the molten pool was captured using a high-speed camera.Laser-arc hybrid welding-brazing was then employed to join Al(6061-T6)to the steel.This process successfully created a short fiber-like interface structure at the joint.The relationship between microstructure and mechanical properties was investigated,compared with Al/bare steel(ABS)joint.The research results indicated that the IMCs layer consisted of FeAl_(3)and Fe_(2)Al_(5).The interface strength of the Al/short fiber-like surface structural steel(ASFSSS)joint reached 153.2 MPa,an 82.2%increase compared to the ABS joint,which reached 84.1 MPa.When the ASFSSS joints without the reinforcement were bent to 58.2°and 25.2°in the longitudinal and transverse direction,respectively,they remained intact.However,cracks were discovered when the bending angle of the ABS reached 39.1°and 0°in the two directions.Numerical simulation revealed that the short fiber-like interface structure significantly reduced residual stress and improved the stress distribution in the weld,thereby enhancing the strength and toughness of Al/steel dissimilar joints.The crack propagation path in the ASFSSS joint was deflected into the weld when it encountered short fibers,and the fracture morphology presented the characteristic of ductile-brittle mixed fracture.展开更多
基金supported by the National Key R&D Program of China(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+1 种基金the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of Technology and University of Science and Technology Beijing,China.
文摘Desulfurization of CaO–Al_(2)O_(3) particles in molten steel was observed in situ using high-temperature confocal scanning laser microscopy.The effects of the aluminum and silicon contents of molten steel on desulfurization were analyzed.When the total aluminum content in the steel increased from 6 to 1100 ppm,the CaS content in CaO–Al_(2)O_(3) particles increased from 2.1wt%to 84.84wt%after the reaction for 90 s.Furthermore,when the silicon content in the steel increased from 0.01wt%to 2.20wt%,the CaS content in CaO–Al_(2)O_(3) particles increased from 1.53wt%to 79.01wt%after the reaction for 90 s.This indicates that the increase in the aluminum and silicon contents of the steel promoted the desulfurization of CaO–Al_(2)O_(3) particles.A kinetic model was established to predict the CaO–Al_(2)O_(3) particles composition,and the diffusion coefficient of sulfur in CaO–Al_(2)O_(3) particles was 9.375×10^(−10)m^(2)·s^(−1) at 1600℃,which provided a new method for the calculation of diffusion coefficient.
文摘Objective:To explore the application effect of digital intraoral scanning impression technique in oral implant restoration for periodontitis patients and analyze its impact on patients’Visual Analogue Scale(VAS)scores.Methods:A total of 80 periodontitis patients who received implant restoration in our hospital from May 2023 to May 2025 were selected as research subjects.They were randomly divided into an observation group and a control group using a random number table method,with 40 cases in each group.The observation group used the digital intraoral scanning impression technique to obtain impressions,while the control group used the traditional silicone rubber impression technique.The impression-taking time,the number of prostheses try-ins,implant survival rate,periodontal health indicators(probing depth,gingival index,bleeding index),and VAS scores(pain during treatment and comfort after restoration)were compared between the two groups.Results:The observation group was superior to the control group in terms of impression-taking time,the number of prostheses try-ins,and implant survival rate(p<0.05).Six months after restoration,the improvement in periodontal health indicators in the observation group was significantly better than that in the control group(p<0.05).In addition,the pain VAS score of the observation group during treatment was lower than that of the control group,and the comfort VAS score after restoration was higher than that of the control group(p<0.05).Conclusion:Digital intraoral scanning impression technology can effectively enhance the efficiency and success rate of implant restoration in periodontitis patients,improve periodontal health,alleviate patients’discomfort during treatment,and increase post-restoration comfort,demonstrating high clinical application value.
文摘Background: The distribution of forest vegetation within urban environments is critically important as it influences urban environmental conditions and the energy exchange through the absorption of solar radiation and modulation of evapotranspiration. It also plays an important role filtering urban water systems and reducing storm water runoff.Methods: We investigate the capacity of ALS data to individually detect, map and characterize large(taller than15 m) trees within the City of Vancouver. Large trees are critical for the function and character of Vancouver’s urban forest. We used an object-based approach for individual tree detection and segmentation to determine tree locations(position of the stem), to delineate the shape of the crowns and to categorize the latter either as coniferous or deciduous.Results: Results indicate a detection rate of 76.6% for trees > 15 m with a positioning error of 2.11 m(stem location). Extracted tree heights possessed a RMSE of 2.60 m and a bias of-1.87 m, whereas crown diameter was derived with a RMSE of 3.85 m and a bias of-2.06 m. Missed trees are principally a result of undetected treetops occurring in dense, overlapping canopies with more accurate detection and delineation of trees in open areas.Conclusion: By identifying key structural trees across Vancouver’s urban forests, we can better understand their role in providing ecosystem goods and services for city residents.
基金supported by Ministry of Business, Innovation and Employment core funding to Crown Research Institutes
文摘Background： Forests are a key component of the global carbon cycle, and research is needed into the effects of human-driven and natural processes on their carbon pools. Airborne laser scanning （ALS） produces detailed 3D maps of forest canopy structure from which aboveground carbon density can be estimated. Working with a ALS dataset collected over the 8049-km2 Wellington Region of New Zealand we create maps of indigenous forest carbon and evaluate the influence of wind by examining how carbon storage varies with aspect. Storms flowing from the west are a common cause of disturbance in this region, and we hypothesised that west-facing forests exposed to these winds would be shorter than those in sheltered east-facing sites. Methods： The aboveground carbon density of 31 forest inventory plots located within the ALS survey region were used to develop estimation models relating carbon density to ALS information. Power-law models using rasters of top-of-the-canopy height were compared with models using tree-level information extracted from the ALS dataset. A forest carbon map with spatial resolution of 25 m was generated from ALS maps of forest height and the estimation models. The map was used to evaluate the influences of wind on forests. Results： Power-law models were slightly less accurate than tree-centric models （RMSE 35% vs 32%） but were selected for map generation for computational efficiency. The carbon map comprised 4.5 million natural forest pixels within which canopy height had been measured by ALS, providing an unprecedented dataset with which to examine drivers of carbon density. Forests facing in the direction of westerly storms stored less carbon, as hypothesised. They had much greater above-ground carbon density for a given height than any of 14 tropical forests previously analysed by the same approach, and had exceptionally high basal areas for their height. We speculate that strong winds have kept forests short without impeding basal area growth. Conclusion： Simple estimation models based on top-of-the canopy height are almost as accurate as state-of-the-art tree-centric approaches, which require more computing power. High-resolution carbon maps produced by ALS provide powerful datasets for evaluating the environmental drivers of forest structure, such as wind.
文摘In order to develop new reference materials for microanalytical nuclear techniques, scanning proton microprobe (SPM) technique was used to determine homogeneity level within 100×200 μm 2 micro area on the small pieces of IAEA urban dust reference materials. The experimental methods were described in detail. The results show that IAEA 396A/M Vienna urban dust is homogeneous enough for small sample analysis of standard reference material (SRM).
基金supported by the Awards to JAR from the UK Macular Society,UKRI Quality Research Strategic Priorities Fund from Public Policy Southampton (New Things Fund) as well as the Gift of Sight Appeal。
文摘Advances in imaging have led to the development of several new types of microscopes such as serial block face scanning electron microscopy (SBF-SEM),lightsheet microscopy,as well as X-ray micro-computed tomography (micro-CT),which enables the study of samples in fundamentally different ways.
文摘The aim of this study was to observe the morphological changes of muscle in the process of rigor mortis. The quadriceps of 40 rats at various postmortem intervals were observed under the scanning electron microscope(SEM) and the light microscope by phosphotungstic acid haematoxylin(PTAH) stain. The results showed that the striations of muscle were blurred within 4 h, but they became apparent from 6 h to 24 h after death. The authors suggest that this phenomenon be associated with the increased resistance of muscle against the postmortal changes. The observations by scanning electron microscopy and light microscopy have revealed that the muscles do contract in the process of rigor mortis because the distance between two Z lines shortens and the I band narrows, compared with those in anaesthetised animals. The basic biochemical process for the formation of rigor mortis is the same as that of muscle contraction except that the former happens postmortem and the latter antemortem.
文摘In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique (EMI) which is based onthe use of piezoelectric Lead Zirconate Titanate (PZT) patches and Scanning LaserDoppler Vibrometry (SLDV) for damage detection purposes of concrete structures andearly age monitoring. Typically the EMI technique utilizes the direct and inversepiezoelectric effect of a PZT patch attached to a host structure via an impedance analyzerthat is used for both the actuation and sensing the response of the PZT-Host structuresystem. In the proposed technique the attached PZTs are actuated via a function generatorand the PZT-Host structure response is obtained by a Scanning Laser DopplerVibrometer. Spectrums of oscillation velocity of the surface of the attached PZTs verticalto the laser beam versus frequency are obtained and are evaluated for SHM purposes.This damage detection approach also includes the use of a damage index denoted asECAR (Ellipse to Circle Area Ratio) based on 2-D error statistics and is compared to theRoot Mean Square Deviation (RMSD) damage index commonly used in SHMapplications. Experimental results include ascending uniaxial compressive load ofconcrete cubic specimens, ascending three point bending of reinforced concrete beamspecimens and early age monitoring of concrete. Results illustrate the efficiency of theproposed technique in damage detection as well as early age monitoring as, in the firstcase, both severity and location of damage can be determined by examining the values ofdamage indices for each damaged state and in the early age monitoring case damageindices follow the strength gain curve.
基金supported by the National Key R&D Program(No.2023YFB3709900)the National Nature Science Foundation of China(No.U22A20171)+2 种基金China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202315)the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing,China.
文摘The characteristics of nonmetallic inclusions formed during steel production have a significant influence on steel performance.In this paper,studies on inclusions using confocal scanning laser microscopy(CSLM)are reviewed and summarized,particularly the col-lision of various inclusions,dissolution of inclusions in liquid slag,and reactions between inclusions and steel.Solid inclusions exhibited a high collision tendency,whereas pure liquid inclusions exhibited minimal collisions because of the small attraction force induced by their<90°contact angle with molten steel.The collision of complex inclusions in molten steel was not included in the scope of this study and should be evaluated in future studies.Higher CaO/Al_(2)O_(3)and CaO/SiO_(2)ratios in liquid slag promoted the dissolution of Al_(2)O_(3)-based in-clusions.The formation of solid phases in the slag should be prevented to improve dissolution of inclusions.To accurately simulate the dissolution of inclusions in liquid slag,in-situ observation of the dissolution of inclusions at the steel-slag interface is necessary.Using a combination of CSLM and scanning electron microscopy-energy dispersive spectroscopy,the composition and morphological evolution of the inclusions during their modification by the dissolved elements in steel were observed and analyzed.Although the in-situ observa-tion of MnS and TiN precipitations has been widely studied,the in-situ observation of the evolution of oxide inclusions in steel during so-lidification and heating processes has rarely been reported.The effects of temperature,heating and cooling rates,and inclusion character-istics on the formation of acicular ferrites(AFs)have been widely studied.At a cooling rate of 3-5 K/s,the order of AF growth rate in-duced by different inclusions,as reported in literature,is Ti-O<Ti-Ca-Zr-Al-O<Mg-O<Ti-Zr-Al-O<Mn-Ti-Al-O<Ti-Al-O<Zr-Ti-Al-O.Further comprehensive experiments are required to investigate the quantitative relationship between the formation of AFs and inclusions.
基金supported by Independent Research Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS-2023-Z13)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)+1 种基金A portion of the work was performed at US National High Magnetic Field Laboratory,which is supported by the National Science Foundation(Cooperative Agreement No.DMR-1157490 and DMR-1644779)the State of Florida.Thanks also to Mary Tyler for editing.
文摘The high-temperature dissolution behavior of primary carbides in samples taken from GCr15 continuous-casting bloom was observed in-situ by confocal laser scanning microscopy.Equations were fitted to the dissolution kinetics of primary carbides during either heating or soaking.Dissolution of carbides proceeded in three stages(fast→slow→faster)as either temperature or holding time was increased.During the heating process and during the first and third stages of the soaking process,the original size of the carbides determined the steepness of the slope,but during the middle(“slow”)stage of the soaking process,the slope remained zero.The initial size of the carbides varied greatly,but their final dissolution temperature fell within the narrow range of 1210-1235℃,and the holding time remained within 50 min.Fractal analysis was used to study the morphological characteristics of small and medium-sized carbides during the dissolution process.According to changes in the fractal dimension before and after soaking,the carbides tended to evolve towards a more regular morphology.
基金supported by National Natural Science Foundation of China(No.52176122).
文摘The centroid coordinate serves as a critical control parameter in motion systems,including aircraft,missiles,rockets,and drones,directly influencing their motion dynamics and control performance.Traditional methods for centroid measurement often necessitate custom equipment and specialized positioning devices,leading to high costs and limited accuracy.Here,we present a centroid measurement method that integrates 3D scanning technology,enabling accurate measurement of centroid across various types of objects without the need for specialized positioning fixtures.A theoretical framework for centroid measurement was established,which combined the principle of the multi-point weighing method with 3D scanning technology.The measurement accuracy was evaluated using a designed standard component.Experimental results demonstrate that the discrepancies between the theoretical and the measured centroid of a standard component with various materials and complex shapes in the X,Y,and Z directions are 0.003 mm,0.009 mm,and 0.105 mm,respectively,yielding a spatial deviation of 0.106 mm.Qualitative verification was conducted through experimental validation of three distinct types.They confirmed the reliability of the proposed method,which allowed for accurate centroid measurements of various products without requiring positioning fixtures.This advancement significantly broadened the applicability and scope of centroid measurement devices,offering new theoretical insights and methodologies for the measurement of complex parts and systems.
基金supported by the National Natural Science Foundation of China(No.52275306)the Beijing Municipal Natural Science Foundation(No.3232021).
文摘The lamellar layer of intermetallic compounds(IMCs)was adversely affected the performance of welding-brazing joints in Al/steel dissimilar metals.In this study,a short fiber-like surface morphology was fabricated on the butt surface of Q235 steel via laser.The interaction behavior between the short fibers and the molten pool was captured using a high-speed camera.Laser-arc hybrid welding-brazing was then employed to join Al(6061-T6)to the steel.This process successfully created a short fiber-like interface structure at the joint.The relationship between microstructure and mechanical properties was investigated,compared with Al/bare steel(ABS)joint.The research results indicated that the IMCs layer consisted of FeAl_(3)and Fe_(2)Al_(5).The interface strength of the Al/short fiber-like surface structural steel(ASFSSS)joint reached 153.2 MPa,an 82.2%increase compared to the ABS joint,which reached 84.1 MPa.When the ASFSSS joints without the reinforcement were bent to 58.2°and 25.2°in the longitudinal and transverse direction,respectively,they remained intact.However,cracks were discovered when the bending angle of the ABS reached 39.1°and 0°in the two directions.Numerical simulation revealed that the short fiber-like interface structure significantly reduced residual stress and improved the stress distribution in the weld,thereby enhancing the strength and toughness of Al/steel dissimilar joints.The crack propagation path in the ASFSSS joint was deflected into the weld when it encountered short fibers,and the fracture morphology presented the characteristic of ductile-brittle mixed fracture.
