The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructur...The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.展开更多
Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with ex...Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with excellent performance.Over the past decade,significant progress has been achieved in deeply understanding the SSP process,the microstructure and performance of the fabricated components in China.This paper starts with a retrospective overview of some common slurry preparation methods,followed by presenting the performance and the underlying mechanisms of SSP fabricated alloys.Then,the mainstream opinions on the microstructure evolution and rheological flow behavior of semi-solid slurry are discussed.Subsequently,the general situation and some recent examples of industrial applications of SSP are presented.Finally,special attention is paid to the unresolved issues and the future directions in SSP of Al and Mg alloys in China.展开更多
Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and al...Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements,hardness and impact strength of GISS alloys were investigated.Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primaryα(A1)in the alloy to change from coarse dendritic to fine globular structure.The best sample which has fine grains of 51.18μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610℃.The impact strength of the GISS optimized samples((4.67±0.18)J/cm^(2))shows an increase of about 40%with respect to the as-cast sample due to the globular structure and fibrous Si morphology.Moreover,the hardness of the optimized GISS sample((89.34±2.85)HB)increases to(93.84±3.14)HB by modification with the Sr and GISS process.The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.展开更多
EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃...EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃ and destabilisation at 1075℃ plus tempering at 500℃, all followed by air cooling. Electron microscopy revealed that, in the as-cast condition, the primary proeutectic austenite was round in shape while the eutectic M7C3 carbide was found as radiating clusters mixed with directional clusters. Tempering did not change the microstructure significantly when observed by scanning or transmission electron microscopy. Destabilisation followed by air cooling led to a precipitation of secondary M23C6 carbide and a transformation of the primary austenite to martensite. Precipitation behaviour is comparable to that observed in the conventionally cast iron. Tempering after destabilisation resulted in a higher amount of secondary carbide precipitation within the tempered martensite in the eutectic structure. Vickers macrohardness and microhardness in the proeutectic zones were measured. Dry wear properties were tested by using a pin-on-disc method. The maximum hardness and the lowest dry wear rate were obtained from the destabilisation-plus-tempering heat treatment due to the precipitation of secondary carbides within the martensite matrix and a possible reduction in the retained austenite.展开更多
It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and se...It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.展开更多
The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore...The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore the possibility of the semi-solid process in manufacturing Ti-47Al-2Cr-2Nb-0.8 B(at%)alloy.An important result is that,except forming a nondendritic globular structure,the semi-solid process also plays a crucial role in refining large borides for the TiAl alloys with boron.In the current alloy,the long ribbon borides can be successfully converted to fine,equiaxed particles with an average size of 2-5μm.Furthermore,subsequent proper heat treatment is necessary to control and achieve a fine,nearly fully lamellar microstructure.The key microstructure-refinement mechanism is due to the fine borides obtained during semisolid process,which act as the effective nucleation centers for the formation of interdendritic fine y grains,providing the pinning effect on priorα-grain boundaries.These results prove that semi-solid process can be an ideal candidate for the microstructure refinement in TiAl alloys.展开更多
An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were grad...An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.展开更多
The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding u...The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（Al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（Al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.展开更多
The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting indust...The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.展开更多
Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle o...Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.展开更多
The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity de...The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.展开更多
Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application...Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application as a function of processing parameters were compared with those of die-cast parts and forged parts. In addition, the locations for the gate during the semi-solid processing were varied to elucidate the distribution of micro-porosities and resulting mechanical properties and the T6 heat tre...展开更多
The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequ...The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequently,under the same condition of thixoforming,the microstructure,surface hardness and tensile properties were observed.Afterwards,quantitative analysis was made for the microstructures of the reheated semi-solid of billet and the thixoforming parts.The results show that when the induction reheating power is 90 kW,the average grain size of the semi-solid billet is the minimum,the microstructures of the thixoforming samples also are the finest,and the mechanical properties of the relevant thixoforming samples are the best.Furthermore,after studying on the relationship between the microstructures of the semi-solid billet of aluminum alloy and the mechanical properties of the thixoforming samples,the reverse design of microstructure is primarily achieved.Finally,the effectiveness of the reverse design for semi-solid microstructure is confirmed by an actual automobile part with complex shape.展开更多
Recent reports suggest that aging is not solely a physiological process in living beings;instead, it should be considered a pathological process or disease(Amorim et al., 2022). Consequently, this process involves a w...Recent reports suggest that aging is not solely a physiological process in living beings;instead, it should be considered a pathological process or disease(Amorim et al., 2022). Consequently, this process involves a wide range of factors, spanning from genetic to environmental factors, and even includes the gut microbiome(GM)(Mayer et al., 2022). All these processes coincide at some point in the inflammatory process, oxidative stress, and apoptosis, at different degrees in various organs and systems that constitute a living organism(Mayer et al., 2022;AguilarHernández et al., 2023).展开更多
Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley a...Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.展开更多
Photovoltaic (PV) modules, as essential components of solar power generation systems, significantly influence unitpower generation costs.The service life of these modules directly affects these costs. Over time, the p...Photovoltaic (PV) modules, as essential components of solar power generation systems, significantly influence unitpower generation costs.The service life of these modules directly affects these costs. Over time, the performanceof PV modules gradually declines due to internal degradation and external environmental factors.This cumulativedegradation impacts the overall reliability of photovoltaic power generation. This study addresses the complexdegradation process of PV modules by developing a two-stage Wiener process model. This approach accountsfor the distinct phases of degradation resulting from module aging and environmental influences. A powerdegradation model based on the two-stage Wiener process is constructed to describe individual differences inmodule degradation processes. To estimate the model parameters, a combination of the Expectation-Maximization(EM) algorithm and the Bayesian method is employed. Furthermore, the Schwarz Information Criterion (SIC) isutilized to identify critical change points in PV module degradation trajectories. To validate the universality andeffectiveness of the proposed method, a comparative analysis is conducted against other established life predictiontechniques for PV modules.展开更多
Recently published in Joule,Feng Liu and colleagues from Shanghai Jiaotong University reported a record-breaking 20.8%power conversion efficiency in organic solar cells(OSCs)with an interpenetrating fibril network act...Recently published in Joule,Feng Liu and colleagues from Shanghai Jiaotong University reported a record-breaking 20.8%power conversion efficiency in organic solar cells(OSCs)with an interpenetrating fibril network active layer morphology,featuring a bulk p-in structure and proper vertical segregation achieved through additive-assisted layer-by-layer deposition.This optimized hierarchical gradient fibrillar morphology and optical management synergistically facilitates exciton diffusion,reduces recombination losses,and enhances light capture capability.This approach not only offers a solution to achieving high-efficiency devices but also demonstrates the potential for commercial applications of OSCs.展开更多
Fenton and Fenton-like processes,which could produce highly reactive species to degrade organic contaminants,have been widely used in the field of wastewater treatment.Therein,the chemistry of Fenton process including...Fenton and Fenton-like processes,which could produce highly reactive species to degrade organic contaminants,have been widely used in the field of wastewater treatment.Therein,the chemistry of Fenton process including the nature of active oxidants,the complicated reactions involved,and the behind reason for its strongly pH-dependent performance,is the basis for the application of Fenton and Fenton-like processes in wastewater treatment.Nevertheless,the conflicting views still exist about the mechanism of the Fenton process.For instance,reaching a unanimous consensus on the nature of active oxidants(hydroxyl radical or tetravalent iron)in this process remains challenging.This review comprehensively examined the mechanism of the Fenton process including the debate on the nature of active oxidants,reactions involved in the Fenton process,and the behind reason for the pH-dependent degradation of contaminants in the Fenton process.Then,we summarized several strategies that promote the Fe(Ⅱ)/Fe(Ⅲ)cycle,reduce the competitive consumption of active oxidants by side reactions,and replace the Fenton reagent,thus improving the performance of the Fenton process.Furthermore,advances for the future were proposed including the demand for the high-accuracy identification of active oxidants and taking advantages of the characteristic of target contaminants during the degradation of contaminants by the Fenton process.展开更多
The Hualien M 7.3 earthquake on April 3,2024,was a significant and strong earthquake in Taiwan,China in the past two decades.The rupture process of the main shock and strong aftershocks is of great significance to the...The Hualien M 7.3 earthquake on April 3,2024,was a significant and strong earthquake in Taiwan,China in the past two decades.The rupture process of the main shock and strong aftershocks is of great significance to the subsequent seismic activity and seismogenic tectonic research.Based on local strong-motion data,we used the IDS(Iterative Deconvolution and Stacking)method to obtain the rupture process of the mainshock and two strong aftershocks on the 23rd.The rupture of the mainshock was mainly unilateral,lasting 31 s,with a maximum slip of 2m,and the depth of the large slip zone is about 41–49 km.There is a clear difference between the rupture depth of the main shock and the two strong aftershocks.The depths of the large slip zones of the latter two are 3–9 km and 8–10 km,respectively.There is also a significant difference in the seismogenic fault between the mainshock and the aftershocks,and we believe that there are two seismogenic fault zones in the study area,the deep and the shallow fault zone.The slip of the deep faults activates the shallow faults.展开更多
In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment techni...In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment technique known as ultrasonic vibration rapid processing(UVRP),which enables the formation of high-density strong magnetic α-Fe clusters,thereby enhancing the soft magnetic properties of Fe_(78)Si(13)B_(9) amorphous alloy ribbon.展开更多
文摘The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.
基金financial supports from the Shenzhen Science and Technology Innovation Commission, China (Nos. KQTD20170328154443162, JCYJ20180305123432756)。
文摘Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with excellent performance.Over the past decade,significant progress has been achieved in deeply understanding the SSP process,the microstructure and performance of the fabricated components in China.This paper starts with a retrospective overview of some common slurry preparation methods,followed by presenting the performance and the underlying mechanisms of SSP fabricated alloys.Then,the mainstream opinions on the microstructure evolution and rheological flow behavior of semi-solid slurry are discussed.Subsequently,the general situation and some recent examples of industrial applications of SSP are presented.Finally,special attention is paid to the unresolved issues and the future directions in SSP of Al and Mg alloys in China.
文摘Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid(GISS)process.The effects of argon inert gas flow rate,starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements,hardness and impact strength of GISS alloys were investigated.Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primaryα(A1)in the alloy to change from coarse dendritic to fine globular structure.The best sample which has fine grains of 51.18μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610℃.The impact strength of the GISS optimized samples((4.67±0.18)J/cm^(2))shows an increase of about 40%with respect to the as-cast sample due to the globular structure and fibrous Si morphology.Moreover,the hardness of the optimized GISS sample((89.34±2.85)HB)increases to(93.84±3.14)HB by modification with the Sr and GISS process.The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.
文摘EfFects of heat treatments on hardness and dry wear properties of a semi-solid processed Fe-26.96 wt pct Cr- 2.91 wt pct C cast iron were studied. Heat treatments included tempering at 500℃, destabilisation at 1075℃ and destabilisation at 1075℃ plus tempering at 500℃, all followed by air cooling. Electron microscopy revealed that, in the as-cast condition, the primary proeutectic austenite was round in shape while the eutectic M7C3 carbide was found as radiating clusters mixed with directional clusters. Tempering did not change the microstructure significantly when observed by scanning or transmission electron microscopy. Destabilisation followed by air cooling led to a precipitation of secondary M23C6 carbide and a transformation of the primary austenite to martensite. Precipitation behaviour is comparable to that observed in the conventionally cast iron. Tempering after destabilisation resulted in a higher amount of secondary carbide precipitation within the tempered martensite in the eutectic structure. Vickers macrohardness and microhardness in the proeutectic zones were measured. Dry wear properties were tested by using a pin-on-disc method. The maximum hardness and the lowest dry wear rate were obtained from the destabilisation-plus-tempering heat treatment due to the precipitation of secondary carbides within the martensite matrix and a possible reduction in the retained austenite.
基金This Work financially supported by the China National Advanced Materials Committee
文摘It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.
基金the National Natural Science Foundation of China(No.51101003)。
文摘The refinement of large boride ribbons in the as-cast TiAl alloy is the essential issue for aerospace industry application,which is difficult to avoid by classical casting techniques.The present paper seeks to explore the possibility of the semi-solid process in manufacturing Ti-47Al-2Cr-2Nb-0.8 B(at%)alloy.An important result is that,except forming a nondendritic globular structure,the semi-solid process also plays a crucial role in refining large borides for the TiAl alloys with boron.In the current alloy,the long ribbon borides can be successfully converted to fine,equiaxed particles with an average size of 2-5μm.Furthermore,subsequent proper heat treatment is necessary to control and achieve a fine,nearly fully lamellar microstructure.The key microstructure-refinement mechanism is due to the fine borides obtained during semisolid process,which act as the effective nucleation centers for the formation of interdendritic fine y grains,providing the pinning effect on priorα-grain boundaries.These results prove that semi-solid process can be an ideal candidate for the microstructure refinement in TiAl alloys.
文摘An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.
基金the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Rio Tinto Alcan through the NSERC Industrial Research Chair in Metallurgy of Aluminum Transformation at Université du Québec à Chicoutimi
文摘The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（Al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（Al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.
基金supports from Prince of Songkla University (No.AGR530031M)the Royal Golden Jubilee Ph.D program (No.PHD/0173/2550)
文摘The gas induced semi-solid(GISS) is a rheocasting process that produces semi-solid slurry by applying fine gas bubble injection through a graphite diffuser.The process is developed to be used in the die casting industry.To apply the GISS process with a die casting process,a GISS maker unit is designed and attached to a conventional die casting machine with little modifications.The commercial parts are developed and produced by the GISS die casting process.The GISS die casting shows the feasibility to produce industrial parts with aluminum 7075 and A356 with lower porosity than liquid die casting.
基金supports from several sources including the Thai Research Fund (No. MRG5280215)Prince of Songkla University (No. AGR530031M)the Royal Golden Jubilee Ph.D. Program (No. PHD/0134/2551 and PHD/0173/2550)
文摘Several rheocasting processes are developed or applied worldwide in the metal forming industry.One of the new rheocasting processes is the gas induced semi-solid(GISS) process.The GISS process utilizes the principle of rapid heat extraction and vigorous local extraction using the injection of fine gas bubbles through a graphite diffuser.Several forming processes such as die casting,squeeze casting,gravity casting,and rheo-extrusion of the semi-solid slurries prepared by the GISS process have also been conducted.The GISS process is capable of processing various alloys including cast aluminum alloys,die casting aluminum alloys,wrought aluminum alloys,and zinc alloys.The GISS process is currently developed to be used commercially in the industry with the focus on forming semi-solid slurries containing low fractions solid(< 0.25) into parts.The research and development activities of the GISS process were discussed and the status of the industrial developments of this process was reported.
基金the funding from Princeof Songkla University for Ph.D. 50% Scholarship,the Royal Golden Jubilee Ph.D. program (Grant No.PHD/0173/2550)
文摘The semi-solid metal forming using high pressures has been applied for several years.In contrast,low pressure casting,such as gravity sand casting,has not been widely studied even though it may help reduce porosity defects and offer a better casting yield.A semi-solid gravity sand casting process using the Gas Induced Semi-Solid process was investigated.The results show that the process can produce complete parts with no observable defects.The ultimate tensile strength and elongation data of semi-solid cast samples are higher than those of the liquid cast samples.In addition,the semi-solid sand casting process gives a better casting yield.It can be concluded that the semi-solid sand casting of an aluminum alloy using the GISS process is a feasible process.
文摘Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application as a function of processing parameters were compared with those of die-cast parts and forged parts. In addition, the locations for the gate during the semi-solid processing were varied to elucidate the distribution of micro-porosities and resulting mechanical properties and the T6 heat tre...
文摘The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power,achieving the same final temperature of 851 K.Subsequently,under the same condition of thixoforming,the microstructure,surface hardness and tensile properties were observed.Afterwards,quantitative analysis was made for the microstructures of the reheated semi-solid of billet and the thixoforming parts.The results show that when the induction reheating power is 90 kW,the average grain size of the semi-solid billet is the minimum,the microstructures of the thixoforming samples also are the finest,and the mechanical properties of the relevant thixoforming samples are the best.Furthermore,after studying on the relationship between the microstructures of the semi-solid billet of aluminum alloy and the mechanical properties of the thixoforming samples,the reverse design of microstructure is primarily achieved.Finally,the effectiveness of the reverse design for semi-solid microstructure is confirmed by an actual automobile part with complex shape.
基金funded by CONAHCYT grant(252808)to GFCONAHCYT’s“Estancias Posdoctorales por México”program(662350)to HTB。
文摘Recent reports suggest that aging is not solely a physiological process in living beings;instead, it should be considered a pathological process or disease(Amorim et al., 2022). Consequently, this process involves a wide range of factors, spanning from genetic to environmental factors, and even includes the gut microbiome(GM)(Mayer et al., 2022). All these processes coincide at some point in the inflammatory process, oxidative stress, and apoptosis, at different degrees in various organs and systems that constitute a living organism(Mayer et al., 2022;AguilarHernández et al., 2023).
基金supported by the General Program of the National Natural Science Foundation of China(No.52274326)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202109)the Seventh Batch of Ten Thousand Talents Plan of China(No.ZX20220553).
文摘Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.
基金supported by the National Natural Science Foundation of China(51767017)the Basic Research Innovation Group Project of Gansu Province(18JR3RA133)the Industrial Support and Guidance Project of Universities in Gansu Province(2022CYZC-22).
文摘Photovoltaic (PV) modules, as essential components of solar power generation systems, significantly influence unitpower generation costs.The service life of these modules directly affects these costs. Over time, the performanceof PV modules gradually declines due to internal degradation and external environmental factors.This cumulativedegradation impacts the overall reliability of photovoltaic power generation. This study addresses the complexdegradation process of PV modules by developing a two-stage Wiener process model. This approach accountsfor the distinct phases of degradation resulting from module aging and environmental influences. A powerdegradation model based on the two-stage Wiener process is constructed to describe individual differences inmodule degradation processes. To estimate the model parameters, a combination of the Expectation-Maximization(EM) algorithm and the Bayesian method is employed. Furthermore, the Schwarz Information Criterion (SIC) isutilized to identify critical change points in PV module degradation trajectories. To validate the universality andeffectiveness of the proposed method, a comparative analysis is conducted against other established life predictiontechniques for PV modules.
基金Technology Development Program of Jilin Province(YDZJ202201ZYTS640)the National Key Research and Development Program of China(2022YFB4200400)funded by MOST+4 种基金the National Natural Science Foundation of China(52172048 and 52103221)Shandong Provincial Natural Science Foundation(ZR2021QB024 and ZR2021ZD06)Guangdong Basic and Applied Basic Research Foundation(2023A1515012323,2023A1515010943,and 2024A1515010023)the Qingdao New Energy Shandong Laboratory open Project(QNESL OP 202309)the Fundamental Research Funds of Shandong University.
文摘Recently published in Joule,Feng Liu and colleagues from Shanghai Jiaotong University reported a record-breaking 20.8%power conversion efficiency in organic solar cells(OSCs)with an interpenetrating fibril network active layer morphology,featuring a bulk p-in structure and proper vertical segregation achieved through additive-assisted layer-by-layer deposition.This optimized hierarchical gradient fibrillar morphology and optical management synergistically facilitates exciton diffusion,reduces recombination losses,and enhances light capture capability.This approach not only offers a solution to achieving high-efficiency devices but also demonstrates the potential for commercial applications of OSCs.
基金supported by the National Natural Science Foundation of China(Nos.22206050 and 52270047).
文摘Fenton and Fenton-like processes,which could produce highly reactive species to degrade organic contaminants,have been widely used in the field of wastewater treatment.Therein,the chemistry of Fenton process including the nature of active oxidants,the complicated reactions involved,and the behind reason for its strongly pH-dependent performance,is the basis for the application of Fenton and Fenton-like processes in wastewater treatment.Nevertheless,the conflicting views still exist about the mechanism of the Fenton process.For instance,reaching a unanimous consensus on the nature of active oxidants(hydroxyl radical or tetravalent iron)in this process remains challenging.This review comprehensively examined the mechanism of the Fenton process including the debate on the nature of active oxidants,reactions involved in the Fenton process,and the behind reason for the pH-dependent degradation of contaminants in the Fenton process.Then,we summarized several strategies that promote the Fe(Ⅱ)/Fe(Ⅲ)cycle,reduce the competitive consumption of active oxidants by side reactions,and replace the Fenton reagent,thus improving the performance of the Fenton process.Furthermore,advances for the future were proposed including the demand for the high-accuracy identification of active oxidants and taking advantages of the characteristic of target contaminants during the degradation of contaminants by the Fenton process.
基金sponsored by the Earthquake Spark Technology Project(XH23051B)。
文摘The Hualien M 7.3 earthquake on April 3,2024,was a significant and strong earthquake in Taiwan,China in the past two decades.The rupture process of the main shock and strong aftershocks is of great significance to the subsequent seismic activity and seismogenic tectonic research.Based on local strong-motion data,we used the IDS(Iterative Deconvolution and Stacking)method to obtain the rupture process of the mainshock and two strong aftershocks on the 23rd.The rupture of the mainshock was mainly unilateral,lasting 31 s,with a maximum slip of 2m,and the depth of the large slip zone is about 41–49 km.There is a clear difference between the rupture depth of the main shock and the two strong aftershocks.The depths of the large slip zones of the latter two are 3–9 km and 8–10 km,respectively.There is also a significant difference in the seismogenic fault between the mainshock and the aftershocks,and we believe that there are two seismogenic fault zones in the study area,the deep and the shallow fault zone.The slip of the deep faults activates the shallow faults.
基金supported by the Major Science and Technology Project of Zhongshan City(No.2022AJ004)the Key Basic and Applied Research Program of Guangdong Province(Nos.2019B030302010 and 2022B1515120082)Guangdong Science and Technology Innovation Project(No.2021TX06C111).
文摘In general,the rapid growth of α-Fe clusters is a challenge in high Fe-content Fe-based amorphous alloys,negatively affecting their physical properties.Herein,we introduce an efficient and rapid post-treatment technique known as ultrasonic vibration rapid processing(UVRP),which enables the formation of high-density strong magnetic α-Fe clusters,thereby enhancing the soft magnetic properties of Fe_(78)Si(13)B_(9) amorphous alloy ribbon.
