To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting,aluminum silicate fibers with the diameter ranging from 5 μm to 25 μm and the length about 1 mm were dispersed in...To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting,aluminum silicate fibers with the diameter ranging from 5 μm to 25 μm and the length about 1 mm were dispersed in the ceramic mould.The effect of the aluminum silicate fibers on the tensile strength,shrinkage rate and the cracking trend of the ceramic mould were investigated.In the ceramic slurry,quartz sand was applied as ceramic aggregate,silica sol containing 30% silicon dioxide as bonder,and the weight ratio of quartz sand to silica sol was 2.69;the dispersed fibers changed from 0 to 0.24vol.%.The mould samples were formed after the slurry was poured and gelled at room temperature,and then sintered at different temperatures ranging from 100 to 800 ℃ to measure the tensile strength and shrinkage rate.The results show that,with the aluminum silicate fiber addition increasing from 0 to 0.24vol.%,the tensile strength increases linearly from 0.175 MPa to 0.236 MPa,and the shrinkage rate decreases linearly from 1.75% to 1.68% for the ceramic mould sintered at 400 ℃,from 1.37% to 1.31% for the ceramic mould at room temperature.As the sintering temperature was raised from 100 ℃ to 800 ℃,the tensile strength increases,and the shrinkage rate decreases at all temperatures,compared with those without fiber dispersion,but their variation patterns remain the same.Furthermore,the cracking trend of the mould and its decreasing proportion were defined and analyzed quantitatively considering both effects of the fiber dispersion on the strength and shrinkage.The cracking trend appears to decrease linearly with increasing fiber content and to reach the maximum reduction of 28.8% when 0.24vol.% fiber was dispersed.Therefore,the investigation proposes a new method to improve the crack-resistance of the ceramic mould,i.e.,inorganic fiber dispersion into the ceramic mould.展开更多
With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density and electromagnetic body force in the liquid aluminum was investigated. Calculated results showed that mag...With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density and electromagnetic body force in the liquid aluminum was investigated. Calculated results showed that magnetic flux density and electromagnetic body force in the aluminum melt are greatly increased when the external part of mould is made from A3 steel. A low-frequency electromagnetic casting 6063 aluminum alloy experiment was conducted in the laboratory with the current value of 120 A and frequency value of 15 Hz. The experiment showed that the microstructure and surface quality of ingots with mould outer part made from A3 steel under low-frequency electromagnetic field are better than that of ingots with mould outer part made from austenitic stainless steel. The surface of the ingots with mould outer part made from A3 steel is smooth and free from exudations and cold shut defects. The as-cast microstructure consists of fine, uniformly distributed equiaxed grains.展开更多
In order to solve the mould filling problem of large thin walled aluminum alloy castings effectively, a new casting technology called electromagnetic die casting has been developed. Emphasis has laid on studying the m...In order to solve the mould filling problem of large thin walled aluminum alloy castings effectively, a new casting technology called electromagnetic die casting has been developed. Emphasis has laid on studying the mould filling ability and microstructure under the mentioned method. The results show that the mould filling ability of A357 is increasing continually with the increasing of the input voltage, that is, the magnetic induction intensity. The pressure head of the molten metal increases from the lowest one at the input of the mould to the highest one at the end of the mould while in a conventional mould the pressure head depends invariably on the sprue height. Under electromagnetic die casting, the grains of A357 alloy are refined, and the pattern of eutectic silicon of alloy changes from rough plate to smooth strip.展开更多
With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density in the aluminum melt and magnetic field interaction of four coils applied with same currents were investig...With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density in the aluminum melt and magnetic field interaction of four coils applied with same currents were investigated. Calculating results showed that magnetic flux density in the aluminum melt was greatly improved and the magnetic field interaction among different coils was decreased when external part of mould is made of soft magnetic material. Based on the finding, a four-strand low-frequency electromagnetic casting 6063 aluminum alloy experiment was carried out in the laboratory . The experiment showed that the surface of the billet was smooth and had no exudations and cold shuts, the as-cast microstructures were fine, uniform, equiaxed, net-globular or globular under low-frequency electromagnetic field. The microstructure becomes finer with increased current value.展开更多
The very latest technique for impeller manufacture is called semi-solid moulding(SSM).Cummins Turbo Technologies Limited,together with Aluminum Complex Components Inc,developed SSM compressor wheels as a way of achiev...The very latest technique for impeller manufacture is called semi-solid moulding(SSM).Cummins Turbo Technologies Limited,together with Aluminum Complex Components Inc,developed SSM compressor wheels as a way of achieving cost and durability performance somewhere between that of cast and machined from solid(MFS) aluminium alloy wheels.Experimental results show SSM material has a superior microstructure and mechanical properties over cast and comparable to MFS materials.Component testing including durability testing,using accelerated speed cycle tests,proves SSM compressor wheels emerge as being significantly more durable than cast equivalents and approaching that of MFS impellers.Further challenges for semi-solid processing in manufacture of other complex components and other materials in automotive industry in terms of both cost and durability are also discussed.展开更多
Based on the experimental data of apparent viscosity about semi-solid A356 aluminum alloy, the apparent viscosity model was developed and inserted into a commercial software Castsoft6.0, and a key-shaped component fil...Based on the experimental data of apparent viscosity about semi-solid A356 aluminum alloy, the apparent viscosity model was developed and inserted into a commercial software Castsoft6.0, and a key-shaped component filling process was simulated. The simulation results are in good agreement with the experimental filling results, which indicates that the apparent viscosity model established is effective and available. The process parameters on the cavity filling of the key-shaped components have been optimized. The injection pressure should be more than 15 MPa, the slurry flowing velocity in the in-gate should be more than 1.73 m/s, and the slurry temperature should be over 585 ℃.展开更多
文摘To improve the crack-resistance of the mould for silica sol bonded quartz based ceramic mould casting,aluminum silicate fibers with the diameter ranging from 5 μm to 25 μm and the length about 1 mm were dispersed in the ceramic mould.The effect of the aluminum silicate fibers on the tensile strength,shrinkage rate and the cracking trend of the ceramic mould were investigated.In the ceramic slurry,quartz sand was applied as ceramic aggregate,silica sol containing 30% silicon dioxide as bonder,and the weight ratio of quartz sand to silica sol was 2.69;the dispersed fibers changed from 0 to 0.24vol.%.The mould samples were formed after the slurry was poured and gelled at room temperature,and then sintered at different temperatures ranging from 100 to 800 ℃ to measure the tensile strength and shrinkage rate.The results show that,with the aluminum silicate fiber addition increasing from 0 to 0.24vol.%,the tensile strength increases linearly from 0.175 MPa to 0.236 MPa,and the shrinkage rate decreases linearly from 1.75% to 1.68% for the ceramic mould sintered at 400 ℃,from 1.37% to 1.31% for the ceramic mould at room temperature.As the sintering temperature was raised from 100 ℃ to 800 ℃,the tensile strength increases,and the shrinkage rate decreases at all temperatures,compared with those without fiber dispersion,but their variation patterns remain the same.Furthermore,the cracking trend of the mould and its decreasing proportion were defined and analyzed quantitatively considering both effects of the fiber dispersion on the strength and shrinkage.The cracking trend appears to decrease linearly with increasing fiber content and to reach the maximum reduction of 28.8% when 0.24vol.% fiber was dispersed.Therefore,the investigation proposes a new method to improve the crack-resistance of the ceramic mould,i.e.,inorganic fiber dispersion into the ceramic mould.
基金The project (G199906490501) was supported by the National Key Fundamental Research and Development Program of China
文摘With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density and electromagnetic body force in the liquid aluminum was investigated. Calculated results showed that magnetic flux density and electromagnetic body force in the aluminum melt are greatly increased when the external part of mould is made from A3 steel. A low-frequency electromagnetic casting 6063 aluminum alloy experiment was conducted in the laboratory with the current value of 120 A and frequency value of 15 Hz. The experiment showed that the microstructure and surface quality of ingots with mould outer part made from A3 steel under low-frequency electromagnetic field are better than that of ingots with mould outer part made from austenitic stainless steel. The surface of the ingots with mould outer part made from A3 steel is smooth and free from exudations and cold shut defects. The as-cast microstructure consists of fine, uniformly distributed equiaxed grains.
文摘In order to solve the mould filling problem of large thin walled aluminum alloy castings effectively, a new casting technology called electromagnetic die casting has been developed. Emphasis has laid on studying the mould filling ability and microstructure under the mentioned method. The results show that the mould filling ability of A357 is increasing continually with the increasing of the input voltage, that is, the magnetic induction intensity. The pressure head of the molten metal increases from the lowest one at the input of the mould to the highest one at the end of the mould while in a conventional mould the pressure head depends invariably on the sprue height. Under electromagnetic die casting, the grains of A357 alloy are refined, and the pattern of eutectic silicon of alloy changes from rough plate to smooth strip.
文摘With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density in the aluminum melt and magnetic field interaction of four coils applied with same currents were investigated. Calculating results showed that magnetic flux density in the aluminum melt was greatly improved and the magnetic field interaction among different coils was decreased when external part of mould is made of soft magnetic material. Based on the finding, a four-strand low-frequency electromagnetic casting 6063 aluminum alloy experiment was carried out in the laboratory . The experiment showed that the surface of the billet was smooth and had no exudations and cold shuts, the as-cast microstructures were fine, uniform, equiaxed, net-globular or globular under low-frequency electromagnetic field. The microstructure becomes finer with increased current value.
文摘The very latest technique for impeller manufacture is called semi-solid moulding(SSM).Cummins Turbo Technologies Limited,together with Aluminum Complex Components Inc,developed SSM compressor wheels as a way of achieving cost and durability performance somewhere between that of cast and machined from solid(MFS) aluminium alloy wheels.Experimental results show SSM material has a superior microstructure and mechanical properties over cast and comparable to MFS materials.Component testing including durability testing,using accelerated speed cycle tests,proves SSM compressor wheels emerge as being significantly more durable than cast equivalents and approaching that of MFS impellers.Further challenges for semi-solid processing in manufacture of other complex components and other materials in automotive industry in terms of both cost and durability are also discussed.
基金supported by the National High-Tech Research and Development Program of China(No.2006AA03Z115)the Major State Basic Research and Development Program of China(No.2006CB605203)
基金Project(2006AA03Z115) supported by the National Hi-tech Research and Development Program of ChinaProject(2006CB605203) supported by the National Basic Research Program of ChinaProject(50774007) supported by the National Natural Science Foundation of China
文摘Based on the experimental data of apparent viscosity about semi-solid A356 aluminum alloy, the apparent viscosity model was developed and inserted into a commercial software Castsoft6.0, and a key-shaped component filling process was simulated. The simulation results are in good agreement with the experimental filling results, which indicates that the apparent viscosity model established is effective and available. The process parameters on the cavity filling of the key-shaped components have been optimized. The injection pressure should be more than 15 MPa, the slurry flowing velocity in the in-gate should be more than 1.73 m/s, and the slurry temperature should be over 585 ℃.
