A kind of Cu base composite reinforced by 0 1μm Al 2O 3 particles were prepared by hot pressing and sintering process for steel continuous casting mould. The microstructure and properties were studied. The result...A kind of Cu base composite reinforced by 0 1μm Al 2O 3 particles were prepared by hot pressing and sintering process for steel continuous casting mould. The microstructure and properties were studied. The results show that the Al 2O 3 particle distribution is uniform, and the particles refine the grain size. The tensile fracture is a mixture of quasi cleavage and dimple due to the moderate interface strength. As a result, the composite has better soft resistance and wear resistance than those of Cu and Cu alloy. With increase in super fine Al 2O 3, the density and electric conductivity of the composite decrease, but hardness and strength increase.展开更多
Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol%SiC p /AlSi9Mg composite melt,respectively.The microstructure along the radial direction of cross-sectiona...Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol%SiC p /AlSi9Mg composite melt,respectively.The microstructure along the radial direction of cross-sectional sample of ingots was presented.SiC particles migrated towards the external circumference of the tube,and the distribution of SiC particles became uniform under centrifugal force.Voids in 20 vol%SiC p /AlSi9Mg composite melt migrated towards the inner circumference of the tube.The quantitative analysis results indicated that not only SiC particles but also primaryαphases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiC p /AlSi9Mg composite melt.In addition,the eutectic Si was broken owing to the motion of SiC p /AlSi9Mg composite melt during centrifugal casting.展开更多
Liquid composite moulding (LCM) processes are used to manufacture high quality and complex-shaped composite parts in the automotive, marine, aerospace and civil industries. On-line sensing plays an important role in c...Liquid composite moulding (LCM) processes are used to manufacture high quality and complex-shaped composite parts in the automotive, marine, aerospace and civil industries. On-line sensing plays an important role in controlling the quality of the final product in the LCM manufacturing environment. The long-period fiber grating (LPG) technology, a new real-time fiber optic sensor system, was developed to monitor the flow front progression. The sensor operation and characterization under various process conditions were discussed in detail. The experimental results showed that LPG sensors were robust and reliable to detect the arrival of resin at pre-selected locations in structures with low-medium fiber volume fraction; however were limited at different depths in structures with high fiber volume fraction.展开更多
The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional preha...The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional prehardened mould steel for plastic markedly influences the precipitation of non-metallic inclusion and the control of composition aided by Thermo-Calc software package minimizes the amount of detrimental oxide inclusion. In addition the modification of calcium is optimized in the light of composition design.展开更多
This study focuses on the thermo-mechanical properties of Carbon Fibre/Polyimide Composite(CFPC)attaching collars under transient heating.The CFPC attaching collars were fabricated by a high-temperature resin transfer...This study focuses on the thermo-mechanical properties of Carbon Fibre/Polyimide Composite(CFPC)attaching collars under transient heating.The CFPC attaching collars were fabricated by a high-temperature resin transfer moulding process,and their thermo-mechanical properties under the conditions of simultaneous transient heating and bending load were investigated.The results show that the attaching collar tends to fail at 118% of the limit load.The failure mode includes the fracture of the connecting screws,local extrusion damage of the hole edges,and slight ablation damage at the outer plies.And there is no observable residual deformation in the composite attaching collar.Furthermore,considering that the material properties vary with temperature,a progressive damage model based on the sequential thermo-mechanical coupling method was established to study the failure mechanism of the attaching collar.Finally,the damage factor of the CFPC was calculated to assess the safety status of the attaching collar.The results show that the primary damage modes of the composite attaching collar are intralaminar failure,which mainly occurs at the heat insulation layer and the hole edges,and these slightly affect the structural bearing capacity.A good correlation between the experiment and FEA is obtained.The test methods and analysis models proposed contribute to the safety assessment of composite structures under transient heating.展开更多
文摘A kind of Cu base composite reinforced by 0 1μm Al 2O 3 particles were prepared by hot pressing and sintering process for steel continuous casting mould. The microstructure and properties were studied. The results show that the Al 2O 3 particle distribution is uniform, and the particles refine the grain size. The tensile fracture is a mixture of quasi cleavage and dimple due to the moderate interface strength. As a result, the composite has better soft resistance and wear resistance than those of Cu and Cu alloy. With increase in super fine Al 2O 3, the density and electric conductivity of the composite decrease, but hardness and strength increase.
基金Funded by Natural Science Foundation Project of CQ CSTC(No.2008BB4177)
文摘Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol%SiC p /AlSi9Mg composite melt,respectively.The microstructure along the radial direction of cross-sectional sample of ingots was presented.SiC particles migrated towards the external circumference of the tube,and the distribution of SiC particles became uniform under centrifugal force.Voids in 20 vol%SiC p /AlSi9Mg composite melt migrated towards the inner circumference of the tube.The quantitative analysis results indicated that not only SiC particles but also primaryαphases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiC p /AlSi9Mg composite melt.In addition,the eutectic Si was broken owing to the motion of SiC p /AlSi9Mg composite melt during centrifugal casting.
基金This work was supported by the National High-Tech Foundation(863)under the gr ant 2001AA335020.
文摘Liquid composite moulding (LCM) processes are used to manufacture high quality and complex-shaped composite parts in the automotive, marine, aerospace and civil industries. On-line sensing plays an important role in controlling the quality of the final product in the LCM manufacturing environment. The long-period fiber grating (LPG) technology, a new real-time fiber optic sensor system, was developed to monitor the flow front progression. The sensor operation and characterization under various process conditions were discussed in detail. The experimental results showed that LPG sensors were robust and reliable to detect the arrival of resin at pre-selected locations in structures with low-medium fiber volume fraction; however were limited at different depths in structures with high fiber volume fraction.
文摘The improvement of machining behavior of prehardened-mould steel for plastic is realized by using computer-aided composition design in this work. The results showed that the matrix composition of large sectional prehardened mould steel for plastic markedly influences the precipitation of non-metallic inclusion and the control of composition aided by Thermo-Calc software package minimizes the amount of detrimental oxide inclusion. In addition the modification of calcium is optimized in the light of composition design.
基金supported by the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(No.2016QNRC001)the Science and Technology Commission of Shanghai Municipality,China(No.19DZ1100300)。
文摘This study focuses on the thermo-mechanical properties of Carbon Fibre/Polyimide Composite(CFPC)attaching collars under transient heating.The CFPC attaching collars were fabricated by a high-temperature resin transfer moulding process,and their thermo-mechanical properties under the conditions of simultaneous transient heating and bending load were investigated.The results show that the attaching collar tends to fail at 118% of the limit load.The failure mode includes the fracture of the connecting screws,local extrusion damage of the hole edges,and slight ablation damage at the outer plies.And there is no observable residual deformation in the composite attaching collar.Furthermore,considering that the material properties vary with temperature,a progressive damage model based on the sequential thermo-mechanical coupling method was established to study the failure mechanism of the attaching collar.Finally,the damage factor of the CFPC was calculated to assess the safety status of the attaching collar.The results show that the primary damage modes of the composite attaching collar are intralaminar failure,which mainly occurs at the heat insulation layer and the hole edges,and these slightly affect the structural bearing capacity.A good correlation between the experiment and FEA is obtained.The test methods and analysis models proposed contribute to the safety assessment of composite structures under transient heating.
