The ballistic resistance and failure pattern of a bi-layer alumina 99.5%-aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study.In ...The ballistic resistance and failure pattern of a bi-layer alumina 99.5%-aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study.In the experimental investigation,damage induced in the ceramic layer has been quantified in terms of number of cracks developed and failure zone dimensions.The resultant damage in the backing layer has been studied with variation in the bulge and perforation hole in the backing layer with the varying incidence velocity.The discussion of the experimental results has been further followed by three dimensional finite element computations using ABAQUS/Explicit finite code to investigate the behaviour of different types of bi-layer targets under multi-hit projectile impact.The JH-2 constitutive model has been used to reproduce the behaviour of alumina 99.5%and JC constitutive model has been used for steel 4340 and aluminium alloy 1100-H12.The total energy dissipation has been noted to be of lesser magnitude in case of sub-sequential impact in comparison to simultaneous impact of two projectiles.The distance between the impact points of two projectiles also effected the ballistic resistance of bi-layer target.The ballistic resistance of single tile ceramic front layer and four tile ceramic of equivalent area found to be dependent upon the boundary conditions provided to the target.展开更多
The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction（XRD）,...The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM） and transmission electron microscope （TEM）. The results show that the compressive stress exists in the products and the bend strength reaches 300MPa. ZrO2 phase and stainless steel phase are uniform in samples. The toughness of ceramic increases with the increasing the content of stainless steel. Through TEM study of the interface, some crystalline orientation relationships are determined.展开更多
Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded to...Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.展开更多
Numerical simulation for the dynamic response of ceramic/metal armours impacted by deformable projectile is carried out with LS-DYNA3D.The simulated penetration processes are shown. The mushrooming of the projectile i...Numerical simulation for the dynamic response of ceramic/metal armours impacted by deformable projectile is carried out with LS-DYNA3D.The simulated penetration processes are shown. The mushrooming of the projectile is displayed. A distinct conoid shaped zone of fragmented ceramic is observed. A significant bending of the backing plate is revealed. Simulation results match fairly well with the experimental values and the theoretical analysis results. The accuracy of the numerical simulation is validated.展开更多
The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mecha...The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mechanical or functional performance in a mass production scale.As the automobile technology transforms from traditional internal combustion engine vehicles to new energy vehicles,PM technology is undergoing significant changes in manufacturing and materials development.This review outlines the challenges and opportunities generated by the changes in the automotive technology for PM.Low-cost,high-performance and light-weight are critical aspects for future PM materials development.Therefore,the studies on PM lean-alloyed steel,aluminum alloys,and titanium alloy materials were reviewed.In addition,PM soft magnetic composite applied to new energy vehicles was discussed.Then new opportunities for advanced processing,such as metal injection molding(MIM)and additive manufacturing(AM),in automotive industry were stated.In general,the change in automotive industry raises sufficient development space for PM.While,emerging technologies require more preeminent PM materials.Iron-based parts are still the main PM products due to their mechanical performance and low cost.MIM will occupy the growing market of highly flexible and complex parts.AM opens a door for fast prototyping,great flexibility and customizing at low cost,driving weight and assembling reduction.展开更多
A new mechanical model for powder metallurgy compaction is presented. In this model, various amount of voids can be introduced into a continuous solid, therefore porosity can be conveniently controlled. The elastic-pl...A new mechanical model for powder metallurgy compaction is presented. In this model, various amount of voids can be introduced into a continuous solid, therefore porosity can be conveniently controlled. The elastic-plastic finite element method was used to analyze the sintered powder material. The model was used to simulate compressing of a sintered cylinder. MSC.Marc of MSC. Software Corporation was applied here, and the sintered powder model was built in MSC.Mentat. The sintered cylindrical powder metallurgy part is treated as a piece of normal metal with pores in the model. The metal block is considered as cylinder with a radius of 6.0 mm and a total height of 10.0 mm. Young’s module was assumed to be 4 000 MPa. Poisson’s ratio was 0.269. The initial yield stress is 210 MPa. Friction coefficient used for the upper and lower contact surfaces is 0.3. Coulomb principle is adopted. Considering axisymmetricity, just half a section is analyzed. Totally there are 1 240 elements. Experiment was carried out by a computer controlled a universal tensile testing machine. During the experiment, the sample was prepared from highly compressible water atomized iron powder with 0.6wt% polymeric lubricant. Particle size is about 100～150 μm. The comparison was performed using a sintered cylindrical sample. The green compact was sintered at 1 140 ℃ for 2 hours. Initially, H0 is 10.20 mm, Φ0 is 12.01 mm and the initial relative density is 0.789. After pressing, H is 7.30 mm, Φ1 is 13.10 mm, Φ2 is 14.64 mm and relative density is 0.88. The load-displacement curves agree with the experimental results very well. Plastic deformation of metallic material is mostly caused by the slipping of crystal lattice. Although very small, a metal powder particle is composed of metallic crystal. Mechanical properties of a powder particle should be very close to their as solid metal counterpart.展开更多
Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were i...Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.展开更多
The difference of sintering crunodes of metal powders and fibers is discussed. The mathematical model of the surface diffusion described by the difference in mean curvature is defined as a Hamilton-Jacobi-type equatio...The difference of sintering crunodes of metal powders and fibers is discussed. The mathematical model of the surface diffusion described by the difference in mean curvature is defined as a Hamilton-Jacobi-type equation, and the model is numerically solved by the level set method. The three-dimensional numerical simulations of two metal powders and fibers(the fiber angle is 0° or 90°) are implemented by this mathematical model, respectively. The numerical simulation results accord with the experimental ones. The sintering neck growth trends of metal powders and metal fibers are similar. The sintering neck radius of metal fibers is larger than that of metal powders. The difference of the neck radius is caused by the difference of geometric structure which makes an important influence on the curvature affecting the migration rate of atoms.展开更多
The literary data on the application of various methods for the production of nanopowders of platinum metals and alloys have been summarized, and the selection of the method of chemical reduction from salt solutions h...The literary data on the application of various methods for the production of nanopowders of platinum metals and alloys have been summarized, and the selection of the method of chemical reduction from salt solutions has been substantiated as the simplest and most affordable. The optimum conditions for the production of nanoparticles of metal palladium and platinum/cobalt alloy, using the effect of boranes with various structures, have been selected.展开更多
文摘The ballistic resistance and failure pattern of a bi-layer alumina 99.5%-aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study.In the experimental investigation,damage induced in the ceramic layer has been quantified in terms of number of cracks developed and failure zone dimensions.The resultant damage in the backing layer has been studied with variation in the bulge and perforation hole in the backing layer with the varying incidence velocity.The discussion of the experimental results has been further followed by three dimensional finite element computations using ABAQUS/Explicit finite code to investigate the behaviour of different types of bi-layer targets under multi-hit projectile impact.The JH-2 constitutive model has been used to reproduce the behaviour of alumina 99.5%and JC constitutive model has been used for steel 4340 and aluminium alloy 1100-H12.The total energy dissipation has been noted to be of lesser magnitude in case of sub-sequential impact in comparison to simultaneous impact of two projectiles.The distance between the impact points of two projectiles also effected the ballistic resistance of bi-layer target.The ballistic resistance of single tile ceramic front layer and four tile ceramic of equivalent area found to be dependent upon the boundary conditions provided to the target.
文摘The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM） and transmission electron microscope （TEM）. The results show that the compressive stress exists in the products and the bend strength reaches 300MPa. ZrO2 phase and stainless steel phase are uniform in samples. The toughness of ceramic increases with the increasing the content of stainless steel. Through TEM study of the interface, some crystalline orientation relationships are determined.
基金funding from the NATO Agency Science for Peace and Security (#G5787)Ballistic investigations were co-financed by Military University of Technology in Warsaw under research project UGB 829/2023/WATSeparate works made in G.V.Kurdyumov Institute for Metal Physics of N.A.S.of Ukraine were partially financially supported by N.A.S.of Ukraine within the frames of project#III09-18。
文摘Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.
基金National Natural Science Foundation of China(10172063)
文摘Numerical simulation for the dynamic response of ceramic/metal armours impacted by deformable projectile is carried out with LS-DYNA3D.The simulated penetration processes are shown. The mushrooming of the projectile is displayed. A distinct conoid shaped zone of fragmented ceramic is observed. A significant bending of the backing plate is revealed. Simulation results match fairly well with the experimental values and the theoretical analysis results. The accuracy of the numerical simulation is validated.
基金Project(51625404)supported by the National Science Fund for Distinguished Young Scholars,China。
文摘The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mechanical or functional performance in a mass production scale.As the automobile technology transforms from traditional internal combustion engine vehicles to new energy vehicles,PM technology is undergoing significant changes in manufacturing and materials development.This review outlines the challenges and opportunities generated by the changes in the automotive technology for PM.Low-cost,high-performance and light-weight are critical aspects for future PM materials development.Therefore,the studies on PM lean-alloyed steel,aluminum alloys,and titanium alloy materials were reviewed.In addition,PM soft magnetic composite applied to new energy vehicles was discussed.Then new opportunities for advanced processing,such as metal injection molding(MIM)and additive manufacturing(AM),in automotive industry were stated.In general,the change in automotive industry raises sufficient development space for PM.While,emerging technologies require more preeminent PM materials.Iron-based parts are still the main PM products due to their mechanical performance and low cost.MIM will occupy the growing market of highly flexible and complex parts.AM opens a door for fast prototyping,great flexibility and customizing at low cost,driving weight and assembling reduction.
文摘A new mechanical model for powder metallurgy compaction is presented. In this model, various amount of voids can be introduced into a continuous solid, therefore porosity can be conveniently controlled. The elastic-plastic finite element method was used to analyze the sintered powder material. The model was used to simulate compressing of a sintered cylinder. MSC.Marc of MSC. Software Corporation was applied here, and the sintered powder model was built in MSC.Mentat. The sintered cylindrical powder metallurgy part is treated as a piece of normal metal with pores in the model. The metal block is considered as cylinder with a radius of 6.0 mm and a total height of 10.0 mm. Young’s module was assumed to be 4 000 MPa. Poisson’s ratio was 0.269. The initial yield stress is 210 MPa. Friction coefficient used for the upper and lower contact surfaces is 0.3. Coulomb principle is adopted. Considering axisymmetricity, just half a section is analyzed. Totally there are 1 240 elements. Experiment was carried out by a computer controlled a universal tensile testing machine. During the experiment, the sample was prepared from highly compressible water atomized iron powder with 0.6wt% polymeric lubricant. Particle size is about 100～150 μm. The comparison was performed using a sintered cylindrical sample. The green compact was sintered at 1 140 ℃ for 2 hours. Initially, H0 is 10.20 mm, Φ0 is 12.01 mm and the initial relative density is 0.789. After pressing, H is 7.30 mm, Φ1 is 13.10 mm, Φ2 is 14.64 mm and relative density is 0.88. The load-displacement curves agree with the experimental results very well. Plastic deformation of metallic material is mostly caused by the slipping of crystal lattice. Although very small, a metal powder particle is composed of metallic crystal. Mechanical properties of a powder particle should be very close to their as solid metal counterpart.
基金Project(JB141405)supported by the Fundamental Research Funds for the Central Universities of China
文摘Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.
基金Projects(51174236,51134003)supported by the National Natural Science Foundation of ChinaProject(2011CB606306)supported by the National Basic Research Program of ChinaProject(PMM-SKL-4-2012)supported by the Opening Project of State Key Laboratory of Porous Metal Materials(Northwest Institute for Nonferrous Metal Research),China
文摘The difference of sintering crunodes of metal powders and fibers is discussed. The mathematical model of the surface diffusion described by the difference in mean curvature is defined as a Hamilton-Jacobi-type equation, and the model is numerically solved by the level set method. The three-dimensional numerical simulations of two metal powders and fibers(the fiber angle is 0° or 90°) are implemented by this mathematical model, respectively. The numerical simulation results accord with the experimental ones. The sintering neck growth trends of metal powders and metal fibers are similar. The sintering neck radius of metal fibers is larger than that of metal powders. The difference of the neck radius is caused by the difference of geometric structure which makes an important influence on the curvature affecting the migration rate of atoms.
文摘The literary data on the application of various methods for the production of nanopowders of platinum metals and alloys have been summarized, and the selection of the method of chemical reduction from salt solutions has been substantiated as the simplest and most affordable. The optimum conditions for the production of nanoparticles of metal palladium and platinum/cobalt alloy, using the effect of boranes with various structures, have been selected.
