Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO...Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.展开更多
Ceramic composites Al_2O_3/(W, Ti)C/Cr_3C_2 with different contents of Cr_3C_2 and (W, Ti)C particles, and with the additive Y_2O_3, were fabricated with hot-pressing technique at 1700 ℃ under 28 MPa pressure for 30 ...Ceramic composites Al_2O_3/(W, Ti)C/Cr_3C_2 with different contents of Cr_3C_2 and (W, Ti)C particles, and with the additive Y_2O_3, were fabricated with hot-pressing technique at 1700 ℃ under 28 MPa pressure for 30 min in N_2 atmosphere. The mechanical properties were tested, and the microstructure was investigated by environment scanning electron microscope (ESEM), transmission electron microscope (TEM), energy dispersive analysis using X-ray (EDAX) and optical microscope (OM). Results indicate that the incorporation of Cr_3C_2 and (W,Ti)C particles can suppress the grain growth of the others, and the toughening and strengthening effects mainly originate from nano-particles, dispersion toughening and solidification strengthening. The multiphase composite ceramic material Al_2O_3/10%Cr_3C_2/20%(W,Ti)C shows good mechanical properties, especially the fracture toughness increases from 4.0 MPa·m 1/2 (Monolithic Al_2O_3 ceramic) to 8.92 MPa·m 1/2, the flexural strength from 260～340 MPa (Monolithic Al_2O_3 ceramic) to 496 MPa, due to incorporation of the suitable contents of Cr_3C_2 and (W,Ti)C particles.展开更多
The implanted ion range, the depth profile and the film sttucture of the implanted layer were studied; the carrier concentration and the mobility were measured; the conductivity mechanism of the film implanted Fe into...The implanted ion range, the depth profile and the film sttucture of the implanted layer were studied; the carrier concentration and the mobility were measured; the conductivity mechanism of the film implanted Fe into Al_2O_3 ceramic was discussed. The conclusion is that the implanted Fe^(2+) ions move into Al_2O_3 lattice and replace Al^(3+) to form subs- titution impurities so that the ion implanted lat- tice, as compared with the original one, presents an effective negative charge which forms a negative charge center. A vacancy is bound arround it, and an acceptor is introduced in the forbidden band.展开更多
Supported γ-Al2O3 membranes without defects were prepared by the sol-gel procedure. The sol-gel method involved peptization of a boehmite (AlOOH) sol prepared from ammonium aluminium sulphate. The morphology of the s...Supported γ-Al2O3 membranes without defects were prepared by the sol-gel procedure. The sol-gel method involved peptization of a boehmite (AlOOH) sol prepared from ammonium aluminium sulphate. The morphology of the supported membranes was characterized by scanning electron microscopy (SEM) and 3D rotational microscopy. Furthermore, the effects of different preparing conditions on morphological characteristics of the membrane were also investigated. The results show that PVA is a good crack-preventing agent and the morphology of supported membranes is affected by many factors, such as Al2O3 and PVA contents of the sol, drying and sintering procedures and intrinsic defects on the substrate surface.展开更多
To enhance the protective performance of ceramic composite armor,ballistic penetration experiments were conducted on Al_(2)O_(3) ceramic-ultra-high molecular weight polyethylene(UHMWPE)composite armor with different t...To enhance the protective performance of ceramic composite armor,ballistic penetration experiments were conducted on Al_(2)O_(3) ceramic-ultra-high molecular weight polyethylene(UHMWPE)composite armor with different thickness configurations.The damage and failure modes of hard projectiles and ceramic-fiber composite targets were analyzed.The recovered projectiles and ceramic fragments were sieved and weighed at multiple stages,revealing a positive correlation between the degree of fragmentation of the projectiles and ceramics and the overall ballistic resistance of the composite targets.Numerical simulations were performed using the LS-DYNA finite element software,and the simulation results showed high consistency with the experimental results,confirming the validity of the material parameters.The results indicate that the projectile heads primarily exhibited crushing and abrasive fragmentation.Larger projectile fragments mainly resulted from tensile and shear stress-induced failure.The failure modes of the composite targets included the formation of ceramic cones and radial cracks under high-velocity impacts.The UHMWPE laminated plates exhibited interlayer separation caused by tensile waves,permanent plastic deformation of the rear surface bulging,and perforation failure primarily due to shear forces.Through extended numerical simulations,while maintaining the same areal density and configuration of9 mm Al_(2)O_(3) ceramic+12 mm UHMWPE laminated composite armor,the thickness configurations of the Al_(2)O_(3) ceramic and UHMWPE laminated backplates were varied,and various thicknesses of UHMWPE laminates were simulated as the cover layer for the ceramic panels.The simulation results indicated that the composite armor configuration of 10 mm Al_(2)O_(3) ceramic+8 mm UHMWPE composite armor increased energy absorption by13.48%.When altering the cover layer thickness,a 4 mm UHMWPE+9 mm Al_(2)O_(3)+8 mm UHMWPE composite armor demonstrated a 27.11%improvement in energy absorption,showing a relatively significant enhancement.展开更多
Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different conce...Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients.The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics,which makes it not easy to extend the sample data by additional experimental or theoretical calculations.In this paper,a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components.In contrast to all-data-driven model,physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties.Based on the model outputs,the positions of morphotropic phase boundary(MPB)with different Sm doping amounts are explored.We also find the components with the best piezoelectric property and comprehensive performance.Moreover,we set up a database according to the obtained results,through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs.展开更多
文摘Al 2O 3-SiO 2-TiO 2-ZrO 2 supported membranes were prepar ed by Sol-Gel method. These composite ceramic membranes are level, even and no macro crack. There exist several crystalline phases such as Al 2O 3, TiO 2(a natase), Al 2SiO 5, and ZrO 2 in these membranes. Changing the molar ratio of Al∶Si∶Ti∶Zr,the kinds and content of crystal phases of composite membranes could be different, which may lead to a variety of microstructure of membranes. The surface nanoscale topography and microstructure of membranes were investiga ted by XRD,SEM,AFM,EPMA. The effects of additives and heat treatments on the sur face nanoscale topography and microstructure of composite ceramic membranes were also analyzed.
文摘Ceramic composites Al_2O_3/(W, Ti)C/Cr_3C_2 with different contents of Cr_3C_2 and (W, Ti)C particles, and with the additive Y_2O_3, were fabricated with hot-pressing technique at 1700 ℃ under 28 MPa pressure for 30 min in N_2 atmosphere. The mechanical properties were tested, and the microstructure was investigated by environment scanning electron microscope (ESEM), transmission electron microscope (TEM), energy dispersive analysis using X-ray (EDAX) and optical microscope (OM). Results indicate that the incorporation of Cr_3C_2 and (W,Ti)C particles can suppress the grain growth of the others, and the toughening and strengthening effects mainly originate from nano-particles, dispersion toughening and solidification strengthening. The multiphase composite ceramic material Al_2O_3/10%Cr_3C_2/20%(W,Ti)C shows good mechanical properties, especially the fracture toughness increases from 4.0 MPa·m 1/2 (Monolithic Al_2O_3 ceramic) to 8.92 MPa·m 1/2, the flexural strength from 260～340 MPa (Monolithic Al_2O_3 ceramic) to 496 MPa, due to incorporation of the suitable contents of Cr_3C_2 and (W,Ti)C particles.
文摘The implanted ion range, the depth profile and the film sttucture of the implanted layer were studied; the carrier concentration and the mobility were measured; the conductivity mechanism of the film implanted Fe into Al_2O_3 ceramic was discussed. The conclusion is that the implanted Fe^(2+) ions move into Al_2O_3 lattice and replace Al^(3+) to form subs- titution impurities so that the ion implanted lat- tice, as compared with the original one, presents an effective negative charge which forms a negative charge center. A vacancy is bound arround it, and an acceptor is introduced in the forbidden band.
基金the National Natural Science Foundation of China (NSFC 20503015)
文摘Supported γ-Al2O3 membranes without defects were prepared by the sol-gel procedure. The sol-gel method involved peptization of a boehmite (AlOOH) sol prepared from ammonium aluminium sulphate. The morphology of the supported membranes was characterized by scanning electron microscopy (SEM) and 3D rotational microscopy. Furthermore, the effects of different preparing conditions on morphological characteristics of the membrane were also investigated. The results show that PVA is a good crack-preventing agent and the morphology of supported membranes is affected by many factors, such as Al2O3 and PVA contents of the sol, drying and sintering procedures and intrinsic defects on the substrate surface.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172179,U2341244,and 11772160)。
文摘To enhance the protective performance of ceramic composite armor,ballistic penetration experiments were conducted on Al_(2)O_(3) ceramic-ultra-high molecular weight polyethylene(UHMWPE)composite armor with different thickness configurations.The damage and failure modes of hard projectiles and ceramic-fiber composite targets were analyzed.The recovered projectiles and ceramic fragments were sieved and weighed at multiple stages,revealing a positive correlation between the degree of fragmentation of the projectiles and ceramics and the overall ballistic resistance of the composite targets.Numerical simulations were performed using the LS-DYNA finite element software,and the simulation results showed high consistency with the experimental results,confirming the validity of the material parameters.The results indicate that the projectile heads primarily exhibited crushing and abrasive fragmentation.Larger projectile fragments mainly resulted from tensile and shear stress-induced failure.The failure modes of the composite targets included the formation of ceramic cones and radial cracks under high-velocity impacts.The UHMWPE laminated plates exhibited interlayer separation caused by tensile waves,permanent plastic deformation of the rear surface bulging,and perforation failure primarily due to shear forces.Through extended numerical simulations,while maintaining the same areal density and configuration of9 mm Al_(2)O_(3) ceramic+12 mm UHMWPE laminated composite armor,the thickness configurations of the Al_(2)O_(3) ceramic and UHMWPE laminated backplates were varied,and various thicknesses of UHMWPE laminates were simulated as the cover layer for the ceramic panels.The simulation results indicated that the composite armor configuration of 10 mm Al_(2)O_(3) ceramic+8 mm UHMWPE composite armor increased energy absorption by13.48%.When altering the cover layer thickness,a 4 mm UHMWPE+9 mm Al_(2)O_(3)+8 mm UHMWPE composite armor demonstrated a 27.11%improvement in energy absorption,showing a relatively significant enhancement.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52272116 and 12002400)the Natural Science Foundation of Shandong Province (Grant No.ZR2021ME096)the Youth Innovation Team Project of Shandong Provincial Education Department (Grant No.2019KJJ012)。
文摘Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients.The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics,which makes it not easy to extend the sample data by additional experimental or theoretical calculations.In this paper,a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components.In contrast to all-data-driven model,physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties.Based on the model outputs,the positions of morphotropic phase boundary(MPB)with different Sm doping amounts are explored.We also find the components with the best piezoelectric property and comprehensive performance.Moreover,we set up a database according to the obtained results,through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs.
