The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and c...The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and codeposited composite material is analyzed. The reinforcement particles injection velocity has to be limited between an upper and a lower critical values. in order to ensure entrapment into the matrix droplets in flight. The thermal history of the injected droplets during the deposition stage is calculated with the assumption that the in-flight solidifying droplets reach the substrate while containing still at least 20% liquid volume fraction, in order to avoid porosity of the deposited material. The substrate to pouring-tube orifice distance where that condition is achieved depends strongly on the atomization pressure and the convective heat transfer coefficient of the substrate. It is demonstrated that 'tailoring' the microstructures and the reinforcement volume percent in the deposited material is feasible. The critical process parameters : the atomization pressure, the melt flow rate. the substrate to pouring-tube orifice distance, the reinforcement particles injection location and rate can all be adequately chosen in order to obtain any desired microstructure, grain size, reinforcement volume percent, with the additional benefit, if wanted, of rapid solidification processing展开更多
With the gradual depletion of shallow geological resources,their development has increased.However,it is difficult to control the stability and bearing capacity of deep-stratum fissure rock bodies under static and dyn...With the gradual depletion of shallow geological resources,their development has increased.However,it is difficult to control the stability and bearing capacity of deep-stratum fissure rock bodies under static and dynamic load coupling.To study the relationship between the mechanical properties of anchor-reinforced fissured rock bodies under static and dynamic loading conditions,this study performed a static compression test and dynamic impact test on anchor-reinforced prefabricated fissured red sandstone with different inclination angles.Research has revealed that under static loading conditions,the mechanical properties of anchor-reinforced specimens are stable,and the peak strength fluctuates between 23-27 MPa.Under dynamic loading conditions,the peak strength and deformation decreased with increasing inclination angle.The peak strength decreased from 47.3 MPa at 15°inclination angle to 35.4 MPa at a 90°inclination angle,and the peak strain and dynamic cut line modulus were 1.28 times and 1.23 times of the static loading,respectively.Under static loading,the specimen cracks mainly developed along the prefabricated cracks to shear damage,and the increase in the inclination angle led to the damage spreading to the specimen ends,forming combined tensile-shear damage.Under dynamic loading,the damage was primarily tensile-shear combination damage parallel to the impact direction.Based on the linear uniaxial strength criterion,a new relationship between dynamic peak strength,strain rate,and static peak strength was established,and the correlation coefficients were 0.90-0.98,indicating a good correlation.展开更多
文摘The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and codeposited composite material is analyzed. The reinforcement particles injection velocity has to be limited between an upper and a lower critical values. in order to ensure entrapment into the matrix droplets in flight. The thermal history of the injected droplets during the deposition stage is calculated with the assumption that the in-flight solidifying droplets reach the substrate while containing still at least 20% liquid volume fraction, in order to avoid porosity of the deposited material. The substrate to pouring-tube orifice distance where that condition is achieved depends strongly on the atomization pressure and the convective heat transfer coefficient of the substrate. It is demonstrated that 'tailoring' the microstructures and the reinforcement volume percent in the deposited material is feasible. The critical process parameters : the atomization pressure, the melt flow rate. the substrate to pouring-tube orifice distance, the reinforcement particles injection location and rate can all be adequately chosen in order to obtain any desired microstructure, grain size, reinforcement volume percent, with the additional benefit, if wanted, of rapid solidification processing
基金supported by the National Natural Science Foundation of China(No.52374121)the National Key R&D Program of China(No.2023YFC2907203)the Science and Technology Research Key Project of Henan Province(242102321165)
文摘With the gradual depletion of shallow geological resources,their development has increased.However,it is difficult to control the stability and bearing capacity of deep-stratum fissure rock bodies under static and dynamic load coupling.To study the relationship between the mechanical properties of anchor-reinforced fissured rock bodies under static and dynamic loading conditions,this study performed a static compression test and dynamic impact test on anchor-reinforced prefabricated fissured red sandstone with different inclination angles.Research has revealed that under static loading conditions,the mechanical properties of anchor-reinforced specimens are stable,and the peak strength fluctuates between 23-27 MPa.Under dynamic loading conditions,the peak strength and deformation decreased with increasing inclination angle.The peak strength decreased from 47.3 MPa at 15°inclination angle to 35.4 MPa at a 90°inclination angle,and the peak strain and dynamic cut line modulus were 1.28 times and 1.23 times of the static loading,respectively.Under static loading,the specimen cracks mainly developed along the prefabricated cracks to shear damage,and the increase in the inclination angle led to the damage spreading to the specimen ends,forming combined tensile-shear damage.Under dynamic loading,the damage was primarily tensile-shear combination damage parallel to the impact direction.Based on the linear uniaxial strength criterion,a new relationship between dynamic peak strength,strain rate,and static peak strength was established,and the correlation coefficients were 0.90-0.98,indicating a good correlation.
