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
In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the ...In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.展开更多
concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentrati...concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentration of feed, the flowrate and liquor temperature in high temperature side and low temperature side on the flux and separation efficiency is investigated. The stability of this composite membrane is also inspected. The experimental results show that the metal PTFE composite membrane can be used in membrane distillation, and its properties are very stable. It is feasible to concentrate sulfuric acid by membrane distillation with this membrane.展开更多
In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,...In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%and 4.0 wt.%were fabricated by solution casting,and then IPMCs were manufactured by electroless plating.The water contents and elastic moduli of the hybrid membranes were tested.The morphology characteristics of the hybrid membranes and the IPMCs were observed,and the current,AC impedance,blocking force and displacement of the IPMCs were measured.The results show that the elastic modulus of the hybrid membranes decreases,the water content increases,and the actuation performance of the IPMCs improves significantly after the addition of GQDs.IPMC with 1.0 wt.%GQDs exhibits the best driving property.Compared with the IPMC without GQDs,the working current,ion conductivity,blocking force,and tip displacement increase by 94.67%,311.11%,53.66%,and 66.07%,respectively.These results lay a solid foundation for the preparation of IPMCs with high performance,and further broaden their applications in biomedical devices and bionic robots.展开更多
In this study,a mathematical model was developed to optimize the heat treatment process for maximum tensile strength and ductility of aluminum(8011) silicon carbide particulate composites.The process parameters are so...In this study,a mathematical model was developed to optimize the heat treatment process for maximum tensile strength and ductility of aluminum(8011) silicon carbide particulate composites.The process parameters are solutionizing time,aging temperature,and aging time.The experiments were performed on an universal testing machine according to centre rotatable design matrix.A mathematical model was developed with the main and interactive effects of the parameters considered.The analysis of variance technique was used to check the adequacy of the developed model.The optimum parameters were obtained for maximum tensile strength.Fractographic examination shows the cracks and dimples on the fractured surfaces of heat-treated specimen.展开更多
Composite materials exhibit the impressive mechanical properties of high damping and stiffness,which cannot be attained by employing conventional single materials.Along these lines,a novel material architecture is pre...Composite materials exhibit the impressive mechanical properties of high damping and stiffness,which cannot be attained by employing conventional single materials.Along these lines,a novel material architecture is presented in this work in order to fabricate composites with enhanced mechanical characteristics.More specifically,entangled metallic wire materials were used as the active matrix,whereas polyurethane was employed as the reinforcement elements.As a result,an entangled metallic wire material-polyurethane composite with high damping and stiffness was prepared by enforcing the vacuum infiltration method.On top of that,the mechanical properties(loss factor,energy consumption,and average stiffness)of the proposed composite materials were characterized by performing dynamic tests,and its fatigue characteristics were verified by the micro-interface bonding,as well as the macro-damage factor.The impact of the density,preloading spacing,loading amplitude,and exciting frequency on the mechanical properties of the composites were also thoroughly analyzed.The extracted results indicate that the mechanical properties of the composites were significantly enhanced than those of the pure materials due to the introduction of interface friction.Moreover,the average stiffness of the composites was about 10 times the respective value of the entangled metallic wire material.Interestingly,a rise in the loading period leads to some failure between the composite interfaces,which reduces the stiffness property but enhances the damping dissipation properties.Finally,a comprehensive dynamic mechanical model of the composites was established,while it was experimentally verified.The proposed composites possess higher damping features,i.e.,stiffness characteristics,and maintain better fatigue characteristics,which can broaden the application range of the composites.In addition,we provide a theoretical and experimental framework for the research and applications in the field of metal matrix composites.展开更多
Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and ind...Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.展开更多
Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust ve...Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(MOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of combustion catalysts in burning rate enhancement. Available information on different types of combustion nanocatalysts is also presented with critical comments.展开更多
The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles...The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles were processed by friction stir processing. Micro-hardness and depth of penetration tests were carried out to evaluate the ballistic properties of the surface composites. The surface hardness of the composite was found to be nearly 70 HV higher than base alloy. The depth of penetration of the steel projectile was 20e26mm in the composites as compared to 37mm in the base alloy. Ballistic mass efficiency factor of the surface composite was found to be 1.6 times higher than base alloy. This is mainly attributed to the dispersion strengthening from the reinforcement particles.展开更多
Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fa...Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fabrication. In this study, AA6061/SiC surface composites were fabricated and the effect of tool plunge depth on pattern of reinforcement particles dispersion in metal matrix was investigated. Six varying tool plunge depths were chosen at constant levels of shoulder diameter and tool tilt angle to observe the exclusive effect of plunge variation. Process parameters chosen for the experimentation are speed of rotation, travel speed and tool tilt angle which were taken as 1400 rpm, 40 mm/min, and 2.5 °respectively. Macro and the microstructural study were performed using stereo zoom and optical microscope respectively. Results reflected that lower plunge depth levels lead to insufficient heat generation and cavity formation towards the stir zone center. On the other hand, higher levels of plunge depth result in ejection of reinforcement particles and even sticking of material to tool shoulder. Thus, an optimal plunge depth is needed in developing defect free surface composites.展开更多
Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation,ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of...Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation,ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of AISI 1030 steel and hybrid AA6063-6 SiC_p-3 Gr_pcomposite, that are difficult to weld by fusion welding technique. Silicon carbide and graphite particle reinforced AA6063 matrix hybrid composite was developed successfully using stir casting method and the joining feasibility of AISI1030 steel with AA6063-6 SiC_p-3 Gr_p hybrid composite was tried out by friction stud welding technique. During friction stage of welding process, the particulates(SiC & Graphite) used for reinforcement, tend to increase the viscosity and lead to improper mixing of matrix and reinforcement. This eventually results in lower strength in dissimilar joints. To overcome this difficulty AA1100 interlayer is used while joining hybrid composite to AISI 1030 steel. Experimentation was carried out using Taguchi based design of experiments(DOE) technique. Multiple regression methods were applied to understand the relationship between process parameters of the friction stud welding process. Micro structural examination reveals three separate zones namely fully plasticized zone, partially deformed zone and unaffected base material zone. Ultra fine dynamically recrystallized grains of about 341 nm were observed at the fully plasticized zone. EDX analysis confirms the presence of intermetallic compound Fe_2 Al_5 at the joint interface. According to the experimental analysis using DOE, rotational speed and interlayer sheet thickness contribute about 39% and 36% respectively in determining the impact strength of the welded joints. It is found that joining with 0.5 mm interlayer sheet provides efficient joints. Developed regression model could be used to predict the axial shortening distance and impact strength of the welded joint with reasonable accuracy.展开更多
Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is use...Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is used for modeling the mechanical behaviors of such different heterogeneous materials. The method is based on particle approach and may be considered as a kind of discrete element method. The main feature of the method is the use of many-body forces of inter-element interaction within the formalism of simply deformable element approximation. It was shown that the strength of reinforcing particles and the width of particle-binder interphase boundaries had determining influence on the service characteristics of metaleceramic composite. In particular, the increasing of strength of carbide inclusions may lead to significant increase in the strength and ultimate strain of composite material. On the example of porous zirconia ceramics it was shown that the change in the mechanical properties of pore surface leads to the corresponding change in effective elastic modulus and strength limit of the ceramic sample. The less is the pore size, the more is this effect. The increase in the elastic properties of pore surface of ceramics may reduce its fracture energy.展开更多
Most conventional ceramic based aluminum metal matrix composites(MMCs) are either heavy,costly or combination of both. In order to reduce cost and weight,while at the same time maintaining quality,cow horn particles(C...Most conventional ceramic based aluminum metal matrix composites(MMCs) are either heavy,costly or combination of both. In order to reduce cost and weight,while at the same time maintaining quality,cow horn particles(CHp) was used with aluminum alloy A356 to produce MMC for brake drum application and other engineering uses. The aim of this research is to model the age hardening process of the produced composite using response surface methodology(RSM) and artificial neural network(ANN),and to use the developed ANN as fitness function for a simulated annealing optimization algorithm(SA-NN system) for optimization of age hardening process parameters. The results show that ANN modeled the age hardening data excellently and better than RSM with a correlation coefficient of experimental response with ANN predictions being 0.9921 as against 0.9583 for the RSM. The SA-NN system optimized process parameters were in very close agreement with the experimental values with the maximum relative error of 1.2%,minimum of 0.35% and average of 0.71%.展开更多
Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess elec...Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess electrical energy and difficulty in handling the arc furnace due to frothing effects.A more efficient process of pre-reducing the ilmenite before smelting has been proposed in the present communication.In particular,studies have been undertaken on the reduction process of ilmenite-coke composite pellets.The difference in the reduction behaviour of raw ilmenite and ilmenite-coke composite pellets has been established and compared with that of the pre-oxidized raw pellets.The effects of various processing parameters like temperature,residence time,and reductant percentage on the metallization of composite pellets in a static bed have been investigated.Metallization of about 90%has been achieved at 1250°C for a reduction period of 360 min with a 4%coke composition.Furthermore,the reduced pellets have been characterized through chemical analysis,optical microscopy,field emission scanning electron microscopy and X-ray diffraction analysis.The reduction behaviour of composite pellets has also been found better than that of pre-oxidized pellets indicating the former to be more efficient.展开更多
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supported by the Science and Technology Development Fund (2015B0201025)the key subject "Computational Solid Mechanics" of China Academy of Engineering Physics+1 种基金the National Outstanding Young Scientists Foundation of China (11225213)the National Natural Science Foundation of China (11521062,11602258)
文摘In the present manuscript numerical analysis on the ballistic performance of a tungsten particle/metallic glass matrix(WP/MG) composite rod is conducted by integrating with related experimental investigations. In the corresponding finite element method(FEM) simulations a modified coupled thermomechanical constitutive model is employed to describe the mechanical properties of metallic glass(MG)matrix, and geometrical models of the WP/MG composite rod are established based on its inner structure. The deformation and failure characteristics of the rod and target materials are analyzed in detail,and the influences of various factors on the ballistic performance of the WP/MG composite long rod are discussed. Related analysis demonstrates that the penetrating performance of the WP/MG rod is similar to that of the tungsten fiber/metallic glass matrix(WF/MG) composite long rod, i.e., a "self-sharpening" behavior also occurs during the penetration process, and correspondingly its penetrating capability is better than that of the tungsten heavy alloy(WHA) rod. However, the mass erosion manner of the WP/MG rod is different and the erosion is relatively severe, thus its penetrating capability is a little lower compared with that of the WF/MG one. Moreover, the impact velocity and the target strength have significant influences on the ballistic performance of the WP/MG composite rod, whereas the effect of initial nose shape is very little.
文摘concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentration of feed, the flowrate and liquor temperature in high temperature side and low temperature side on the flux and separation efficiency is investigated. The stability of this composite membrane is also inspected. The experimental results show that the metal PTFE composite membrane can be used in membrane distillation, and its properties are very stable. It is feasible to concentrate sulfuric acid by membrane distillation with this membrane.
基金Projects(51605220,U1637101)supported by the National Natural Science Foundation of ChinaProject(BK20160793)supported by the Jiangsu Provincial Natural Science Foundation,ChinaProject(NS2020029)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%and 4.0 wt.%were fabricated by solution casting,and then IPMCs were manufactured by electroless plating.The water contents and elastic moduli of the hybrid membranes were tested.The morphology characteristics of the hybrid membranes and the IPMCs were observed,and the current,AC impedance,blocking force and displacement of the IPMCs were measured.The results show that the elastic modulus of the hybrid membranes decreases,the water content increases,and the actuation performance of the IPMCs improves significantly after the addition of GQDs.IPMC with 1.0 wt.%GQDs exhibits the best driving property.Compared with the IPMC without GQDs,the working current,ion conductivity,blocking force,and tip displacement increase by 94.67%,311.11%,53.66%,and 66.07%,respectively.These results lay a solid foundation for the preparation of IPMCs with high performance,and further broaden their applications in biomedical devices and bionic robots.
文摘In this study,a mathematical model was developed to optimize the heat treatment process for maximum tensile strength and ductility of aluminum(8011) silicon carbide particulate composites.The process parameters are solutionizing time,aging temperature,and aging time.The experiments were performed on an universal testing machine according to centre rotatable design matrix.A mathematical model was developed with the main and interactive effects of the parameters considered.The analysis of variance technique was used to check the adequacy of the developed model.The optimum parameters were obtained for maximum tensile strength.Fractographic examination shows the cracks and dimples on the fractured surfaces of heat-treated specimen.
基金National Natural Science Foundation of China(Grant No.52175162,51805086 and 51975123)Natural Science Foundation of Fujian Province(Grant No.2019J01210)Health education joint project of Fujian Province(Grant No.2019-WJ-01)。
文摘Composite materials exhibit the impressive mechanical properties of high damping and stiffness,which cannot be attained by employing conventional single materials.Along these lines,a novel material architecture is presented in this work in order to fabricate composites with enhanced mechanical characteristics.More specifically,entangled metallic wire materials were used as the active matrix,whereas polyurethane was employed as the reinforcement elements.As a result,an entangled metallic wire material-polyurethane composite with high damping and stiffness was prepared by enforcing the vacuum infiltration method.On top of that,the mechanical properties(loss factor,energy consumption,and average stiffness)of the proposed composite materials were characterized by performing dynamic tests,and its fatigue characteristics were verified by the micro-interface bonding,as well as the macro-damage factor.The impact of the density,preloading spacing,loading amplitude,and exciting frequency on the mechanical properties of the composites were also thoroughly analyzed.The extracted results indicate that the mechanical properties of the composites were significantly enhanced than those of the pure materials due to the introduction of interface friction.Moreover,the average stiffness of the composites was about 10 times the respective value of the entangled metallic wire material.Interestingly,a rise in the loading period leads to some failure between the composite interfaces,which reduces the stiffness property but enhances the damping dissipation properties.Finally,a comprehensive dynamic mechanical model of the composites was established,while it was experimentally verified.The proposed composites possess higher damping features,i.e.,stiffness characteristics,and maintain better fatigue characteristics,which can broaden the application range of the composites.In addition,we provide a theoretical and experimental framework for the research and applications in the field of metal matrix composites.
基金financial support received from Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT)
文摘Titanium metal matrix composite(Ti-MMC)has excellent features and capabilities which can be considered a potential candidate to replace commercial titanium and superalloys within an extensive range of products and industrial sectors.Regardless of the superior features in Ti-MMC,however,referring to several factors including high unit cost and existence of rigid and abrasive ceramic particles in the generated matrices of the work part,the Ti-MMC is grouped as extremely difficult to cut with a poor level of machinability.Furthermore,adequate process parameters for machining Ti-MMCs under several lubrication methods are rarely studied.Therefore,adequate knowledge of this regard is strongly demanded.Among machinability attributes,ultrafine particles(UFPs)and fine particles(FPs)have been selected as the main machinability attributes and the factors leading to minimized emission have been studied.According to experimental observations,despite the type of coating used,the use of higher levels of flow rate led to less UFPs,while no significant effects were observed on UFPs.Under similar cutting conditions,higher levels of FPs were recorded under the use of uncoated inserts.Moreover,cutting speed had no significant influence on UFPs;nevertheless,it significantly affects the FPs despite the type of insert used.
文摘Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(MOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of combustion catalysts in burning rate enhancement. Available information on different types of combustion nanocatalysts is also presented with critical comments.
基金supported by Defence Institute of Advanced Technology(DIAT),Pune(DIAT-In house Project)
文摘The present work aims to enhance the ballistic resistance of AA7005 alloy by incorporating the TiB2 and B4C ceramic reinforcement particles. Surface composites with different weight fractions of TiB2 and B4C particles were processed by friction stir processing. Micro-hardness and depth of penetration tests were carried out to evaluate the ballistic properties of the surface composites. The surface hardness of the composite was found to be nearly 70 HV higher than base alloy. The depth of penetration of the steel projectile was 20e26mm in the composites as compared to 37mm in the base alloy. Ballistic mass efficiency factor of the surface composite was found to be 1.6 times higher than base alloy. This is mainly attributed to the dispersion strengthening from the reinforcement particles.
基金the University Grants Commission (UGC) for its financial assistance (vide sanction order No. F.3-40/2012 (SAP-II) under its SAP (DRS-I) sanctioned to the Department of Mechanical Engineering for the project entitled Friction Stir Welding, Ultrasonic Machining
文摘Aluminium matrix surface composites are gaining alluring role especially in aerospace, defence, and marine industries. Friction stir processing(FSP) is a promising novel solid state technique for surface composites fabrication. In this study, AA6061/SiC surface composites were fabricated and the effect of tool plunge depth on pattern of reinforcement particles dispersion in metal matrix was investigated. Six varying tool plunge depths were chosen at constant levels of shoulder diameter and tool tilt angle to observe the exclusive effect of plunge variation. Process parameters chosen for the experimentation are speed of rotation, travel speed and tool tilt angle which were taken as 1400 rpm, 40 mm/min, and 2.5 °respectively. Macro and the microstructural study were performed using stereo zoom and optical microscope respectively. Results reflected that lower plunge depth levels lead to insufficient heat generation and cavity formation towards the stir zone center. On the other hand, higher levels of plunge depth result in ejection of reinforcement particles and even sticking of material to tool shoulder. Thus, an optimal plunge depth is needed in developing defect free surface composites.
基金financial support of this work by SERB of Department of Science&Technology,New Delhi.(Vide Letter No.:SERB/F/1452/2013-2014 dated 10.06.2013)
文摘Joining of metals and aluminium hybrid metal matrix composites has significant applications in aviation,ship building and automotive industries. In the present work, investigation is carried out on Friction Welding of AISI 1030 steel and hybrid AA6063-6 SiC_p-3 Gr_pcomposite, that are difficult to weld by fusion welding technique. Silicon carbide and graphite particle reinforced AA6063 matrix hybrid composite was developed successfully using stir casting method and the joining feasibility of AISI1030 steel with AA6063-6 SiC_p-3 Gr_p hybrid composite was tried out by friction stud welding technique. During friction stage of welding process, the particulates(SiC & Graphite) used for reinforcement, tend to increase the viscosity and lead to improper mixing of matrix and reinforcement. This eventually results in lower strength in dissimilar joints. To overcome this difficulty AA1100 interlayer is used while joining hybrid composite to AISI 1030 steel. Experimentation was carried out using Taguchi based design of experiments(DOE) technique. Multiple regression methods were applied to understand the relationship between process parameters of the friction stud welding process. Micro structural examination reveals three separate zones namely fully plasticized zone, partially deformed zone and unaffected base material zone. Ultra fine dynamically recrystallized grains of about 341 nm were observed at the fully plasticized zone. EDX analysis confirms the presence of intermetallic compound Fe_2 Al_5 at the joint interface. According to the experimental analysis using DOE, rotational speed and interlayer sheet thickness contribute about 39% and 36% respectively in determining the impact strength of the welded joints. It is found that joining with 0.5 mm interlayer sheet provides efficient joints. Developed regression model could be used to predict the axial shortening distance and impact strength of the welded joint with reasonable accuracy.
基金the Projects Nos. III.23.2.3 (I.S. Konovalenko, S.P. Buyakova) and III.23.2.4 (S.G. Psakhie) of the Basic Scientific Research Program of State Academies of Sciences for 2013e2020the RFBR Project No. 12-01-00805-a (A.Yu. Smolin, E.V. Shilko)the grant No. 14-19-00718 of the Russian Science Foundation (A.Yu. Smolin, E.V. Shilko, S.V. Astafurov)
文摘Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is used for modeling the mechanical behaviors of such different heterogeneous materials. The method is based on particle approach and may be considered as a kind of discrete element method. The main feature of the method is the use of many-body forces of inter-element interaction within the formalism of simply deformable element approximation. It was shown that the strength of reinforcing particles and the width of particle-binder interphase boundaries had determining influence on the service characteristics of metaleceramic composite. In particular, the increasing of strength of carbide inclusions may lead to significant increase in the strength and ultimate strain of composite material. On the example of porous zirconia ceramics it was shown that the change in the mechanical properties of pore surface leads to the corresponding change in effective elastic modulus and strength limit of the ceramic sample. The less is the pore size, the more is this effect. The increase in the elastic properties of pore surface of ceramics may reduce its fracture energy.
文摘Most conventional ceramic based aluminum metal matrix composites(MMCs) are either heavy,costly or combination of both. In order to reduce cost and weight,while at the same time maintaining quality,cow horn particles(CHp) was used with aluminum alloy A356 to produce MMC for brake drum application and other engineering uses. The aim of this research is to model the age hardening process of the produced composite using response surface methodology(RSM) and artificial neural network(ANN),and to use the developed ANN as fitness function for a simulated annealing optimization algorithm(SA-NN system) for optimization of age hardening process parameters. The results show that ANN modeled the age hardening data excellently and better than RSM with a correlation coefficient of experimental response with ANN predictions being 0.9921 as against 0.9583 for the RSM. The SA-NN system optimized process parameters were in very close agreement with the experimental values with the maximum relative error of 1.2%,minimum of 0.35% and average of 0.71%.
基金Project(MLP-52)supported by the Council of Scientific and Industrial Research(CSIR),India。
文摘Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess electrical energy and difficulty in handling the arc furnace due to frothing effects.A more efficient process of pre-reducing the ilmenite before smelting has been proposed in the present communication.In particular,studies have been undertaken on the reduction process of ilmenite-coke composite pellets.The difference in the reduction behaviour of raw ilmenite and ilmenite-coke composite pellets has been established and compared with that of the pre-oxidized raw pellets.The effects of various processing parameters like temperature,residence time,and reductant percentage on the metallization of composite pellets in a static bed have been investigated.Metallization of about 90%has been achieved at 1250°C for a reduction period of 360 min with a 4%coke composition.Furthermore,the reduced pellets have been characterized through chemical analysis,optical microscopy,field emission scanning electron microscopy and X-ray diffraction analysis.The reduction behaviour of composite pellets has also been found better than that of pre-oxidized pellets indicating the former to be more efficient.
