Ballistic performance of titanium-based layered composites made using blended elemental powder metallurgy and hot isostatic pressing

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.

Chemical Composition of Pineapple Press Residues (Ananas comosus) and Effect on Growth Performance of Rabbit (Oryctolagus cuniculus)

With a view to improving rabbit production performance, a trial on the chemical composition of pineapple press residue (Ananas comosus) and the effect of its incorporation in the ration on rabbit growth performance (Oryctolagus cuniculus) was carried out at the KUATE Cunicole Farm in Bandjoun, in Western Cameroon. To do this, 36 rabbits of the local breed, aged 53 days with an average weight of 1337 ± 119 g were distributed and randomly assigned to 3 experimental rations corresponding respectively to treatments or batches T0, T1 and T2. The animals in treatment T0 received a ration containing no pineapple press residue, while those in treatments T1 and T2 received a ration containing 20% and 40% pineapple press residue, respectively. These residues were dried and ground for chemical composition analysis. The feed served as well as refusals from the previous day were weighed each morning to assess feed intake. The animals were weighed every 7 days to assess weight performance. At the end of the trial which lasted 7 weeks, the animals were fasted for 24 hours, then sacrificed to evaluate carcass characteristics and the relative weights of some digestive organs. The results of this study showed that pineapple press residues had a high crude fiber content (19.2%) and energy (2500 Kcal/kg DM). Their incorporation had no significant effect on feed intake and feed conversion ratio. The average live weight, weight gain and average daily weight gain of the animals receiving the ration with 20% inclusion of pineapple press residue were comparable to those of the control group and significantly higher than those of animals fed with 40% inclusion of pineapple residue. The highest carcass yields were obtained with rabbits fed 20% pineapple press residue in their ration. The cost of feed for the production of a kilogram live weight of rabbit tends to decrease with the ration incorporated with 20% pineapple press residue. Pineapple press residues constitute a by-product that can be recycled and their incorporation at 20% can increase rabbit growth performance and reduce production costs.

Microstructures and mechanical properties of 2024Al/Gr/SiC hybrid composites fabricated by vacuum hot pressing

The 2024Al/Gr/SiC hybrid composite plates with 5%-10% SiC particles （volume fraction） and 3%-6% flaky graphite （Gr） （volume fraction） were fabricated by vacuum hot pressing and hot extrusion processing. The effects of SiC and Gr on the microstructures and mechanical properties of the composites aged at 160, 175 and 190℃ were studied by optical microscopy, scanning electron microscopy （SEM）, and hardness and tensile tests. The results indicate that the SiC particles have a more obvious effect on accelerating the aging response as compared with the Gr. Both the tensile strength and elongation are reduced by the Gr and SiC particles added into the matrix, while the Gr has a more negative influence on the elongation than the SiC particles. The tensile strength （ab）, yield stress （as） and elongation （δ） of the 2024Al/3Gr/10SiC composite aged at 165℃ for 8 h are 387 MPa, 280.3 MPa and 5.7%, respectively. The hybrid composites are characterized by ductile fracture, which is associated with the ductile fracture of the matrix and the tearing of the interface between the matrix and the particles.

Preparation and Study of Carbide-SiAlON Composite in SiC-SiAlON-Al2O3 Syste

Goal: Synthesis of SiAlON by reaction coating method using aluminosilicate natural raw material geopolymer (kaolin), corundum and silicon carbide and on its basis obtaining a composite with high physical and technical properties by hot pressing for use in armor and rocket technology. For the intensification of SiAlON formation and sintering processes, the influence of various additives was studied, such as: aluminum powder, elemental silicon, yttrium and magnesium oxides. Method: A SiAlON-containing composite with an open porosity of 15% - 16% was obtained by the metallothermic process and the method of reactive annealing in nitrogen. The resulting material was milled to a dispersion of 1 - 3 μm and hot pressed at 1620°C to obtain a product with high density and performance properties. We studied the process of SiAlON formation and the microstructure of the composite by X-ray phase, optical and electronmicroscopy analysis methods. Result: In the selected composition the β-SiAlON was formed at 1400°C instead of 1800°C, which was due to the mutual influence of the initial raw materials: geopolymer kaolin, perlite, corundum, aluminum, silicon, SiC, the development of the process is facilitated by the vitreous dopant perlite (96 glass phase). The use of perlite, which is eutectic with geopolymer at low temperatures, creates a good prerequisite for intensive diffusion processes with other components. Conclusion: A SiAlON-containing composite with high physical and technical properties was obtained in the SiC-SiAlON-Al2O3 system by the method of reactive sintering and hot pressing, with the following properties: the strength limit in compression is 1940 MPa, and in bending it is 490 MPa. The process of making SiAlON has been studied using X-ray phase and electron microscopy analysis methods. The physical and technical properties of the obtained composite are studied by modern research methods.

Interfacial reaction process of the hot-pressed WC/2024Al composite

12 vol%WCp/2024Al composite was fabricated from mixed powders by hot-pressing at various tempera-tures. Investigation of the interfacial reaction between the WC phase and the Al alloy matrix was performed by X-ray diffraction （XRD）, transmission electron microscope （TEM） and energy dispersive spectroscopy （EDS）. A multiple layer interface structure, which is composed of Al/ WAl12/AlnC3/WC, is found to form by the interfacial reaction during hot-pressing. Further study shows that the AlaC3 layer forms along with a given crystal orientation of WC phase and might retard the interfacial reaction process.

Fabrication of FeAl/TiC composites through reactive hot pressing

FeAl/TiC composites were fabricated by reactive hot pressing blended elemental powders. The TiC content was varied from 50% to 80%(volume fraction) and the aluminum content in the binder phase was changed from 40% to 50%(mole fraction). The effects of these compositional changes on the densification process and mechanical properties were studied. The results show that with the increase of TiC content, densities of the composites decrease due to insufficient particle rearrangement aided by (dissolutionreprecipitation) reaction during hot pressing. Closely related with their porosities and defect amount, the hardness and bend strength of the composites show peak values, attaining the highest values with TiC content being 70% and 60%, respectively. Increasing the aluminum content is beneficial to the densification process. But the hardness and bend strength of the composites are reduced to some extent due to the formation of excessive oxides and thermal vacancies.

Electrospinning-hot pressing technique for the fabrication of thermal and electrical storage membranes and its applications

The combination of electrospinning and hot pressing,namely the electrospinning-hot pressing technique(EHPT),is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance.The emerging composite membrane prepared by EHPT,which exhibits the advantages of large surface area,controllable morphology,and compact structure,has attracted immense attention.In this paper,the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed.Moreover,the state-of-the-art applications of composite membranes in these two fields are introduced.In particular,in the field of thermal energy storage,EHPT-prepared membranes have longitudinal and transverse nanofibers,which generate unique thermal conductivity pathways;also,these nanofibers offer enough space for the filling of functional materials.Moreover,EHPT-prepared membranes are beneficial in thermal management systems,building energy conservation,and electrical energy storage,e.g.,improving the electrochemical properties of the separators as well as their mechanical and thermal stability.The application of electrospinning-hot pressing membranes on capacitors,lithium-ion batteries(LIBs),fuel cells,sodium-ion batteries(SIBs),and hydrogen bromine flow batteries(HBFBs)still requires examination.In the future,EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.

Influence of Formulation and Hot-Pressing Conditions on the Performance of Bio-Based Molasses Adhesive for Plywood

Molasses can serve as a natural adhesive for plywood and particleboard.However,several disadvantages remain,including lower dimensional stability and low bonding strength compared to other adhesives.Therefore,modifications are needed to use molasses as an adhesive for plywood.This research aims to improve bio-based molasses(MO)adhesive for plywood using citric acid(CA)adhesive.In addition,this research aims to analyze the effect of adding citric acid and to investigate the optimum hot-pressing temperature to produce the best quality plywood.In the first stage,the molasses and citric acid were combined in a ratio of 100:0,75:25,50:50,25:75,0:100 w/w%.Then,the second stage focuses on analyzing the influences of pressing temperature based on an optimum first stage.The research demonstrated that the addition of CA altered the gelation time,solid content,viscosity,and pH of the molasses adhesives.In addition,the thermal properties of molasses adhesives were changed after mixing with citric acid.These phenomena indicate changes in characteristics,such as the curing of adhesive.Overall,the characteristics of plywood showed a steady improvement as the CA ratio increased but revealed a significant decline for the 25:75 MO-CA ratio.By raising the pressing temperature from 180℃ to 200℃,the quality of plywood was effectively improved.The plywood that was bonded using adhesives with a 50:50 MO-CA ratio exhibited superior mechanical properties and improved dimensional stability compared to the plywood bonded solely with MO.Furthermore,the optimal mechanical and physical properties resulted in plywood bonded with a 50:50 MO-CA ratio when subjected to a pressing temperature of 200℃.The Thermal and FTIR measurements revealed that CA established ester bonds with both the MO and wood veneers.In conclusion,the mechanical characteristics of plywood were improved,while maintaining its excellent dimensional stability.

Carbon-fiber-reinforced silicon carbide composites prepared by precursor pyrolysis-hot pressing

The Cf/SiC composites were prepared by precursor conversion-hot pressing sintering with AIN and Y2Os as additives. The effects of sintering temperature and additives on the microstructures and properties of the composites were investigated. The composite sintered at as low as 1 75O℃ already showed higher density and better mechanical properties, which was mainly attributed to the liquid-phase-sintering and the formation of the AIN-SiC solid solution. With increasing the sintering temperature to 1 800 ℃, the flexural strength and fracture toughness of the composite were substantially improved up to 691. 6 MPa and 2O. 7 MPa’ m1/2 respectively in spite of the slightly elevated density, and the composite exhibited "tough" failure. Despite the improved density, the composite sintered at 1 85O℃ displayed brittle failure, which mainly attributed to the strongly bonded fiber/matrix interface and the degradation of the properties of the fibers.

Mechanical properties and microstructure of in situ TiB_2/Cu composite fabricated by reactive hot pressing

A copper matrix composite reinforced by TiB_2 particle was fabricated by reactions of Cu,Ti and B powders.The microstructure and mechanical properties of the in situ composite were investigated.The results showed that the in situ formed TiB_2 particles,which has a size of no larger than 1 μm,exhibits a uniform distribution in the copper matrix.Due to TiB_2 reinforcement,the mechanical properties in terms of Young's modulus and yield and ultimate tensile stress of the in situ TiB_2/Cu composite are improved greatly.In addition,even if the volume fraction of TiB_2 reinforcement are the same,the composite in the present study containing fine TiB_2 particles exhibits much higher properties than that of the composite reinforced with coarse ones.

Preparation of TiAl/Ti_2AlC Composites with Ti/Al/C Powders by In-situ Hot Pressing

TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.

Thermodynamic Analysis of Combusion Synthesis and Reaction Hot Pressing of Al_2O_3/B_4C Composite

The equilibrium phases and adiabatic temperature for combustion synthesis and reaction hot pressing of Al 2O 3/B 4C employing ① Al, B 2O 3 and C ② C, B, Al 2O 3 as starting reactants were analyzed by the CALPHAD technique. It is shown that the equilibrium phases at the adiabatic temperature in the combusion system (1) are not the intended composite Al 2O 3/B 4C but other phases. Good agreement with the experimental data was achieved for the calculated adiabatic temperature. The results were discussed with respect to the elimination of the by product in the combustion synthesis. It also revealed that the reactant mixture (2) is a weak exothermic or endothermic reaction system, which can be employed in the reaction hot pressing.

Study on Squeeze Casting Metal-zirconium Composite Die Material by Hot Press Sintering

ZrO_(2)-5CrMnMo composite samples were prepared by hot press sintering.When NiCoCrAlY powders were used as the bonding layer and the different mixtures of NiCoCrAlY alloy and 3YSZ (3mol% yttria stabilized zirconia) ceramic powders were used as the transition layers,the connection between zirconia ceramic and 5CrMnMo steel were strengthened.Three composite samples with different structures were fabricated by heat spraying and hot press sintering.Shear and thermal shock cycle tests were conducted to characterize connection strength and thermal shock resistance of these samples.The shear strength reached 95.69 MPa,and the heating shock cycles achieved to the maximum value of 27.7 times.Microstructures and connection interfaces were analyzed by scanning electron microscopy.The hardness and wearing resistance of 3YSZ coat and 5CrMnMo substrate were compared,and the heat insulation property of composite samples were also discussed.It is shown that these composite materials fabricated in this research are benefited to be used as squeeze casting dies.

Reactive Hot-press Sintering of Al-B_4C Composites at Relative Low Temperature

A new process of reactive hot-press sintering with boron carbide(B4C) and aluminum powders was proposed to overcome difficulties in the sintering of dense B4C ceramic materials.The B4C powder with different content of pure metallic aluminum particle were milled,hot-pressed and sintered at 1600 ℃ for 1 hour.The mechanism of sintering at relative low temperature was analyzed.The phase constitution of the composites was determined.Effects of Al content on the hardness and fracture toughness of the composites were discussed.The results show that thermite reaction procedure in B2O3+Al was the mechanism of sintering at relative low temperature,B4C,Al2O3 and metallic aluminum are the major constituents of the composites.The microhardness of the composites decreases with the increasing of Al content,but the fracture toughness increase obviously.The composite with 5wt% Al content has the best microhardness and fracture toughness in all the composites.

Mechanical properties of C_f/Si-O-C composites prepared by hot-pressing assisted pyrolysis of polysiloxane

Silicon oxycarbide composites reinforced by three-dimensional braided carbon fiber （3D-B Cf/Si-O-C） were fabricated via precursor infiltration and pyrolysis of polysiloxane, and the effects of processing variables on mechanical properties and microstructures of 3D-B Cf/Si-O-C composites were investigated. It is found that the mechanical properties and densities of 3D-B Cf/Si-O-C composites can be increased if the first pyrolysis cycle is assisted by hot-pressing. Pyrolysis temperature has great effects on mechanical properties and microstructures of 3D-B Cf/Si-O-C composites. The composite, which is hot-pressed at 1 600 ℃ for 5 min with pressure of 10 MPa in the first pyrolysis cycle, exhibits high mechanical properties: bending strength 502 MPa and fracture toughness 23.7 MPa·m1/2. The high mechanical properties are mainly attributed to desirable interfacial structure and high density.

Influence of FeCrAl fiber on microstructure and mechanical properties of FeCrAl(f)/HA composites

FeCrAl fiber-reinforced hydroxyapatite（HA） biocomposites（FeCrAl（f）/HA） were fabricated by the hot pressing technique.The metallographic microscopy,X-ray diffractometry,scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS） were used to observe and analyze the microstructure and composition of FeCrAl（f）/HA composites,respectively.The mechanical properties of FeCrAl（f）/HA composites were measured by the three-point-bending test.The results show that the composite can be reinforced by FeCrAl fiber and enhanced gradually,and then declined with the increase of the content of FeCrAl fiber（0-11%,volume fraction） in the whole range of experiments.Both the HA matrix and FeCrAl fiber integrate very tightly and bit into each other very deeply and counter-diffusion takes place to some extent at two-phase interface.The optimum parameters of FeCrAl（f）/HA composite are diameter of 22 μm,length of 1-2 mm and of volume faction of about 7% for FeCrAl fibers.

Fabrication of aluminum matrix composite reinforced with carbon nanotubes

1.0wt.% carbon nanotube （CNT） reinforced 2024Al matrix composite was fabricated by cold isostatic press and subsequent hot extrusion techniques. The mechanical properties of the composite were measured by a tensile test. Mean-while,the fracture surfaces were examined using field emission scanning electron microscopy. The experimental results show that CNTs are dispersed homogeneously in the composite and that the interfaces of the Al matrix and the CNT bond well. Although the tensile strength and the Young’s modulus of the composite are enhanced markedly,the elongation does not decrease when compared with the matrix material fabricated under the same process. The reasons for the increments may be the extraordinary mechanical properties of CNTs,and the bridging and pulling-out role of CNTs in the Al matrix composite.

Al_2O_3 PARTICLE REINFORCED COPPER MATRIX COMPOSITE USING FOR CONTINUOUS CASTING MOULD

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.