Increasing Compaction Pressure Research Articles

Upgrading Characteristics of Empty Fruit Bunch Biopellet with Addition of Bintaro Fruit as Co-firing

The low density of mass and energy are the main reason for the underutilization of great potential of Empty Fruit Bunch (EFB) as a raw material of alternative and renewable fuels. The using of bintaro fruit as co-firing and treatment of torre faction – densification processes were believed to increase the density of mass and energy of the EFB bio pellet. This study aims to determine the effect of residence time, compaction pressure, and addition of bintaro fruit to the characteristics of EFB bio pellet according to ISO 17225-6 standards. Bio pellet machine was carried out two processes sequence, namely the torre faction process and the densification process. The torre faction process was carried out at 275°C with residence time variations 30, 45, and 60 minutes. The densification process was carried out without binder with compaction pressure variations 30, 40, and 50 bar. Characteristics of moisture content and volatile content decreased while ash content, fixed carbon content, and heating value increased with increasing residence time. Characteristics of density increased with increasing compaction pressure. Characteristics of proximate and heating value increased while density properties of bio pellet decreased with the addition of bintaro fruit as co-firing.

Synthesis and Characterization of Zn-Mg Alloys as Biodegradable Materials

The Zn-Mg alloy is a suitable candidate for the manufacture of biomaterials that can be excessively degraded in the human body without producing a mixture. This study was conducted with the aim to determine variations in the mechanical characteristics of Zn-Mg alloys with Mg ratio of 1%, 3%, 5%, and 7%wt, and to study variations in composition and sintering of the degradation rate of Zn-alloy Mg uses the powder metallurgy method. The synthesis results were characterized by using a defense test and obtained the best value at Zn7% Mg of 117.5 ± 25.37. The presence of MgZn2 and Mg2Zn11 phases that were confirmed by XRD characterization could increase the material hardness. Dynamic degradation test was carried out on samples with the best mechanical properties (Zn7% Mg) with variations in compacting pressure and sintering temperature. The increase in compaction pressure and sintering temperature could reduce the degradation rate of Zn-Mg alloys. The best degradation test was obtained at a pressure of 400 MPa with a sintering temperature of 400°C of 0.70mmpy. The degradation test results were as expected because previous studies stated at the degradation rate (0.40mmpy-1.53mmpy) on statistical testing and the degradation rate (4.9-7.0) mmpy on the change policy supported for bone scaffolding applications. Scanning Electron Microscope (SEM) characterization results showed that samples with compacting pressure and low sintering temperature do not have perfect particle bonding. Samples with high compacting pressure and sintering temperature have good bonding between particles so they do not have a pore composition in the alloy.

Effect of compaction pressure on mechanical properties of AA7075/B4C/graphite hybrid composite fabricated by powder metallurgy techniques

Composite materials are at top in material selection process due to its superior mechanical and tribological properties, properties of a composite can be modified by reinforcing different hard ceramic particles in a matrix material depend upon the requirement needed. Strength of the composite can be improved by creating good interface bond between matrix and reinforcements which can be achieved by selecting proper processing parameters i.e., compaction pressure, sintering temperature, sintering time. Present work focuses on fabrication of AA7075/B4C/Graphite hybrid composite by varying the compaction pressures while cold compaction process. In AA7075 matrix material 6 wt% Boron carbide (B4C) and 2 wt% graphite was added to optimize the ductility and brittleness of the composite material. Mechanical response of the hybrid composite was noted in compression and hardness tests, results reveal that increased compaction pressure has very positive impact on mechanical properties of the composite material, micro structural analysis reveals effect of increased compaction pressure clearly.

Development of Mg based biomaterial with improved mechanical and degradation properties using powder metallurgy

Abstract In the present work, biocompatible materials such as niobium (Nb), zinc (Zn) and calcium (Ca) have been blended with magnesium (Mg) to develop a novel biomaterial (BM) with improved mechanical and corrosion resistant properties. Powder metallurgy (PM) technique was used to fabricate Mg based BM. The powder of all aforementioned materials were mixed homogenously in specific quantities to create a uniform composite component. In order to analyse the influence of process parameters on the mechanical properties of the fabricated part, experiments were performed considering central composite design (CCD). The effect of powder metallurgical parameters namely percentage Nb, compaction pressure, heating rate, sintering temperature and soaking time on the ultimate compressive strength (UCS) and sintered density was studied in the present study. It was found that the UCS and sintered density increased with increase in compaction pressure, heating rate and sintering temperature. The results also revealed that the increase in soaking time and percentage Nb, increased sintered density and UCS to a certain limit. Subsequent increase in these two parameters, sintered density and UCS decreased. Scanning electron microscopy (SEM) images of the fabricated samples showed reduction in porosity with the increase in heating rate. Moreover, X-ray diffraction (XRD) results revealed that no other phase or impurities were found during sintering of Mg based BMs. The optimum process parameters were obtained to develop Mg based BM for maximum UCS and sintered density. Furthermore, the Mg based BM samples fabricated at optimum process parameters were used for corrosion testing in simulated body fluid (SBF) solution at a temperature of 37±0.5°C. The Mg based BM yielded improved mechanical properties with reduced corrosion rates as compared to pure Mg.

Effect of Compaction Pressure and Moisture Content on Quality Parameters of Perennial Biomass Pellets

In Poland the use of solid biomass obtained from intentional plantations of energy plants is increasing. This biomass is most often processed into solid fuels. There are growing indications that renewable energy sources, in particular biomass production, will continue to develop, so the better we know the raw material, the more effectively we will be able to use it. The results of tests that determine the impact of compaction pressure on selected quality parameters of pellets made from selected biomass types are presented. Material from plants such as Giant miscanthus (Miscanthus × giganteus Greef et Deu), Cup plant (Silphium perfoliatum L.), Virginia mallow (Sida hermaphrodita (L.) Rusby) was studied. The compaction process was carried out using the SIRIO P400 hydraulic press with a closed chamber with a diameter of 12 mm. Samples were made in four pressures: 131; 196; 262; 327 MPa and three moisture levels: 8%, 11%, 14%. It was found that with increasing compaction pressure and moisture content up to a certain point, the density and durability of the pellets also increased. Each of the materials is characterized by a specific course of changes in the parameters tested.

Cold Compression Molding of Pyrolytic Carbon from Tires for Oil Absorbers

Circular Economy and Environment Management can be strictly connected by integrating latest technologies for material recycling. Project Tyrecs (Tyre Recycling for Clean Seas) aims to produce smart devices for sea cleaning by using recycled materials. Filters are made by cold compression molding of pyrolytic carbon from tire recycling. These filters would be integrated in marine buoys made by rotational molding of recycled polyethylene. Experimental tests have been performed to correlate cold compression conditions with the final filter density and its absorbing capability. By increasing compaction pressure, mechanical strength increases as well as material handling and usage, but absorbing performances reduce. In this study, first physical prototypes of filters have been produced to show their ability for selective recovery of oil from a water surface. Moreover, conceptual studies of the cleaning buoy have been performed to allow optimal integration of the compression molded filters.

MgB2 Superconducting Joint Technique Based on Mg Diffusion Method

MgB2, which has a high stransition temperature (Tc) of 40 K, has great potential for superconducting applications. Recently, significant improvements in the performance of MgB2 wires have enabled applications, such as superconducting magnets, magnetic shielding devices, flux transformers, and gradient meters. However, the problem of superconducting joints in some applications must be solved. In this study, low resistance joints between MgB2 wires were fabricated using the Mg diffusion method. The MgB2 wires were inserted into B bulks and compacted to different densities. Liquid Mg was reacted with the B bulk to form MgB2. The impact of the compaction pressure of the B bulk was studied. With the increase of compaction pressure, the Tc of the joint decreased while the critical current (Ic) of the joint increased. The highest Tc value of the joint was 39 K, and the highest Ic value of the joint at 0 T was 51 A at 20 K.

Effect of compaction pressure on the densification, microstructure, and mechanical properties of Ti‐1Al‐8V‐5Fe alloy based on TiH 2 and HDH‐Ti powders

The high-strength of Ti-1Al-8V-5Fe (Ti-185) alloy is due to TiH2 powders produced at different compaction pressures and compared with hydride–dehydride-Ti powders. The objective of this work was to investigate the microstructural evolution and mechanical properties of Ti-185 alloy under different compaction pressures. The dehydrogenation characteristics of TiH2-185 and the oxygen contents of sintered samples were evaluated by thermogravimetric analysis and mass spectrometer (TG-MS) and oxygen/nitrogen (O/N) analysers. The corresponding microstructural evolution and change in mechanical properties were analysed by means of scanning electron microscopy, X-ray diffraction, electro-universal tester, and hardness tester, respectively. Results show that with the increase in compaction pressure, the green and sintered density and densification rates increase, but the volume fraction of α-phase decreases. The TiH2-185 samples have higher densification and sintered density, lower oxygen content than Ti-185 samples, which is attributed to its better compressibility and superior self-cleaning ability as well as more water produced. In addition, the sintered TiH2-185 samples exhibit higher yield strength and hardness in comparison with the sintered Ti-185 samples. The enhanced mechanical properties are attributed to its higher density and less soft α-phase in the microstructure.

Mechanical and Electrochemical Characterization of Supersolidus Sintered Austenitic Stainless Steel (316 L)

Abstract The present study compares the mechanical properties and electrochemical behaviour of austenitic (AISI 316 L) stainless steel compacted at different pressures (200, 400 and 600 MPa), which are conventionally sintered at supersolidus temperature of 1,400°C. As expected, increase in compaction pressure (from 200 MPa) to 600 MPa has shown decreased shrinkage (from 7.3% to 4.2% radial and 5.5% to 3.4% axial, respectively) and increased densification (up to ~92%). Their electrochemical behaviour was investigated in 0.1 N H2SO4 solution by potentiodynamic polarization and electrochemical impedance spectroscopy. The mechanical properties (such as yield-, tensile- and transverse rupture strength) and electrochemical behaviour with pressure have been correlated with densification response and microstructure (pore type, volume and morphology). Highest densification (~92% theoretical) achieved at 600 MPa (compaction pressure) and 1,400°C (sintering temperature) resulted in excellent combination of tensile strength and ductility (456 ± 40 MPa and 25 ± 1.1% respectively), while showing lowest corrosion rate (0.1 mmpy or 4.7 mpy) due to the presence of isolated porosity in the sintered samples.

Finite element analysis of densification of Fe-40at%Al composite powders

Finite element analysis was conducted to study the compaction densification mechanism of Fe-40at%Al composite powders. Firstly, the effect of compaction methods on the property of the compact was characterized by finite element simulation and physical experiment. It was shown that the double compaction could obtain denser compacts comparing with that in uniaxial compaction under the same initial conditions. The simulation result was consistent with the experiment result, and they were well fitted with Van Der Zwan-Siskens model. Furthermore, the effect of compaction pressure was analyzed. It was observed that the increase in compaction pressure could improve the relative density and stress of the compact. Finally, the effect mechanism of the die wall friction was analyzed. And a fitting equation of Fe-40at%Al composite powders was proposed on the basis of Van Der Zwan-Siskens model. The results indicated that friction was the primary reason that induced inhomogeneous density and stress distributions.

Characterization of Mechanical Property Distributions on Tablet Surfaces.

Powder densification through uniaxial compaction is governed by a number of simultaneous processes taking place on a reduced time as the result of the stress gradients within the packing, as well as the frictional and adhesive forces between the powder and the die walls. As a result of that, a density and stiffness anisotropy is developed across the axial and radial directions. In this study, microindentation has been applied to assess and quantify the variation of the module of elasticity () throughout the surface of cylindrical tablets. A representative set of deformation behaviors was analyzed by pharmaceutical excipients ranging from soft/plastic behavior (microcrystalline cellulose) over medium (lactose) to hard/brittle behavior (calcium phosphate) for different compaction pressures. The results of the local stiffness distribution over tablet faces depicted a linear and directly proportional tendency between a solid fraction and for the upper and lower faces, as well as remarkable stiffness anisotropy between the axial and radial directions of compaction. The highest extent of the stiffness anisotropy that was found for ductile grades of microcrystalline cellulose (MCC) in comparison with brittle powders has been attributed to the dual phenomena of overall elastic recovery and Poisson’s effect on the relaxation kinetics. As a reinforcement of this analysis, the evolution of the specific surface area elucidated the respective densification mechanism and its implementations toward anisotropy. For ductile excipients, the increase in the contact surface area as well as the reduction and closing of interstitial pores explain the reduction of surface area with increasing compaction pressure. For brittle powders, densification evolves through fragmentation and the subsequent filling of voids.

Design of experiments for bio-based composites with lignosulfonates matrix and corn cob fibers

Bio-based composites with lignosulfonates as a matrix and corn cob particles as reinforcement were developed. Their mechanical strength in compression mode was evaluated with determination of Young modulus (E) and ultimate compressive strength (σmax). The influence of fiber content, fibers particle size, and compaction pressure applied on the composite during processing was investigated with a design of experiments approach. The model enabled to calculate an optimum for σmax equal to 18 MPa for a corresponding Young modulus of 0.27 GPa. Particle size was found to be the most influent parameter on mechanical properties responses. In order to understand this dependency, an automated optical particle analysis was performed to measure size and shape of corn cob particles. Distribution leading to the highest σmax was the one with the less smooth surface of particles (low convexity shape parameter), providing a better mechanical adhesion between fiber and matrix. Increasing compaction pressure and fiber content was in favor of compressive strength. Interface between lignosulfonates and corn cob inside the composites was observed with X-ray microtomography technique. It was noticed that interlocking occurred between the two phases.

Numerical Simulation of Densification of Cu–Al Mixed Metal Powder during Axial Compaction

The densification mechanism of Cu–Al mixed metal powder during a double-action die compaction was investigated by numerical simulation. The finite element method and experiment were performed to compare the effect of the forming method, such as single-action die compaction and double-action die compaction, on the properties of compact. The results showed that the latter could significantly raise the densification rate and were in good agreement with Van Der Zwan–Siskens compaction equation. The effects of the different initial packing structures on the properties of the compact were studied. The results showed that a high-performance compact could be obtained using a dense initial packing structure at a given compaction pressure. Additionally, the effects of the Al content and compaction pressure on the relative density and stress distribution were analyzed. It was observed that, with an increase in the Al content at a given compaction pressure, the relative density of the compact increased, whereas the stress decreased. Furthermore, when the Al content was fixed, the relative density and stress increased with increasing compaction pressure. The relationship between the relative density and the compaction pressure under different friction conditions was characterized and fitted according to the Van Der Zwan–Siskens compaction equation. The influence mechanisms of die wall friction on the compaction behavior were investigated. It was revealed that friction is a key factor that causes the inhomogeneity of the powder flow and stress distribution. Finally, the effects of the dwell time and height–diameter ratio on the densification behavior were analyzed, and it was found that an increase in the dwell time promoted the densification process, whereas an increase of the height–diameter ratio could hinder the process.

Effect of compaction pressure on microstructure, density and hardness of Copper prepared by Powder Metallurgy route

The Copper samples were prepared by powder metallurgy route and conventional sintering. The objective of the present work is to study the effect of compaction pressure on the bulk hardness, densification behaviour and microstructure of the Copper. The Copper powder is compacted with compaction pressure 500, 600, 700 and 730 MPa. The sintering of all green compact is performed at 750°C for 1.5 hour in conventional muffle furnace. Compaction pressure highly influences the pore size as well as number of pores. With increase in compaction pressure the surface contact area of the powder particles increase which reduce the porosity. The maximum valve of the density and hardness is obtained for 700 MPa and 3 min dwell time. Different characterization techniques such as Scanning electron microscope (SEM), X-ray diffraction (XRD) were used to characterize the sintered copper.

Effects of compaction pressure on the temperature distribution in bunker type silage silo

The aim of the research has been to determine effects of compaction pressureon temperature distribution in the silage material in bunker silo.The pressure measurement systemdeveloped within the scope of this research was used to measure the pressure distribution in the silo. Hobo E-348-UA-002–08 model temperature sensors were also used for temperature measurements.The all sensors were positioned in the silo at predetermined points. Temperature and pressure values were recorded in a datalogger during ensiling, fermentation and after fermentation stages.The data collection system is based on a graphical programming language NI LabVIEW software and NI CompactDAQ hardware modules.Work machine having palette of which weight was 13700 kg has been used to compact of maize silage.The average temperature of silage in the silo was 23.35 °C during ensiling, 29.04 °C during fermentation and 23.45 °Cduring the after fermentation stage.The maximum pressure on the silage material was applied during storage with a mean value of 0.34 bar. The highest temperature and pressure wereon the line in thefront of the silo while the lowest temperature and pressure were in the close to the rear wall of the silo.The effect of compaction pressure applied during the ensiling stage also continued during the fermentation stage.It was determined that there is a relationship between the pressure applied to silage and temperature. Results showed that temperature in the silage has been increased with increasing compaction pressure.

Relationship Between the Microstructure and Magnetic Properties of Fe–Si–Cr Powder Cores

Magnetic components prepared using Fe–Si–Cr alloy powders have been widely used in high-current power inductors due to their high initial permeability, high-saturation magnetization, and excellent dc-bias characteristics. Fe–Si–Cr alloy bodies were prepared in this paper using a uniaxial molding press at different compaction pressures. Samples were then annealed at different temperatures to form a chromium-rich oxide insulating layer on the powder surface to reduce the core loss. The compaction pressure and the annealing temperature effects on the microstructure, internal strain, and insulating layer thickness and the electromagnetic properties for Fe–Si–Cr alloy powder compacts were investigated. The results showed that the relative density gradually increased with increasing compaction pressure, leading to increased saturation magnetization, thereby improving the initial permeability from 29 to 37. After annealing, the internal strain was reduced, which resulted in the initial permeability increasing substantially. Moreover, the electric resistivity and dc-superposition characteristics also increased with increasing heat treatment temperature. However, excessively thick insulating layer formed on the Fe–Si–Cr alloy powder surface resulting from annealing at too high temperature leading to initial permeability and saturation magnetization degradation.

Effect of additives on sintering of zirconia ceramics

The effect of two types of additives on the sintering processes of zirconium ceramics was investigated. The impact of both polyvinyl alcohol (12 mass%) and bismuth oxide (1 mass%) on compaction of ultradisperse powders of stabilized zirconia produced by plasma-chemical method and on densification of the compacts during sintering was studied. In the initial state, plasma-chemical powders demonstrate hindered compactibility and sinterability. The additives were incorporated through mechanical stirring with intermediate sieving using a sieve. It was found that introduction of polyvinyl alcohol significantly reduces wall friction and hence facilitates the compaction process. However, no effect on densification and sintering kinetics was observed. Incorporation of bismuth oxide microadditives decreases the temperature of the peak compacting rate. In one-step sintering, the compacts are found to markedly expand at the isothermal ageing stage. The expansion is more distinct at increased compaction pressure. It is shown that this expansion is associated with an increase in the volume of pores surrounded by the liquid phase of bismuth oxide. Two-step sintering with an intermediate stage of isothermal ageing at 1200 °C shows a 100 °C decrease in the sintering temperature, no expansion of the samples occurs at the final ageing stage at sintering temperature, and the ceramics produced exhibits good operational parameters. Recommendations are given on the use of low-melting microadditives in sintering ultradisperse powders obtained by plasma-chemical method.

Optimization of Electro-Discharge Coating Process using Harmony Search

Electro-discharge machining (EDM) is a non-traditional machining process widely used in the machining of difficult to machine materials. The EDM process is extensively used in aerospace, biomedical, die and mold making industries. In some cases, the corrosion resistance and hardness of the work piece materials are required to be improved for their applications in different environmental conditions. Coating is sometimes used to enhance the resistance property of hard materials. Coating is an extended process in EDM by the utilization of tool electrode prepared by powder metallurgy (PM) route. To meet the required applications, the electro-discharge coating (EDC) specimen must be prepared with high accuracy and excellent surface finish. In this work, the electro-discharge coating (EDC) process is performed taking AISI 1040 stainless steel as work piece and copper-tungsten prepared by powder metallurgy (PM) route as electrode. The copper-tungsten tool electrodes are prepared by varying PM process parameters like compaction pressure and sintering temperature. The EDC is performed varying different PM process parameters like compaction pressure and sintering temperature along with EDC parameters like discharge current (Ip), duty cycle (τ) and pulse-on-time (Ton). The surface roughness parameters like average roughness (Ra), maximum height of the profile (Rt) and average height of the profile (Rz) are measured by the use of surface roughness measurement machine. To reduce the number of experiments, design of experiment (DOE) approach like Taguchi L18 orthogonal array has been used. The surface properties of the EDC specimen are optimized by Taguchi based VIKOR method combined with Harmony search algorithm and the best parametric setting is reported for the EDC process. Interaction of sintering temperature and compaction pressure is found to be the significant term followed by compaction pressure. With the increase in compaction pressure, specimens with superior surface quality are produced in EDC process.

Influence of different reinforcements on toughening and strengthening of sintered stoneware from modified marble powder

In the stone processing industry, huge amounts of marble wastes should be properly disposed to prevent the environmental pollutions and health hazards. In this work, waste marble powder was recycled into artificial stoneware by means of surface modification and low temperature sintering. Mullite fibers and boehmite platelets were used as the reinforcements to improve the mechanical properties of sintered stoneware. For the single reinforcements, the flexural strength and fracture toughness firstly increased and then decreased with increasing the reinforcement content. There exists a percolation threshold of reinforcements to form the uniform reinforcement networks with respect to the optimization of mechanical properties. The increase of compaction pressure for the powder compacts promoted the densification and strengthening of stoneware. The composite reinforcements with fibers and platelets exerted the synergetic effect on the toughening of stoneware. As for the mechanical properties, the reinforced stoneware was high superior to the unreinforced stoneware and natural marble. The toughening mechanisms involved crack deflection and crack bridging, while the strengthening mechanisms included the reduction of flaw size, enhanced interface adhesion and toughening of stoneware. The reinforced stoneware with excellent mechanical properties was promising for the reutilization of marble wastes in construction tiles.

Evolution of microstructure and electrochemical corrosion characteristics of cold compacted magnesium

Abstract The main advantage of magnesium and its alloys is high specific strength and biocompatibility. A modern approach to magnesium-based materials preparation is powder metallurgy. This technique allows preparation of new materials with a unique structure, chemical composition, and controlled porosity. In this study, cold compaction of magnesium powder was studied. Magnesium powder of average particle size of 30 μm was compacted applying pressures of 100 MPa, 200 MPa, 300 MPa, 400 MPa and 500 MPa at laboratory temperature. Influence of compacting pressure was studied with microstructural and electrochemical corrosion characteristics analysis. The resulting microstructure was studied in terms of light and electron microscopy. Obtained electrochemical characteristics were compared with those of wrought magnesium. Compacting pressure had a significant influence on microstructure and electrochemical characteristics of prepared bulk magnesium. With the increase in compaction pressure, the porosity decreased. Compacting pressures of 300 MPa, 400 MPa and 500 MPa led to the similar microstructure of the prepared material. Polarization resistance of compacted magnesium was much lower and samples degraded faster when compared to wrought magnesium. Also, the corrosion degradation mechanism changed due to the microstructural differences between the material states.