Hot Compaction Method Research Articles

Geometry effect of copper nanoparticles and nanowires on polyetheretherketone-matrix nanocomposites: Thermal conductivity, dynamic mechanical properties and wear resistance

Polyetheretherketone (PEEK)-matrix nanocomposites filled with copper nanowires (Cu NWs) and copper nanoparticles (Cu NPs) were prepared by hot compaction method. The effects of Cu NWs and Cu NPs on the thermal conductivity, dynamic mechanical performance, and tribological property of PEEK-matrix nanocomposites were investigated. Results indicate that Cu NPs and Cu NWs with different geometry exhibit different influences on the crystallization behavior, melting behavior, dynamic mechanical properties, and friction and wear behavior of PEEK matrix. Namely, Compared to Cu NPs, Cu NWs can more efficiently better dissipate heat and transfer stress at PEEK/nanofiller interface. Moreover, the friction and wear behavior of the PEEK-matrix nanocomposites is also related to the geometry of the Cu nanofillers to some extent. This is because Cu NPs can act as roll bearings to reduce friction; and Cu NWs with a high thermal conductivity can prevent softening of PEEK matrix and increase the wear resistance via well dissipating friction heat away from the sliding interface. In one word, the comprehensive properties of PEEK-matrix nanocomposites are closely related to the geometry effect of Cu NPs and Cu NWs, which could be of significance for revealing the relation between the micro morphology and the macro application of inorganic nanofillers.

Low percolation behavior of HDPE/CNT nanocomposites for EMI shielding application: Random distribution to segregated structure

In this study, three different types of nanocomposites with random (r-CPC), segregated (s-CPC) and semi-segregated (ss-CPC) distribution of carbon nanotubes in High Density Polyethylene matrix were fabricated using hot compaction method. Microstructure of nanocomposite samples were observed by Scanning Electron Microscopy, which revealed the formation of carbon nanotubes conductive network at the polymer granule interfaces in segregated structure. While, partial formation of segregated structure was shown in semi-segregated samples. A significant reduction of Young modulus and strength of s-CPC6 and ss-CPC6 compared to r-CPC6 nanocomposite has been correlated to weak interface and voids between HDPE granules in segregated structure. DSC results proved that the crystallinity index of HDPE decreases when the distribution of CNTs in polymer matrix changes from segregated to random structure. Electrical conductivity was measured using four-point probe. Segregated structure samples showed electrical conductivity up to 9 and 5 order of magnitude larger than semi-segregated and random structure nanocomposites, respectively. Nanocomposites follow percolation behavior and applying percolation theory showed a decrease in percolation threshold from 7.1 vol% in r-CPC to 0.099 vol% in s-CPC. Finally, Electromagnetic Interference shielding properties were studied and the highest Shielding Effectiveness (SE) was obtained 21.8 dB in segregated sample at 6 wt% CNTs. While, in random structure the highest EMI SE was 9 dB at 20 wt% CNTs. Absorption and reflection were the dominant shielding mechanisms in segregated and random structure nanocomposites, respectively.

Investigation of tensile strength, hardness and wear of titanium diboride reinforced AA6061 composite

This paper studies the mechanical properties of AA6061 matrix composite material reinforced with Titanium diboride particulates. Hot compaction method was employed to produce three composites having 2%, 4% and 6% weight composition of the reinforcement particulates. The resulting composites were tested for tensile strength, hardness and wear. The properties were compared with a base material having the matrix element only. The composite material having 4% composition of the reinforcement particulates developed increase in tensile strength by 0.5%, hardness by 19.3% and reduces wear by 53.9% respectively in comparison with the base material may improve driver shaft life. All the composite materials exhibited improved properties compared to the base material. The changes in the mechanical properties were proportional to the composition of the reinforcement particles in the composite. It is concluded that the mechanical properties of composite materials improve by adding up to 4 wt% of Titanium diboride particulates as the reinforcement particles.

Effect of milling parameters on EMI shielding of the PES/MWCNT nanocomposites

Abstract Poly(ether-sulphone) (PES)/MWCNT nanocomposites were fabricated using planetary ball mill followed by hot compaction method. The ball milling was carried out for 1 h, 3 h and 5 h to optimize the milling time. Scanning electron microscopy revealed improved dispersion of the MWCNT in the matrix at higher milling time. The fabricated nanocomposites were studied for dielectric properties. It was investigated that the dielectric properties increased with increasing milling time which indirectly increases the electromagnetic interference shielding effectiveness (EMI-SE) for a given volume fraction of MWCNT. Moreover, for a given composition, the dielectric constant increases with increasing thickness which resulted in higher EMI-SE probably due to increase in absorption.

A Comparative Study of Structural Changes in Conventional and Unconventional Machining and Mechanical Properties Evaluation of Polypropylene Based Self Reinforced Composites

Abstract The present study addresses the mechanical behavior of polypropylene self-reinforced composites (SRC’s) considering polymeric structural changes after cutting. Self-reinforced polypropylene composite is fabricated using the HOT compaction method by maintaining the processing temperature at 164∘C. Conventional and unconventional cutting methods were used to cut the samples of standard dimensions. FTIR images revealed the formation of C=C, C-F, Halogen bonds after AWJ cutting initiated a decrease in the surface roughness value to 4.5μm (R a ). SEM analysis is performed to analyse structural integrity and damage of SRC’s. Structural changes formation after AWJ cutting leads to improve the ultimate tensile strength of the laminate by 20% compared to conventional cut samples. A similar trend is noticed for flexural properties and Shore –D hardness values for the SRC composite laminate correlated to polymeric changes with Conventional cutting due to the formation of C-N bond is observed after Laser cutting.

Mechanical and physical characterization of Mg-TiO2 and Mg-ZrO2 nanocomposites produced by hot-pressing

Mg metal matrix nanocomposites reinforced by 0, 1.5, 3 and 5 vol fractions of TiO2 and ZrO2 nanoparticles were fabricated using hot quasi-static compaction method under the pressure of 600 MPa at 450 °C for 25 min. The density, hardness, ultimate compressive strength (UCS) and coefficient of thermal expansion (CTE) of the samples were experimentally measured. The results indicated that by increasing the volume fraction of nanoparticles, the relative density and CTE were reduced but hardness and UCS were improved. The results also indicated that relative density of Mg-ZrO2 was higher than that of Mg-TiO2. The CTE of the nanocomposites was decreased by 1.1 and 1.4% for the 5 vol % fraction of the TiO2 and ZrO2 reinforcing particles, respectively. The highest hardness was obtained for the Mg-5vol. % ZrO2. UCS of samples was improved by 22% and 10% for the material reinforced by 3 vol % and 5 vol % of ZrO2 and TiO2, respectively.

A novel correlative formulation of interfacial, quasi-static and dynamic behavior of polyamide self reinforced polymer composites

This study investigates the damage and failure mechanism of polyamide self-reinforced composites under low velocity impact loading by experimental method. Scope of this research also involves developing two novel scaling parameters called force and energy evolution coefficient to correlate quasi-static and interface properties of these materials with its low velocity impact dynamic property. Laminates are fabricated through hot compaction method after analysing the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) data. Post impact samples are inspected through optical method and Scanning electron microscope. Deep insight of the damage evolution could be obtained through correlative study of quasi-static, dynamic, interfacial properties with their failure extent and nature.

Simulation and Physical Experiment Study on Powder Metallurgy Preparation of Silicon Composite Powder

The compaction and sintering processes of multi-component silicon powders, including single-action die compaction, uniaxial hot pressing and bidirectional hot compaction, were numerically performed by FEM (finite element method) modelling. The relationships of initial packing structure, compaction method, pressing pressure and sintering temperature between overall relative densities of multi-component silicon components were systematically discussed and studied. Meanwhile, various macro- and microscopic properties of silicon composite powders were carefully characterized, such as overall and local relative density, local stress distributions and void filling behaviour. The results show that fully compacted silicon composite targets with low internal stress can be obtained by using uniaxial hot pressing or bidirectional hot compaction method. And the physical experiments were carried out to verify the accuracy of the simulation results.

Simultaneous effects of strain rate and temperature on mechanical response of fabricated Mg–SiC nanocomposite

Mg–SiC nanocomposite samples were fabricated using split Hopkinson pressure bar for different SiC volume fractions and under different temperature conditions. The microstructures and mechanical properties of the samples including microhardness and stress–strain curves were captured from quasi-static and dynamic tests carried out using Instron and split Hopkinson pressure bar, respectively. Nanocomposites were produced by hot and high-rate compaction method using split Hopkinson pressure bar. Temperature also significantly affects relative density and can lead to 2.5% increase in density. Adding SiC-reinforcing particles to samples increased their Vickers microhardness from 46 VH to 68 VH (45% increase) depending on the compaction temperature. X-ray diffraction analysis showed that by increasing temperature from 25℃ to 450℃, the Mg crystallite size increases from 37 nm to 72 nm and decreases the lattice strain from 45% to 30%. In quasi-static tests, the ultimate compressive strength for the compaction temperature of 450℃ was improved from 123% for Mg–0 vol.% SiC to 200% for the Mg–10 vol.% SiC samples compared with those of the compaction at room temperature. In dynamic tests, the ultimate strength for Mg–10 vol.% SiC sample compacted at high strain rate increased remarkably by 110% compared with that for Mg–0 vol.% SiC sample compacted at low strain rate.

Manufacture and Characterization of Biofoam Based On Composite of Taro Leaves Powder Reinforced Polyvinyl Acetate

Biofoam material has been made for application of styrofoam substitute food packaging material from a mixture of raw materials: taro leaf powder and PVAc through a hot compaction method with variations of the composition of taro leaf powder: PVAc (80:20)% wt, (75:25)% wt, (70 : 30)% wt, (65:35) wt%, (60:40) wt%, (55:45)% wt, (50:50)% wt and (45:50)% wt. The first stage of taro leaves was blended and sifted with 100 mesh particle size. The second stage of the leaf powder of taro mixed with wet mixing was then mixed with PVAc as a matrix. The third stage of the homogeneous mixture was then put into the mold then compressed by heat to make it more dense with a pressure of 100 MPa and held for 10 minutes at 60 oC. Each biofoam sample that is ready to be characterized includes: physical properties (density, water absorption, functional groups and biodegredability), mechanical properties (tensile strength, elastic modulus, and elongation) and thermal properties (melting points). The characterization results showed that taro leaf powder: the optimum PVAc was (45: 55) wt% with a density value of 0.744 x 103 kg/m3, water absorption capacity of 1.765%, composed of OH and CH groups of PVAc and cellulose and C = C groups of lignin so that it has degrading properties of 91.2% for 50 days. Mechanical properties with tensile strength of 0.357 MPa, elastic modulus of 1.449 MPa, and elongation of 246.416%. Thermal properties with a melting point of 350.21 oC whose results have met the standards of conventional brand Synbra Technology. The results of biofoam material based on composite taro leaves and PVAc can be applied as food packaging.

Analysis on the effect of pressure and mass fraction of chromium to mechanical properties and electrical conductivity of copper-chromium composite in hot compaction process

Cu-Cr composite is used in the electronic industry as a material which is directly connected to the electricity, as a component of a circuit breaker, cable contact, circuit board, etc. In this study, hot compaction method was employed to manufacture Cu-Cr composite which has excellent hardness and electrical conductivity. Composite manufacturing was based on powder metallurgy technique while mixing used mechanical milling method in regards to its better homogeneity. Hot compaction process set at the temperature of 300°C was applied to the powder material to increase the plasticity so the compaction can be done easier. Some variation was made on the composition of Cu : Cr ratio (90 : 10, 80 : 20, 70 : 30, and 60 : 40), and the compaction pressure (500, 700, and 1000 MPa). Sintering was conducted at 85°C with holding time of 1 h. Based on the results, the optimum sintering density of 96.81% of its theoretical density was obtained at Cu : Cr ratio as of 80 : 20. Maximum hardness at 60%Cu : 40%Cr and P = 1000 MPa was 129 VHN. And, electrical conductivity was reached its optimum value of 82.6% IACS when the Cu:Cr ratio was 90:10 at P = 1000 MPa.

Analysis on the effect of pressure and mass fraction of chromium to mechanical properties and electrical conductivity of copper-chromium composite in hot compaction process

Cu-Cr composite is used in the electronic industry as a material which is directly connected to the electricity, as a component of a circuit breaker, cable contact, circuit board, etc. In this study, hot compaction method was employed to manufacture Cu-Cr composite which has excellent hardness and electrical conductivity. Composite manufacturing was based on powder metallurgy technique while mixing used mechanical milling method in regards to its better homogeneity. Hot compaction process set at the temperature of 300°C was applied to the powder material to increase the plasticity so the compaction can be done easier. Some variation was made on the composition of Cu : Cr ratio (90 : 10, 80 : 20, 70 : 30, and 60 : 40), and the compaction pressure (500, 700, and 1000 MPa). Sintering was conducted at 85°C with holding time of 1 h. Based on the results, the optimum sintering density of 96.81% of its theoretical density was obtained at Cu : Cr ratio as of 80 : 20. Maximum hardness at 60%Cu : 40%Cr and P = 1000 MPa was 129 VHN. And, electrical conductivity was reached its optimum value of 82.6% IACS when the Cu:Cr ratio was 90:10 at P = 1000 MPa.

Influence of aging, varying particle size & volume fraction of Al2O3 particles on the hardness and wear behavior of Al 7150 alloy composite produced by hot uniaxial compaction method

The influence of aging, particle size and volume fraction (5, 10, 20 & 25%) of alumina particulates on the hardness & wear behavior of Al 7150 alloy composites produced by hot uniaxial compaction method was investigated. The as-received Al2O3 particulates were first mechanically ball milled for durations of 45, 180, 360, 420 and 580 min to reduce its particle size. The milled alumina particles of 165 nm, 65 nm, 45 nm, 27 nm and 21 nm were later independently blended with the Al 7150 alloy powders to produce five sets of cylindrical specimens using a punch-die setup. The compaction pressure was 500 MPa with a holding time of 3 h, at a temperature of 400 °C. The Vickers microhardness tests revealed an improvement in the hardness with the increase in the volume % of the reinforcement and decreasing particulate size. The Age hardenability of the composites was also investigated by first solutionizing the composite samples followed by aging at 3 h (T4-underage), 24 h (T6-peak age) & 96 h (T7-overage). The wear behavior of the samples was studied by comparing the wear rate of the un-reinforced alloy and non-heat treated (reinforced) Al 7150 alloy composite samples with T6 heat treated composite specimens using a pin on disc wear testing machine under different load and sliding distance conditions. The test specimens were characterized using XRD, FESEM and EDS analysis. Apart from the effect of particle size and volume fraction of Al2O3 reinforcement, the precipitation hardening which occurred during aging, influenced the microhardness and wear behavior of the composite samples.

Effect of Modifying Additives on the Sintering and Properties of SiC/SiCw Ceramic Composite Material

Spark plasma sintering and hot compaction methods were used to obtain experimental samples of a composite material of the SiC‒SiCw system with various modifying additives (AlN, B4C, HfB2, Y2O3, Al2O3, Si3N4). The effect of the modifying additives on the sintering process, physicomechanical, and thermal properties of the ceramic composite material was examined. The introduction of the modifying additives lowered the sintering temperature of silicon carbide produced by the hot compaction method by 200°C and that formed with spark plasma spark sintering by 300‒450°C as compared with the sintering temperature of silicon carbide without additives.

Analysis and optimization of machining parameters of laser cutting for polypropylene composite

Present works explains about machining of self-reinforced Polypropylene composite fabricated using hot compaction method. The objective of the experiment is to find optimum machining parameters for Polypropylene (PP). Laser power and Machining speed were the parameters considered in response to tensile test and Flexure test. Taguchi method is used for experimentation. Grey Relational Analysis (GRA) is used for multiple process parameter optimization. ANOVA (Analysis of Variance) is used to find impact for process parameter. Polypropylene has got the great application in various fields like, it is used in the form of foam in model aircraft and other radio-controlled vehicles, thin sheets (∼2-20μm) used as a dielectric, PP is also used in piping system, it is also been used in hernia and pelvic organ repair or protect new herrnis in the same location.

Laser assisted additive manufacturing of continuous fiber reinforced thermoplastic composites

Herein, we proposed a novel laser assisted additive manufacturing (AM) methodology that utilizes prepreg composites (glass fiber-polypropylene) with continuous fiber reinforcement to fabricate 3D objects by implementing laser assisted bonding and laser cutting. The microstructure analysis demonstrated no visible void content and excellent interfacial bonding. The bonding strength of the proposed method was evaluated through lap shear strength and peel strength testing; resulting in 50% higher peel strength than hot compaction method, with lap shear strength up to 96% of compression molding benchmark data. Tensile properties of components printed by our method were superior to those of fused deposition modeling (FDM) printed short fiber composites with 300% and 150% of increase in tensile strength and modulus, respectively. Tensile strength of our printed components was comparable to compression molding and stamping, however, tensile modulus was 50% lower in average. Flexural strength of the laser assisted AM parts was also in the range of stamping and compression molding methods, with flexural modulus up to 100% higher than these methods. Overall, our proposed new technique offers an alternative direction in AM of continuous fiber reinforced thermoplastic polymer composites to solve the issues associated with current techniques.

On the synthesis and microstructure analysis of high performance MnBi

Highly anisotropic MnBi powder with over 90 wt% low-temperature phase can be prepared using conventional arc-melting and 2 hour-low energy ball milling (BM) followed by magnetic separation. After proper alignment, the purified Mn55Bi45(Mn45Bi55) powder show remarkable magnetic properties: mass remanence of 71(65) Am2/kg and coercivity of 1.23(1.18) T at 300 K. The nominal maximum energy product of 120 kJ/m3 is achieved in the purified 2h-BM Mn55Bi45 powder, close to theoretical value of 140.8 kJ/m3. The Mn55Bi45(Mn45Bi55) bulk magnets show the highest volume remanence of 0.68(0.57) T at 300 K, while they were consolidated at 573(523) K by a pressure of 200 MPa for 5 minutes using hot-compaction method. In addition to the observed grain size, the coercivity of the hot-compacted samples at 300 K was found to be strongly related to the amount of metallic Mn and Bi residue at the grain-boundary. Our study proves that the magnetic properties of the Mn45Bi55 bulk magnets are stable up to 500 K, and the nominal (BH)max values are still above 40 kJ/m3 at 500 K showing the potential ability for high-temperature applications.

Calorimetric Investigations of Oriented Polypropylene Tapes and Self‐Reinforced Composites

SummaryDifferential scanning calorimetry (DSC) is a commonly applied method of determining various physical properties of thermoplastic polymers. Analyzing DSC melting and crystallization curves it is possible to verify whether the macromolecules orientation occurs in fibers, films and self‐reinforced polymer composites (SRC). This paper presents the comparison of the results of calorimetric investigations of polypropylene (PP) single polymer composites (SRC) with the investigations of constrained PP tape samples additionally annealed before the measurement. The program of thermal treatment resembled temperature changes in the mold during SRC production by hot compaction method. The results confirmed a substantial influence of compression molding pressure on the melting process of oriented PP reinforcement used in the production of single polymer composites.

Polypropylene composites obtained from self‐reinforced hybrid fiber system

ABSTRACTThe purpose of the study was to obtain a composite material with the self‐reinforced structure, which processing provide increased mechanical properties. The composites used in presented work were prepared from the two types of fiber mixtures, both were based on polypropylene fibers, the difference was in used cellulose or wood flour filler. Composites were prepared using the hot compaction method. The presented research describes the effect of the composite composition and processing conditions. The results include the static tension measurements, tensile impact tests and thermal analysis, including: DSC and DMTA. The structure has been studies using the SEM observations. Results of presented studies confirm the self‐reinforcing effect in obtained hybrid composites. It provides in the comparison to the standard wood polymer composites to the higher level of material reinforcement with lower amount of natural filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43283.

Novel Positive Temperature Coefficient Effect of Electrical Resistivity in Ni Particles Filled Two Semi-Crystalline Polymer Intermixture Nanocomposite

A novel positive temperature coefficient (PTC) effect nanocomposite by employing both of polyvinylidene fluoride (PP) and polypropylene (PVDF) intermixture in 1-1 volume ratio as host materials and Ni nanoparticles as conductive filler was prepared via a simple hot compaction method. This study focused on the effect of Ni content on percolation threshold and temperature dependence of direct current (DC) resistivity, as well as frequency dependence of alternating current (AC) resistivity of nanocomposites. This kind of material showed a very small percolation threshold value (about 6.0 vol% of Ni) and a novel strong PTC effect of electrical resistivity between temperatures ranging 150-167 °C, which coincided with the both melting temperatures of PP and PVDF. Close to the percolation threshold, abnormal electrical behavior was observed and interpreted based on the tunnel conductivity between Ni clusters. The curves of the AC resistivity versus the frequency, at different loadings of Ni and at different temperatures, offered a further image of the arrangement of conducting clusters within the host.