Particle-reinforced Composites Research Articles

Enhancing the Performance of Polylactic Acid (PLA) Reinforcing with Sawdust, Rice Husk, and Bagasse Particles

Polylactic acid (PLA) is the most popular thermoplastic biopolymer providing a stiffness and strength alternative to fossil-based plastics. It is also the most promising biodegradable polymer on the market right now, thus gaining a substitute for conservative artificial polymers. Therefore, the current research focuses on synthesizing and mechanical characterization of particlereinforced PLA composites. The hot compression molding technique was used to fabricate PLA-based composites with 0, 2.5, 5, and 7.5 weight % of sawdust, rice husk, and bagasse particle reinforcements to enhance the performance of the PLA. The pellets of PLA matrix were taken with an average size of 3 mm and particle reinforcements of an average size of 50 m were used as the raw materials. After processing the PLA composites, microstructural and mechanical characterization studies were carried out to check the uniform distribution of the reinforced particles on the PLA matrix and the improvement in their strength, respectively. The results found hardness varied from 29.7 to 36.1 Shore D, tensile strength from 46.2 to 62.5 MPa, impact strength from 14.5 to 17.4 kJ/m2 and flexural strength from 78.9 to 93 MPa from all processed composites. In addition, SEM images were taken to perform a microstructural evaluation of the PMCs.

The influence of particle surface oxidation treatment on microstructure and mechanical behavior of 3D-SiCp/A356 interpenetrating composites fabricated by pressure infiltration technique

In this work, the 3D-SiCp/A356 composites with interpenetrating microstructure were prepared by pressure infiltration of A356 aluminum alloy into a porous 3D-SiC ceramic preform, which served as reinforcement. The effects of the surface oxidation treatment of the SiC particles on microstructure, thermal expansion coefficient, and bending strength of as-fabricated composites were investigated. The results revealed that the initial structure of the 3D-SiC ceramic preform could be retained after pressure infiltration, the pores of the preform were filled with A356 aluminum alloy, and the particles were uniformly distributed in the A356 matrix alloy. The thermal expansion coefficient of the SiC/A356 composite reinforced by oxidized SiC particles was lower than that of the unoxidized SiC particle-reinforced composite. It increased with increasing temperature for both, eventually reaching maxima at 420 °C and 350 °C, respectively, and decreased thereafter. However, a rapid decrease in the thermal expansion coefficient was evident at 565 °C because of the over-burning of the A356 aluminum matrix. In particular, the surface oxidation treatment of SiC particles changed the nature of bonding between SiC and Al, which reduced the strength of the composites. As a result, the bending strength of the unoxidized SiC particle-reinforced composite was approximately twice that of the oxidized SiC particle-reinforced composite. Additionally, the bending strength values of the SiC–Al showed an obvious anisotropic behavior. The bending strength measured by loading parallel to the infiltration direction was 2.5 times larger than that of a perpendicular loading.

Study on the Microstructure and Mechanical Properties of ZrB2/AA6111 Particle-Reinforced Aluminum Matrix Composites by Friction Stir Processing and Heat Treatment

Study on the Microstructure and Mechanical Properties of ZrB2/AA6111 Particle-Reinforced Aluminum Matrix Composites by Friction Stir Processing and Heat Treatment

Two-scale modeling of particle crack initiation and propagation in particle-reinforced composites by using microscale analysis based on Voronoi cell finite element model

In this study, a two-scale finite element model has been developed for the elastic analysis of composite materials. The coarse finite element mesh was assumed for the macroscale analysis, while Voronoi cell finite element model (VCFEM) was used for the microscale analysis of heterogeneous domains. The adaptive coupling between the two scales in non-critical and critical regions was accomplished through the master–slave nodes method. Two scale elements were connected together through the use of shared nodes and the order of the edge displacement interpolation. A new extended VCFEM was proposed to simulate particle damage generation, and a remeshing algorithm was constructed to simulate particle crack generation and propagation in particle-reinforced composites. For crack propagation analysis, four new combined Voronoi elements were developed and analyzed at the microscale. The obtained results for the stresses, stress intensity factors, and crack path were compared with those calculated using the commercial calculation software Abaqus. The two sets of results are in very good agreement, confirming the accuracy of the proposed method used for determining the stress concentrations and also for coarse-mesh discretization.

Effect of the in-situ formed CuO additive on the fracture behaviour and failure mechanism of Ag-SnO2 composites

Oxide additives can significantly improve the mechanical properties of ceramic particle-reinforced metal matrix composites. In this study, the fracture behaviour and failure mechanism of the Ag-SnO2 composites without and with in-situ formed CuO additive are investigated using in-situ scanning electron microscope (SEM) and numerical simulation. The results show that the CuO additive significantly enhances the fracture toughness of the Ag-SnO2 composite. The initiation and propagation of secondary cracks near the primary crack tip are effectively inhibited, and large dimples are formed around SnO2 particles. The improvement in the mechanical properties is attributed to the stress concentration relief in the Ag matrix and enhanced interfacial strength. Interface debonding at the sharp corners of the SnO2 particles initiates the formation of cracks in the Ag-SnO2 composite without CuO. The initiated cracks propagate through the high-stress concentration region at an angle of 45° to the loading direction, resulting in a matrix fracture. For the Ag-SnO2 composite with CuO nanoparticles, the propagation rate of the primary cracks reduces significantly, and microcracks are primarily induced near clustered SnO2 particles. Moreover, the damage initiation shifts from the SnO2/Ag interface to the Ag metal matrix with reduced SnO2 particle aggregation in the Ag-SnO2(CuO) composite.

Synergetic grain refinement and ZrB2 hardening in in-situ ZrB2/AA4032-type composites by ultrasonic assisted melt treatment

In this work, the effects of ultrasonic treatment on in-situ ZrB2 particle-reinforced AA4032-based composites were studied. The composites were synthesized from Al–K2ZrF6–KBF4 system via an in-situ melt reaction. The phase composition, macrostructure characteristics, hardness and tensile properties of the composites were investigated. The results showed that the addition of in-situ submicron ZrB2 particles into the composites resulted in grain refinement, and the increased hardness and tensile properties. The ultrasonic treatment effectively enhanced the uniformity of in-situ ZrB2 distribution, which further enhanced the structure and mechanical properties of the composites. The mechanisms of the ultrasonic treatment in the improvement of in-situ particle distribution and mechanical properties of the composites were discussed.

Biobased Epoxy Composites Reinforced with Acetylated Corn Straw.

Corn straw/epoxy resin composites (CS/ECs) and maleic anhydride acetylated CS/ECs (MA-CS/ECs) were prepared through dry mixing and high-temperature curing. Corn straw is a kind of abundant, eco-friendly, and low-cost biomass material. Unmodified and modified corn straws were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The interfacial affinity of the composite was testified by the contact angle. The results of XPS and SEM demonstrated that maleic anhydride had been successfully bonded onto the structure of corn straw. Corn straw particle-reinforced epoxy resin composites were prepared using a casting and molding process. Results showed that the MA-CS/EC had better impact and flexural resistance than the unmodified corn straw/epoxy resin composites when the corn straw addition was 15 wt %. The result of the contact angle showed that the interfacial compatibility between composites is also stronger than that of CS/EC.

Universal rate-dependence in electro-magneto-active polymeric composites

Universal relations are mathematical statements for any material in a given class; the larger the class, the more powerful the universal rule. Such generic relations are to be likely explored in particle-reinforced smart polymeric composites for all possible energy functions and boundary traction forms. Such relations have mainly been developed for an isotropic material class after Ericksen’s seminal work. The present work develops an experimentally validated novel class of coupled universal relations for electro-magneto-active (EMA) polymeric composites under electromagnetic field interaction accounting for the rate-dependent inelastic effect. In such a material class, unless the preferred directions of the material are specified, there would be no general solutions. An EMA polymeric composite material class is of co-axial type if and only if the Cauchy stress (S) and deformation tensor (b) are co-axial for all types of deformation which is preserved in isotropic material class. Co-axiality in the transversely isotropic material class, on the other hand, does not follow the same rule, i.e. (Sb≠bS). Real-world materials, such as soft tissues and smart polymeric composites, do not exhibit co-axiality and instead reveal the dissipation mechanism, necessitating the current study. The proposed theory unifies the pseudo transverse isotropy and rate-dependent phenomena for EMV smart composites in the context of particle reinforcement. Additionally, the current study conducts an experimental investigation to confirm the applicability of the proposed universal relation.

Effect of nano-TiC/TiB2 particles on the recrystallization and precipitation behavior of AA2055-TiC+TiB2 alloys

In this study, particle-reinforced aluminum matrix composites (PRAMCs) of 2055 Al–Cu–Li alloy were prepared with nano-sized TiB2+TiC particles, and electron probe microanalyzer (EPMA), differential scanning calorimetry (DSC), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to investigate the recrystallization and aging behavior of 2055 + TiB2+TiC alloy. The relationship between TiB2+TiC nanoparticles and the T1 strengthening phase during aging was investigated, and the promotion effect of nanoparticles on the T1 phase during aging was explained by the stored energy and mismatch in the coefficient of thermal expansion (CTE). The grain size of as-cast 2055, 0.5, and 1.0 alloys were 112 μm, 87 μm, and 68 μm, respectively. The TiB2+TiC nanoparticles were found to hinder the development of α-Al dendrites in solidification and refine the grains. The recrystallization behavior during solid solution treatment was mainly a particle stimulated nucleation (PSN) mechanism, and TiB2+TiC nanoparticles enhanced the recrystallization resistance. The number density of T1 phase in the pre-deformed 2055 + TiB2+TiC alloy was 452 ± 12/μm−2 with an average size of 73 ± 3 nm, which was finer than 2055 alloy, resulting from the retention of more dislocations or CTE effects at the TiB2 or TiC interface in the deformed 0.5 or 1.0 alloy. These factors cause Cu atoms to aggregate and provide favorable conditions for T1 phase precipitation. Compared with 2055, the ultimate tensile strength of the 0.5 sample was increased from 424 MPa to 455 MPa under condition A and from 498 MPa to 550 MPa after pre-deformation. This study can be used as a reference for improving the mechanical properties of Al–Li alloys.

Interfacial precipitation of the in-situ TiB2-reinforced Al–Zn–Mg–Cu–Zr composite

The interfacial precipitation of reinforced particles has a critical influence on particle-reinforced aluminum-matrix composites. In this study, TiB2 interfacial precipitation of 6 wt% TiB2/Al–10Zn–2.3 Mg–2Cu–0.12Zr composite was studied. The results demonstrate that the TiB2 surface has a considerable impact on precipitation during different states of the composite preparation process (including heat treatments). The TiB2 surface acted as a nucleation site for D023–Al3Zr and was wrapped with the T phase during solidification; a good orientation relationship existed between TiB2 and D023–Al3Zr: (0 00 1)TiB2//(1‾ 03‾)D023–Al3Zr, (1 01‾ 0)TiB2//(1 05‾)D023–Al3Zr, and [1 21‾ 0]TiB2//[0 1 0]D023–Al3Zr. After homogenization or solution, the TiB2 wall hindering solute atoms diffused into the matrix, particularly for Mg and Cu, causing the T phase to dissolve incompletely, and the residual T phase on the TiB2 surface transformed to the S phase layer at a longer holding time. Additionally, the hindering effect of the TiB2 walls results in the enhancement of the local high solute atom concentration and provides a high precipitation driving force. Therefore, the interfacial phase, Mg(Cu2-XZnX), preferentially precipitated at the D023–Al3Zr and S phase interface during peak aging. In this process, the periodic misfit dislocations of the interface facilitate the diffusion of solute atoms and reduce the nucleation energy barrier, promoting interfacial precipitation. Eventually, the interfacial precipitates layer relieved the local stress concentration but consumed the solute atoms, which was considered to be beneficial to plasticity at the cost of strength weakening to achieve excellent comprehensive mechanical properties.

Experiment and simulation for ultrasonic wave propagation in multiple-particle reinforced composites

The study of ultrasonic wave propagation is a crucial foundation for the application of ultrasonic testing in particle-reinforced composites. However, in the presence of the complex interaction among multiple particles, the wave characteristics are difficult to be analyzed and used for parametric inversion. Here we combine the finite element analysis and experimental measurement to investigate the ultrasonic wave propagation in Cu-W/SiC particle-reinforced composites. The experimental and simulation results are in good agreement and quantitatively correlate longitudinal wave velocity and attenuation coefficient with SiC content and ultrasonic frequency. The results show that the attenuation coefficient of ternary composites (Cu-W/SiC) is significantly larger than that of binary composites (Cu-W, Cu-SiC). This is explained by numerical simulation analysis via extracting the individual attenuation components and visualizing the interaction among multiple particles in a model of energy propagation. The interaction among particles competes with the particle independent scattering in particle-reinforced composites. SiC particles serve as energy transfer channels partially compensating for the loss of scattering attenuation caused by interaction among W particles, which further blocks the transmission of incident energy. The present work provides insight into the theoretical basis for ultrasonic testing in multiple-particle reinforced composites.

Effect of carburized time on microstructure and properties of W[sbnd]Cu composites fabricated by vacuum pulse carburization

In this study, gradient WCX ceramic particle-reinforced WCu composites were successfully fabricated by vacuum pulse carburization and an infiltration sintering process. The effects of carburization time on the microstructure, hardness, compressive strength, wear resistance, and electrical conductivity were investigated in detail. With an increase in carburization time, the edges of the W particles became coarse until a large number of cracked structures appeared. The WC phase and a small amount of the W2C phase were the primary carbides generated upon carburization for 60 to 100 min. The WCX gradient microstructure significantly improved the mechanical properties of the WCu composites. The gradient structure also ensured the electrical conductivity of the WCu composites.

The utilisation of coconut shell ash in production of hybrid composite: Microstructural characterisation and performance analysis

Agriculture waste-reinforced hybrid metal matrix composites (HMMCs) have developed as a potentially green, productive, economical, and ideal replacement for particle-reinforced composites. A number of industries, including aerospace, automotive, and packaging, have demonstrated a keen interest in the development of new and innovative composites in a sustainable manner, is bio-waste particulate reinforced composite. The effect of reinforcements is investigated in the current research work, which employs the ultrasonic stir casting method with SiC (ranging from 3 to 9% by weight) and coconut shell ash (5% by weight in equal proportion) as reinforcement along with the aluminium matrix. With the two-stage ultrasonic stir casting process, the distribution of reinforcement in the aluminium matrix is ensured to be uniform. The microstructure evolution, mechanical and tribological behaviours were also evaluated to ascertain the integrity of fabricated composites. The XRD analysis confirms the reinforcements and oxide layer formed on the specimen surface. Currently, the fabricated composite improves monolithic alloy in terms of hardness and tensile strength approximately by 60% and 66%, respectively, while reducing wear rate by 51%. The nanoindentation investigation implies that the composites that have been developed have improved nanomechanical properties. Overall, using CSA along with SiC in HMMCs could be a potential product to reduce the usage of synthetic fiber and application design for economical products.

Texture evolution, segregation behavior, and mechanical properties of 2060 Al-Li (aluminium-lithium) composites reinforced by TiC (titanium carbide) nanoparticles

Particle-reinforced Metal Matrix Composites (PMMCs) of 2060 Al-Li (aluminium-lithium) were prepared with nano-sized TiC (titanium carbide) particles and investigated the physico-chemical behavior of these nanoparticles using the electron probe microanalyzer (EPMA), differential scanning calorimetry (DSC), electron back-scattered diffraction (EBSD), transmission electron microscope (TEM), and simulations. A model, coupling heat-flow-solute-phase field was established, linking macroscopic and microscopic conditions, which predicts the cooling rate, grain size, discrete phase distribution, and segregation law. The relationship between the TiC nanoparticles and aluminium matrix was evaluated, and (111) TiC was found to be parallel to the (111) Al, with low mismatch and smooth interfacial connections, which, in turn, facilitated efficient nucleation of the aluminium matrix. The grain size of the direct casting samples (DC) is 541.8 μm, and that of the direct casting samples reinforced by nano-particles (TDC) is 41.3 μm, a substantial reduction of 92.4%. Compared to DC, the tensile strength of TDC increased from 516 MPa to 575 MPa, and its elongation increased from 5.6% to 9.9% after T8 treatment. The reinforced nanoparticles were found to be rotation sensitive and reduced the localized large deformation, thus weakening the texture, and reducing the structural anisotropy; the nanoparticles reduced the accumulation of high-concentration solutes in the liquid phase, and also reduced the segregation gradient. The relatively simple preparation process makes it suitable for large-scale industrial production of PMMCs Al-Li alloys.

Enhanced softening resistance and mechanical properties of Mo2C particle-reinforced Cu-matrix composites

Enhanced softening resistance and mechanical properties of Mo2C particle-reinforced Cu-matrix composites

Effect of Cu concentration on high-temperature mechanical properties and microstructures of Al-Si alloy for forging fabricated by continuous casting process with the heat-insulating-mold

Al-Si alloy billets with 0, 2, 4, and 6 mass%Cu have been fabricated by the Heat-Insulating-Mold method. The microstructures and high-temperature mechanical properties at 423 K, 523 K, and 623 K have been investigated. Increasing Cu concentration changed the types of constituent particles and increased their area fraction. 0.2% proof stress (σ0.2) and ultimate tensile strength (σUTS) increased with increasing Cu concentration at each temperature. SEM observation showed that precipitates increased with increasing Cu concentration and remained in the matrix below 523 K but dissolved into the Al matrix at 623 K. The former suggested that the precipitates contributed to the strength below 523 K. On the other hand, significant work-hardening was confirmed until 0.2% strain at 623 K, which suggested that the constituent particles contributed to the strength just like particle-reinforced composites. The work-hardening rate and the amount of work-hardening increased with increasing Cu concentration and correlated with the interparticle spacing of the constituent particles. It indicated that decreasing interparticle spacing enhanced constraining matrix deformation, and it led to an increase of σ0.2 and σUTS.

Microstructure and properties of FeCoNiCrAl high-entropy alloy particle-reinforced Cu-matrix composites prepared via FSP

Although copper has excellent thermal conductivity, poor wear resistance seriously limits its development. In this paper, a Cu matrix surface composite material reinforced by FeCoNiCrAl high-entropy alloy particles was prepared by friction stir processing. The microstructure and properties of the composite were investigated. The results showed that both the FSP process and the addition of HEA particles contributed to the refinement of the Cu-matrix grains. A diffusion layer with a width of about 0.8 µm was formed at the interface between the HEA particles and the Cu matrix. Compared with received Cu, the microhardness of Cu matrix in the composites was increased by 69.8%, the wear rate was reduced by 29.7%, and the wear resistance was significantly improved. Mean while, the ductility of the composite was consistent with that of the received Cu, and the thermal conductivity reached 87% of the received Cu. Therefore, this paper provided a new possibility for developing multifunctional structural materials with high wear resistance, high ductility, and high thermal conductivity.

Improving the wear resistance of 50 wt% Si particle-reinforced Al matrix composites treated by over-modification with a Cu-P modifier

As lightweight wear-resistant structural materials, Sip/Al composites have the potential to be utilized in the automotive, aerospace, and electronics industries. However, coarsening of the Si particles occurs, thereby limiting the development of such materials. In this work, the effects of a Cu-P modifier on the microstructure and wear resistance of a 50 wt% Sip/Al composite are investigated using SEM, EBSD, TEM, nanoindentation, and reciprocating wear tests. The refining effect on Si particles in the composite is optimal when the modifier content is 3 wt%, but the wear resistance is not ideal. After over-modification, the wear performance reaches a peak with a wear rate of 3.32 × 10−7 mm2/N, realizing a reduction of 83.6 % and 21.7 % compared to the unmodified and optimal modified composites. Since the Al2Cu phase is formed in situ in the Cu-P modified composites and the strength of the Al2Cu phase is higher than that of the matrix, the performance of the over-modified composite is improved. The wear of the unmodified composite is dominated by delamination wear, accompanied by oxidation wear, adhesive wear, and abrasive wear. After modification, the composite is subject to the combined action of abrasive wear, oxidation wear, and adhesive wear. These results suggest that the over-modification of the Cu-P modifier is an effective approach to improving the wear resistance of Sip/Al composites.

Investigation of the effects of reinforcement particles in polymers on their grindability in single grit scratch test

Recently, polyether ether ketone (PEEK) and its particle-reinforced composites have found a special place in various industries due to their high strength-to-weight ratio, anti-allergic properties, high resistance to buckling, and other superior properties. These materials have widely been used in the aerospace and medical industries and are commonly finished in the final step through the grinding process. In this work, the single grain scratch test was performed to fundamentally study the grinding process and material removal mechanism of PEEK and its particle-reinforced composites. In this method, the material removal is realized by a single grit penetrating the workpiece. It was found that the amount of flowed or piled-up (side flow) materials around the scratch in the pure polymer is higher than the other two composites. Pure polymer with 2.5 J/mm3 and glass fiber-reinforced composite with 1.1 J/mm3 resulted in the highest and lowest specific energies, respectively. The specific energy of all three materials is reduced significantly by increasing the grit penetration depth, showing the significant role of the size effect in grinding these materials. The main reasons for the different results are the high heat transfer coefficient and higher strength of CFRP composite compared to PEEK and PEEK GF 30.

Novel solid-state metal powder surface modification process for additive manufacturing of metal matrix composites and alloys

Although metal additive manufacturing has been widely studied owing to its flexible product shape design, the material selection window for metal additive manufacturing remains narrow owing to limited feedstocks. To address the challenges in additive manufacturing, an innovative metal powder fabrication process was developed in this study. This process is known as surface modification and reinforcement transplantation (SMART), and it efficiently produces surface-modified feedstock powders, such as spheroidized, surface-alloyed, surface-coated, or composite powders, which facilitate the exploration of new alloys and composites via additive manufacturing. In this study, the working principles of the SMART process were established, and some practical applications of the SMART process were considered by fabricating specialized metal additive manufacturing feedstocks such as carbon nanotube-coated, Mo alloyed, and TiC particle-reinforced Inconel 625 powders. Furthermore, Mo-alloyed and TiC particle-reinforced powders were utilized in the directed energy deposition process to validate the performance of the SMART powder by fabricating Mo-controlled alloy and TiC particle-reinforced composites. The SMART process was compared with the existing processes and proved to be advantageous. Therefore, this study provides a novel method for producing feedstock powders for additive manufacturing.