Composite Processing Methods Research Articles

Promising improved mechanical, wear, corrosive properties by the impact of CNTs on Al alloy by FSP – A review

The monolithic alloys of aluminium have the qualities of less density, elevated strength and high resistance to corrosion. Generally, alloys of aluminium are most comprehensively used in the fields of aerospace sectors such as skeleton parts of aircraft, fuselages, bulk heads, wing ribs, wing spars, automobile and transportation industries, architectural parts, electrical and electronic applications, etc.The evolution of microstructure, and mechanical characteristics such aselongation, hardness, tensile strength, tribological property, and corrosion resistance are examined in this paper for the composites of aluminium-carbon nano-tubes (CNTs). With the use of a surface composite processing method known as friction stir processing, CNTs are added as reinforcements to improve the various properties of the base metal. The CNTs provide a wide variety of characteristics, such as outstanding electrical conductivity, thermal stability, high strength, and superior elastic properties.Numerous collections of published literature have been thoroughly studied, and it discusses a few of the essential underlying assumptions needed to achieve the optimal combination of CNTs with the aluminium under friction processing technique. From the comprehensive review, the statements are summarized that will assist future research work involving the accumulation of CNTs reinforced with aluminium alloy and utilized in various applications of aerospace and aircraft sectors.

Modeling and control of electrical discharge wire sawing of single-crystal silicon

Electrical discharge wire sawing (EDWS) is a new composite processing method that combines wire electrical discharge machining with fixed abrasive wire sawing. During processing, relying on the grinding effect of the abrasive grains, craters and recast layers generated by discharge are removed. The surface roughness of the workpiece is reduced while the cutting efficiency is improved. In this study, the relationship between discharge voltage and workpiece surface roughness in composite machining is investigated. A single-input single-output control system model with applied resistance as the input and discharge voltage as the output is established. Based on the theory of system identification and parameter estimation, the order of the model is identified by calculating the variance of the model residuals and using the F-test method. The model parameters of the control system are estimated online using a recursive least squares algorithm with a forgetting factor. A generalized predictive controller is designed on the basis of the predictive control theory and the identified discharge voltage control system model. Using LabVIEW software, a discharge voltage prediction control system is constructed for the processing of single-crystal silicon by EDWS, and its prediction control performance is experimentally verified. The results show that the discharge voltage control system designed in this study can successfully control the composite machining of single-crystal silicon in real time. Under the same machining conditions, the surface roughness of the workpiece machined with predictive control was 23.5 % lower than that without predictive control.

Construction of Ag-TiO2 Hierarchical Micro-/Nanostructures on a Ti Plate for Photocatalysts via Femtosecond Laser Hybrid Technology.

Titanium dioxide photocatalysts can break down pollutants using natural light. They possess notable light stability, chemical stability, and catalytic effects, thus leading to extensive research worldwide. However, the limited light absorption range of titanium dioxide and their inefficiencies in generating and transporting photogenerated carriers hinder the enhancement of their photocatalytic performance. In this study, we employ a femtosecond laser composite processing method to create an Ag-TiO2 nanoplate composite catalyst. This method doubles the catalytic efficiency compared with the structure processed solely with the femtosecond laser. The resulting Ag-TiO2 nanoplate composite catalysts show significant promise for addressing environmental and energy challenges, including the photodegradation of organic pollutants.

Fabrication of 4H-SiC piezoresistive pressure sensor for high temperature using an integrated femtosecond laser-assisted plasma etching method

The processing, particularly, etching of brittle, hard, and anti-corrosion materials represented by the third-generation wide bandgap semiconductor silicon carbide (SiC), is a significant challenge. Although SiC has excellent electrical, mechanical, and chemical properties, the difficulty of processing limits its application in various sensor devices. To solve this problem, in this study, an integrated processing method of femtosecond laser-assisted SiC dry etching is proposed, which realizes high surface quality and high rate etching of the SiC microstructure. Specifically, the effects of different laser processing parameters on the processing effect were first studied through orthogonal experiments. Experiments indicate that compared with laser power and laser scan times, laser processing speed has a more obvious impact on the processing effect. Subsequently, considering the elastic modulus anisotropy of SiC, a 5 MPa piezoresistive pressure sensor chip was designed. Using the proposed composite processing method, a chip sensitive diaphragm was obtained. The diaphragm thickness and diameter are 76 μm and 1700 μm respectively. The overall sensor chip dimension was 4000 μm × 4000 μm × 350 μm. Static tests demonstrated that the sensor have excellent performance with sensitivity of 6.8 mV/MPa, linearity of 0.69% FS, and repeatability of 0.078% FS. In addition, by designing high-temperature packaging, the sensor achieved a pressure test at 400 °C. This study verifies the feasibility of the composite processing method, realizes the fabrication and measurement of high-temperature pressure sensors, and provides a reference for the micro-and nanostructure processing of various SiC sensors.

Functionalised biochar in biocomposites: The effect of fire retardants, bioplastics and processing methods

Fire retardants, although can impart fire-safety in polymeric composites, are detrimental to the mechanical properties. Biochar can be used, in conjunction with fire retardants, to create a balance between fire-safety and mechanical performance. It is possible to thermally dope fire retardants into the pores of biochar to make it functionalised. Thus, the current work is intended in identifying a composite having the combination of the most desirable fire retardant, bioplastic, and a suitable processing method. A comparison was made between two fire retardants (lanosol and ammonium polyphosphate), bioplastics (wheat gluten and polyamide 11), and composite processing methods (compression and injection moulding). It was found that wheat gluten containing ammonium polyphosphate-doped biochar made by compression moulding had the best fire-safety properties with the lowest peak heat release rate (186 kW/m2), the highest fire performance index (0.6 m2s/kW), and the lowest fire growth index (1.6 kW/ms) with acceptable mechanical properties compared to the corresponding neat bioplastic. Thus, for gluten-based polymers, the use of ammonium polyphosphate thermally doped into biochar processed by compression moulding is recommended to both simultaneously improve fire-safety and conserve the mechanical strength of the resulting biocomposites.

Preparation, Characteristics, and Application of Biopolymer Materials Reinforced with Lignocellulosic Fibres

Various environmental concerns motivate scientists and researchers to look out for unique new materials in science and technology. In order to address the demand for polymeric materials with partial biodegradability, the usage of lignocellulosic fibre in the polymer matrix has risen. Lignocellulosic fibres are a cheap, easily renewable resource that is readily available in all regions. Cellulosic plant fibres also have a plethora of possibilities for use in polymer reinforcement because of their properties. Many researchers put their effort into developing a natural polymer with better mechanical properties and thermal stability using nanotechnology and the use of natural polymers to make its composites with lignocellulosic fibres. This study provides a review of the biodegradable composite market, processing methods, matrix-reinforcement phases, morphology, and characteristic improvements. In addition, it provides a concise summary of the findings of significant research on natural fibre polymer composites (NFRCs) that have been published. Indeed, a noticeably brief discussion is provided on the significant issues faced during composite extraction as well as the challenges encountered during the machining. Recent developments in the study of lignocellulosic fibre composites or NFRCs have demonstrated their enormous potential as structural elements in vehicles, aerospace structures, buildings, ballistics, soundproofing, and other structures.

Experimental Study on Surface Integrity of Solar Cell Silicon Wafers Sliced by Electrochemical Multi-Wire Saw.

Electrochemical multi-wire sawing (EMWS) is a hybrid machining method based on a traditional multi-wire sawing (MWS) system. In this new method, a silicon ingot is connected to a positive electrode; the slicing wire is connected to a negative electrode. Material is removed by the interaction of mechanical grinding and an electrochemical reaction. In this paper, contrast experiments of EMWS and MWS were conducted based on industrialized equipment to verify the beneficial effects of the hybrid method. The experimental statistical results show that the composite processing method improved the processing qualification rate by 1.28%, and the Bow of silicon wafers was reduced by about 2.74 microns. Further testing on the surface of the silicon wafer after electrochemical action showed that obvious holes were present on the surface, and the surface hardness of the wafer decreased significantly. Therefore, the scratches on the surface of wafer sliced by EMWS were reduced; in addition, the thickness of the surface damage layer was reduced by about 9 microns. After standard texturing, the average reflectivity of the wafers sliced by EMWS was about 2–10% lower than that of the wafers sliced by MWS in the wavelength of 300–1100 nm. In this paper, the voltage parameter of the composite machining is set to 48 V; the amount of electrolyte added in each experiment is 2 L; and a good machining effect is obtained. In the future, the electric parameters and cutting fluid components will be further studied to improve the electrochemical effect.

Characterization of Mechanical and Electrical Properties of Polystyrene Composite Reinforced by Hybrid Reinforcement Filler

Nowadays, electrically conductive polymer plays some important roles in the modern electronic devices because the crucial importance in telecommunication and biosensors. This type of materials offers an obvious decrease in the weight of the devices and it also has an environmental compatibility. A conductive polymer composite is promising alternative materials that has several advantages in the electronic applications currently. Polyester was used as a matrix, and copper –Tin /Zink inform of particulates with Copper short wires were considered electrically conductive fillers. The study prepared two groups (A and B) using different filler materials (Cu- Tin /Zink - Polyester and Cu- Tin /Zink –Cu- short wires / Polyester) with a weight fraction percentage of up to 50%. A composite processing method was slip casting to produce rectangular and cylindrical samples; after that samples were cured at room temperature for 48 hrs. Produced samples from both mixed were tested for density, ultimate tensile strength and scan electron microscope. AC conductivity test were performed for all samples using a frequency range from 50 Hz to 50 MHz to measure the dielectrically loss factor and electrical conductivity. From the study, it has been found that filler powder almost proved better ultimate strength behavior, and the peak value was determined at 30% wt., while short wires above 40 % wt. can cause a dramatic reduction in tensile strength. The results revealed that short wires filler van improves the electrical conductivity by approximately 50%; when compared with using particulate filler only. The result from the microstructure showed that short wires with metals powder could provide a connected network for improving the conductivity in the polymer matrix.

Feature Extraction of 3T3 Fibroblast Microtubule Based on Discrete Wavelet Transform and Lucy-Richardson Deconvolution Methods.

Accompanied by the increasing requirements of the probing micro/nanoscopic structures of biological samples, various image-processing algorithms have been developed for visualization or to facilitate data analysis. However, it remains challenging to enhance both the signal-to-noise ratio and image resolution using a single algorithm. In this investigation, we propose a composite image processing method by combining discrete wavelet transform (DWT) and the Lucy–Richardson (LR) deconvolution method, termed the DWDC method. Our results demonstrate that the signal-to-noise ratio and resolution of live cells’ microtubule networks are considerably improved, allowing the recognition of features as small as 120 nm. The method shows robustness in processing the high-noise images of filament-like biological structures, e.g., the cytoskeleton networks captured by fluorescent microscopes.

Anisotropy of material removal during laser-induced plasma assisted ablation of sapphire

Sapphire crystals have a special lattice structure, which causes anisotropy in their processing quality due to anisotropy of the physical and mechanical properties. Laser-induced plasma assisted ablation (LIPAA) is a new processing technology used to process transparent, hard, and brittle materials. LIPAA is regarded as a photoelectric composite processing method that makes the material removal and surface generation mechanisms more complicated. In this study, a surface generated by LIPAA processing showed much higher quality than a surface generated by direct laser ablation. Moreover, LIPAA has the advantage of a lower etching energy threshold than that of infrared laser direct ablation. Infrared laser-induced plasma assisted ablation was performed on different sapphire crystal orientations to explore the influence of anisotropy on LIPAA processing. The LIPAA material removal rates for different sapphire planes were presented and compared with results for direct laser ablation-focused ion beam (FIB) processing. The results showed that thermal removal was most dominant during LIPAA processing of sapphire. The material removal rate was highest in the [10 1‾ 0] direction and lowest in the [112‾ 0] direction.

Distribution states of graphene in polymer nanocomposites: A review

Graphene has emerged as one of the promising nanoscale components of polymer nanocomposites owing to its exceptional properties. The 2D graphene material, when distributed appropriately in the host polymer can significantly alter the load, electron, and phonon transfer behavior of the nanocomposites. The in-plane strong covalent bonds in graphene are accountable for these unique properties, whereas the weak van der Waals forces existing between the adjacent monolayer graphene planes are responsible for the re-stacking or agglomeration of layers. Hence, the most critical challenge in translating these properties in high-performance graphene polymer nanocomposite is to alleviate the agglomeration of graphene. This can be achieved by improving the distribution states of graphene in the matrix by; (1) enhancing the dispersion and (2) controlling the relative lattice orientation of graphene in substrates to create an alignment or orientation. Mitigating the agglomerates during the composite fabrication will significantly extend the benefits of graphene's inherent properties to the nanocomposite. In this review article, various methods for improving dispersion and orientation of graphene in polymer nanocomposites is elucidated. A decision flowchart on the choice of dispersion or orientation based on the properties is considered and the techniques to quantify and verify the same is deliberated. Furthermore, composites' performance in terms of mechanical, electronic, and thermal enhancements due to the molecular level dispersion or anisotropic orientation of graphene is discussed. This review provides a constructive guidance in the composite processing methods and to correlate the enhancement of properties with the distribution state of graphene in composites. Predominantly epoxy and PDMS polymers are reinforced by 3D graphene as fillers due to their structural stability and wider applications. It is also witnessed that 3D graphene reinforced composites are mainly investigated for electrical and thermal properties followed by mechanical and acoustic properties.

Molecular Dynamics Modeling of Epoxy Resins Using the Reactive Interface Force Field

Predictive computational modeling of polymer materials is necessary for the efficient design of composite materials and the corresponding processing methods. Molecular dynamics (MD) modeling is especially important for establishing accurate processing-structure-property relationships for neat resins. For MD modeling of amorphous polymer materials, an accurate force field is fundamental to reliable prediction of properties. Reactive force fields, in which chemical bonds can be formed or broken, offer further capability in predicting the mechanical behavior of amorphous polymers subjected to relatively large deformations. To this end, the Reactive Interface Force Field (IFF-R) has been recently developed to provide an efficient means to predict the behavior of materials under these conditions. Although IFF-R has been proven to be accurate for some crystalline organic and inorganic systems, it has not yet been proven to be accurate for amorphous polymer systems. The objective of this study is to use IFF-R to predict the thermo-mechanical properties of three different epoxy systems and validate with experimental measurements. The results indicate that IFF-R predicts thermo-mechanical properties that agree closely with experiment. Therefore, IFF-R can be used to reliably establish mechanical properties of polymers on the molecular level for future design of new composite materials and processing methods.

Multi-scale analysis of mechanical properties and damage behavior of polypropylene composite (GF50-PP) plate at room and cryogenic temperatures

In this paper, glass fiber-reinforced polypropylene (GF50-PP) composite composed of long fibers was prepared by the thermo-compression process for the very first time. This composite presents high mechanical strength and is used in infrastructures, which demand resistance against severe conditions. Mechanical strength and multi-scale damage analysis of GF50-PP composite at ambient and cryogenic temperatures have been investigated in this study using a special sampling procedure according to the microscopy observation, X-ray microtomography, ultrasonic measurement, and pyrolysis. The results demonstrated the exceptional behavior of the GF50-PP at the cryogenic temperature of −70 °C mainly due to the employment of a novel processing method (thermo-compression) for composites with long fibers, which have been previously prepared by traditional injection molding process. Tensile results presented no difference in failure strain at 20 °C and −70 °C and the fatigue lifetime for different fiber orientations was similar in 3-points bending fatigue tests for different orientations of fibers or in samples taken from different regions of the composite plate, indicating the efficinecy of this processing method. Moreover, the results of damage analysis through monotonic loading presented that by decreasing the temperature from 20 °C to −70 °C, the plasticity threshold didn’t change notably. Overall, the proposed preparation method provided outstanding uniformity and excellent mechanical properties in GF50-PP composite even at temperatures as low as −70 °C, which has not been investigated at this cryogenic temperature before.

Analysis on the Conductivity of Graphene-based Composite Material

Electric energy is the main energy source in production and life. How to make efficient transmission and utilization of electric energy is a problem that requires long-term research. Graphene, as a material with a single-layer two-dimensional honeycomb lattice carbon chain structure, has good electrical conductivity. Its composite with conductive polymer or inorganic metal materials can effectively improve its electrical conductivity and obtain more outstanding electrochemical performance. In order to understand the application of graphene’s electrical conductivity in life in more detail, this article first reviews the electrical properties of graphene, and then reviews and analyzes the research progress of graphene polymer electrical conductivity based on different composite materials and processing methods. The author also points out that the biggest problem facing graphene composites now is that the expensive price of graphene nanosheets and its unavailableness in large-scale applications and industrial production, as well as proposes that the future of graphene composites is still through scientific research in a short period of time. Continuously improving its electrical conductivity is necessary, yet the long-term strategic goal should be reducing the cost of industrialized production of graphene products and find the preparation conditions of graphene composite materials that are more suitable for industrial production.

Tuning the piezoresistive strain‐sensing behavior of poly(vinylidene fluoride)–CNT composites: The role of polymer–CNT interface and composite processing technique

AbstractIn order to understand the role of polymer–carbon nanotube (CNT) interface and composite processing method on strain‐sensing properties, poly(vinylidene fluoride) (PVDF)‐CNT composites have been prepared by melt‐mixing and solution‐casting methods using pristine and acid‐treated CNTs with CNT content of 0.15–4 wt%. The strain rate applied was in the order of s−1. Besides the improved mechanical properties of the composites over pristine PVDF, the piezoresistivity was also profoundly affected by the gentle acid‐treatment of CNTs and the composite processing method leading to tunable strain‐sensing properties. The stability of the strain‐sensors has been further predicted by employing cyclic piezoresistive tests. Interestingly, the pristine CNT composites showed higher strain‐sensitivity likely due to weak interface with polymer and higher initial resistance than the acid‐treated counterparts; while the acid‐treated CNT composites showed better retention of sensing properties under repeated cycles. On the other hand, composites with larger CNT length showed higher strain‐sensitivity than that having shorter CNTs. The temperature dependence of strain‐sensitivity showed a transition from positive to negative temperature coefficient at ~90°C. Finally, the composites subjected to a large number of bending cycles showed excellent performance and stability of strain‐sensing properties, paving the way for development of robust strain‐sensors for structural health monitoring.

The Challenges and Future Perspective of Woven Kenaf Reinforcement in Thermoset Polymer Composites in Malaysia: A Review.

In this review, the challenges faced by woven kenaf thermoset polymer composites in Malaysia were addressed with respect to three major aspects: woven kenaf reinforcement quality, Malaysian citizen awareness of woven kenaf thermoset composite products, and government supports. Kenaf plantations were introduced in Malaysia in the last two decades, but have generally not produced much kenaf composite product that has been widely accepted by the public. However, woven kenaf fiber enhances the thermoset composites to a similar degree or better than other natural fibers, especially with respect to impact resistance. Woven kenaf composites have been applied in automotive structural studies in Malaysia, yet they are still far from commercialization. Hence, this review discusses the kenaf fiber woven in Malaysia, thermoset and bio-based thermoset polymers, thermoset composite processing methods and, most importantly, the challenges faced in Malaysia. This review sets guidelines, provides an overview, and shares knowledge as to the potential challenges currently faced by woven kenaf reinforcements in thermoset polymer composites, allowing researchers to shift their interests and plans for conducting future studies on woven kenaf thermoset polymer composites.

A grinding force prediction model for SiCp/Al composite based on single-abrasive-grain grinding

Grinding is the main processing method for particle-reinforced composites, and grinding force prediction models are very important for research on removal mechanisms. In this study, single-abrasive-grain grinding experiments on SiCp/Al composites were conducted to determine the grinding forces at different grinding process parameters. In addition, a prediction model for the single-abrasive-grain grinding force was established to study the influence of the grinding process parameters and grinding grain angle on the grinding force of SiCp/Al composite. Moreover, multi-abrasive-grain grinding experiments were conducted at different grinding process parameters, which resulted in different grinding forces. The support vector machine (SVM) prediction method based on particle swarm optimisation (PSO) was used to establish a prediction model for the multi-abrasive-grain grinding force; the single-abrasive-grain grinding forces at different grinding grain angles were the input, and the average experimental grain grinding force was the output. The results show that the error between the predicted and experimental grinding forces is below 12%. Furthermore, the grinding force decreases with increasing wheel speed and increases with increasing feed velocity and grinding depth. The PSO–SVM algorithm–based grinding force prediction model can accurately predict the grinding force of SiCp/Al composite and provides theoretical support for improved surface quality.

碳化硅晶圆的快速高质量复合加工方法

碳化硅晶圆的快速高质量复合加工方法

Conifer Needles as Thermoplastic Composite Fillers: Structure and Properties

This study describes the properties of thermoplastic polymer composites based on polyethylene (of low and high density) and ethylene-propylene copolymers using various types of conifer needles (pine, spruce, fir, and cedar) as fillers. For the needles, thermogravimetric analysis (TGA) and TGA/Fourier transform infrared spectroscopy (TGA/FTIR) were performed to investigate their structures and thermal resistance, as required for the composite processing methods. Moreover, structural differences were studied for the analyzed fillers and composite materials (FTIR). The results were compared with the values obtained for composites with conifer wood flour. Composites with conifer needles (pine) had increased water absorption and similar strength properties. However, irrespective of the degree of filling, composites with pine needles were positively characterized by the highest melt mass flow rate (MFR) values and showed a slightly better impact resistance than composites filled with other flours. Thus, shredded coniferous needles with sufficient thermal resistance could be successfully used as fillers in composites. This conclusion was based on thermoplastic polymers as an alternative and/or supplement to the wood flour used in the manufacture of wood-polymer composites.

Structure design and rotation control of the disc milling head in blisk manufacturing

Blisks are the most important and critical components in the gas turbine engines, which could reduce the weight obviously and improve the efficiency significantly. To achieve high efficient machining of the titanium-based blisk, a powerful and composite processing method is proposed and structure of disc milling head with high stiffness and high precision is designed, including mechanical transmission, electrical system, rotating control, locking device, and tool changer. Then, static and dynamic analyses are carried out for the disc milling head, and calculation results show that the static and dynamic performances are perfect, which satisfy the processing requirements. Considering friction and backlash in the worm gear transmission, parameters perturbation in the electrical control system, and process noise and measurement noise in the system have serious impact on the positioning precision of disc milling rotation system, a robust sliding mode control (SMC) algorithm based on linear quadratic optimal control (LQC) is proposed. Based on the traditional LQC, introduce the state estimation based on Kalman filter and control input, improve the system state space model, and define a new sliding surface equation, then, a robust SMC based on LQC is finished. Simulation and experiment results show that the designed controller is robust to the nonlinearities and uncertainties in the rotation control system of disc milling head and can achieve high positioning precision.