Hot-pressing Parameters Research Articles

Study on Innovative Laminated Flooring with Resin-Impregnated Paper

A new type of laminated flooring decorated by resin impregnated paper (LWFWRIP) was designed, with the advantages of low formaldehyde emission, improved flame retardant, and high wear resistance. The structure of this new type of wood flooring is based on the ordinary laminated flooring, followed by a decorative layer of thin wood pieces, and then the transparent improved flame retardant, wear-resistant paper is added to the top. It is found that the hot-pressing temperature is the most significant factor affecting the adhesion of resin impregnated paper. The optimal hot-pressing parameters are selected as the hot-pressing pressure of 3.5 MPa, hot-pressing temperature of 180 °C, and hot-pressing time of 40 s. The new laminated flooring was improved with high flame retardant, high wear-resistant, combined with the conventional advantages of both solid wood composite flooring and reinforced wood flooring. The new laminated flooring decorated by resin impregnated paper has broad application prospects.

The influence of the hot-pressing process on the mechanical properties of continuous aramid fiber-reinforced PA12 composites

Abstract Hot-pressing post-treatment can effectively improve the mechanical properties of composite specimens. In order to improve the impact resistance of continuous aramid fiber-reinforced nylon 12 (CAF/PA12) composites, the effect of hot-pressing parameters on the interlaminar shear strength of the composite was studied. The effects of hot-pressing temperature, hot-pressing time, and hot-pressing pressure on the interlaminar shear strength of composite formed specimens were studied by single factor test. Based on the optimized parameters of hot-pressing, the influence of hot-pressing on low-speed impact performance was analyzed. The results shown that the interlaminar shear strength first increased and then decreased with the increase of hot-pressing temperature and pressure. With the extension of hot-pressing time, the interlaminar shear strength continued to increase. When the hot-pressing parameters were 170°C, 30 min, and 600 kPa, the shear strength and specimen quality were the best. Under this hot-pressing process, the low-speed impact performance was increased by 36.0%. In this paper, the research content of the hot-pressing process of composite materials was expanded, which provided a reference for the research of impact resistance of continuous aramid fiber-reinforced PA12 composite materials.

Study on Preparation Optimization Technology and Surface Properties of Decorated Bamboo Filament Board

To further improve the manufacturing process and product performance of decorated bamboo filament board, the Box–Behnken response surface analysis method was used to analyze the correlation between the hot-pressing parameters and surface bonding strength, and the optimal process optimization parameters were obtained. In addition, the wettability and color of each group of samples were tested. The results show that the optimum process parameters of decorated bamboo filament boards were 130 °C, 165 s and 2.00 MPa, and the surface bonding strength was 1.58 MPa. The relative error between the measured value and the predicted value was less than 5%. The contact angle of the bamboo filament after hot pressing was higher than without hot pressing. However, there was no correlation between wettability and the hot-pressing parameters. There was no effect on the change in bamboo surface color. This indicates that the temperature range selected in this study meets the requirements of surface color control in production.

Fabrication and Characterization of PZT/PVDF Composite Films for Force Sensor Applications

AbstractThis study explored the impact of hot press parameters on PZT/PVDF composite films designed for force‐sensing applications. The systematic fraction (PZT/PVDF), pressure, temperature, and time during hot pressing processes are subject to variation during hot pressing processes. The focus is on the resulting composite film thickness and its subsequent influence on the piezoelectric properties, which are essential for the performance of force sensors. The present study investigates the characteristics and performance of PZT/PVDF composite films with fraction ratios 2/5, 5/5, and 7/3 and Hot Pressure (HP) 10, 40, and 60 MPa and temperature at 150°C for 2 h. The characterization of these films was conducted using X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), Atomic force microscopy (AFM), and scanning electron microscopy (SEM). The piezoelectric properties (d33 and d31 constant) were measured using impact and extraction tests to evaluate the performance of films to applied forces. The results show that the highest piezoelectric coefficients (d33 and d31) were determined to be 35.8 pC/N and 12.60 pC/N, with fraction ratios of 7/3 and 2/5. The study revealed a positive correlation between the PZT/PVDF ratio and sensitivity, indicating that an increase in the ratio leads to an increase in sensitivity. Conversely, a negative relationship was observed between the impact load and the sensor's sensitivity, suggesting that an increase in the impact load results in a sensitivity drop. The results of this work demonstrate the great potential of piezoelectric PZT/PVDF composite films in force sensors for small load applications.This article is protected by copyright. All rights reserved.

Optimization of the Effect of Hydraulic Hot-Pressing-Process Parameters on Tensile Properties of Kapok Fiber Nonwoven Web Based on Taguchi Experimental Design

This paper investigates the effect of temperature on the physical properties of Kapok fiber web formed via the hot-pressing method. The kapok web was prepared using the Ashford drum carder. Test samples were subjected to heat treatment in a hydraulic hot-press under three different temperatures (160, 170, and 180°C), heating durations (5, 7.5, and 10 min), and pressures (500, 750, and 1000 psi). This study was conducted to clarify the tensile properties of kapok fabrics under optimal hot-press-forming process parameters such as temperature, heating time, and pressure; here, the Taguchi L27 orthogonal array experimental design was adopted for the optimization. The surface morphologies and tensile properties of kapok fabrics were investigated. The optimum combination of process factors was obtained through signal-to-noise (S/N) ratio analysis. Furthermore, analysis of variance was employed to determine the importance of the process parameter levels. Moreover, regression analysis was adopted to mathematically model the metamorphism of tensile properties with process parameters. A set of confirmation tests was also conducted, and the results verified the presented models. This study results showed that all three processing factors had significant influences on the tensile strength of the carded nonwoven kapok. The combination of hot-pressing parameters to obtain the optimum tensile strength was obtained as follows: 170°C temperature, 1000 psi pressure, and 10 min heating time.

Optimization of the Consolidation Parameters for Enhanced Thermoelectric Properties of Gr-Bi2Te2.55Se0.45 Nanocomposites

Hot pressing represents a promising consolidation technique for ball-milled bismuth telluride alloys, yet deep investigations are needed to understand its effect on the thermoelectric properties. This paper studies the effect of hot-pressing parameters (temperature and pressure) on the thermoelectric properties of the n-type Gr-Bi2Te2.55Se0.45 nanocomposite. Ultra-high pressure, up to 1.5 GPa, is considered for the first time for consolidating Bi2(Te,Se)3 alloys. Results from this study show that increasing the temperature leads to changes in chemical composition and causes noticeable grain growth. On the contrary, increasing pressure mainly causes improvements in densification. Overall, increments in these two parameters improve the ZT values, with the temperature parameter having a higher influence. The highest ZT of 0.69 at 160 °C was obtained for the sample hot-pressed at 350 °C and 1 GPa for 5 min, which is indeed an excellent and competitive value when compared with results reported for this n-type Bi2Te2.55Se0.45 composition.

Investigation of the catalyst ink compositions for a uniform microporous catalyst layer preparation via electrospray deposition technique and MEA assembling conditions in PEMFC specific

High utilization of catalyst and preserving evenly distributed pores for Proton Exchange Membrane Fuel Cell (PEMFC) electrodes were optimized using an in-house designed electrospray system. In order to hold the porous electrode structure prepared through the electrospray technique by varying ink compositions. Using optimized electrodes and commercially available Nafion-212 membrane, a series of membrane-electrode assemblies (MEAs) were fabricated by varying the hot-pressing parameters of pressure, temperature, and time for evaluating the performance at 60 °C to 80 °C with varying relative humidity. The MEAs were hot-pressed at 8 MPa for 390 s at a temperature of 150 °C generating a maximum peak power density of 903 mW cm−2 and current density of 1040 mA cm−2 at 0.6 V and calculated electrochemical surface area (ECSA) is 23.96 m2/gPt. In contrast, the MEAs hot-pressed for the same length of time at the same temperature but with a lower pressure of 2.67 MPa generated higher peak power density of 1130 mW cm−2, higher current density of 1320 mA cm−2 at 0.6 V, despite having a lower ECSA of 19.18 m2/gPt. Overall, results in this study present that low hot-pressing pressure and a high pressing temperature enable a negative effect on the porous structure of electrospray electrodes for producing the high achievement of MEA performance.

The study on surface morphology and decorative properties of Magnesium-glass-board (MGB).

In order to improve the decorative properties of Magnesium-Glass-Board (MGB), the surface morphology and decoration performance of MGB, are studied in detail by using profilometer, microscope and SEM, and the influence of its characterization, such as surface roughness, surface porosity and wettability, on decorative properties of MGB is analyzed by comparing with medium density fiberboard (MDF) and medium density particleboard (MDP). The results first showed that the surface of MGB has a porous structure, but MDF and MDP are not, resulting in a poor decorative performance of MGB. Second, it is found that the surface wettability of MGB is better than others. Third, the hot-pressing parameters including pressure, temperature and time have different influence on decorative performance of MGB during hot-pressing experiment. Finally, the surface bonding strength is positively correlated with pressure, but not with temperature and time. In general, a higher surface bonding strength led to a better decorative performance of MGB. The furthermore research can concentrate on the modification method of the MGB's surface according to this paper's conclusion to improve the lamination performance of melamine paper.

In Situ X-ray imaging of HT-PEMFC hot-pressing using contrast enhancement

A contrast enhancement agent is used to visualise phosphoric acid penetration and distribution in high-temperature polymer electrolyte membrane fuel cells. This new method is demonstrated in the investigation of hot-pressing parameters on phosphoric acid penetration and distribution. In situ radiography of the hot-press process showed acid plumes breaking through the catalyst layer, microporous layer (MPL) and gas diffusion layer (GDL). The phosphoric acid volume and distribution within the MPL and GDL are quantified, and their dependence on hot-press pressure, duration and compression control are analysed. Increasing hot-press pressure and duration was found to increase acid penetration and delamination of the membrane and catalyst layers. The absence of a compression control gasket also led to significant infiltration into the MPL and GDL. Penetration occurred first at the anode for all tests, which was attributed to a higher number of cracks and greater degree of crack connectivity. Phosphoric acid entered the MPL and GDL either through initial breakthrough of the catalyst layer, or from acid pooling on the GDL surface and being compressed into the fibres. This work provides a novel method to improve visualisation of phosphoric acid and highlights the acid loss mechanisms resulting from hot-press conditions.

Effects of hot-pressing parameters on microstructure and mechanical properties of composites synthesized by Al-TiO2in-situ reaction

Effects of hot-pressing parameters on microstructure and mechanical properties of composites synthesized by Al-TiO2in-situ reaction

Microstructure and microchemistry changes at U-10Mo fuel/AA6061 cladding interfaces with varying hot isostatic pressing conditions

Monolithic uranium - 10 wt.% molybdenum (U-10Mo) is a promising high-assay low-enriched uranium fuel system for nuclear reactors used in research, medical isotope production, and remote power applications. During manufacturing, an aluminum alloy (AA6061) cladding is bonded to the U-10Mo fuel plate via hot isostatic pressing, during which diffusion and fuel/cladding chemical interaction occurs at plate edges. The microstructure and microchemistry changes that occur at fuel/cladding interfaces are important to understand as a function of process parameters to develop a reliable fuel fabrication process and to meet the desired specifications. Here, microstructural and microchemical changes are studied using complementary electron microscopy and atom probe tomography for two manufactured fuel plates with varied hot isostatic pressing (HIP) parameters. Results highlight that modifying thermomechanical processing parameters significantly changes the interaction layer thickness between U-10Mo and AA6061 by an order of magnitude. In addition, the distribution and concentration of elements (i.e., Al, Si, Mg) from cladding to fuel are investigated.

Effects of HIP Process Parameters on Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by SLM

Ti-6Al-4V titanium alloy products formed by selective laser melting (SLM) are characterized by high strength and low plasticity. In addition, there may be pores inside the material, which may become a fracture sprouting point and accelerate the failure of the parts. Using an optical microscope (OM), scanning electron microscope (SEM), and electronic universal testing machine, the effects of hot isostatic pressing (HIP) parameters on the microstructure and tensile property of SLM-formed Ti-6Al-4V titanium alloy were investigated. The results show that HIP performed below the β-phase transition temperature, and the structure of the Ti-6Al-4V titanium alloy is composed of an α phase and β phase. With the increase in the HIP temperature, the α lath coarsens into a short rod, the content of the β phase increases and coarsens, and the tensile strength and yield strength of Ti-6Al-4V show a decreasing trend. With an HIP process performed at a temperature of 910 °C and pressure of 130 MPa for 2 h, the Ti-6Al-4V titanium alloy obtains the best matching of strength and plasticity.

Room Temperature Synthesis of Branched ZnO Nanowires Array with Tunable Morphology

Herein, a novel method is proposed to synthesize B-ZnO NWA by simply immersing the Zn NWA in NaOH solution at room temperature (25 °C). Based on the systematic investigation of various factors that affect the growth of B-ZnO NWA, the growth mechanism of B-ZnO NWA is clarified. Guided by the growth mechanism, the control of the morphology of B-ZnO NWA is achieved by adjusting the pore structure of anodized aluminum oxide templates, hot-pressing parameters, NaOH concentration, solution temperature, and immersion time. In contrast to previous reports, the prepared B-ZnO NWA has hollow trunks, which can further increase the specific area of B-ZnO NWA. Considering the facile, environmental, and low-cost synthesis, the prepared B-ZnO NWA with tunable morphology has great prospects in a wide range of applications, especially those related to the conversion and utilization of solar energy, which are gaining increasing interest nowadays.

Design, manufacturing, and testing of a laser textured piston ring surface reinforced with a CuCoBe–diamond composite by hot-pressing

A CuCoBe–diamond composite was used to reinforce a laser textured 410 stainless steel piston ring by hot-pressing. Different hot-pressing parameters were used to optimize the sintering process of the CuCoBe particles (P = 25 and 50 MPa, T = 820 and 980 °C, and t = 15 and 30 min). The results showed an increase in the hardness of the hot-pressed samples (50.5% and 48.5% for P = 25 and 50 MPa, respectively). Three textures with different track widths and distances between them were produced by laser on the compression piston rings’ surface. The composite powders were used for the reinforcement of the textures by hot-pressing at the optimized sintering parameters (T = 980 °C, P = 25 and 50 MPa, and t = 15 min). The tribological results revealed that larger texture dimensions led to enhanced tribological performance.

이황화몰리브덴을 촉매로 활용한 막 전극 조립체 열 압축 최적화에 대한 연구

Recently, Proton Exchange Membrane Electrolyzer Cell (PEMEC) is drawing attention as a hydrogen energy production device. However, the high price of platinum used as a catalyst for the Gas Diffusion Electrode (GDE), which is one of the components of PEMEC, is making it difficult to commercialize. Therefore, the use of alternative catalysts in GDE and the optimization of membrane electrode assembly (MEA), which is a combination of GDE, are essential. Accordingly, the MEA was optimized using a hot pressing method as a catalyst molybdenum disulfide. The experiment was carried out under 8 conditions using the 2³ design of experiment method. In order to fabricate the MEA, an experiment was conducted using the main parameters of hot pressing, such as process time, pressure, and temperature, as variables. The temperature was set to 100-120℃, the pressure was 35-105 bar, and the process time was 1-3 minutes. After hot pressing, cyclic voltammetry was performed 10 times for stabilization, and then the current density was measured through chromoamperometry. Based on this, the main effects and interaction effects of major variables were analyzed through minitap software. As a result of the analysis, it was confirmed that temperature had the most major influence on performance, and the optimal conditions were 100℃, 35 bar, and 1 minute. These studies are expected to have an impact on the activation of various types of catalyst research that will be applied to PEMEC in the future.

Parameter optimization: Effect of Humidity and Fabrication Process on Flexural Strength of Kenaf/Polylactic Acid Biocomposite

Biocomposite from kenaf reinforced polylactic acid (Kenaf/PLA) has the potential to replace a synthetic reinforcement and matrix in polymer composite applications. Kenaf is well known as a natural fiber that can be replaced with synthetic fiber and reinforced with synthetic resin, whether thermoset or thermoplastic. An increase in environmental impact drives increased usage of a biodegradable polymer such as PLA in the application of biocomposite. However, moisture uptake from the humidity and elevated temperature exposure during fabrication of composite is mostly a factor that affects the properties of biocomposite. Therefore, this study aims to optimize the factors consisting of humidity exposure, temperature and time holding during hot press using the design of experiment (DOE) by Box-Behnken Design (BBD) approach. The kenaf/PLA was exposed to the humidity range from 40% up to 80% before undergoing composite fabrication. Then produce the composite using a hot press molding where the parameter consists of elevated temperature (range from 160 <sup>o</sup>C up to 200 <sup>o</sup>C) and time holding (range from 3 minutes up to 10 minutes) that possibly affects the mechanical properties of kenaf/PLA. These three factors were evaluated based on optimizing maximum results on flexural properties, where all the combination factors were assessed using DOE. Using analysis of variance (ANOVA) revealed that humidity exposure and hot press temperature are essential factors affecting kenaf/PLA flexural strength. The results indicated that the selected humidity and hot press parameters were 40 %RH, 160 <sup>o</sup>C press molding temperature, and a 3-minute heating duration for optimal flexural strength. The parameter will obtain 111.61 MPa of flexural strength. Implementing the chosen factor can produce the kenaf/PLA biocomposite with an optimum flexural strength of 111.61 MPa.

Overlaying performance and bonding mechanism of wood-based panels decorated by EVA film reinforced decorative wood veneer

ABSTRACT In order to understand the bonding mechanism of thermoplastic film reinforced wood veneer and broaden its application to wood-based panels, EVA film reinforced decorative wood veneer (EVA-RDV) was prepared and used for decoration of medium density fiberboard (MDF) and plywood (PW) respectively in this study. Decorative veneered wood-based panels were prepared by hot pressing followed by cold pressing, and their surface bonding strength and immersion peel performance were tested. The results showed that both veneered panels prepared in optimized hot-pressing parameters met the requirements of interior materials in GB/T 17657-2013. But due to the different surface properties between MDF and PW, their bonding effect with EVA-RDV was slightly different. Generally, the surface bonding strength of veneered MDF was higher than that of veneered PW, while its immersion peel performance was weaker. When the EVA film thickness was 0.3 mm, the surface bonding strength of veneered MDF and veneered PW was 1.74 and 1.30 MPa, respectively. Due to the low surface roughness of MDF and the existence of a pre-curing layer, cold pressing played a much more important role in the manufacturing process of veneered MDF.

Electrochemical and operation performance of electrolytic air dehumidification with different catalyst coated membrane methods

ABSTRACT Proper catalyst coated membrane (CCM) methods are significant for membrane electrode assembly (MEA) of PEM-based electrolytic dehumidification. In this work, four CCM processes, doctor blade, decal, electrostatic spraying, and modified pneumatic spraying methods, were employed for fabricating dehumidifier assemblies with low-load (0.6 mg/cm2) IrO2 catalyst layers (CLs). The physical and electrochemical properties of the as-prepared CLs were characterized, and the mass transfer resistance and dehumidification rate of the MEA were tested during actual operations. The optimal hot-pressing parameters were also determined. Results showed that the modified pneumatic spraying method can significantly improve the pore distribution and CL flatness by promoting the evaporation of solvent from catalyst slurry. The charge-transfer and ohmic resistances of MEA was 25.3 and 27.8 mΩ/cm2, respectively, which are the best values for those prepared using the four methods. The dehumidification rate was also the highest (0.105 g/h), 20–40% higher than that of other methods. Although the overall mass transfer resistance of assembly prepared by the electrostatic spraying was low, the CL structure was obviously loose and unable to bind to the membrane surface tightly, leading to high electrochemical resistance (6.6-fold that of pneumatic spray method). Besides, catalyst particles tend to agglomerate using the doctor blade method. The pore size of the CL prepared using the decal method was found to be too small (<300 nm), hindering reactant transfer and resulting in a low overall mass transfer coefficient. This study provides a practical direction for the preparation of economical and high-performance dehumidifiers or electrolyzers.

Optimizing the Mechanical and Microstructure Characteristics of Stir Casting and Hot-Pressed AA 7075/ZnO/ZrO2 Composites

The composite was made using the stir cast manufacturing method. Many parameters, like stirring speed, stirring time, ZrO2% reinforcement, and cast temperature, are evaluated in a Taguchi experimental design to see how they affected the composite properties. In terms of composite properties, ZrO2% reinforcement and the stir speed have the most significant impact. There were 25.02% gains in ultimate tensile strength and hardness, as well as a decrease in composite wear loss, when the optimal stir casting parameters were used compared to the initial stir casting settings. To get insight into the process and the qualities of the composite, the hot-pressing parameters were studied. Pressure, followed by temperature, is the most critical factor in determining the properties of composites. When a hot-pressing setting was determined to reduce the wear loss by a significant 39.3%, it was deemed perfect by the superranking concept. Under ideal conditions, hot-pressing procedures reduced wear loss by 40.8% while boosting ultimate tensile strength and hardness by 19.83% and 9.6%, respectively. The resulting microstructures and worn surface morphologies from stir casting and hot pressing show vastly different properties.

A machine-learning model to predict tensile properties of Ti6Al4V parts prepared by laser powder bed fusion with hot isostatic pressing

In this work, a machine-learning model was established to predict the influence of post-treatment, hot isostatic pressing (HIP) parameters on the tensile properties of Ti6Al4V parts prepared by Laser Powder Bed Fusion (LPBF), also known as Selective Laser Melting (SLM). The database was established by collecting published reports on HIP treatment of LPBF Ti6Al4V from 2010 to 2019, employing the following online resources: Google Scholar, Science Direct, Research Gate, and Springer. Using the established model, it is possible to prescribe HIP parameters and predict properties after HIP for LPBF Ti6Al4V parts with high confidence. The model shows great accuracy in the prediction of Yield Strength (YS) and Ultimate Tensile Strength (UTS). Of the predictions, 87.5% were within a 5% error range for YS in all datasets, and this value was 100% for UTS. It was found that the YS and UTS are sensitive to the HIP parameters, including temperature and holding time. The initial YS and UTS of as-printed parts are weaker influencing factors for YS and UTS of final parts, as compared with the HIP parameters. The model suggests that a HIP process with a holding temperature lower than 970 °C and a holding time of approximately 2 h is sufficient for LPBFed Ti6Al4V parts to achieve mechanical properties that comply with the ASTM standard of Ti6Al4V for surgical implant applications (Standard Specification for Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications -UNS R56401-). However, the prediction of strain to failure showed lower accuracy. Only 62.1% of predicted strain results were within a 10% error range. The differences among the printing processes by multiple research groups may have resulted in large variations of structural defects and thus led to significant scattering of the elongation data. The model also shows that elongation after HIP has a higher dependence on the as-printed samples.