Hot Moulding Research Articles

High-temperature tribological behaviours of H13 hot work mould steel by low-temperature plasma nitriding process

ABSTRACT H13 hot work mould steel was treated via low-temperature plasma nitriding (LTPN) to obtain a nitrided layer. The morphologies, phases and hardness of the nitrided layer were characterised using a scanning electron microscope (SEM), X-ray diffraction (XRD) and Vickers hardness tester, respectively. The friction-wear behaviours of the nitrided layer at 500°C were investigated using a wear tester, and the effects of normal loads on the coefficient of friction (COF) and wear rate were discussed. The results show that the nitrided layer was composed of γ’-Fe4N and ϵ-Fe2–3N hard phases. The average COFs of the nitrided layer under the normal loads of 2, 4 and 6 N were 0.85, 0.57 and 0.50, respectively; and the corresponding wear rates were 7.30 × 10−5, 6.96 × 10−5 and 1.40 × 10−4 mm3 N−1 m−1, respectively, indicating that the wear resistance under the normal load of 4 N is the best among the three kinds of normal loads. The nitrided layer effectively improves the anti-wear performance of substrate, and the oxidisation wear decreases with the increase of normal load.

Effect of different currents and compositions of Cu, MoS2 and HBN on the coating thickness of mild steel substrate using electric discharge coating

The substrate deposited on the workpiece is used by surface coating for the achievement of various properties in terms of hardness, smoothness, tear or wear etc But various methods such as electro-plating, conversion coating or several, are less effective because of costly machine involvement, complexity during operation, complexity during work-surface installation, specific (high/low) temperatures and thick coating. To achieve better coating among all, a layer of the modified composite coated surface using Copper (Cu), Molybdenum disulfide (MoS2) and Hexagonal Boron Nitride (HBN) with the help of an Electrical Discharge Machine (EDM) with reverse polarity is formed. In this process, the effect of two variable parameters current and composition (powder mixing ratio) of Cu, MoS2 and HBN with a 50% duty factor on the thickness of the deposited layer is observed. During the deposition process, each green compact electrode is formed by mixing the powdered material in a mortar for approximately 2.5 h and after processing in a hot press moulding machine. The deposited layer of the coating has also been analyzed using FESEM, XRD and tribological properties, where the highest deposition or thickness of the coating has been achieved at a powder mixing ratio of 20/40/40 to Cu/HBN/MoS2 with a current of 10 A at the same duty factor. Overall, better coating with controllable thickness can be achieved by using EDC, which can be helpful in automobiles or other industries where metal-to-metal friction causes performance loss.

Improvement on Tensile Properties of Epoxy Resin Matrix Sugarcane Fiber and Tamarind Seed Powder Reinforced Hybrid Bio-Composites

Nowadays, hybrid bio-composites are being developed by combining different natural resources as reinforcement and filler components, and this has raised their necessary qualities dramatically. Sugarcane fibre and tamarind seed powder particles added to an epoxy resin matrix to test the material's tensile strength were the focus of this study. A reinforcing material is sugarcane fibre, while filler components include tamarind seed powder particles. Different reinforcement and filler materials were used to make hybrid bio-composite specimens, while the epoxy resin weight percentage was maintained constant. Utilizing the hot press compression moulding technology, hybrid bio-composite boards were manufactured from start to finish. Water jet machining is used to remove hybrid bio-composite specimens for compression tests in accordance with ASTM standards from the hybrid bio-composite boards. It has been shown in experiments, for example, that adding tamarind seed powder particles to a sugarcane fiber/epoxy resin matrix considerably increases the hybrid bio-composites' tensile characteristics.

Experimental investigation on mechanical, thermal behaviour and characterisation analysis of aquatic waste water hyacinth plant fibre, powder and ash reinforced polymer composite material – Dangerous aquatic threat into successive product approach

The purpose of this study is to investigate the mechanical and thermal properties of aquatic wastewater hyacinth plant natural power, ash and fibre reinforced polymer composite samples. This work is primarily concerned with creating sustainable products from this aquatic waste in a sustainable manner. Hyacinth plant fibres, powders and ash particles are used in this work as reinforcement material for composite samples, which are made by utilising the hot press compression moulding technique and epoxy matrix. In this study, new mechanical way of fibre extraction process is used to extract the fibres of the water hyacinth. Mechanical strength and thermal properties thermo gravimetric analysis, differential thermo gravimetric, thermo gravimetric peaks of hyacinth composite samples are evaluated. Fourier Transform Infrared Spectroscopy and X-ray diffraction techniques are used to characterise the hyacinth composite. A scanning electron microscope is used to examine the fractured surfaces of hyacinth composite sample samples. By using this technique, fibre clusters, fibre fractures and fibre pull-outs can be identified. Waste management and waste recycling concepts are heavily influenced by this manuscript. The zero-waste concept has been achieved through this work. According to all the findings of this study, the natural plant fibres from the water hyacinth plant and ash particles can be used as reinforcement materials in conjunction with an epoxy resin matrix for making lightweight particleboard products and other lightweight materials in general.

Investigation of the mechanical and thermal stability of ultra-high molecular weight polyethylene by using amide-multi-walled carbon nanotubes as a reinforcement material

In this research, an investigation of the thermal and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) reinforced with pristine and modified multi- walled carbon nanotubes (Amide-MWCNTs)-MWCNTs nanocomposite was conducted. The nanocomposites were prepared by ultra-sonication mixing and hot press moulding methods. The MWCNTs surface was functionalised with amide group. The prepared nanocomposites were characterised based on structure, thermal, and mechanical properties by x-ray diffraction (XRD), differential scanning calorimeter (DSC), and universal testing machine, respectively. The crystallinity, crystal size, space between atomic lattice and lattice constant were calculated from the XRD patterns. Results showed the decrease in UHMWPE crystallinity without affecting the crystal structure of UHMWPE when adding pristine MWCNTs and Amide-MWCNTs (1−5 wt%). Tensile test results showed an increase in the composites stiffness for all percentages in the range of 19%–65%, while the elongation at break for the 3 wt% Amide-MWCNT nanocomposite increased up to 71%. This indicates that the interfacial adhesion was enhanced by the amide group.

Research on maximizing the diamond content of diamond/SiC composite

Diamond content is a key factor affecting diamond/SiC composite performance, especially thermal and mechanical properties, but the composite with high diamond content manufacturing is still challenging issues. Hot mold pressing combined with liquid silicon infiltration to make diamond/SiC composites with high diamond content and relative density has been proposed in this paper. In addition, the effect of diamond particle size on the maximization of diamond content as well as properties of the composites were evaluated. The experiment shows that the content of diamond in the composites increases with the increase of the diamond particle size. When the particle size of diamond is 400 µm, the volume fraction of diamond reaches 59.08%. The highest thermal conductivity (ddia= 300 µm) and highest bending strength (ddia= 50 µm) are 616.77 W/m K (It is the maximum TC of diamond/SiC prepared by pressureless infiltration at present) and 380 MPa, respectively. This work provides a novel and efficient preparation method for further improving the thermal conductivity of diamond/SiC composites.

Machine learning approaches for prediction of properties of natural fiber composites : Apriori algorithm

ABSTRACT The selection of materials with the required properties was developing rapidly. There is no single rule to choose suitable material for a particular product. The complexes interrelation among the properties of composites makes more difficult to suggest suitable material for material scientist. The forecasting of relationship among material properties with throughput screening methods can help for the discovery of novel materials. The conventional way of selection of material need more investigations and time consuming. Recently, machine learning approaches are widely used in mechanical domain. Hence in this work, machine learning-based method was proposed to discover the relationship between the properties of natural fibres composites. To apply machine learning approach, there are 26 different natural fibres composites of Coir, Jute, Banana etc. were taken in to consideration. These materials are reinforced with pure export with different manufacturing methods such as Hand layup, Spray layup, Hot press moulding, and Compression moulding to produce the samples as per ASTM standards. The properties like density, tensile strength, hardness etc. were measured and interrelation among them was recognised using proposed method.

Role of polymer‐filler interaction on Mg(OH)2 and alumina trihydrate‐loaded ethylene propylene diene monomer based polymer composite for high voltage insulation application

AbstractUse of polymer composite as a high voltage insulator material is currently under investigation for its commercial application, longer durability, and cost effectiveness. This work probes the effect of polymer‐filler interaction on mechanical, morphological, thermal and dielectric properties of ethylene propylene diene monomer (EPDM) based polymer composite. EPDM composites were successfully prepared using two roll‐mill and vulcanized in a hot press compression mold. Surface morphology indicates uniform dispersion of filler at lower filler loading, whereas at higher loading cluster/agglomeration was observed. 30 phr magnesium hydroxide (Mg(OH)2) loaded sample showed the highest static contact angle of 102.3°. Mg(OH)2 based samples show higher tensile strength because of strong interfacial interaction between filler and polymer. In addition, alumina trihydrate (ATH) and Mg(OH)2 based composite exhibit high thermal stability with initial thermal degradation temperature of ~200 and ~320°C, respectively. FTIR spectrum reveals the formation of strong –OH bonds between Mg(OH)2 and polymer molecules. A maximum enhancement in dielectric breakdown strength of ~50% and ~30% were recorded for 60 phr ATH and 30 phr Mg(OH)2 loaded EPDM composites respectively. Finally, the results indicate a strong possibility of developing EPDM based polymer composites as an efficient high voltage insulator.

Effect of pore structure on the thermophysical and frictional properties of high-density graphite

High density graphite is widely used in friction and sealing area. The pore structure inside, which were mainly affected by molding method, has a great effect on its thermophysical properties and friction performance. Herein, isostatic pressing, compression molding and hot molding method were utilized in our work to prepare high density graphite with different pore structure in order to study the relationship between pore structure and the comprehensive property. The results showed that the properties of graphite vary significantly in different directions, which was mainly affected by porosity, pore size distribution, the specific surface area, pore shape and fractal dimension. The influence mechanism of three graphite materials with different pore structures on thermophysical properties was delved, and the correlation between the comprehensive properties of graphite materials and their pore structures was verified. The in-plane comprehensive properties of hot molding graphite were the best, the graphitization degree was the highest (75.4%) and the total porosity was the lowest (15.08%). Especially, according to the pore structure analysis of the graphite, we found a positive correlation between the fractal dimension and the friction and wear properties of the graphite materials. Furthermore, research of pore structure explained the properties of graphite materials and proved the potential application of graphite in friction and sealing fields. • Graphite with different pore structures were prepared by different forming process. • The evolution of pore structure was deduced during the preparation of graphite products. • Pore structure characteristic parameters effect the comprehensive property of graphite. • Hot Molding can improve the orientation and degree of graphitization of the graphite. • Fractal dimension was positively correlated with the friction and wear properties.

Experimental investigations on mechanical and water absorption properties of epoxy resin-banana fiber-tamarind seed particles hybrid biocomposites

In recent years, a variety of natural resources have been used as reinforcing and filler components in the development of hybrid bio-composites. The epoxy resin matrix was subjected to trials in which tamarind seed powder and banana fiber were added. Banana fiber and tamarind seed powder are used as reinforcement materials. Hybrid bio-composites samples were developed by varying the weight percent of reinforcement materials while keeping the epoxy resin weight percentage constant. Biopolymer composite boards were produced by hot injection moulding. The water jet machining procedure is employed to cut out hybridized biocomposites sample for different mechanical and water absorption tests from the hybrid biocomposites boards. The incorporation of a small amount of tamarind seed powder and banana fibre into the epoxy resin matrix considerably improves the hybrid biocomposites' mechanical and water absorption capabilities.

Experimental investigations on tensile and flexural properties of epoxy resin matrix waste marble dust and tamarind shell particles reinforced bio-composites

A great gain has been made in recent years in the creation of hybrid bio-composites by combining different natural resources as reinforcement and filler elements. The waste marble dust particles and tamarind shell powder particles were additional to the epoxy resin matrix in this experiment to study the tensile and flexural characteristics of the epoxy resin matrix. Tamarind shell powder and waste marble dust particles are used as reinforcing materials. To create hybrid bio-composite specimens, researchers varied the reinforcement material weight percentages while maintaining the epoxy resin weight percentage as constant. Hot injection moulding was used to create hybrid biocomposites boards. The hybrid bio-composite specimens for tensile and flexural tests are cut away from the hybrid bio-composite boards using the water jet machining method as per ASTM specifications. Research shows that adding small amounts of fine waste marble dust particles and tamarind shell powder to an epoxy resin matrix enhances the hybrid bio-composites' tensile and flexural capabilities significantly. The maximum tensile strength, yield strength, elongation percentage, flexural strength and flexural modulus of 34.63 MPa, 32.81 MPa, 3.3 %, 36.17 and 38.53 MPa were obtained from 35 wt% tamarind shell powder and 15 wt% waste marble dust powder composite specimens (C4 Composites) correspondingly.

Interlaminar fracture toughness of 3D printed continuous carbon fibre- reinforced polyamide

In this study, the interlaminar fracture toughness of 3D printed continuous carbon fibre-reinforced polyamide was characterized under Mode I and II loadings. 3D printing of fracture test samples presents difficulties, mainly shrinkage and excessive warping. To minimize these effects, two solutions were developed. The results show that the Mode I interlaminar fracture behaviour of the printed samples is similar to that obtained by hot compression moulding. In mode II, however, propagation is not effective due to the type of microstructure of the 3D printed material. The hot pressing of the printed material reduces the fracture toughness under Mode I, but significantly improves the fracture toughness under Mode II. The causes of these behaviours are discussed in the paper.

Experimental investigations on flexural and compressive properties of epoxy resin matrix sugarcane fiber and tamarind seed powder reinforced bio-composites

Hybrid bio-composites have been developed in recent years by incorporating various natural resources as reinforcement and filler components to achieve the desired qualities. Experiments were conducted in this study to investigate the impact of short sugarcane fibres and tamarind seed powder particles on epoxy resin matrix flexural and compressive characteristics. Reinforcement elements include sugarcane fibres and tamarind seed powder particles. Samples of hybrid bio-composite material were created by altering the proportion of reinforcing components and maintaining the same proportion of the epoxy resin. A hot injection moulding machine was used to create hybrid bio-composite boards. With the use of a water jet machining technique, hybrid bio-composite specimens for flexural and compression testing are cut away from the hybrid bio-composite boards. The maximum flexural strength, flexural modulus and compressive strength of 36.543 MPa, 12.129 GPa and 21.32 MPa was obtained for 35 wt% SCF/15 wt% TSP composites correspondingly. The minimum flexural strength, flexural modulus and compressive strength of 25.058 MPa, 5.828 GPa and 14.21 MPa was obtained for 40 wt% SCF and 10 wt% TSP composites correspondingly. For the hybrid bio-composites, restricted insertion of short sugarcane fibre and tamarind seed powder particles into epoxy resin matrix greatly improves certain flexural and compressive performances.

Development of the temperature-dependent constitutive model of glass fiber reinforced polypropylene composites

ABSTRACT Plain-woven glass fiber-reinforced polypropylene (PW-GFRPP), as the typical advanced CoFRTP, has been rapidly emerged in aerospace, civil and automobile fields, thanks to its low cost and excellent performances. The fiber yarns of PW-GFRPP will undergo large rotations and shear deformations with immersions of molten polypropylene resin during the hot mold pressing process. The shear deformations of fiber yarns not only directly affect the formability quality of the preformed structures but also make an impact on the mechanical performances of cured products. Thus, the scope of this study is to construct the temperature-dependent material constitutive model of PW-GFRPP and investigate the influences of temperature and blank holding force (BHF) on the formability of PW-GFRPP prepregs. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests were first implemented to determine the melting and degradation temperatures of polypropylene. Next, the bias-extension tests for PW-GFRPP prepregs were carried out accounting for three temperature values (190°C, 220°C and 250°C). Then the temperature-dependent constitutive model was developed and validated. Finally, the validated constitutive model was used to explore the influences of temperature and blank holding force on the formability of PW-GFRPP composites on a double dome benchmark.

Comparison of the efficiency of the most effective heterogeneous nucleating agents for Poly(lactic acid)

We selected the thirteen most effective nucleating agents for Poly(lactic acid) (PLA) from the literature, and synthesized and compounded them with two different PLA grades: 3001D (1.4% D-lactide content) and 3100HP (0.5% D-lactide content, considered PLLA). We determined the crystallinity and crystallization of PLA with different nucleating agents in identical conditions (same nucleating agent content, same cooling rate) with the help of differential scanning calorimetry. We compared the efficiency of each nucleating agent and found that for both PLA grades, Zinc PhenylPhosphonate was the most effective. However, even when nucleated PLA was injection molded into a cold mold (25 °C), it still could not fully crystallize during cooling and the heat deflection temperature did not increase significantly. The maximum achieved crystallinity, in this case, was between 32.4 and 35.7%. On the contrary, when a 90 °C “hot mold” and in-mold crystallization together were applied, the specimens achieved full crystallization during the injection molding cycle (crystallinity was between 44.5 and 50.0%), and the heat deflection temperature increased to an average of 88.8 °C. We also examined the mechanical properties of the nucleated PLA and found that the usage of nucleating agents together with a hot mold improved tensile strength, tensile modulus, and Charpy impact strength but decreased elongation at break.

Effect of Granular Silica Aerogel as Filler on Tensile and Flexural Strengths and Moduli of Stone-Wool-Fibre-Reinforced Composite as Rigid Board Roof Insulation Material

Installation of stone wool as thermal insulation in the roof assembly can be adopted to store heat in the living space, if the building is exposed to cold weather, and, inversely, to retard heat from entering the living space, if it is exposed to hot weather. In spite of the effectiveness of stone wool as a roof insulation material, during installation, it can cause irritation to the skin and can be hazardous to the lungs. Therefore, incorporation of stone wool with other materials to form a rigid board, without compromising its effectiveness as a roof insulation material, is imperative. Strength properties of a stone-wool-fibre-reinforced high-density polyethylene (HDPE) composite roof insulation material were studied. Granular silica aerogel, which possesses an ultra-low thermal conductivity, was added as filler to reduce the thermal conductivity of the composite. Hot compression moulding was performed to prepare samples of the composite with varying silica aerogel content of 0, 1, 2, 3, 4, and 5 wt. %. Findings suggest that 2 wt.% is the optimum silica aerogel content as it resulted in the highest flexural strength and modulus, which is 24.4 MPa and 845.85 MPa, respectively, even though it reduced the tensile strength and modulus by 10% and 4.45% respectively, relative to 0 wt. %, which can be considered as inconsequential. Higher silica aerogel content above 2 wt. % may result in poor interfacial adhesion and low compatibility to the stone wool fibre and HDPE, which further reduces the tensile and flexural strengths and moduli of the composite.

Experimental investigation and simulation assessment on fluidity and hot tearing of Mg-Zn-Cu system alloys

The influence of copper (Cu) on fluidity and hot tearing susceptibility (HTS) of Mg-7Zn-xCu (x = 0, 1, 2, 3) ternary alloys was studied by experimental investigation and simulation assessment. The experimental investigations were carried out using bespoke fluidity and “T-shaped” hot tearing test molds. The microstructure and morphology were characterized by scanning electron microscopy system equipped with an energy dispersive spectroscopy system, and transmission electron microscope. The simulation assessment, which was carried out by using ProCAST software, focused on the solid fraction, phase fraction, and effective stress of the alloys during solidification. The solidification parameter obtained by DTA were used as input data to simulate HTS, the results shown a higher agreement with the experimental results than that obtained by simulation with the parameters from the software database. The results displayed that the fluidity increased and HTS decreased with Cu addition in the range from 0 to 3 wt.%. Moreover, the phase fraction of MgZnCu phase in Cu-containing alloys increased. The simulation results of HTS with DTA solidification parameters presented a higher agreement with the experimental results.

Design of Large Hot Runner Injection Mold for Interior Part Based on CAE Analysis

According to the shape and structural characteristics of an automotive interior plastic part, this paper has designed a large hot runner injection mold in accordance with the customers’ layout requirement, i.e., one mold and two cavities. It then analyzes the mold filling, cooling, and weld lines via the software, Moldflow, and hence determines a reasonable pouring system; a side core pulling mechanism, “lifter block + square push bar”, has been adopted for the large inverted part on the inner side of the plastic part, while a “lifter + insert” is organized for the two bayonet catches or inverted buckles on the inner side of the plastic part; the combination form of “ejector pin + lifter” has also been employed for the mold release system, with complicated mold structure. Practices prove that the mold structure is reasonable and reliable, and the production of plastic parts meet the quality requirements.

Thermoplastic starch/beeswax blend: Characterization on thermal mechanical and moisture absorption properties

Cassava starch has acquired many attentions owing to its ability to be developed as thermoplastic cassava starch (TPCS) where it can be obtained in low cost, making it to be one of alternatives to substitute petroleum-based plastic. An attempt was made to investigate the thermal, mechanical and moisture absorption properties of thermoplastic cassava starch blending with beeswax (TPCS-BW) fabricated using hot moulding compression method in the range of beeswax loading from 0, 2.5, 5 to 10 wt%. Addition of beeswax has significantly reduced tensile strength, elongation and flexural strength while improving tensile modulus and flexural modulus until 5 wt% beeswax. Incorporation of 10 wt% beeswax has successfully produced the lowest value of moisture absorption and water solubility among the bio-composite which might be attributed to the beeswax's hydrophobic properties in improving water barrier of the TPCS-BW bio-composite. Furthermore, the addition of beeswax resulted in the appearance of irregular and rough fractured surface. Meanwhile, fourier transform infrared (FT-IR) spectroscopy presented that incorporation of beeswax in the mixture has considerably improve hydrogen bonding of blends indicating good interaction between starch and beeswax. Hence, beeswax with an appropriate loading value able to improve the functional properties of TPCS-BW bio-composite.

Mechanical properties of waste silk fibre reinforced PLA bio composites manufactured through hand layup method

In recent years, biodegradable and eco-friendly composites have gained popularity. Using the hot moulding technique, biodegradable polylactic acid (PLA) biocomposites reinforced with waste silk fibre were fabricated in this paper. They also underwent a variety of mechanical tests like tensile strength and modulus. While not surface-treated, the waste silk fibre reinforced PLA matrix bio composites mechanical properties. The fibre content of 30 wt per cent is optimal for achieving superior properties. Owing to the reinforcing effect of silk fibres, the quasi-static mechanical properties of waste silk fibre/PLA bio composites were enhanced.