13 - Injection Molding Technology

Since the appearance of the continuous extrusion process, the section shape of the feedstock is round. The shape of the feedstock directly affects metal deformation and metal flow characteristics during the continuous extrusion process. Based on finite element method (FEM), using the Deform-3D software, this paper simulates continuous extrusion forming process for copper bus bar, and analyzes the effect of different feedstock shape on metal flowing temperature, velocity, rotating torque. The results show that: the size of the rectangular feedstock must be within a reasonable range, otherwise the continuous extrusion process can not be established; the rectangular feedstock is benefit to the flow uniformity comparing with the round feedstock; the temperature of the billet and tooling with rectangular feedstock is lower than that with round feedstock, as the feedstock width increases, the temperature decreases and the area of high temperature becomes smaller; the change of the feedstock shape and size has no effect on the extrusion wheel torque value.

Investigation on laminar burning velocity measurements of premixed Ethane-Air mixture at higher pressure and temperature conditions

The Longmaxi shale samples are used to investigate the anisotropic hydration damage characteristics of shale under high temperature conditions. The FEI Qemscan 650F energy dispersive spectroscopy (EDS)-field emission scanning electron microscope (FESEM) is used to help observe the evolution characteristics of shale clay mineral and micro-structure under different temperature, pressure and soaking time conditions from beddings vertical and parallel directions. It comes to the conclusion that the hydration characteristic induced by microscale anisotropy of Longmaxi shale varies a lot. The damage behavior in the bedding-parallel plane is characterized by dilatation-closure-collapse process of primary fractures which exists in a large amount of nano-scale and micro-scale corrosion pores. While the damage behavior in the bedding-vertical plane is mainly represented as a mass of nano-scale and micro-scale corrosion pores. It’s also found that the shale hydration damage is faster under higher temperature condition when the soaking time and pressure are the same. Besides, under the same temperature and pressure conditions, the shale microstructure hydration process trends to increase at the beginning and be flat at last. The higher temperature shorten the time spending on shale hydration and its inner relationship is required more experiments.

HI-Light: A Glass-Waveguide-Based "Shell-and-Tube" Photothermal Reactor Platform for Converting CO2 to Fuels.

Calculation of hydrogen adsorption isotherms and Henry coefficients with mixed CO2 and CH4 gases on hydroxylated quartz surface: Implications to hydrogen geo-storage

Auto-ignition and knocking combustion characteristics of iso-octane-ammonia fuel blends in a rapid compression machine

Continuous leaching of uranium from an Indian ore: Residence time scale up and heat effects

As a result of negligible connected porosity—and thus, minimal matrix permeability—the fluid-transport characteristics of crystalline rocks are strongly influenced by the fractures at all scales. Understanding the flow behaviour of fractured rock under extreme stress and temperature conditions is essential for safe and effective deep geo-engineering applications, such as deep geothermal recovery, geological nuclear waste disposal, oil and gas extraction, geological storage and deep mining operations. Therefore, this study aims to investigate the flow characteristics of mechanically fractured Australian Strathbogie granite under a wide range of stress (confining pressures 1–80 MPa) and temperature conditions (20 °C to 350 °C). The study utilised a sophisticated high-temperature, high-pressure tri-axial setup capable of simulating extreme geological conditions, followed by a numerical simulation. According to the experimental results, a linear increment in the steady-state flow rate was observed, with increased injection pressure for the experimental conditions considered. Therefore, linear laminar Darcy flow was considered, and the fracture permeability was calculated using the cubic law. It was found that stress and temperature strongly depend on the flow of fluid through fractures. The steady-state flow rate decreased exponentially with the increase in normal stress, showcasing fracture shrinkage with an increment in effective stress. With regard to permeability through the fractures, increasing temperature was found to cause an initial reduction in fracture permeability due to an increased interlock effect (induced by thermal overclosure), followed by increments because of the thermally induced damage. Furthermore, the increasing temperature caused significant non-linear increments in the fluid flow rates due to the associated viscosity and density reduction in water. Considering the laboratory-scale flow-through exercises, a fully coupled numerical model that can predict hydro–thermo–mechanical variations in the reservoir rocks was developed using the COMSOL Multiphysics simulator. The developed model was calibrated, utilising the temperature- and pressure-dependent properties of granite rocks and fluid (water); was validated against the experimental results; and was used to predict the permeability, pressure development and strain of rock samples under extreme conditions, which were difficult to achieve in the laboratory.

A set-up for fibre-optical in-line near infrared spectroscopic monitoring of hydrocarbons in supercritical CO2 has been developed, which can be operated under flow-through conditions. It consists of a high-pressure optical cell, which is adapted to an FT-NIR spectrometer via a fibre-optic interface. NIR spectra of squalane in supercritical CO2 have been measured for varying concentration, temperature and pressure conditions. A partial least squares (PLS) regression model was developed with a calibration set of 36 samples spanning the 0–32 × 10−3 g cm−3 squalane concentration range and with CO2 densities between 0.62–0.86 g cm−3. Based on the corresponding absorbance data in the 4900–4200 cm−1 spectral range, squalane and CO2 were modelled with standard deviations of 0.24–10−3 and 3.8 × 10−3 g cm−3, respectively. Comparable standard deviations were obtained by validating the model with independent test samples. The developed calibration models allow for the in-line quantification of both constituents under varying temperature and pressure conditions from a single spectral measurement. The results obtained encourage the use of NIR spectroscopy/PLS calibration for fast in-line analysis of continuous flow extraction processes for the deoiling of metal parts based on supercritical CO2.

Numerical modeling and optimization of process parameters in continuous extrusion process through response surface methodology, artificial neural network & genetic algorithm

Polystyrene (PS) clay nanocomposites were synthesized and used to prepare foams in both batch and continuous extrusion process. It was found that the addition of a small amount of clay could greatly reduce cell size and increase cell density. Once exfoliated, the nanocomposite foam exhibits the highest cell density and the smallest cell size at the same particle concentration. Exfoliated microcellular nanocomposite foams with good surface quality was successfully produced using supercritical carbon dioxide.

The development of a long-span load-bearing reinforced-plastics roofing and walling unit

Metals are being replaced with high-performance and lightweight polymers, but their low thermal conductivity and poor electrostatic dissipative properties are significant problems. For the protection of sensitive electronic circuitry in automotive and aerospace parts, some device housing materials must provide electrostatic discharge and dissipate heat generated at higher rates as electronic circuits are increasingly miniaturized. Micro-texturing on the film surface can greatly enhance the heat dissipation area and was investigated in this study using low-cost graphite nanoplatelet (GNP)-filled LLDPE films. Micro-finned films (30 vol% GNP) having a 51 ± 10% larger heat-dissipation area were successfully produced using a continuous extrusion process. The through-thickness thermal conductivity of 30 vol% GNP-filled LLDPE was measured at 1.3 W/m·K, which represents a 200% improvement over that of pure LLDPE. For a GNP content of 30 vol%, the surface and volume electrical conductivity of the composite films also increased by 8 orders of magnitude (resistivity down from ≈1015 to 107 Ω·cm) and electrostatic decay time reduced to a below-resolution limit of 0.01 s, at par with military standard requirements. Thus, micro-fin textured GNP-LLDPE offers a unique combination of electrical and thermal transport desired for the protection of electronic encapsulation materials.

This work was focused on the influence of the internal structure of natural rubber (NR)-based core-shell particles on the toughness of polystyrene (PS). Several emulsion polymerization processes were used to control the degree of grafting of the NR phase and the site of polymerization, which determines the final morphology of the prepared composite NR-based particles. PS subinclusions were introduced into the NR core in order to determine their influence on the deformation behaviour of PS. A continuous extrusion process was adapted for the direct feeding of the wet NR-based latexes into the molten PS matrix. Impact testing indicated that core-shell particles based on NR containing a large number of small crosslinked PS subinclusions toughened PS most effectively. A very effective toughening agent is obtained if a hard shell of 25 wt% crosslinked PMMA surrounds the composite rubber particle. Grafting of NR chains during the subinclusion synthesis has to be avoided since a high rubber particle modulus is detrimental for craze nucleation in PS. From the fracture surface morphology the craze nucleating and stabilizing efficiency of composite NR particles having different morphologies or grafting degrees could be deduced.

Creep behavior of the ZK60 magnesium alloy was investigated using impression creep technique. The tests were carried out under constant punching stress at high temperatures (175, 200 and 225 °C) under low stresses (25, 50, 75 and 100 MPa) and at low temperatures (100, 125 and 150 °C) under high stresses (100, 125, 150 and 175 MPa). The creep mechanism of the extruded ZK60 magnesium alloy is grain boundary sliding by dislocation climbing obtained at low temperature and high pressure. At high temperature and under low pressure, the creep mechanism of the extruded ZK60 magnesium alloy is grain boundary diffusion by grain boundary sliding. The initial microstructure of the extruded ZK60 magnesium alloy was composed of mainly Mg phase and a little MgZn phase. Under the conditions of low temperature and high pressure, MgZn2 phase precipitated during creep deformation. Under the conditions of high temperature and low pressure, MgZn2 phase and a small amount of Zr-Zn phase precipitated during creep deformation. The creep resistance of magnesium alloy ZK60 under the conditions of low temperature and high pressure is better than under the conditions of high temperature and low pressure.