Papers by Keyword: Feedstock

Abstract: The influence of polyamide-6 (PA6), polyamide-12 (PA12), and their compositions was analyzed to determine the rheological behavior of the feedstock with 43% solid loading. The feedstock with Cu/PA composite constituents were extruded into filaments. The sphericity of particles, particle distribution, and voids was identified using Scanning Electron Microscopy (SEM). The capillary rheometer method was utilized to examine how shear rate and temperature impact the results. The viscosity and shear rate of the material was assessed at different temperatures and shear rates using an L/D ratio of 20 mm and a diameter of 11 mm capillary rheometer. The test results indicated that the polyamide composition influenced the feedstock's rheological properties. The viscosity of the feedstock decreased with an increase in the polyamide composition. Feedstock Cu/PA6 with a composition of 14wt%-Cu has the higher rheological properties among the variation of other composition both for PA-6 and PA-12. Viscosity and Flow energy activation Cu/PA-12 higher than Cu/PA-6.

Abstract: An experimental study was performed to evaluate the effect of iron, ferronickel, and stainless steel 304L (85-92wt%) powder injection molding (PIM) on the compressive strength and rheological behavior of polyamide (PA6/M) composite. The feedstock, prepared at 260°C, was extruded into a composite film. The effect of particle shapes and size distribution was investigated using Scanning Electron Microscopy (SEM) to evaluate the relative viscosity value of the PA6/M feedstock. The results showed that the compressive strength and rheological behavior were determined by the blend composition. The increase in compressive strength was due to the higher strength of the metal powders compared to PA6, along with heightened surface energy leading to mechanical interlocking. Furthermore, the metal powders generated frictional resistance resulting in an increase in viscosity, making the feedstock unstable and decreasing the rheological properties. According to the compression and rheology test, all variations with an 85wt% metal powder exceeded the minimum specifications for frangible projectile materials. The highest compressive strength of PA6/85Fe was 144.503 MPa and the lowest viscosity of PA6/85FeNi was 352.85 Pa.s.

Abstract: TiBw reinforced titanium matrix composites (TMCs) are the most promising engineering materials in aerospace and transportation owing to their excellent properties such as lightweight, high strength, wear resistance. The electron beam powder bed fusion (EB-PBF) characterized by its rapid solidification process during the manufacturing, which can effectively controlling the microstructure and mechanical properties of DRTMCs. The state of feedstock used in EB-PBF has a significant influence on the microstructure and mechanical properties of DRTMCs prepared by EB-PBF. However, there is no commercial feedstock available for EB-PBF fabricating DRTMCs. The disadvantages of premixed ball-milled powder are degraded flowability or incomplete reaction and agglomeration of reinforcements, which causes metallurgical defects in the as-fabricated composites. These issues severely affect the stability of mechanical properties of DRTMCs prepared by EB-PBF. The introduction of TiBw led to the formation of melt pool structure. At the boundary of the melt pool, TiBw exhibits an equiaxed continuous network distribution, while at the center of the melt pool, TiBw exhibits a columnar continuous network distribution; Moreover, the introduction of TiBw resulted in a 75% grain refinement, a 40% increase in yield strength, a 54% increase in tensile strength, and a decrease in elongation (13.2%) in the composite material. The improvement in strength of Ti-TiBw composite material prepared by EBM is due to grain refinement and the good load transfer effect generated by high aspect ratio TiBw, while the decrease in plasticity of the composite material is due to the connectivity failure of TiBw on the matrix. Based on the current research of DRTMCs prepared by EB-PBF, the future research trend focus on TiBw reinforced DRTMCs prepared by EB-PBF is discussed.

Abstract: Although fossil fuel continues to play a dominant role in global energy system unfortunately their life span is threatened as the fossil reserves are running out. Except for the fact that they are readily available, tried and tested, unfortunately they bring about a negative environmental and climate impact. When the fossil fuels are burned, they produce both carbon dioxide and carbon monoxide which is the largest driver of global climate change and air pollution. This has caused a need to explore and transition to a cleaner and renewable energy resource like biofuel. Biofuel is a combination of fatty acid alkyl esters achieved by the esterification and transterification of triglycerides that can either be animal fats and vegetable oil with methanol and ethanol. Biodiesel provides several positive benefits by helping in decreasing the country’s dependence on the importation of crude oils, it also reduces the greenhouse gas emissions and advances the lubricating property. Biodiesel is produced and deployed globally with China being the country with the highest biofuel capacity in the world, with nearly 29.8 gigawatts as of 2021. It is followed by Brazil which is ranked second, with a biofuel capacity of 16.3 gigawatts. The selection of a feedstock in biofuel production has a noticeable impact as it determines if a biofuel will be formed or not from the transesterification process performed. The fatty acid / triglyceride content especially the Mono-Unsaturated Fatty Acids (MUFA’s) are of interest. The higher the MUFA’s, the higher possibility of a successful transterification hence biofuel being the by-products/formation with less catalyst and alcohol used. Feedstocks with over 40% fatty acids, especially the MUFA’s are favorable for biodiesel formation. Almost 80% of Macadamia’s fatty acids (MFAs) are palmitoleic acids (C16:1; ~20%) and Monounsaturated, mostly oleic (C18:1; ~60%). This study reviews the preparation of biofuel utilizing Macadamia nut oil (MNO) as a feedstock for sustainable biodiesel Production.

Abstract: Metal injection molding (MIM) feedstock is composed of Cu powder and a complex binder system that consists of PA6, MgSt, and GMS with various solid loading (43-53vol%). Cu powders used are fabricated by gas and water atomization. Powder particle shapes used have spherical and dendritic shapes. Sphericity of particles can be identified by Scanning Electron Microscopy (SEM). A rheology test is used to ensure the optimum solid loading and investigate the influence of particle shape. The pseudo-plastic behavior of all the feedstock is exhibited by decreasing viscosity along with increasing shear rate for all working temperatures. In this study, rheological test result such as viscosity, flow activation energy, and flow behavior index of feedstock indicates that the optimum solid loading was selected as 43 vol%. Both gas and water atomized powders are desirable for MIM feedstock. According to the rheology behavior test, gas-atomized powders with spherical shape has better rheology stability than water-atomized powders with dendritic shape. The proper MIM feedstock was selected to solid loading 43 vol% with gas-atomized powders.

Abstract: In this work, to reduce the cost of production of parts using injection molding metal technology (MIM technology), it is proposed to use additive technologies (AT) for the manufacture of green parts. The use of AT allows us to abandon expensive molds and expand the field of use of the MIM of technology in single and small-scale production. For manufacture of green parts, the technology of manufacturing fused filament (Fused Filament Fabrication – FFF) is offered. The original composition of the metal powder mix (feedstock) and the filament manufacturing modes for 3D printing have been developed for the FFF technology. The cost of filament is much lower than its analogs. The factors affecting the print quality of green part are considered. All factors are divided into two groups depending on the possibility of their change during printing. The research of the influence of the coefficient filament supply on the geometry of green parts during 3D printing is presented.

Abstract: In this paper, to reduce the cost of production of parts by injection molding technology of metal powder mixtures (MIM technology), it is proposed to use metal powder mixtures (feedstock) with high fluidity for the manufacture of green parts. High fluidity is achieved by increasing the proportion of paraffin wax in the binder. This can significantly reduce the pressing pressure when pressing the feedstock into the mold cavity to values less than 1 bar, and eliminate the use of expensive injection molding machines with high compression pressure. High fluidity also allows the use of powders with large particle sizes, which significantly reduces the cost of feedstock. The absence of high pressure on the mold walls during the pressing of the feedstock allows the use of molds made of cheaper materials such as silicone, plastic, gypsum and others.

Abstract: Conventional and nanometer aggregate ZrO₂-7wt.%Y₂O₃ ceramic powders taken as raw materials, plasma spraying and plasma spraying-laser remelting compound technology was used to prepare conventional and nanostructured thermal barrier coatings on the TiAl alloy surface. Effects of powder structure (feedstock) and laser remelting on organizational structure and phase of the coatings were analyzed using scanning electron microscope (SEM) and X-ray diffractometer (XRD). Results indicate that: conventional plasma sprayed ceramic coating presents typical lamellar stacking features; plasma sprayed nanostructured coating consists of fully melted region and partially melted region, presenting a two-phase structure. Under the comprehensive impacts of laser power, energy density, temperature field distribution in the laser action region, ceramic heat conductivity coefficient and coating thickness and other factors, the coating presents obvious lamellar structural features after laser remelting; the upper part is compact columnar crystal remelting region and the lower part is residual plasma spraying region. Due to toughening effect of residual nanoparticles in the remelting region of laser remelted nanostructured coating, grain-boundary strength is high and there are a considerable number of transgranular fractures, but the fractures in the remelting region of laser remelted conventional coating are basically intergranular fractures. Conventional plasma sprayed ceramic coating is mainly of tetragonal phase together with a small quantity of monoclinic phases, but nanometer plasma sprayed ceramic coating only has non-equilibrium tetragonal phases. After laser remelting, both conventional coating and nanometer coating mainly have non-equilibrium tetragonal phases with a small quantity of cubic phases.

Abstract: In the present work, to reduce the cost of production of the parts with MIM technology, proposed to use a new metal powder mixture (feedstock are presented) with the increased size of the powder to 50 microns. New feedstock are presented recommended for use in the manufacture of parts with a wall thickness of 5 mm. Shows the main physical and technological properties of new metal powder mix (feedstock) 40ХМА of steel intended for the manufacture of parts via MIM technology. Given the results of determination of granulometric composition and particle shape. The obtained values of tensile strength, hardness and roughness. The results of determining the dependence of viscosity on shear rate. For simulation of rheological properties of selected elastic-visco-plastic model of Bingham type with nonlinear dependence of viscosity on shear rate and temperature. The example of the calculation of feedstock fill the cavity of the mold. The analysis of defects in green part, associated with an irregular velocity field in the flow channels feedstock form.

Abstract: Water atomized and gas atomized 17-4 PH stainless steel powder were used as feedstock in selective laser melting process. Gas atomized powder revealed single martensitic phase after printing and heat treatment. As-printed water atomized powder contained dual martensitic and austenitic phase. The H900 heat treatment cycle was not effective in enhancing mechanical properties of the water atomized powder after laser melting. However, after solutionizing at 1315 oC and aging at 482oC fully martensitic structure was observed with yield strength of 1000 MPa and ultimate tensile strength of 1261 MPa which are comparable to those of gas atomized, 1254 MPa and 1300 MPa, respectively. Improved mechanical properties in water atomized powder was found to be related to presence of finer martensite. Our results imply that water atomized powder is a promising cheaper feedstock alternative to gas atomized powder.