Accelerating advancements in technological systems have demonstrated a need for alloys with drastically improved thermomechanical and chemical properties, called superalloys. Ceramic molds are ...typically used in near-net shape investment casting processes of superalloy components due to their chemical inertness and high-temperature capabilities. Ceramic molds, however, often suffer from shortcomings in vital properties including flexural strength, thermal shock resistance, permeability, dimensional stability, corrosion resistance, and leachability, which have restricted their ability to adequately process modern alloy castings. This study analyses these limitations and illustrates how to address them, particularly regarding ceramic mold and slurry design, processing of shells and cores, material selection, and testing and characterization. By utilizing advanced processing methods including additive manufacturing and gel-casting, more dimensionally accurate and preferentially built molds can be formed. Additionally, by varying the mold composition to achieve more chemically inert structures, reactions with the mold can be mitigated to reduce chemically induced defects.
The shrinkage ratio is a key parameter in designing the investment casting die for hollow turbine blades of high-performance aircraft engines. To avoid extensive modifications to the die shape, we ...took a single-crystal hollow turbine blade as the typical part to determine the nonuniform shrinkage distribution while considering its structural characteristics during investment casting. By using the structural identification method, different geometrical structures were identified, and the displacement field was established and verified via numerical prediction and experimental measurement. The deformation characteristics, including the wall-thickness distribution and shrinkage ratio, can be established by deformation decoupling analysis. The optimized die profile designed on the basis of the calculation results is in good agreement with the investment casting die in actual use, which indicates that the proposed method is beneficial for improving the geometrical accuracy of hollow turbine blades.
Advanced methods for manufacturing high quality parts should be used to ensure the production of competitive products for the world market. Investment casting (IC) is a process where a wax pattern is ...used as a sacrificial pattern to manufacture high precision casting of solid metal parts. Rapid casting is in turn, a technique that eases the IC process by combining additive manufacturing (AM) technologies with IC. The use of AM technologies to create patterns for new industrial products is a unique opportunity to develop cost-effective methods for producing investment casting parts in a timely manner. Particularly, stereolithography (SLA) based AM is of interest due to its high dimensional accuracy and the smooth surface quality of the printed parts. From the first appearance of commercially available SLA printers in the market, it took a few decades until desktop SLA printers became available to consumers at a reasonable price. Therefore, the aim of this review paper is to analyze the state-of-the-art and applicability of SLA based 3D printing technology in IC manufacturing, as SLA based AM technologies have been gaining enormous popularity in recent times. Other AM techniques in IC are also reviewed for comparison. Moreover, the SLA process parameters, material properties, and current issues are discussed.
The present study addresses a thin-walled investment casting methodology of AZ91D-1 wt% CaO magnesium alloy for stent manufacturing. Additive manufacturing and Yttria-based coating were applied to ...optimize the process. An induction melting furnace assisted by vacuum was used to cast magnesium alloy stents with 0.4 mm and 0.8 mm wall thickness under an argon-protective atmosphere. According to the proposed methodology and the results obtained for coated models, no metal-mould interface reactions were found, revealing samples with a good surface finish and sane microstructure. The cast magnesium stents without coating were compromised, resulting in samples with a high degree of reactions and impurities. Microscopic examination and hardness measurements demonstrated the effectiveness of the process.
Metal casting with investment casting method is metal casting which has the ability to produce accurate parts and has a controlled fineness. Current technological developments are very influential in ...the development of investment casting. One of them has been found mold-lay filament as a substitute for wax, which is now wax is one of the main components in investment casting process. Mold-lay filament is printed using a 3D Printer machine. In this study, the wax in the investment casting process was replaced by a mold-lay filament with the specifications 0.75kg / 0.55 lb of 1.75mm MOLDLAY filament, prints at temperatures of 170-180 ° C. The result show that mold-lay flutes are also able to come out well from slurry molds, but require more time than wax, this is because one of the plastic mold-lay compositions, which takes a long time for the moldlay fillment to come out of the mold. Further research suggestions are needed further testing in terms of roughness of the product with moldlay filament and compared with wax. This will also see if there are any remaining moldlay filaments from the mold.
In this research article, a novel method of additive manufacturing (AM) assisted investment casting (IC) has been demonstrated (by using the patterns prepared from waste materials reinforced with ...ceramic particles) for development of a metal matrix composite (MMC). In first stage, recycled low density polyethylene (LDPE) has been selected as matrix material, while ceramic reinforcement of SiC and Al2O3 has been blended in LDPE by screw extrusion. Initially, the recycled LDPE has been collected in granules form from the local market and processed on single screw extruder to prepare pallets. The ceramic particles and LDPE were blended together to prepared the final blend in different proportions on twin screw extruder. After that Taguchi L9 orthogonal array has been employed to ascertain the affect of different input parameters of FDM machine to prepare the functional prototypes in the form of cubical patterns. Instead of using conventional IC, a rapid method has been employed to prepare sacrificial pattern by using siladent powder (which is being used for preparing cast in clinical dentistry for dentures). Further this method has been explored as an alternate route of rapid IC, which requires very less time as compared to the traditional methods. At final stage cast were prepared with aluminium (Al) alloy as matrix material reinforced with SiC and Al2O3 (which were present in the mould cavity after removal of LDPE). The properties of MMC prepared via this novel route were subjected to hardness and grain size testing supported by photomicrographs and EDAX analysis.
Ti-6Al-4V turbine blade-like geometries were cast in ZrSiO4 and Al2O3 based investment shells at different preheating temperatures to identify the least reactive conditions. The Cold Crucible ...Induction Melting method was employed to prevent unexpected melt reactions. The resulting sample α-case composition and characteristics of each sample were extensively analysed and the effect of mould stability and preheating temperature were evaluated. This work highlights the diffusion barrier effect that mould-metal reaction products provoke in the detrimental element transport. Interestingly, the results demonstrate that in the less stable preheated ZrSiO4 mould the diffusion layer thickness was 50μm less than that of the more stable Al2O3. This likely occurred because the reaction products present in the outer reaction layer hindered the detrimental element transport and a thinner diffusion layer was obtained.
The permeability of shell molds is a key property for investment casting technologies because it affects casting defects like non-fill and de-wax cracking. Currently, the permeability measurement ...method for investment casting shell molds is not specified in Japanese Industrial Standard (JIS). Permeability is presently measured by two common methods : Ping pong ball method and Pipe method. Because the mold cracks during the preparation of shell mold samples, there is room for improving these methods. In JIS, permeability measurement for ceramics materials is specified in JIS R 2115 (2008). Thus, in this study, we investigated a method to prepare shell mold samples and a method to measure investment casting shell molds based on JIS R 2115 (2008). Moreover, the influence of stucco size and firing temperature on the permeability value were reviewed. The results showed that the permeability value is affected by the sintering extent and crack number or its size.
The mechanical properties of open-cell aluminum foams can be influenced by enhancing the microstructure of the struts. The foams produced by investment casting face slow cooling rates, which makes it ...challenging to improve the morphology of the phases. In the case of aluminum silicon cast foams, the silicon phase accumulates on the surface of the struts, which leads to brittle fractures. In the present study, we successfully modified the silicon phase in open-cell AlSi7Mg and AlSi10Mg cast foams by adding strontium and investigated the influence of the strontium content on the microstructure and mechanical properties at the foam and strut levels. Despite the cooling rates of less than 0.5 °C/s during solidification, the strontium addition of 200–800 ppm effectively decreased the size of the silicon particles and improved their distribution in the micrometer-sized struts. Improvements in the compressive properties of the foams and the tensile properties of the struts only occurred at the strontium levels of 200 and 400 ppm. The effective modification in this casting condition is due to the limited solidification space, which favors the formation of the atomic clusters responsible for the modification.
•Strontium modifies eutectic silicon in cast aluminum foams even at slow cooling rates during solidification below 0.5 °C/s•Possibility of higher modification efficiency in confined solidification spaces such as micrometer-sized foam struts•3D morphology of eutectic silicon phase in Al-Si alloy observed under modified and unmodified conditions•Sr addition (max 400 ppm) enhances peak/plateau compressive stresses, UTS, and deformation strains in Al-Si foams
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