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This article presents the results of testing the suitability of X-ray computed tomography for the quality control of the casting moulds used for producing turbine blades. The research was focused on the analysis of cross-sectional images, spatial models and the porosity of moulds using a Phoenix L 450 microtomograph. The research material consisted of samples from three mixtures of ceramic materials and binders intended for producing casting moulds using the lost wax method. Various configurations of filling materials (Molochite and quartz flours) and binder (Remasol, Ludox PX 30 and hydrolysed ethyl silicate) mixtures were considered. X-ray computed tomography enabled the detection of a number of defects in the ceramic mass related to the distribution of mass components, porosity concentration and defects resulting from the specificity of the mould production. It was found that casting mould quality control on cross-sectional tomographic images is faster and as accurate as the analysis of three-dimensional models and allows for the detection of a whole range of ceramic defects, but the usefulness of the images is greatest only when the cross-sections are taken at an appropriate angle relative to the object being examined. [ABSTRACT FROM AUTHOR]

The latest generation of high-performance cylinder blocks are produced with the Precision Sand Castings Process which sometimes uses a monolithic cast iron chill that promotes enhanced solidification conditions that improve both tensile and fatigue performance. However, monolithic chills tend to be re-used quite quickly and thus can be significantly above room temperature during the next subsequent casting. To deter the potential deleterious effects, this may cause most casting practitioners to enforce a strict room temperature condition of the chill prior to use. However, this may necessitate a higher number of chills in the system or the implementation of chill cooling stations, both of which involve higher capital investment. The authors will address the most optimal method to address thermal management of chills by documenting the mechanical and microstructural property impact and its compliance in the bulkhead (next to chill) and head bolt columns (60 mm away from the chill) to the chill temperature prior to casting. The Quality Index will reflect the chill temperature impacts based on the mechanical properties results for this manuscript. [ABSTRACT FROM AUTHOR]

The manufacturing process of investment casting technology urgently needs to seek new materials, processes, and technologies in order to improve efficiency and reduce costs. To address this issue, PMMA powder is selected as the raw material, and the mold is formed using Binder Jetting. Combined with traditional investment casting technology, a rapid casting technology is achieved to obtain metal products. This technology can complete the rapid development and trial production, and mass casting of metal products. The production speed is dozens of times faster than traditional investment casting, with almost no ash residue, which well meets the requirements of investment casting. [ABSTRACT FROM AUTHOR]

Y 2 O 3 and CaO are ideal ceramic materials for precision casting of TiAl alloy, overcoming challenges associated with intricate component removal, such as turbine blades, leveraging the stability of Y 2 O 3 and the water solubility of CaO. To address these challenges, we employed Isobam104 in a novel gel casting method, serving as both a dispersant and a gelling agent. This method enabled us to create a stable Y 2 O 3 –CaCO 3 slurry with high solid content (up to 55 vol%) and low viscosity (101.51 mPa·s at a shear rate of 10 s−1). Following sintering at 1500 °C for 2 h, Y 2 O 3 –CaO composite ceramics were produced. Surprisingly, two distinct characteristics of CaO were noted. One showed a rod-shaped morphology with high chemical reactivity crucial for water solubility, while the other displayed a flat-like feature, forming a well-maintained interface due to its coherent or semi-coherent matching relationship with Y 2 O 3 , thereby providing excellent hydration resistance. Ultimately, we acquired composite ceramics showcasing a 30-day "shelf life" alongside exceptional water solubility. This establishes the theoretical groundwork for storing and employing soluble ceramic cores in the precision casting of TiAl alloy. [ABSTRACT FROM AUTHOR]

The surface of superalloy precision castings might exhibit defects after forming, posing a significant risk to their service life, necessitating inspection during post-process. Radiographic inspection, with its extensive research in automation, can achieve efficient and accurate detection of defects. However, it is limited in surface defects detection due to limited sensitivity to non-volumetric defects and high cost. In contrast, fluorescent penetrant inspection (FPI) is highly efficient for surface defect inspection due to its low cost, high sensitivity, and speed. However, manual examination introduces variability in the results, impacting the consistency and reliability of the inspection process. Automation is needed to ensure consistency and reliability of inspection. The implementation of an automated defect identification system based on FPI using convolutional neural networks (CNNs) was systematically investigated. Among the CNN models tested, MobileNetV2 exhibited exceptional performance, achieving a remarkable recall rate of 0.992 and an accuracy of 0.992. Additionally, the effect of class imbalance on model performance was carefully examined. Furthermore, the features extracted by the model were visualized using Grad-CAM to reveal the attention of the CNN model to the fluorescent display features of defects. This study underscores the strong capability of deep learning architectures in identifying defects of precision casting components, paving the way for the automation of the entire FPI process. [ABSTRACT FROM AUTHOR]

Ceramic cores are the key components of precision casting hollow turbine blades, and 3D‐printed silica‐based ceramic cores are crucial to the development of the aerospace industry. However, silica‐based ceramic cores have problems in terms of mechanical properties and friction properties. In this paper, silica ceramics were prepared by stereolithography‐based 3D printing technology and processed at different sintering temperatures. The effect of sintering temperature on the microstructure, physical–mechanical properties, and friction and wear properties of the silica ceramics was investigated. The results show that, with the increase of sintering temperature, the average particle size and bulk density of the samples increased, while the open porosity and layer thickness decreased. The surface of ceramics became more and more flat with the increase in temperature. The flexural strength first increased with increasing temperature, and then suddenly decreased at 1350°C. The average surface roughness decreased with increasing temperature. The wear of the material decreased with increasing sintering temperature and increased at 1350°C. The optimum sintering temperatures were 1250°C and 1300°C, giving a flexural strength of 23.18 and 23.25 MPa, bulk density of 1.72 and 1.78 g/cm3, and open porosity of 24.49% and 23.66%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The main commercial method of preparing precision metal parts with a high surface finish, for example, the blades of a turbo-ram jet engine, is lost waste casting. On preparing a wax model, a ceramic immuring element (rod) is placed in side the model in order to form cavities of complex shape, intended to reduce the mass of the casting and for forming channel of the cooling system of the blades cooled by the secondary air flow after a rod is removed. The main technological problems on removal of the inner rods are their strength and high chemical inertness, as a result of which their removal time and labor costs are quite large. This article investigates a method of preparing ceramic rods whose strength is not uniform along depth, which makes it possible, first of all, to remove (quite easily) the soft center and then to dissolve the stronger periphery. [ABSTRACT FROM AUTHOR]

Although silica‐based ceramic cores have important applications in the precision casting of metallic devices, their high‐temperature stability and removal performances are seriously affected by the liquid phase sintered fused silica. Herein, we develop a manufacturing strategy of high‐collapse silica‐based ceramic core via using cristobalite crystals as the sintering inhibitor, waterglass as the binder, and injection moulding at 100°C and 80 MPa, followed by heat treatment simulating the casting process for sintering at 1200°C and 1500°C. The results demonstrated that the addition of cristobalite crystals could effectively form the core skeleton to ensure high‐temperature performance. Meanwhile, it inhibited the liquid flow during sintering and induced the crytsallization from fused SiO2 glass into cristobalite crystals, and the resulting plenty of micropores and microcracks within the microstructure effectively improve the removal performance. Especially, the porosity was highest up to 35.36% and the flexural strength was only 6.74 MPa when the addition of cristobalite reached 45%, realizing a 100% removing by high‐frequency and fast‐speed specific mechanical vibration. And, the casting is guaranteed to be flat and free of defects. This work provides a simple and flexible strategy to manufacture high‐collapse silica‐based ceramic cores, which can be removed by specific mechanical vibration without immersion in acid or alkali solutions after casting. [ABSTRACT FROM AUTHOR]

India is the goldmine of handicrafts. 'Dhokra' or 'Dokra' is a traditional metal casting art. It has enormous respect in both national and international markets. Dhokra is always considered art, whereas it is a technologically sound casting method. In the foundry world, it is famous as the 'investment casting process', 'near net shape casting processes', or 'lost wax casting process. The technical name of Dhokra is "wax-based investment casting in hot clay mold". Few tribal communities of eastern India (West Bengal, Chhattisgarh, Orissa, and Jharkhand) practice this technique. This 5000-year-old technology needs some development because only love and emotion are not enough to survive this technique. A planned technical analysis in light of modern engineering techniques is required to improve the quality and degree of excellence. Then only casting defects can be eradicated, and yielding and production costs can be minimized. [ABSTRACT FROM AUTHOR]

Electron-beam casting technology has great potential in obtaining high-quality precision titanium castings due to its good ability to remove inclusions from the metal. In this study, the interfacial reactions of titanium with the face coats of the ceramic mold were investigated using microstructural analysis and microhardness measurement. Refractories—Al2O3, ZrO2, ZrSiO4 and Y2O3 were used as fillers for face coats. The study of the microstructure of cast samples from technically pure titanium showed that the Al2O3 face coat led to the formation of an α-case with a thickness of 300–400 μm. The Y2O3 coating in combination with Al2O3 and ZrO2 stucco ensured the formation of a twice-thin α-case. A combined face coat, which contained 70% ZrO2 + 30% Y2O3 slurry fillers and ZrO2 as stucco, ensured the formation of an α-case up to 200 μm thick. Measurement of microhardness made it possible to determine the nature of the interaction of titanium castings with ceramics and the distribution of gas impurities in the surface layers of the metal. Electron beam processing in combination with electromagnetic stirring leads to the formation of a fine structure in titanium castings. The low overheating of the titanium melt specific for EBCT and the low temperature of the mold contribute to reducing the interaction of titanium with ceramics. The combined face coat showed good technological properties and can be recommended for the production of thin-walled castings from titanium alloys by electron-beam casting technology. [ABSTRACT FROM AUTHOR]

High temperature alloys are an important guarantee for the development of aviation engines and gas turbines. Precision casting is the main technology for manufacturing high-temperature alloy castings. Due to the severe working conditions, such as high temperature, high vacuum and frequent temperature fluctuation as well as the existence of active metal elements in high-temperature alloys, high requirements to crucibles for casting are needed. There are many types of crucibles for precision casting of high-temperature alloys, showing different application problems. Crucibles made of different materials for precision casting of high-temperature alloys and their research status were summarized. The research direction of crucibles for precision casting of high-quality high-temperature alloys was prospected. [ABSTRACT FROM AUTHOR]

The lost wax foundry industry has been rapidly expanding in recent years, generating a large amount of waste due to the fact that most of the durable goods include castings and the need for dimensional precision castings for specific purposes, such as the automotive and aeronautics sectors. The waste produced by this industry is currently being deposited in landfills because practical applications are not known and cannot be reused in a new production process, and recycling is also a challenge because of the economics of the process. Thus, the main objective of this study consists in the incorporation of the produced wastes by the lost wax casting foundry industry (ceramic molds shells and paraffin wax) as substitutes for natural aggregate in exterior coatings mortars, evaluating their behavior under normal operating conditions and against freeze–thaw actions. The obtained results revealed porosity, flexural strength, and compressive strength adequate under normal operating conditions. The freeze–thaw performance of the mortars with waste incorporation was similar to the mortars developed with natural aggregates. Thus, the potential of the ceramic mold shells and paraffinic waxes utilization in cementitious mortars for the construction sector was demonstrated. [ABSTRACT FROM AUTHOR]

The purpose of this study was to combine simulations and experiments in order to present the first stage of construction in product lifecycle management. Based on the simplification of casting models, the relationship between the filling and solidification characteristics, casting methods, and geometrical classifications of aluminum alloy precision casting products was investigated. By rearranging and summarizing the data, the casting models could be digitally managed; moreover, the digitized data could be used as the basis for intelligent processes in further developments. The simulations calculated and analyzed the casting speeds, defect locations, material densities, and critical fraction of a solid A356 aluminum–silicon alloy; the actual casting was carried out and samples were taken for metallographic observation to confirm the simulation results. The part model was simplified with four basic geometric shapes: solid cylinder, tubular, block rectangle, and thin-shell rectangle. The 150 casting models were summarized using 37 combinations, which were further classified into five main categories to match the casting method: solid cylindrical, tubular, and thin-shell rectangular for side casting, and discoidal and plate rectangular for bottom casting. File-compression rates of up to 75% were achieved after classification and archiving, and data integrity was maintained. Finally, model training using random forest classification resulted in an 88.8% accuracy when predicting the casting method. This research is based on the practical issues raised by business owners and R&D engineers, and a solution was obtained. From the perspective of product lifecycle management, the results of this study show the consistency and uniformity of product design rules, as well as the reusability of product process planning, which can be integrated with carbon emissions trading and carbon taxes to save energy and achieve corporate sustainability. [ABSTRACT FROM AUTHOR]

For a long time, research on the pre-Han (before 202 BCE) Chinese use of the lost-wax process was targeted at demonstrating that it was of no use at all. That position was severely shaken when the zun-pan set of Zeng Hou Yi ("Marquis Yi of Zeng," d. 433 BCE) was unearthed at Hubei Suizhou in 1978, along with subsequently excavated finds or rediscovered artifacts carrying similarly interpenetrating openwork. Since the early 2000s, however, there has been a persistent revival of a research orientation against the use of the lost-wax process in Bronze Age China. After surging first in Chinese academia, the new tide took some time to arrive in the West. A response to Donna Strahan's prestigious lecture, "Debating the Use of Lost-wax Casting in Ancient China," this article presents my thinking about lost wax versus piece molds in early Chinese casting practices. Strahan's studied "diatrete" ornamentation in the Metropolitan Museum of Art, to me, can be securely identified as lost-wax cast thanks to some telltale traces. Through this critical investigation, I invite my fellow art historians, archaeologists, and historians of metal technology to emerge from the "doubting of lost wax" era to tackle new challenges in early Chinese archaeo-metallurgy. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents an attempt to produce aluminum matrix composites reinforced with short carbon fibers by precision casting in a chamber with a pressure lower than atmospheric pressure. The composite casting process was preceded by tests related to the preparation of the reinforcement. This is related to the specificity of the precision casting process, in which the mold for shaping the castings is fired at a temperature of 720°C before pouring. Before the mold burns, the reinforcement must be inside, while the carbon fiber decomposes in the atmosphere at 396°C. In the experiment, the reinforcement in the form was secured with flake graphite and quartz sand. The performed firing procedure turned out to be effective. The obtained composite castings were evaluated in terms of the degree of alloy saturation and the displacement of carbon fibers. As a result of the conducted tests, it was found that as a result of unfavorable arrangement of fibers in the CF preform, the flow of metal may be blocked and porosity may appear in the casting. [ABSTRACT FROM AUTHOR]

The solidification process of IN713C Ni-based superalloy rod castings made by the investment casting method without and with the use of novel insulating module applied on the ceramic mold was studied in this article. The design of the cone-shaped insulating module was developed based on numerical simulations of the distribution of local solidification parameters, ensuring the lowest centerline shrinkage porosity along the castings. The effectiveness of the design of the insulating module was tested in industrial casting trials. It was found that the use of a novel insulation module increases temperature gradient G and decreases cooling rate v, thus leading to a favorable increase of the Niyama criterion value (Ny = G/√v) and also ensuring directional solidification of the casting rod compared to the process where thermal insulation was not used. In this way, the centerline shrinkage porosity was removed, maintaining the equiaxed grain structure of the castings. The presented results show that it is possible to use the same insulating module multiple times, in the subsequent manufacturing processes, to control the solidification of Ni-based superalloy precision castings in industrial conditions. [ABSTRACT FROM AUTHOR]

Purpose: To compare precision and trueness of digital and printed casts produced from several intraoral and extraoral scanners in full arch and short span scanning. Materials and Methods: A fully dentate maxillary phantom cast was used to represent full arch scanning, and a mandibular phantom cast, including posterior 3‐unit fixed partial denture preparations to represent short span scanning. Reference casts (RCs) were fabricated and scanned 10 times by a reference extraoral scanner (Medit T510, Seoul, Korea) to provide reference digital casts. RC was then scanned 10 times by 5 scanners: 2 intraoral scanners (Trios 3shape [Trios 3] and Dental Wings [DW]), and 3 extraoral scanners (3shape E3 [E3], S600 ARTI [S600], and Ceramill Map 600 [M600]). Digital standard tessellation language (STL) files obtained from the 5 scanners were sent to a stereolithography 3D printer to fabricate printed casts. Trueness was obtained by comparing STL files of each digital/printed cast to the RC, while precision was obtained by comparing the digital/printed STL file of each scanner to the other files of same digital/printed group. The lower the precision and trueness values, the higher the accuracy of casts. Multivariate analysis of variance was performed to assess the association of precision and trueness with the type of scanner, type of cast, and scanning span. Results: There was a significant difference in precision and trueness of casts produced from different scanners (p <0.001). The lowest precision and trueness were demonstrated by casts produced from DW. Digital casts showed significantly higher precision and trueness compared to 3D printed casts (p <0.001). Regarding the scanning span, full arch scanning showed significantly lower precision and trueness than short span scanning (p <0.001). Conclusions: Extraoral scanners exhibited higher trueness and precision than intraoral scanners. Trios 3 showed comparable accuracy to that of the studied extraoral scanners in the case of short span scanning. DW was the least accurate scanner in all studied groups, while E3 showed the highest accuracy level among the mentioned scanners. Digital casts showed higher trueness and precision compared to 3D printed casts. [ABSTRACT FROM AUTHOR]

• Castability and dimensional shrinkage are handled simultaneously. • Quantitative framework for dimensional shrinkage is established. • Efficient formulation with low computational cost is offered. • Both 2D and 3D numerical examples are verified. Solidification shrinkage and surface finishing cause the inevitable dimensional shrinkage between the blueprint and model designs, thereby creating huge cost and precision challenges to casting designs. This paper proposes an efficient structural topology optimization approach to simultaneously achieve the blueprint and model designs with uniform dimensional shrinkage in only one optimization setting. An appropriate two-projected-field scheme is established to simulate the blueprint and model designs by extending the density-based threshold projection approach. And, an effective quantitative framework is constructed to precisely predict the shrinkage rules. Besides, to ensure the castability of both the two projected designs, the Poisson equation-based constraint method is subtly integrated with the two-projected-field scheme. More importantly, to reduce the computational burden involving multiple designs and constraints, an efficient formulation is presented by reasonably considering the projected fields in the objective and constraint functions. Typical 2D and 3D numerical examples as well as one real-world example are provided to validate the effectiveness of the proposed strategies. The results show that the traditional one-projected-field scheme is difficult to yield the model design through the filtered field associated with the blueprint design. The proposed approach enables this and can help engineers achieve predictable dimensional shrinkage in an optimization way. [ABSTRACT FROM AUTHOR]

In the present study, a superalloy round tube specimen prepared by directional precision casting without mechanical turning is experimentally investigated under the thermomechanical fatigue conditions of the in‐phase and out‐of‐phase thermomechanical angels from 500°C to 1000°C. The deformation behavior and damage mechanism of the round tube specimens under TMF load are discussed. It was confirmed that the tension–compression asymmetry under TMF cycling is affected by temperature–load phasing and mechanical strain range. Moreover, the damage to round tube specimens includes creep, fatigue and oxidation. Due to the concentrated stress, the rough surface of the specimen provides suitable locations for crack initiation. A novel life prediction approach that combines the Neu–Sehitoglu model and modified Manson–Coffin model was proposed in response to the traditional life model's insufficient prediction performance. This method may explain the TMF life of precision cast specimens. Highlights: TMF of precision casted round tube specimens was investigated.Crack initiation at the notches of rough surface due to stress concentration.A new life prediction method was proposed for precision casted specimens. [ABSTRACT FROM AUTHOR]

In order to investigate the distribution of temperature field in directionally solidified DZ4125 columnar superalloy, and to study the effects of different withdrawl rates on the changes of temperature gradient and mushy zone, the directional solidification processes with withdrawal rates of 3, 5 and 7 mm/min were simulated by ProCAST software. The results show that when the test rod is located in the heating zone, the isotherm is inclined distribution with low outside and high inside. And when the test rod is located in the cooling zone, the isotherm is inclined distribution with high outside and low inside. With the increase of withdrawal rate, the temperature gradient decreases gradually. The shape of the mushy zone depends on the withdrawal rate and the distance from the water-cooled plate. When the withdrawl rate is 5 mm/min, the horizontal state of the solidification front is maintained for a longest time. On this basis, the precision casting experiment of directional solidification test rod is carried out, and the relationship between the shape of liquidus and grain structure is found for castings withdrawn at 3 and 7 mm/min. It is found that when the liquidus is concave and convex, the grain grows towards the center and the surface of the test rod, and the horizontal liquidus can promote the grain growth along the axis of the test rod. [ABSTRACT FROM AUTHOR]

Purpose: To compare the marginal vertical misfit between implant-supported frameworks fabricated using CAD/CAM systems and the conventional technique (lost-wax casting).Materials and Methods: This review was performed according to PRISMA criteria and registered on PROSPERO (CRD42017055685). An electronic search was performed independently by two examiners in the MEDLINE (Pubmed), Embase, Web of Science, and Cochrane Library databases to find studies published up to April 2018.Results: The database search yielded 507 references. After removing duplicate references, 384 studies remained. Eleven in vitro studies were selected according to the eligibility criteria (inter-reader κ = 0.88). Nine different CAD/CAM systems were used to fabricate 172 frameworks of different materials, including zirconia, monolithic lithium disilicate, and metallic alloys. Subgroup analyses were performed for different types and retention systems of the frameworks. In the general analysis, marginal misfit observed with the CAD/CAM systems was lower than with the conventional method (P = .003), as was observed in the subgroup analysis for single-unit frameworks (P < .00001). For fixed (P = .89), cemented (P = .60), and screwed (P = .18) frameworks, no significant difference was observed between the evaluated techniques.Conclusion: The CAD/CAM systems showed improved marginal fit over the conventional lost-wax casting technique for fabricating single-unit frameworks; however, in the subgroup analyses, no difference was observed for the fixed implant-supported type or for the retention systems evaluated. [ABSTRACT FROM AUTHOR]

The numerical simulation is similar to the experimental research, which uses the computer. 3D printing is an experimental study, which is compared with simulation. 3D printing and precision casting of impellers are frequently used in industrial scenarios. To address the problem of low casting yield of aluminium alloy impellers in gypsum-type casting, three-dimensional modelling by magics, casting simulation, and parameter optimization method by applying ProCAST software are used to improve the casting yield of impellers. The results show that the optimized structure of the casting system is more reasonable, so that the shrinkage and shrinkage defects are concentrated in the location of the riser; the maximum stress value of the casting and the casing during the solidification stage is 2.71 MPa, which is much smaller than the stress limit of the casing; the maximum horizontal displacement of the casting along the X and Y axes after solidification is completed at 0.025 mm and 0.022 mm, respectively, and the maximum displacement along the Z axis due to the presence of the riser is 0.009 mm, which greatly improves casting accuracy and molding quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metrics for the advancement of the circular economy were proposed; • Classification, Potentiality, Quantity/viability, and Applicability were evaluated; • Ceramic Shell Waste was used as a case study; • Ceramic filters and refractory aggregates were suggested as products. The problem of waste generation has grown because of the need to extract natural resources, obtain materials, and consume energy to meet current societal needs. Many studies have been conducted worldwide in favor of technological solutions for the valorization of industrial waste (IW) but few discussed relevant data for effective recovery. In this study, a case study of ceramic shell waste (CSW) was performed using, for the first time, a waste valorization system based on the classification, potentiality, quantity/viability, and applicability criteria (CPQvA) in a specific region (Brazil). CPQvA is a multicriteria decision-making system that acts as a guide to help managers and researchers connect the potential of IW with the feasibility of its application in a product or another process. Using the proposed systematic criteria, it was possible to demonstrate similarities and differences in waste applications. Thirteen possible products made from CSW were analyzed based on all the parameters of CPQvA. Ceramic filters and refractory aggregates were the most viable products. Creating public policies that encourage the use of waste as a raw material could make the precision casting industry process cleaner and the economy more circular. [ABSTRACT FROM AUTHOR]

'Dhokra' or 'Dokra' casting is a sophisticated cast metal craft tradition of the Indian subcontinent. It has been practiced by the countryfolk now since the Copper Age. It is a lost wax casting process in the hot clay mold. The technology is such sophisticated that it can produce up to 400 µm thin-walled hollow cast products with complicated and intricate shapes using Brass, Bronze, Copper, and other copper alloys. The investigation was for engraving Brass (2% lead) which is used by Dhokra artisans nowadays. In a field visit during dimensional analysis, one discrepancy was identified. The metal thicknesses of hollow castings are thicker than the thickness of the wax pattern. This cast metal dilation phenomenon is unusual. Shrinkage of metals compared to the pattern dimension is familiar in the casting world. The same abnormalities in the repeated investigation at different sites were observed. All the studies and experiments were organized to explain the reason hidden behind the phenomenon. [ABSTRACT FROM AUTHOR]

Nickel-based alloys are considered promising materials for primary circuits of high-temperature gas reactors (HTGRs), specifically for gas turbines. The primary helium (He) coolant in the gas-turbine-based HTGRs is expected to reach temperatures of up to 900 °C; therefore, the selected materials should adequately perform over a long service life at such an environment. A promising manufacturing method in the production of reactor components is precision casting, where the content of revert (recyclate) material in the alloy differs and can influence the material behavior. In our study, Inconel alloy 738 was manufactured by casting 50% and 100% of revert material and tested in HTGR conditions to examine the influence of helium coolant on the material's properties. Tensile specimens were exposed at 900 °C for 1000 h in helium containing a specified amount of gaseous impurities. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), in combination with X-ray diffraction (XRD) and nano-, microhardness methods, were used for material characterization after performing the tensile tests at room temperature. The presence of three types of layers was observed: a thin layer formed by aluminum and chromium oxides on the surface; non-uniform surface oxides Ti3O5 with inner (Al,Cr)2O3; and the inner fine-grained Inconel Cr-enriched phase (approx. 10–20 µm below the surface), which can act as a protective surface layer. Mechanical properties of both revert materials decreased after exposure to HTGR conditions but did not show a significant difference as a result of the content of the revert material. The increase of nano-hardness in line profiles throughout the specimen's cross-section was observed locally at the surface oxides and in the precipitates and grain boundaries. After exposure, Rp0.2 values decreased by 20% and 17.7%, and Rm values by 12.3% and 20.8% in samples with 50 and 100% revert content, respectively. Furthermore, a decrease in microhardness values (HV0.1) was detected by 4.98% in longitude and 5.80% in cross-section for samples with 50% revert material and by 3.85% in longitude and 7.86% in cross-section for samples with 100% revert material. It can be concluded that both revert materials have similar corrosion resistance in HTGR conditions. The presented results complement the knowledge about the degradation of alloys in the coolant environment of advanced gas-cooled reactors. [ABSTRACT FROM AUTHOR]

The complex structure of the ceramic cores is key to the preparation of an aero-engine hollow blade with excellent cooling performance. The traditional methods such as hot-press moulding are difficult to prepare complex-structured ceramic cores, and 3D printing technology provides a new idea for the preparation of complex-structured ceramic cores. Using SiO 2 and Y 2 O 3 as mineralizers in Al 2 O 3 -based ceramic cores, high-performance ceramic cores with a core-shell structure was successfully prepared by 3D printing. Additionally, the changes in microstructure and properties at different sintering temperatures were studied. The results showed that with an increase in the sintering temperature, a core-shell structure with Y 2 Si 2 O 7 as the shell and Y 2 O 3 as the core was formed, and the reinforced phases such as mullite were generated at the same time. The formation of core-shell particles suppressed the energy loss of cracks. The generation of the liquid phase led to the tight bonding of the Al 2 O 3 particles. The synergistic effects of the core-shell structures and the reinforced phases enhanced the flexural strength. When the sintering temperature was 1380 °C, the comprehensive performance met the application requirements of the ceramic cores, and the flexural strength and porosity were 19.3 MPa (at 1500 °C) and 30.5%, respectively. The 3D-printed ceramic core by low-temperature sintering with a core-shell structure was successfully prepared, which promoted the wider application of DLP-3D printed ceramic cores technology in the field of precision casting. This is expected to reduce the energy consumption during the sintering process and promote the production of high-performance complex-structured ceramic cores. [Display omitted] [ABSTRACT FROM AUTHOR]

Obtaining the desired characteristics of products having complex geometry from compositions comprising powdered dissimilar materials used in the formation of consumable patterns allows the scope of application of specific precision casting methods to be extended. It is established that, when forming compacts having complex configurations using a mixture of wax and water-soluble components, it is impossible to achieve the distribution of properties in the volume of the final product, which determines the change in the geometry of compacts as a result of the elastic response of compacted material. The issue associated with the elastic response of such compacted material can be solved in an experiment, establishing the influence of the initial packing and compacting parameters of wax elements on the stress-strain state of the compact. In the paper, the research results represented as experimental polynomial dependences of stress on deformation in compacted bodies with various initial packing options, deformable plastic and elastic elements, are presented. The means of controlling the dimensional and geometric parameters of the final compacts from wax model materials obtained in the process of uniaxial compaction by regulating its stress-strain state are presented. [ABSTRACT FROM AUTHOR]

Alumina-mullite ceramic shell moulds were developed to cast single-crystal hollow high-pressure turbine blades (SX-HPTB). Mullite and fine alumina powders were used as fillers. Two colloidal silica binders were used to bind the filler particles. One colloidal silica binder (binder A) had no polymer and the second colloidal silica binder (binder B) had 8 wt % polymer. Eight slurry compositions with fine alumina substitution (0, 10, 30 and 50 wt %) were prepared. Silica cores were used to achieve hollow castings. The effect of alumina substitution and binders on the slurry characteristics, flexural strength of green and fired samples, air permeability and self-load sag resistance was studied. It was observed that with an increase in alumina percentage, the test specimens showed increased viscosity, pick-up weight, density, green strength and fired residual strength. In addition, the slurries prepared from binder B possessed larger values of viscosity and pick-up weight compared to the slurries prepared from binder A. The residual strength of fired test specimens containing binder A was higher than those containing binder B. The test specimens with 30 wt % fine alumina substitution showed the highest self-load sag resistance w.r.t. each test temperature. Also, the air permeability of the fired samples was higher than the green (de-waxed) samples. The casting of hollow HPTB components was performed at two temperatures (1525 °C and 1550 °C) using nickel-based superalloy CMSX4. The HPTB components, cast at 1550 oC from ceramic shell mould having binder B and 30 wt % fine alumina substitution, resulted in an acceptable aerofoil profile and surface roughness. [ABSTRACT FROM AUTHOR]

The subject matter of the above paper presents part of the research carried out as part of the robotization of the manufacturing processes of aircraft engine components. The paper concerns robotic deburring of the V2500 diffuser's sharp edges. The diffuser is a precision casting characterized by a slight variation in the geometry of the workpiece depending on the accuracy of the casting molds and the phenomenon of shrinkage during solidification. Due to the small degree of deburring and thus low cutting forces, robotic machining with the FDB150 tool was used. This tool is characterized by compliance with adjustable force, which enables machining of workpieces with a randomly changing shape. The authors of the paper propose a procedure for carrying out work allowing for the selection of suboptimal process parameters. In the analyzed case, these parameters are the speed of movement of the characteristic point of the tool (TCP) and the tool/workpiece contact force. The proposed procedure for determining the parameters of the force and speed of movement allowed for indicating a set of parameters ensuring the performance of the product in accordance with the requirements defined in the documentation. The proposed solution is of an engineering nature and is not a classic search for the extreme of a function from the point of view of the adopted criteria (quality indicators). Its advantage is simplicity, which is very important from the point of view of an industrial application. [ABSTRACT FROM AUTHOR]

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Using 3D printing technology to prepare ceramic shell used for precision investment casting can realize short process and efficient preparation of the ceramic shell, which has a great application potential in the casting field. However, the 3D printed ceramic shells often have the problems of low strength and accuracy. In this paper, a silica sol room temperature dip coating treatment combined with high temperature sintering method was proposed to improve the strength and surface precision of the ceramic shell prepared by the binder jetting. The effects of silica sol concentration and dip coating time on performance and surface precision of the alumina ceramic shell were studied. The mechanical properties and surface precision of the alumina ceramic shell prepared by the binder jetting were improved significantly with the increases of the sol concentration and dip coating time. With the dip coating time of 90 s and sol concentration of 30%, the maximum bending strength of the alumina ceramic reached 44.8 MPa, which was 18.9 times higher than that of the untreated alumina ceramic. The top surface roughness and side roughness of the alumina ceramic decreased from 6.87 μm to 5.70 μm and 7.55 μm–6.46 μm, respectively, compared to those of the untreated alumina ceramic. [ABSTRACT FROM AUTHOR]

In the manufacture of aeronautical parts by precision casting in ceramic molds, the key parameters are the uniformity of the composition and strength of ceramic molds associated with their manufacturing technology. The technologically optimal strength of ceramics can be achieved by re-impregnation of a ceramic part with a binder, but this raises issues with the isotropy of the mechanical properties of the parts. This article reports the results of R&D on the use of a secondary binder to regulate the uniformity of impregnation of ceramic samples. [ABSTRACT FROM AUTHOR]

Over the last decades, additive manufacturing (AM) has become the principal production technology for prototypes and components with high added value. In the production of metallic parts, AM allows producing complex geometry with a single process. Also, AM admits a joining of elements that could not be realized with traditional methods. In addition, AM allows the manufacturing of components that could not be realized using other types of processes like reticular structures in heat exchangers. A solid mold investment casting that uses printed patterns overcomes typical limitations of additive processes such as expensive machinery and challenging process parameter settings. Indeed, rapid investment casting provides for a foundry epoxy pattern reproducing the component to exploit in the lost wax casting process. In this paper, aluminium radiators with flat heat pipes seamlessly connected with a cellular structure were conceived and produced. This paper aims at defining and investigating the principal foundry parameters to achieve a defect-free heat exchanger. For this purpose, different device CAD models were designed, considering four pipes' thickness and length. Finite element method numerical simulations were performed to optimize the design of the casting process. Three different gate configurations were investigated for each length. The numerical investigations led to the definition of a castability range depending on flat heat pipes geometry and casting parameters. The optimal gate configuration was applied in the realization of AM patterns and casting processes [ABSTRACT FROM AUTHOR]