Ceramic Shell Research Articles

Investigation on Role and Impact of 3D Printing Technology in Sand Casting

3D printing has been recognized to be such a game-changer in manufacturing that it has now permeated virtually every aspect of the industry, including mould and die casting. A thorough examination of 3D printing's past, present and future in the business is provided here. Casting procedures may be enhanced or drastically altered by 3D printing. The design of goods, assemblies, and parts will be transformed by 3D printing, which is more than just a manufacturing technology. With the aid of 3D printing, sand casting is a technique that can make complex components out of almost any metal alloy at a reasonable cost. Using this integration, producers may build massive components in the least amount of time. It has also established a distinctive place in other casting elements; Examples include the ceramic shell, sand mould sand core, and wax pattern, we'll learn more about sand casting and 3D printing this week.

Crafting the voice of God: ceramic waylla kepa shell horn technology in the Andes

This paper addresses the enchainment of skills and interactions for the production of ceramic shell horns, and the meaning of these musical instruments whose sounds have shaped the ritual soundscapes of the central Andes since the boom in public architecture in the second millennium BC (early Formative Period c. 3800–3300 BP). Linguistic and ethnohistoric reviews shed light on performance practices and meanings at the time of conquest. Contextual analysis of thin sections of ceramic shell horns excavated in Keushu (Yungay, Ancash, Peru) and dated to the Early Intermediate Period and early Middle Horizon (c. 2200–1600 BP) suggests the agency of specialist itinerant potters. Crafting processes are reconstructed by bringing together material analysis (petrography, X-ray tomography, X-ray diffraction), bioarchaeology, studies of instrument organology, and ceramic ethnoarchaeology. Informed by experimental reconstruction distinct modeling techniques are distinguished and crossed with available provenience data to suggest three independently arising traditions or hotspots in northern Ecuador, on the central Andean coast, and in the highlands of northern Peru. The ritual sounds and soundscapes of the latter area are discussed. Like earlier conch horns, ceramic shell horns played a pivotal part in ritual performances that accompanied the development of irrigation-dependent agrarian and pastoral lifeways in the Andes. Enduring symbolic linkages between shell horn sounds, the sea and irrigation water may indeed represent a powerful embodiment of the voice of God.

Development of removal modes of 3D-printed polymer patterns from ceramic molds

The use of additive technologies, particularly 3D printing, to make patterns instead of traditional wax patterns is promising for casting into ceramic molds. However, when using polymer patterns, there is a problem of cracking ceramic shells during their firing. The goal of the work was to develop optimal thermo-kinetic modes of removal of disposable plastic patterns from ceramic molds, which will prevent the formation of cracks in ceramics. During the study, samples of patterns made by 3D printing from various plastics were selected and examined. Laboratory tests were carried out on a batch of ceramic shells made of electrocorundum. The methods of removing plastic patterns from ceramic molds by means of two-stage firing in thermal furnaces were investigated. The low-temperature stage of firing consisted in gradually heating the ceramics up to 350 °C. During it, the material of the patterns was compacted, softened, melted, and partially gasified. This reduced uncontrolled gas pressure and stress in the ceramic and prevented the formation of cracks in it. The high-temperature firing phase (1000—1100 °С) was performed for sintering ceramics and removing the remains of plastic materials. The influence of different plastic materials on the quality of the casting mold was investigated. It is proposed to use PLA plastic for the 3D printing of patterns, as it meets the requirements of environmental friendliness and cost. The possibility of improving the surface quality of ceramic shells by coating them with a thin layer of wax-like material is also considered. According to the results of research on the surface of ceramic forms, it is proposed to add structural elements to plastic patterns that reduce deformations of ceramic forms during firing. The developed firing modes of the patterns are used in the production of ceramic molds for endoprostheses.

Design, Modeling and Fabrication of a Novel Class V Flextensional Transducer: The Sea-Shell.

In this study, a novel class V flextensional transducer (FT) was developed by assembling symmetrically convex ceramic and metal caps to form a seashell-like structure. The transducer was designed and analyzed using ATILA finite element analysis (FEA) software. The diameter, thickness, and radius of curvature of the ceramic and metal shells have been investigated as design parameters. The transducer was found to display four distinct flextensional modes in addition to the main radial resonance mode between 1 and 200 kHz frequency range. Prototypical devices were fabricated from four different commercial lead zirconate titanate (PZT) compositions and underwater performances were compared. Transmitting voltage responses (TVRs) were observed to range between 120 and 135 dB (ref 1 μ Pa/V) at frequencies above 50 kHz.

A Fully Implantable and Programmable Epidural Spinal Cord Stimulation System for Rats with Spinal Cord Injury.

Epidural spinal cord stimulation (ESCS) is a potential treatment for the recovery of the motor function in spinal cord injury (SCI) patients. Since the mechanism of ESCS remains unclear, it is necessary to study the neurophysiological principles in animal experiments and standardize the clinical treatment. In this paper, an ESCS system is proposed for animal experimental study. The proposed system provides a fully implantable and programmable stimulating system for complete SCI rat model, along with a wireless charging power solution. The system is composed of an implantable pulse generator (IPG), a stimulating electrode, an external charging module and an Android application (APP) via a smartphone. The IPG has an area of 25×25 mm2 and can output 8 channels of stimulating currents. Stimulating parameters, including amplitude, frequency, pulse width and sequence, can be programmed through the APP. The IPG was encapsulated with a zirconia ceramic shell and two-month implantable experiments were carried out in 5 rats with SCI. The main focus of the animal experiment was to show that the ESCS system could work stably in SCI rats. The IPG implanted in vivo can be charged through the external charging module in vitro without anesthetizing the rats. The stimulating electrode was implanted according to the distribution of ESCS motor function regions of rats and fixed on the vertebrae. The lower limb muscles of SCI rats can be activated effectively. The two-month SCI rats needed greater stimulating current intensity than the one-month SCI rats The results indicated that the stimulating system provides an effective and simplified tool for studying the ESCS application in motor function recovery for untethered animals.

On comparison of crack resistance of ceramic shell moulds during solidification and cooling in them of cylindrical and spherical steel castings

The results of a theoretical study of the patterns in change in the stress state of a ceramic shell investment mould according in the process of solidification and cooling of steel castings of a "cylinder" and "ball" types in it are presented.

Ceramic shell waste valorization: A new approach to increase the sustainability of the precision casting industry from a circular economy perspective

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.

Characterization and mechanism analysis of interaction between Inconel 713C superalloy and a novel crucible-shell “integrated” mold

A novel crucible-shell “integrated” mold for rapid preparation of supercharged turbines was quantitatively characterized, and the interaction mechanism between refractory and melt was systematically analyzed. The results show that Inconel 713C superalloy is not easy to react with aluminum silicate fiber crucible, and the interaction between them is physical penetration. At the same time, the slag balls in the crucible are easy to peel off into the alloy and form inclusions. The reaction between Inconel 713C superalloy and shell surface material (ZrSiO4) can be divided into Penetration, Stalling/dissolution, Reaction and Diffusion stages. The interface reaction layer is composed of Nb2O5, Al2O3, ZrO2, Cr2O3 and TiO2. The oxide elements produced by the reaction come from the alloy and ceramic shell. Compared with the traditional preparation of turbocharger turbine under discontinuous vacuum, the use of “integrated” mold to prepare turbine under continuous vacuum environment reduces the oxygen, nitrogen and hydrogen content of castings, and the purity of Inconel 713C superalloy is higher and the preparation time is faster, which is conducive to industrial production, which can shed new lights on choosing alternative refractory material for the rapid preparation of high-purity superalloys.

Manufacture of thin-walled steel castings via consumable additive patterns

The problems of thin-walled steel casting are usually connected with insufficient level of alloy fluidity in the field of operating casting temperatures, as well as with appearing counter-pressure for the alloy which fills the narrow mould sections. These sections correspond to thin walls of the future casting, depending on restricted gas permeability of a mould. To solve these problems, the methods of precise casting via thermodeleting patterns, as well as the methods of external effect on metallic melt which fills the mould. This work analyzes the accumulated experience of casting via lost and consumable patterns, the features of their practical realization in the conditions of a casting mould vacuum treatment; their disadvantages are shown as well. The authors formulated the task to eliminate the revealed disadvantages, to provide stability of the technological process and high quality of manufactured castings (in particular for surface defects, non-metallic inclusions, violations of geometrical shape and dimension accuracy) together with lowering of labour intensity and energy intensity of casting in comparison with Replicast–CS-process as a prototype. The innovative technology of casting via consumable patterns was suggested and successfully tested in the conditions of operating production facilities. This technology differs from the prototype in such way, that the patterns are fabricated via additive technologies providing obtaining of internal cellular adjustable structure from the material which is burnt at the temperature not more than the lower temperature threshold of polymorphic transformations of a filling agent of refractory suspension. This refractory suspension is applied on the pattern block with 1-2 layers, sintering of ceramic shell and burning of a pattern block are carried out after placing the pattern block in a moulding box and its filling by fluid self-hardening mixture. Then mould filling by metallic melt is conducted after solidification and restoration of the required gas permeability of fluid self-hardening mixture, while vacuum treatment of the mould is stopped after reaching the solidus temperature by metal. The authors believe that the suggested technology can be used for manufacture of castings of special duty from low-carbon steels and other alloys, which are sensitive to destruction of consumable patterns manufactured via additive technologies (additive patterns).The research was carried out at the expenses of subvention within the framework of Kazan(Privolzhskiy) Federal University in order to rise its competitiveness among the leading global scientific and education centers.

Mortars with the incorporation of treated ceramic molds shells wastes

About 48 billion tons of aggregates are consumed in the construction, causing a depletion of natural resources. Thus, it is important to apply new solutions that suppress these needs, without environmental impacts and preferably reversing negative impacts associated to other industries, such as foundry industry, a large waste producer commonly deposited in landfills. The main objective of this work was the evaluation of the waste treatment methods effectiveness in the physical and mechanical mortar properties. Fourteen compositions were developed with different contents of ceramic mold shells (0%, 25%, 50%, 75% and 100%) and different types of treatment (series 1 – unwashed ceramic mold shells, series 2 – washed ceramic molds shells and series 3 – washed ceramic mold shells and fibers). The results showed that the treatment of washing residues was quite effective, resulting in an elimination of the expandability and water absorption of the mortars, which led to an increase in the flexural and compression strength, since the microstructure of the mortars was no longer fragile.

Effect of waste oyster shell powder on the properties of alkali-activated slag–waste ceramic geopolymers

The ceramic and oyster farming industries produce large amounts of waste ceramics and oyster shells. Meanwhile, alkali-activated materials are less environmentally impacted materials with the potential to replace Portland cement. Adding ceramic powder (CP) and waste oyster shell powder (WOS) to alkali-activated materials can relieve the pressure on landfills and protect the environment, thereby having important implications. This study aims to add WOS to alkali-activated adhesives and investigate their effects on the properties of the samples. The blast furnace slag and ceramic powder were partially replaced by 0–20 wt% WOS. The specimens for control, 10% WOS, and 20% WOS are named as WOS-0, WOS-10, and WOS-20, respectively. Experimental studies on the compressive strength testing, heat of hydration, ultrasonic pulse velocity (UPV), thermogravimetric (TG) analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and electrical resistance rate were performed. The experimental results are as follows: (1) An increase in the WOS substitution rate increased the hydration heat release rate and decreased the compressive strength. At 3 days of age, the compressive strength of the WOS-20 sample decreased by 4.3 MPa compared with the WOS-0 sample. (2) UPV and resistivity decreased with increasing WOS substitution. At 3 days of age, the UPV of the WOS-20 sample decreased by 0.11 km/s compared with the WOS-0 sample. (3) The TG results showed that WOS participated in the alkali-activated reaction. For the WOS-20 sample, the amount of calcium carbonate decreased by 2.9% as the age increased from 3 days to 28 days. (4) XRD and FT-IR spectra showed the intensified carbonate peak with the increase in the WOS content. These findings suggest that CP and WOS can be used as complementary gelling agents for alkali-activated materials.

3D-printing of ceramic filaments with ductile metallic cores

The additive manufacturing of composite structures can open possibilities in the design and fabrication of devices but also demands new approaches. In this work, we use thermally reversible pastes to fabricate ceramic matrix (Al2O3) composites reinforced with continuous metallic fibres (steel). The approach is based on the micro-extrusion of ceramic–metal filaments with core–shell and layered arrangements. These filaments are employed in the additive manufacturing of dense and light-weight cellular structures that combine the stiffness and strength of the ceramic shell with the fracture resistance and energy absorption capabilities provided by the metal core. The approach can be used to extrude filaments with thin porous interlayers separating the core and the shells to create a weak fibre/matrix interphase. The cellular structures fabricated with these filaments exhibit higher compressive strengths and energy absorption capabilities than those fabricated from pure ceramics. The works of fracture of the dense composites are one to two orders of magnitude above those of the ceramic matrix (103 J/m2) while the bending strengths remain comparable to those of 3D printed alumina (200–350 MPa). The technique could be easily extended to other material combinations opening new opportunities in the additive manufacturing of multi-material parts and devices.

Energy-efficient ceramics

How using ceramic containment shells in magnetic drive pumps could improve energy efficiency and save costs.

Algicidal granules from ceramized rocks. Part 1. Development of criteria for the selection of rocks

Until recently, there was no production of ceramized roofing granules as a product in the Russian Federation. The basis for obtaining such granules is the formation of a protective and decorative shell on a mineral carrier (rock). Such granules should have chemical elements in their shell that prevent biofouling and destruction of the protective layer. The criteria for the selection of rocks in Russia with a certain mineral form of iron fixation are established. A scale of thermogravimetric activity of the rock has been developed. The production technology involves the application of two layers, of which the inner layer contains a biocide in the form of copper-zinc brass. The ceramic shell is formed from a solution of kaolin, pigments and sodium liquid glass. As a result of firing, the ceramized granules are covered with a colored insoluble shell. The solubility of the shell of granules is determined by their surface alkalinity. Ill. 2. Ref. 20.

A Novel Packaged Ultra-High Q Silicon MEMS Butterfly Vibratory Gyroscope.

A novel three-dimensional (3D) wafer-level sandwich packaging technology is here applied in the dual mass MEMS butterfly vibratory gyroscope (BFVG) to achieve ultra-high Q factor. A GIS (glass in silicon) composite substrate with glass as the main body and low-resistance silicon column as the vertical lead is processed by glass reflow technology, which effectively avoids air leakage caused by thermal stress mismatch. Sputter getter material is used on the glass cap to further improve the vacuum degree. The Silicon-On-Insulator (SOI) gyroscope structure is sandwiched between the composite substrate and glass cap to realize vertical electrical interconnection by high-vacuum anodic bonding. The Q factors of drive and sense modes in BFVG measured by the self-developed double closed-loop circuit system are significantly improved to 8.628 times and 2.779 times higher than those of the traditional ceramic shell package. The experimental results of the processed gyroscope also demonstrate a high resolution of 0.1°/s, the scale factor of 1.302 mV/(°/s), and nonlinearity of 558 ppm in the full-scale range of ±1800°/s. By calculating the Allen variance, we obtained the angular random walk (ARW) of 1.281°/√h and low bias instability (BI) of 9.789°/h. The process error makes the actual drive and sense frequency of the gyroscope deviate by 8.989% and 5.367% compared with the simulation.

Fabrication and characterization of Sn@Viod@Ceramic phase change macrocapsules for medium-temperature thermal storage

Metallic phase change material (PCM) has great application prospects in the field of medium-temperature thermal storage. Macro-encapsulated PCMs with larger core-shell volume ratio and higher heat storage density can solve the millimeter level packaging problem of metallic PCM. However, it is easy to break for the macrocapsules after thermal cycling due to the large volume expansion during phase change. To solve this problem, a novel metal phase change macrocapsule with a thermal expansion void is prepared successfully with Sn powders as PCM core and ceramic powders (Al2O3, AlN, Kaolin or SiC, respectively) as shell raw materials. The voids are introduced by the packing spaces of raw Sn powders as core balls. The results show that the void can accommodate volume expansion of the metal PCM during heat storage and the four kinds of ceramic shells show high corrosion resistance and high compatibility. Thermal analysis indicates that the melting temperature of core (Sn PCM) after 50 cycles is 232.2 °C and the latent heats are 58.0 J/g and 58.3 J/g for melting and crystallization, respectively. Thermal tests confirm that the macrocapsules have excellent oxidation resistance, thermal stability and cycle durability in the practical working temperature range (about 100–300 °C).

Large Scale Vat-Photopolymerization of Investment Casting Master Patterns: The Total Solution.

The material properties and processing of investment casting patterns manufactured using conventional wax injection Molding and those manufactured by vat photopolymerization can be substantially different in terms of thermal expansion and mechanical properties, which can generate problems with dimensional accuracy and stability before and during ceramic shelling and shell failures during the burn-out of the 3D printed casting patterns. In this paper and for the first time, the monofunctional Acryloyl morpholine monomer was used for 3D printing of casting patterns, due to its thermoplastic-like behavior, e.g., softening by heat. However, the hydrophilic behavior of this polymer led to an incorporation of up to 60 wt% of Hexanediol diacrylate, to control the water absorption of the network, which to some extent, compromised the softening feature of Acryloyl morpholine. Addition of a powdered wax filler resulted in a delayed thermal decomposition of the polymer network, however, it helped to reduce the thermal expansion of the parts. The dimensional accuracy and stability of the wax-filled formulation indicated an excellent dimensional tolerance of less than ±130 µm. Finally, the 3D printed patterns successfully went through a burn out process with no damages to the ceramic shell.

Effect of silica sol on performance and surface precision of alumina ceramic shell prepared by binder jetting

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.

Preparation and analysis of a hybrid ceramic shell for investment casting

Preparation and analysis of a hybrid ceramic shell for investment casting

Optimized Preparation of a Low-Working-Temperature Gallium Metal-Based Microencapsulated Phase Change Material

Gallium has been considered for application in the thermal management of electronic equipment because of its high heat transfer ability and heat storage density. To address the issues of metal corrosion and leakage, a microencapsulation method, through which a stable corrosion-resistant ceramic shell can be formed from the liquid metal, is proposed. In this study, an optimized fabrication method for a microencapsulated phase change material (MEPCM) consisting of liquid-state Ga droplets, possessing high durability and heat storage density, is presented. A fabrication route comprising particle formation, hydrothermal treatment, and calcination is proposed. In particular, the thickness and crystal size of the GaOOH shell are controlled by changing the pH during hydrothermal treatment to produce a highly durable shell. The morphology and microstructure, phase composition, heat storage capacity, and durability of the prepared Ga-MEPCM are investigated. In addition, treatment conditions and the shell formation mechanism are analyzed. The results show that pH 9 is the most suitable shell-forming condition, at which the thickest Ga2O3 shell with the smallest crystal size can be produced, which is beneficial for ensuring durability. The MEPCM achieved 200 cycles without leakage and 300 cycles without shape deformation with a high heat storage density of 369.4 J·cm–3.