Processing Of Ceramic Materials Research Articles

Investigations on the processing of ceramic materials using Fused Filament Fabrication

This paper represents the current status of the investigation into the processing of ceramic components, using Fused Filament Fabrication (“FFF”). The process chain, beginning from the additive manufacturing (“AM”), through the post processing, the debinding and sintering procedure, to the finished part is described. The examined materials are silicon nitride (Si3N4) and silicon carbide (SSiC), prepared by the company SiCeram/Qsil. Furthermore, comprehensive investigations on the materials are done, both in the green and in the sintered state. In addition, sources of occurring problems and defects in the process chain are pointed out and possible solutions are shown. Finally, the current status of investigations, regarding to the transfer into the industry, is discussed.

A bioinspired surface tension-driven route toward programmed cellular ceramics

The intriguing biomineralization process in nature endows the mineralized biological materials with intricate microarchitected structures in a facile and orderly way, which provides an inspiration for processing ceramics. Here, we propose a simple and efficient manufacturing process to fabricate cellular ceramics in programmed cell-based 3D configurations, inspired by the biomineralization process of the diatom frustule. Our approach separates the ingredient synthesis from architecture building, enabling the programmable manufacturing of cellular ceramics with various cell sizes, geometries, densities, metastructures, and constituent elements. Our approach exploits surface tension to capture precursor solutions in the architected cellular lattices, allowing us to control the liquid geometry and manufacture cellular ceramics with high precision. We investigate the geometry parameters for the architected lattices assembled by unit cells and unit columns, both theoretically and experimentally, to guide the 3D fluid interface creation in arranged configurations. We manufacture a series of globally cellular and locally compact piezoceramics, obtaining an enhanced piezoelectric constant and a designed piezoelectric anisotropy. This bioinspired, surface tension-assisted approach has the potential to revolutionize the design and processing of multifarious ceramic materials for structural and functional applications in energy, electronics and biomedicine.

Perspectives Toward Damage-Tolerant Nanostructure Ceramics.

Advanced ceramic materials and devices call for better reliability and damage tolerance. In addition to their strong bonding nature, there are examples demonstrating superior mechanical properties of nanostructure ceramics, such as damage-tolerant ceramic aerogels that can withstand high deformation without cracking and local plasticity in dense nanocrystalline ceramics. The recent progresses shall be reviewed in this perspective article. Three topics including highly elastic nano-fibrous ceramic aerogels, load-bearing nanoceramics with improved mechanical properties, and implementing machine learning-assisted simulations toolbox in understanding the relationship among structure, deformation mechanisms, and microstructure-properties shall be discussed. It is hoped that the perspectives present here can help the discovery, synthesis, and processing of future structural ceramic materials that are insensitive to processing flaws and local damages in service.

Parallel Grooved Microstructure Manufacturing on the Surface of Si3N4 Ceramics by Femtosecond Laser.

Machining special microstructures on the surface of silicon nitride ceramics helps improve their service performance. However, the high brittleness and low fracture toughness of silicon nitride ceramics make it extremely difficult to machine microstructures on their surface. In this study, a femtosecond laser is used to machine parallel grooved microstructures on the surface of silicon nitride ceramics. The effects of the laser polarization angle, laser single pulse energy, scanning line spacing, and laser scan numbers on the surface morphology and geometric characteristics of grooved microstructures are researched. It is found that a greater angle between the direction of the scanning path and laser polarization is helpful to obtain a smoother surface. As the single pulse energy increases, debris and irregular surface structures will emerge. Increasing the laser scan line spacing leads to clearer and more defined parallel grooved microstructures. The groove depth increases with the increase in the scan numbers. However, when a certain number of scans is reached, the depth will not increase further. This study serves as a valuable research foundation for the femtosecond laser processing of silicon nitride ceramic materials.

Complex shapes of lithium disilicate glass-ceramics developed by material extrusion

The fabrication of high-end ceramics by additive manufacturing gained increasing research interest due to the capacity of these techniques to break through the limitations of traditional extractive manufacturing. Although efficient strategies for the processing of ceramic materials by additive manufacturing have been shown, with notable examples in the dental field, the processing of dense glass-ceramics by the same means is almost unexplored. Herein, a processing strategy for the manufacture of complex shapes of lithium disilicate glass-ceramics by material extrusion is detailed shown for the first time. An aging behaviour was observed on the glass loaded aqueous suspensions and in-deep studied, being related with the leaching of Li+ ions. Based on this, a hydrogel-based ink with high solid content (ϕ≈ 50 vol%), suitable rheological properties (G´≈106 and τ ≈ 1500 Pa) and recovery time was developed. By using the optimized ink, a propeller component with high aspect ratio and small internal connected channels, as well as a dental crown were successfully printed. A debinding schedule was tuned by the combination of differential thermal analysis and hot stage microscopy. The sintered lithium disilicate glass-ceramic parts presented good relative density (≈ 96.7 ± 0.8%) and translucency. Outstanding mechanical properties were achieved (Hv ≈5.3 GPa, KIf ≈2.1 MPa.m0.5, σ ≈ 279 ± 44 MPa), comparable to values usually attained for these materials by powder technology. The low deviation of the flexural strength data reported here is related with the absence of meaningful processing defects on the analysed fracture surfaces and the homogeneous distribution of the residual porosity as microporous, resulting in a good Weibull characteristic strength σ0 = 301 MPa. The results of the present work emphasized the potential of Direct ink Writing, a material extrusion technique, to fabricate lithium disilicate glass-ceramic parts with complex geometries, as dental crowns.

Towards Lunar In-Situ Resource Utilization Based Subtractive Manufacturing

In recent years, space agencies, such as the National Aeronautics and Space Administration (NASA) and European Space Agency (ESA), have expanded their research activities in the field of manufacturing in space. These measures serve to reduce limitations and costs through fairing size, launch mass capabilities or logistic missions. The objective, in turn, is to develop technologies and processes that enable on-demand manufacturing for long-term space missions and on other celestial bodies. Within these research activities, in-situ resource utilization (ISRU) and recycling are major topics to exploit local resources and save transport capacity and, therefore, costs. On the other hand, it is important to carefully consider which items can be brought and which must be manufactured on the Moon. Consequently, on-demand needs in future space missions are considered regarding frequency, raw material and required manufacturing processes according to investigations by ESA and NASA. In conclusion, manufacturing in space state-of-the-art shows a strong focus on additive processes, primarily considering semicrystalline or amorphous plastics. The subtractive processing of metallic or ceramic materials, in turn, currently represents a research gap. Consequently, an approach for in-situ resource utilization-based subtractive manufacturing in space is presented to supplement the existing processes. The latter uses a high-pressure jet of water, with regolith simulate as abrasive in suspension, being directed at the workpiece, which is moved to separate metal and glass. Proof-of-concept results are presented, including suitable process windows, achieved cutting geometries, as well as the effects of parameter variations on the system technology and consumables used. The focus of the investigations supplements the general requirements for the design of machine tools for space applications with inertial process-specific boundary conditions as a step towards higher technology maturity.

Influence of laser-processed surfaces on heat transfer performance of microflow channels

Microchannel heat dissipation systems are widely used in micro-electro mechanical systems owing to their high thermal conductivity and small size. Laser processing has the advantages of high efficiency and no tool contact, and is one of the best ways to process ceramic materials. However, the roughness of the machined surface will significantly affect the heat dissipation performance of the microchannel. In order to study the influence of roughness element characteristics on the heat dissipation efficiency of the micro-channel radiator, the surface roughness was simulated with typical shape, and the influence of different roughness element shape, height and spacing on the pressure field, velocity field and temperature field of the micro-channel radiator was analysed. The results indicate that the semi-circular roughness element has the highest heat transfer efficiency and that the overall flow is stable. With an increase in the height of the roughness element and a reduction in the spacing, the heat transfer efficiency and inlet/outlet pressure drop increased. When the height of the roughness element is 17.2 μm, the heat transfer ability was significantly improved and the pressure drop ratio is reduced by >20% compared with that for a height of 19.5 μm. When the distance between roughness elements is 33.5 μm, the maximum temperature of the heat dissipation system was only 331.85 K. Compared with other models, the temperature of the optimized model is reduced by 14.44K, and the heat transfer efficiency is the highest. The results of heat dissipation experiments show that compared with dry burning temperature, the optimized model can reduce the temperature of the micro-channel heat dissipation system by more than 73 K.

The Effect of Air Relative Humidity on the Drying Process of Sanitary Ware at Low Temperature: An Experimental Study

Drying is a thermodynamic process in which the moisture contained in the solid is removed by evaporation through the supply of an appreciable amount of thermal energy. It is recognized as a critical and intricate stage in the manufacturing process of ceramic materials. In general, drying at higher temperatures and lower air-relative humidity provokes severe hydric, thermal, and mechanical fractures in the ceramic parts, thus reducing product quality after the process. Then, this process must be realized under controlled conditions. From an industrial point of view, the drying process of sanitary ware takes place in two stages: drying at low temperatures (less than 40 °C) and drying at high temperatures (above 50 °C). Thus, the purpose of this work is to experimentally investigate the drying process at low temperatures in sanitary toilets. Drying experiments were conducted in an oven with the same temperature (35 °C) and different relative humidity of the drying air. The results of the moisture content, temperature, and dimension variations along the process, as well as drying and heating rates, are reported and analyzed. The results indicate that the higher the air’s relative humidity, the slower the moisture removal. Herein, aspects of the product quality after the drying process are also discussed.

Alumina-based ceramic cores prepared by vat photopolymerization and buried combustion method

Alumina (Al2O3)-based ceramic cores are extensively employed to form cavities within complex or difficult-to-form casting parts. As a conventional manufacturing process, investment casting requires molds and is labor-intensive. Therefore, it is crucial to develop a direct method for preparing Al2O3-based ceramic cores at a low cost. As an AM process, vat photopolymerization (VPP) can produce high-quality parts with smooth surface finish and fine details. Therefore, extensive attentions have been attracted to processing ceramic materials by VPP. Despite these benefits, the layer-by-layer accumulation strategy of VPP inevitably induces low bonding strength between adjacent layers, and induces cracks in the sintered parts. To mitigate these problems, burying VPP-printed Al2O3 green bodies into silica has been proposed in this investigation. Results show that cracks and deformation problems have been reduced when the buried combustion method is adopted. To create Al2O3-based ceramic cores with desired porosity and flexural strength properties, process parameters have been optimized. A systematic study on how the inclusion of SiO2 particles and variations in sintering temperature impact the microstructure and mechanical properties of Al2O3-based ceramic cores fabricated through VPP printing is presented. Based on experimental results, a 1300 ℃ sintering temperature is selected to produce appropriate shrinkages (4%∼8%), open porosity of over 20%, and flexural strength ranging from 20 to 50 MPa of ceramic cores.

STUDYING THE POSSIBILITIES OF USING IRON ORE WASTE İN THE PRODUCTION OF CERAMIC PRODUCTS

Decorative ceramic brick for interior decoration is one of the most modern trends in architecture and construction. This type of masonry, facing wall materials, which became popular in the middle of the last century, is becoming more and more widespread over time. In order to expand the disposal of industrial waste, the issues of using iron ore recycling products together with other industrial waste in the technology of wall ceramic materials were considered. The functional purpose of the studied iron-containing waste in ceramic technology is based on the well-known role of iron oxides, which ensure the progress of the sintering process of ceramic materials with the presence of a liquid phase at a significantly lower combustion temperature. 10 mln. in the process of enriching the iron ore extracted from the Dashkasan iron ore deposit located in the territory of the Republic of Azerbaijan. more than a ton of waste was collected. This waste contains up to 12-20% iron, it also contains cobalt, copper and zinc metals. It is clear that producing products from man-made deposits is much cheaper than natural deposits. For this purpose, it is possible to obtain a quality product by using man-made waste using existing technologies and saving natural raw materials. Both blast furnace and agglomeration wastes generated in the mine are considered complex raw materials for obtaining iron, cobalt, copper and zinc from them, although they are useful for high-grade concrete, construction and repair of highways. Therefore, the recycled waste obtained after removing the iron and non-ferrous metals contained in them can be used to buy building bricks, silicate bricks and other ceramic products, but for the final solution of this issue, it is necessary to conduct more precise technological and semi-industrial tests. Keywords: beneficiation "waste", iron ore, sintering, decorative wall brick, magnetic separation waste, strength

Investigating the Drying Process of Ceramic Sanitary Ware at Low Temperature

Drying is one of the stages with the highest energy consumption in the manufacturing process of ceramic materials and aims to reduce the product’s moisture to levels necessary for safe firing stage, reducing the chances of defect formation. For sanitary ware, there is an additional energy cost in the pre-drying stage, which takes place immediately after removing the parts from the molds, and is carried out in an environment with lower temperatures (ranging from 30 to 40 °C). This work aims to experimentally study the drying process of sanitary ware at low temperatures, with particular reference to sanitary toilets with industrial dimensions. Four drying experiments were carried out in an oven with different operating conditions (temperature and relative humidity). The results indicate that an increase in temperature and reduction in relative humidity provoke a faster drying rate. For some physical situations, it is more interesting to dedicate efforts to reducing the relative humidity of the drying air instead of seeking solutions to raise its temperature. Furthermore, a correlation between the linear retraction and moisture content was observed; the greater the moisture loss, the greater the sample shrinkage.

A study of the intersectionality and contemporary translation of lacquer pottery art

Material is the basis of creation, it is the means and the end. With the progress of technology, the times have given materials a new artistic language, and the comprehensive use of multiple materials is presented in the art world, each with a unique texture and touch, giving people a different association of thoughts and feelings. Through an in-depth analysis of the historical and traditional background of the two materials, the tension of material expression, and the interplay between the two processes of lacquer and ceramic materials, the possibilities of interpretation from traditional lacquer and ceramics, based on an understanding of tradition, the combination of traditional lacquer and ceramics is experienced from the perspective of contemporary cultural confidence, and is important to reflect the value of contemporary transcreation.

Data Analysis of Ceramic Material Color Matching Collection Points in Furniture Design Based on the Image Difference Prediction Model

The manufacturing process of ceramic materials and exquisite patterns is not simply artistic acts. At the same time, it condensed the excellent traditional culture of ancient China. The application of ceramic materials in modern furniture can not only enhance the taste of living room culture but also show the charm of China’s ceramic culture. Objective. To optimize the scientific data model required by traditional ceramic materials. On the basis of image difference prediction calculation, the data of ceramic material color matching collection points were analyzed and processed, and the image difference prediction model was established. This paper introduces the application and development of ceramic materials in furniture industry. On the basis of the traditional image difference prediction algorithm, the consideration of image difference and difference prediction expansion is added, and the image difference prediction calculation model of ceramic material color matching is established. The survey results show that 83% of customers are very satisfied with the color matching of new ceramic materials calculated by image difference prediction. This experiment uses image difference prediction model to remove the redundant pixels of ceramic material color and make multiple judgments on color display. According to the initial color data of the collection points, this experiment finally obtained a new combination color matching of ceramic wardrobe, which is more suitable for the “minimalist” and “quiet” styles.

Process Development of Zirconolite Ceramics for Pu Disposition: Use of a CuO Sintering Aid

Zirconolite-structured ceramics are candidate wasteform materials for the immobilisation of separated Pu. Due to the refractory properties of zirconolite and other titanates, removing residual porosity remains challenging in the final wasteform product when utilising a conventional solid state sintering route. Herein, we demonstrate that the addition of CuO as a sintering aid increases densification and promotes grain growth. Moreover, zirconolite phase formation was enhanced at lower process temperatures than typically required (≥1350 °C). CuO addition allowed an equivalent density to be reached using process temperatures of 250 °C lower than the undoped composition. At 150 °C lower than the undoped zirconolite, the addition of CuO resulted in a favourable microstructure and phase assemblage, as confirmed via X-ray diffraction and scanning electron microscopy. Secondary phases of CaTiO3 and Ca0.25Cu0.75TiO3 were observed at some processing temperatures, which may prove deleterious to wasteform performance. The use of a CuO sintering aid provides an avenue for the further development of the thermal processing of ceramic wasteform materials.

Study of the structure and mechanical properties of composites used in the oil and gas industry

<abstract> <p>This article describes the structure and properties of the developed hybrid composite Hastelloy X (NiCrFeMo)-AlMoNbTaTiZr-cBNSiCNiAlCo. The composite was obtained by the high velocity oxygen fuel spraying (HVOF) method in a protective atmosphere with a subsequent high-temperature thermomechanical treatment. In order to obtain new information about the structure, we studied the metallophysical properties of the composite using electron microscopy and X-ray diffraction analysis, as well as the mechanical properties and phase composition. We studied the influence of high-energy mechanical processing of high-entropic and ceramic materials on the structural-phase state and composite quality. We determined the optimal technological parameters of HVOF in a protective atmosphere, followed by a high-temperature thermomechanical treatment. Additionally, we optimized these parameters to form a hybrid composite providing the highest adhesion and low porosity. Moreover, we investigated the microhardness of the composite layers. On the basis of complex metallophysical studies, we examined the composite formation. In order to determine the endurance limit in comparison to various other composite materials, we carried out cyclic endurance tests of the developed materials.</p> </abstract>

Theoretical and experimental investigations on material removal characteristics of small-diameter aspherical silicon carbide mould with weak magnetization-enhanced force-rheological polishing

Multi-field composite polishing with non-Newtonian fluids is a potential technology for manufacturing optical moulds. However, the correlation between the micromaterial removal mechanism and the properties of magnetic shear thickening fluid (MSTF) for weak magnetization-enhanced stress-rheological polishing (WMESRP) is still unclear. In this study, we propose a weak magnetization- enhanced stress-rheological polishing (WMESRP). Based on non-Newtonian fluid dynamics, microscopic contact mechanics, and vector discrete methods, a multi-scale material removal model (MRR) was established. Under a series of fixed-point polishing experiments, the maximum change rate between the experiment and theory was obtained as less than 5.7%. In addition, comparative experiments revealed that polishing liquids containing polyethylene glycol inhibit excessive agglomeration of particle clusters, thereby achieving a smooth surface. The proposed WMESRP method can accomplish non-destructive processing of hard and brittle ceramic materials, which can be used in various applications.

INTENSIFICATION OF THE SINTERING PROCESS OF CERAMIC MATERIALS BASED ON THE BaO – Al2O3 – SiO 2 SYSTEM

The article examines the effect of additives on the intensification of the sintering process of ceramic materials based on the BaO – Al2O3 – SiO2 system. Taking into account different mechanisms of interaction of additives with the main matrix, modifiers – MgO, Cr2O3, ZrSiO4, TiO2 and mineralizers – CaCO3, B2O3, MoO3, SnO2 : Li2O were selected for research. On the basis of the conducted complex of studies, it was established that the most promising intensifier for the celsian sintering process is the eutectic additive SnO2 : Li2O in the amount of 1 wt.% with the following characteristics: water absorption – 5.1%, porosity – 13.4%, apparent density – 2.62 g/cm3. The results of the X-ray phase analysis show that the celsian synthesis reaction is complete at a synthesis temperature of 1200 °С, which is a confirmation of a decrease in the synthesis temperature of the phase by 100 °С. The obtained celsian ceramics meet the requirements for radio-transparent materials and can be used for the manufacture of individual parts in the aerospace industry.

Rapid thermal processing of garnet-based composite cathodes

Rapid thermal annealing techniques enable quick and non-contact processing of ceramic materials and are particularly promising for materials containing elements with high vapor pressure. For example, Li-ion conductive oxide-ceramics such as the garnet-type Li7La3Zr2O12 (LLZO) need to be densified in order to be used as separators or in composite cathodes of all-solid-state batteries (ASB), but suffer from lithium loss at elevated temperatures. To address this issue, the sintering method “rapid thermal processing” (RTP) is used to fabricate ceramic composite cathodes of LLZO and LiCoO2 (LCO), the cathode active material. The cathodes were deposited on LLZO separators by screen-printing, a scalable industrial process for the fabrication of ceramic components. A detailed analysis by Raman spectroscopy and X-ray diffraction analysis confirms the successful mitigation of secondary phase formation between LCO and LLZO. The subsequent application of In-metal anodes resulted in fully inorganic ASB that were electrochemically cycled.

Solid State Synthesis of Aluminum Doped Li7La3Zr2O12 Garnet with Enhanced Thermal Processing Stability

Lithium lanthanum zirconium oxide garnet (LLZO) is a solid-state lithium ion conducting electrolyte being studied extensively for all-solid-state batteries (ASSB) owing to its high lithium conductivity and chemical stability against lithium metal anodes. This material, though useful, is highly sensitive to lithium stoichiometry in terms of crystalline stability and functional properties including conductivity. Stabilizing agents such as aluminum oxide and excess lithium are needed to preserve the cubic phase and compensate for lithium volatility during high temperature processing. Material engineering that allows LLZO to be fabricated with lower sensitivity to processing conditions is an important enabler in ultimate implementation of this material.Given the range of ceramic materials processing constraints such as ball milling, calcination, and sintering at temperatures above 1000oC, lithium volatility can drive deleterious phase formation. This study was designed to consider mechanisms that reduce the processing sensitivities of aluminum doped LLZO along its path to being utilized in a ceramic-manufacturing optimal ASSB. Processing sensitivities ameliorated via direct incorporation of excess lithium within LLZO lattice provides a key advantage towards the densification over topical additions of excess lithium precursors. By utilizing thermogravimetric analysis in conjunction with in-situ XRD analysis of solid state LLZO precursor synthesis the sensitivity of the LLZO cubic phase to lithium volatility can be reduced via early incorporation of excess lithium carbonate during initial formation. Details of in-situ phase evolution of LLZO from precursors were further clarified via temperature resolved mapping of diffraction patterns. The improved suppression of lithium volatilization has helpful implications for the scalable production of LLZO powders and assembly of ASSBs.

Application of Digital 3D Printing Technology in Ceramic Art Creation

3D printing technology is a modern technical means and process based on three-dimensional molding, digital manufacturing, reverse engineering, and other emerging fields. 3D printing ceramics is one of the diversified designs of modern ceramics. At the same time, with the development of 5G technology, the platform access method will make 3D printing easier and more common. The purpose of this paper is to study the printing, preparation, and sintering processes of ceramic materials based on 3D printing technology and realize the rapid prototyping of ceramic parts, which can meet the requirements of low-cost, single-piece, and small-batch processing. This paper proposes to focus on the research on materials, design methods, and technological processes suitable for ceramic 3D printing technology from the perspective of the integration of art and science. By using 3D printing technology to perform geometric functions, mixing, recombination, and other cutting-edge tasks, the composite design of works is enhanced. The experimental results show that in the high temperature sintering stage, 1600°C is the holding temperature, the heating rate is 0.5°C/min, and the holding time is 600 min, and the sintering effect of ceramic parts is better. The measured shrinkage rate of the ceramic sample does not exceed 16%, the porosity is 47%, the bulk density is 2.27 g/cm3, and the density is 53.2%. The results show that the ceramic parts prepared by this process can meet the basic performance requirements.