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- 521 to 526
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The materials’ consolidation, especially ceramics, is very important in advanced research development and industrial technologies. Science of sintering with all incoming novelties is the base of all these processes. A very important question in all of this is how to get the more precise structure parameters within the morphology of different ceramic materials. In that sense, the advanced procedure in collecting precise data in submicro-processes is also in direction of advanced miniaturization. Our research, based on different electrophysical parameters, like relative capacitance, breakdown voltage, and [Formula: see text], has been used in neural networks and graph theory successful applications. We extended furthermore our neural network back propagation (BP) on sintering parameters’ data. Prognosed mapping we can succeed if we use the coefficients, implemented by the training procedure. In this paper, we continue to apply the novelty from the previous research, where the error is calculated as a difference between the designed and actual network output. So, the weight coefficients contribute in error generation. We used the experimental data of sintered materials’ density, measured and calculated in the bulk, and developed possibility to calculate the materials’ density inside of consolidated structures. The BP procedure here is like a tool to come down between the layers, with much more precise materials’ density, in the points on morphology, which are interesting for different microstructure developments and applications. We practically replaced the errors’ network by density values, from ceramic consolidation. Our neural networks’ application novelty is successfully applied within the experimental ceramic material density [Formula: see text] [kg/m 3 ], confirming the direction way to implement this procedure in other density cases. There are many different mathematical tools or tools from the field of artificial intelligence that can be used in such or similar applications. We choose to use artificial neural networks because of their simplicity and their self-improvement process, through BP error control. All of this contributes to the great improvement in the whole research and science of sintering technology, which is important for collecting more efficient and faster results.more » « less
Ceramic–polymer composites are of interest for designing enhanced and unique properties. However, the processing temperature windows of sintering ceramics are much higher than that of compaction, extrusion, or sintering of polymers, and thus traditionally there has been an inability to cosinter ceramic–polymer composites in a single step with high amounts of ceramics. The cold sintering process is a low‐temperature sintering technology recently developed for ceramics and ceramic‐based composites. A wide variety of ceramic materials have now been demonstrated to be densified under the cold sintering process and therefore can be all cosintered with polymers from room temperature to 300 °C. Here, the status, understanding, and application of cold cosintering, with different examples of ceramics and polymers, are discussed. One has to note that these types of cold sintering processes are yet new, and a full understanding will only emerge after more ceramic–polymer examples emerge and different research groups build upon these early observations. The general processing, property designs, and an outlook on cold sintering composites are outlined. Ultimately, the cold sintering process could open up a new multimaterial design space and impact the field of ceramic–polymer composites.
The cold sintering process (CSP) is a low-temperature consolidation method used to fabricate materials and their composites by applying transient solvents and external pressure. In this mechano-chemical process, the local dissolution, solvent evaporation, and supersaturation of the solute lead to “solution-precipitation” for consolidating various materials to nearly full densification, mimicking the natural pressure solution creep. Because of the low processing temperature (<300°C), it can bridge the temperature gap between ceramics, metals, and polymers for co-sintering composites. Therefore, CSP provides a promising strategy of interface engineering to readily integrate high-processing temperature ceramic materials (e.g., active electrode materials, ceramic solid-state electrolytes) as “grains” and low-melting-point additives (e.g., polymer binders, lithium salts, or solid-state polymer electrolytes) as “grain boundaries.” In this minireview, the mechanisms of geomimetics CSP and energy dissipations are discussed and compared to other sintering technologies. Specifically, the sintering dynamics and various sintering aids/conditions methods are reviewed to assist the low energy consumption processes. We also discuss the CSP-enabled consolidation and interface engineering for composite electrodes, composite solid-state electrolytes, and multi-component laminated structure battery devices for high-performance solid-state batteries. We then conclude the present review with a perspective on future opportunities and challenges.more » « less
A simple and facile method was developed to fabricate functional bulk barium titanate (BaTiO3,
BT) ceramics using the paste extrusion 3D printing technique. The BTceramic is a lead‐free ferroelectric material widely used for various applications in sensors, energy storage, and harvesting. There are several traditional methods (eg, tape casting) to process bulk BTceramics but they have disadvantages such as difficult handing without shape deformation, demolding, complex geometric shapes, expansive molds, etc. In this research, we utilized the paste extrusion 3D printing technique to overcome the traditional issues and developed printable ceramic suspensions containing BTceramic powder, polyvinylidene fluoride ( PVDF), N,N‐dimethylformamide ( DMF) through simple mixing method and chemical formulation. This PVDFsolution erformed multiple roles of binder, plasticizer, and dispersant for excellent manufacturability while providing high volume percent and density of the final bulk ceramic. Based on empirical data, it was found that the maximum binder ratio with good viscosity and retention for desired geometry is 1:8.8, while the maximum BTcontent is 35.45 vol% (77.01 wt%) in order to achieve maximum density of 3.93 g/cm3(65.3%) for 3D printed BTceramic. Among different sintering temperatures, it was observed that the sintered BTceramic at 1400°C had highest grain growth and tetragonality which affected high performing piezoelectric and dielectric properties, 200 pC/N and 4730 at 103 Hz respectively. This paste extrusion 3D printing technique and simple synthesis method for ceramic suspensions are expected to enable rapid massive production, customization, design flexibility of the bulk piezoelectric and dielectric devices for next generation technology.
Many natural materials present an ideal “recipe” for the development of future damage‐tolerant lightweight structural materials. One notable example is the brick‐and‐mortar structure of nacre, found in mollusk shells, which produces high‐toughness, bioinspired ceramics using polymeric mortars as a compliant phase. Theoretical modeling has predicted that use of metallic mortars could lead to even higher damage‐tolerance in these materials, although it is difficult to melt‐infiltrate metals into ceramic scaffolds as they cannot readily wet ceramics. To avoid this problem, an alternative (“bottom‐up”) approach to synthesize “nacre‐like” ceramics containing a small fraction of nickel mortar is developed. These materials are fabricated using nickel‐coated alumina platelets that are aligned using slip‐casting and rapidly sintered using spark‐plasma sintering. Dewetting of the nickel mortar during sintering is prevented by using NiO‐coated as well as Ni‐coated platelets. As a result, a “nacre‐like” alumina ceramic displaying a resistance‐curve toughness up to ≈16 MPa m½with a flexural strength of ≈300 MPa is produced.