Design and development of advanced ceramics for a wide range of applications, e.g., from engineering, resource processing and power generation to aerospace, and defense-oriented applications are the quite challenging task of the modern material science and engineering. It is undeniable that the requirements for advanced ceramics, composites, and coatings depend primarily on the growth of end-user demands and specific market features. On the other hand, the modern industry needs the development and implementation of new ceramic-based materials and innovative processing methods in order to improve the quality and reliability of the engineering products, to increase manufacturing efficiency and to provide opportunities to use advanced materials in the next generation technologies and devices. It is well known that the properties and performance of ceramics-based materials and coatings strongly depend on the processing routes and their features. Dedicated research and development of advanced technologies and their optimization should enable improvement of the materials performance. This is particularly important when advanced ceramic components are produced on a large industrial scale. At the same time, innovative or improved technologies may allow materials and components with unique properties to be produced, which could not be obtained using only “established” processing routes.
The topic of the advanced ceramic processing is considered at the international conferences, such as Shaping of Advanced Ceramics, International Conference of Advanced Ceramics and Composites (e.g., Symposium 8) held in Daytona Beach, FL, MS&T, EUROMAT, MSE, and some others with related publications of the symposia proceedings and in the ceramic and materials science journals.
There are particular demands for complex-shaped advanced ceramic-based materials with high reliability for a variety of applications such as wear-, corrosion- and thermal shock-resistant parts for oil, gas, mining, mineral and chemical industries, power generation, engine components, filter and catalyst supports and some other parts for automotive manufacturing, biomedical implants and artificial teeth, armor parts and structures, filter and catalytic systems for chemical and environmental uses, components for metal and slug processing and many others. The engineering components may be from fully dense to highly porous structures, with a uniform microstructure or to be heterogeneous when one or a few phases are bonded by similar or dissimilar materials or reinforced by fibers, whiskers, or particulates. Depending on the application and properties, size and shape complexity, manufacturing productivity, and volume, different processing methods can be used. They include injection moulding, slip casting, gelcasting and direct coagulation casting, thixotropic casting, infiltration of the porous preforms and reaction bonding, additive manufacturing, uniaxial and isostatic pressing, extrusion, as well as their combinations, and some other methods. Regardless the selected forming method, the colloidal processing should be emphasized in the manufacturing of the components with high reliability. It includes such important features as the starting materials selection (from nano-size to even hundreds micron particles), their dispersion to obtain stable colloidal suspensions with a high solid content and low viscosity, selection of the appropriate temporary organic or preceramic ingredients provided high strength of the green body and its consolidation and which may provide a particular phase formation at the next step, a high level of compaction to achieve good sinterability and reasonable shrinkage (or its absence) minimizing stresses occurred at the firing. Selection and preparation of starting materials with controllable properties are important to obtain advanced engineering materials with desired structures and working parameters, and starting materials define, in a high extent, not only the materials properties, but the technology and the selecting processing route. When manufacturing of monolithic ceramics is not possible because of the size and shaping factors, as well as particular application conditions, special protective or functional coatings onto different substrates are produced. As another key point of the advanced materials technology, the materials consolidation and structure formation should be outlined. Only the combination of the optimized colloidal processing, forming method and firing or consolidation provides the desirable ceramic microstructures and reduced level of flaws, internal micro-stresses, and irregularities, which negatively affect the reliability and reproducibility of ceramic components and composites that is especially important in large-volume industrial manufacturing. The management of the ceramic and composite microstructures with minimal grain boundary stressed conditions or the coating structure and the coating--substrate interface, which are defined by the processing features and optimization, can define the reliability of the components.
Hence, any future progress in the field of innovative processing should be based on the improvement of the existing technologies or, alternatively, on the development of new approaches with an emphasis on the routes allowing the near-net formation of ceramic structures, while optimizing the design of new materials and of the part architecture. In order to reduce time and cost involved in R&D in the field of the ceramic-based innovative processing, it might be useful to combine both of the approaches to enhance the processing technologies. Such an integrated approach can widely reduce unproductive parallel work. The innovative processing of ceramic-based materials is promoted by the joint efforts from several different schools of thought, such as materials science and engineering, mechanical engineering, computer science, electrical, electronic, and communication engineering, together with the experience of the manufacturers and end-users. Besides these synergetic effects between decentralized R&D institutions, a pooling of resources can also help to expedite the research efforts to their commercialization.
This special issue of the Journal of Advanced Engineering Materials is dedicated to novel processing of advanced ceramics, composites, and coatings, as well as to the research and optimization of earlier developed processing routes, which improve the productivity and quality of the materials. The issue contains 18 invited papers prepared by or with participation of the well-recognized ceramic specialists from academia and industry. The manuscripts cover different aspects of ceramic and coating processing, such as: preparation and use of special ceramic powders and precursors materials, colloidal processing, forming routes of different advanced engineering (ceramics, composites, and coatings) for variety of applications, materials consolidation, studies of the influence of processing on structure and properties of the materials, and large-scale manufacturing. The results of some selected papers have been presented at International Materials Conferences, but some papers describe absolutely new results. Some papers cover the extensive studies conducted by the authors for a number of years and even implementation of the materials and processes with the features of industrial experience. The readers can see that the papers presented in this issue were prepared by the authors from different countries of North America, Europe, Asia, and Australia, and they demonstrate a successful collaboration between the organizations not only from one country, but also from other countries and even continents.
As the guest editors, we are grateful to all authors for their contribution to the special issue of Advanced Engineering Materials and their efforts to prepare the manuscripts in time. We are also grateful to all reviewers for their work and advice, which helped to improve the quality of the papers for publication. We hope that this special issue will be interesting and useful for many ceramic and advanced materials specialists from academia and industry, who work with the development and manufacturing of ceramics, composites, and coatings, as well as the specialists who use advanced materials in modern devices and technologies.
The guest editors
Dr. Eugene Medvedovski and Dr. Nahum Travitzky*
Endurance Technologies Inc., Calgary, Canada
*University of Erlangen-Nuremberg, Erlangen, Germany
Dr. Eugene Medvedovski
Dr. Nahum Travitzky