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Manufacturing Technology Insights | Sunday, January 29, 2023
3D printing, chemical synthesis, and digital models have revolutionized ceramic shaping techniques, offering precise control over structures and minimizing material waste.
FREMONT, CA: Ceramics are vital in various sectors, ranging from technology and science to everyday life. With a definition provided by ASTM International, advanced ceramic materials are highly engineered, non-metallic, and inorganic substances with specific functional attributes. This broad definition implies that anything not classified as a metal or polymer falls under ceramic material. Ceramics are omnipresent, from aerospace and automotive applications to energy systems and electronics. They find applications in various industries, including medicine, telecommunications, kitchenware, construction, optics, and nuclear power.
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The majority of ceramic materials are manufactured using powders as starting materials. The characteristics of the final product heavily rely on the properties of the initial particles. While there is an extensive range of commercially available ceramic powders, ongoing research focuses on developing new compositions and sizes, particularly at the nanometric level. Utilizing nanometric powders with particle sizes smaller than approximately 100 nm offers several advantages, including lower sintering temperatures and reduced grain sizes. This results in improved mechanical, magnetic, electrical, and optical properties. Compared to conventional micrometric powders, the sintering process begins at lower temperatures when nano-particles are used. However, the mechanisms of densification and the challenges associated with nano-powders are not fully understood. Agglomeration, in particular, poses significant obstacles in achieving homogeneous packing and optimal densification.
The synthesis method employed for ceramic powders influences their shape, size, and degree of aggregation. Specific properties such as micrometric size, equiaxial shape, high chemical and mineralogical purity, and minimal agglomeration are desired in producing advanced ceramics. Bottom-up techniques involving chemical synthesis approaches are preferred for producing nano-powders over top-down processes that rely on mechanical comminution. Chemical synthesis methods are crucial for making pure particles or composites composed of complex compounds like mixed oxides.
Forming techniques play a crucial role in creating ceramic devices and components. These techniques include the preparation of suspensions or mixtures for pressing, slip and tape casting, extrusion, and additive manufacturing processes. Achieving well-deflocculated suspensions or homogeneous mixtures is essential when working with nanometric powders. The homogeneity and density of the final ceramic material depend on the ability of the starting particles to rearrange during sintering at high temperatures. To ensure optimal green compacts, organic deflocculants are typically added to facilitate particle dispersion in a solvent. Using nano-particles often requires higher amounts of dispersants, which can introduce defects in the final material. Therefore, there is a growing demand for compounds with superior de-flocculant properties that can be more easily removed during heating. Similar challenges exist for other processing additives, such as binders, plasticizers, and wetting agents used in different shaping methods.
In recent years, the ceramic materials sector has witnessed significant growth in shaping techniques based on additive manufacturing (AM), commonly known as 3D printing. AM technology enables the production of objects layer by layer, starting from a 3D digital model generated through computer-aided design (CAD). This technology has gained popularity owing to its ability to produce highly complex shapes with minimal waste.
3D printing techniques can produce dense and porous objects when applied to ceramics, although most applications focus on porous components. The benefits of 3D printing include precise control over pore size, shape, and distribution and the ability to create intricate interlaced structures. Additionally, alternative methods are available for manufacturing dense ceramic objects, providing a range of options for different requirements.
Ceramic materials have become indispensable in various industries, contributing to technological advancements and enhancing everyday life. The production of ceramic materials starts with powders, where the final product's characteristics depend on the initial particles' properties. Ongoing research explores nanometric powders, enabling lower sintering temperatures and improved material properties. The synthesis methods employed play a crucial role in achieving desired characteristics, with bottom-up chemical synthesis techniques favored, particularly for nano-powders. Forming techniques, such as creating suspensions and mixtures, are essential for achieving homogeneous green compacts, especially when working with nanometric powders. As ceramic materials advance, their versatility and impact on various sectors will continue to grow.
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