Using ceramics to 3D print consumer products | VoxelMatters - The heart of additive manufacturing

Oct 15, 2024

The use of ceramics in 3D printing of consumer products remains a small niche within a segment with huge potential. However, any accurate analysis of ceramic 3D printing must separate technical ceramics such as alumina, zirconia, and silicon carbide from traditional ceramics such as sand, clay, and concrete. Both are used to produce high-value prototypes, tools, and parts. However, the former is used in very small quantities (a few grams) to medium-sized quantities (a few kilograms), while the latter is used from medium-sized to very large quantities (several kilograms).

Technical ceramics are not commonly used in consumer products, except for certain applications of zirconia in jewelry, watches, and luxury items through stereolithography. Alumina is also used in high-end consumer electronics like antennas, earphones, and textile manufacturing machinery. Technical silica has been used, mostly at an experimental level, to produce consumer products as well, with a potential for lower material costs if the process were to be scaled.

Alumina, or aluminum oxide (Al2O3), is the most widely used oxide ceramic material. It typically consists of at least 80% aluminum oxide, along with small proportions of silica (SiO2), magnesia (MgO), and zirconia (ZrO2). Alumina has a melting point of 2072 °C and possesses several notable mechanical properties, including high flexural strength, hardness, wear resistance, chemical resistance to strong acids and alkalis (even at high temperatures), stiffness, excellent insulation, and an extremely low coefficient of thermal expansion. Moreover, alumina has desirable traits such as fracture toughness, thermal conductivity, and biocompatibility.

Alumina is widely used in various industries, including electronics and industrial machinery (particularly in the textile industry). In consumer products and 3D printing, alumina finds applications in telecommunications equipment and high-end electronic devices.

Zirconia, sometimes referred to as “Ceramic Steel,” is an oxide of zirconium, a strong and malleable (and costly) metallic element. As a technical ceramic, zirconia (ZrO2, zirconium dioxide) exhibits numerous desirable properties, including high fracture resistance, excellent wear resistance, exceptional temperature resistance, low thermal conductivity, high refractory properties (such as a high melting point, low thermal expansion, and high chemical resistance), and a low friction coefficient. Zirconia is also non-magnetic.

With a melting point of 2715 °C, zirconia is used in the production of ultra-strong ceramics designed to withstand heat shocks, such as furnace linings, foundry bricks, and abrasive tools like grinding wheels and sandpapers. In consumer products, zirconia is employed in the manufacturing of cutting utensils, scissors, cosmetics, antiperspirants, microwave filters, and more. In 3D printing, the use of zirconia is becoming more prevalent in the production of luxury goods like jewelry (rings, pins), watches, and decorative items. For instance, 3DCeram used stereolithography to manufacture a set of chess pieces in zirconia for a well-known luxury brand.

Traditional ceramics are primarily used in the consumer product segment for making designer products and pottery. Recently, there has been a rise in the production of intricate lamps, bathroom ware, vases, and other interior decorating items using sand binder jetting technologies. Clay 3D printing via extrusion is used for artisanal products and, in some cases, the serial manufacturing of tableware, cups, vases, and other household accessories, including complex 3D tiles. Concrete 3D printing is mainly used for producing furniture items for exteriors.

Silica sand is primarily composed of silicon dioxide (SiO2) and is commonly found in the Earth’s crust. It has various industrial applications, particularly in foundry castings. However, it can also be used for directly additively manufacturing large sand objects such as architectural elements, artistic decorations, statues, and more. It is essentially made of sand and gravel containing silica; the definition includes ordinary silica sand, refined silica sand, and high-purity silica sand. Depending on impurities, its particles, primarily white or translucent, can assume other colors. Its melting point stands at approximately 1,750°C.

Quartz sand, on the other hand, is crystalline and derived from quartz stone. Although it is also silica-based, it differs greatly in appearance and production methods from silica sand. Produced by crushing quartz stone, quartz sand is a chemically stable, wear-resistant non-metallic silicate mineral. It is often milky white or colorless and translucent and is extensively used in casting and various other sectors. Quartz sand is a natural material that is unique primarily because of its haptics (sense of touch). Its thermal properties make it ideal for bathroom applications as it can store heat for a long time. In the production of binder jetting 3D printing, the company Sandhelden uses sand sourced exclusively from regional sources in Germany to ensure sustainability.

Different types of clay can be used for 3D printing, with earthenware, stoneware, and porcelain being the most common. These clays are used for making pottery (both functional and decorative) as well as construction items like bricks and tiles. Most often, these clay materials are 3D printed using paste deposition technologies, a form of material extrusion. However, they can also be 3D printed through binder jetting.

Tethon 3D, a specialized ceramic 3D printing material supplier, is a leading supplier of clay materials for binder jetting 3D printing under the Tethonite brand. They offer ceramic powders in earthenware (terracotta), stoneware, and porcelain varieties primarily for binder jetting technology. Additionally, Tethon 3D provides mullite, a type of aluminum-based sand, in powder form for binder jetting. They also have other clay materials suitable for paste deposition processes. These additive manufacturing technologies typically use standard pottery clay optimized for printing in terms of water content. Both first-party and third-party suppliers offer extrusion earthenware and porcelain products that have been specifically optimized for 3D printing.

While all clays are usable for 3D printing, some perform better than others. Clays with a consistent texture that dry quickly are particularly effective. The addition of clinker enhances clay’s printability by reducing viscosity and adding structure. Suppliers often indicate the clinker content on their packaging. Refined, loose stoneware clay is generally suitable.

For extrusion 3D printing, the clay must be soft enough to be fed into the machine but firm enough to support stacked layers as they dry. Different clays have different characteristics and require varying amounts of water to achieve the desired consistency. Clay is pushed through the printing system using compressed air or mechanical tamping. If the clay is too hard, the printed layers may not adhere properly, resulting in delamination or cracking.

Clay for 3D printing can be sourced from wet clay bags or dry powder clays designed for pottery wheels, with water acting as a lubricant. Each clay type exhibits a different shrinkage rate. As clay dries and water evaporates, it contracts, and it shrinks further when fired in a kiln. The shrinkage is more pronounced at higher firing temperatures. Generally, clay contracts uniformly in all directions, but in 3D printed forms, vertical shrinkage tends to be greater than horizontal shrinkage.

Earthenware is a pottery material that does not require firing to vitrification, making it permeable to water. It is typically made up of clay, quartz, and feldspar, with terracotta being a type of earthenware. Whether glazed or unglazed, fired terracotta is porous. Terracotta has a wide range of applications, from vessels and water/wastewater pipes to bricks and decorative elements in construction. Throughout history, it has been a popular medium for ceramic art. Earthenware is primarily 3D printed using paste deposition and pneumatic extrusion systems, both from first-party suppliers and third-party providers like Ceramic Collett Sio-2. Tethon 3D also offers earthenware powder for binder jetting.

Stoneware, whether vitreous or semi-vitreous, is primarily made from stoneware clay or non-refractory fire clay. Stoneware is fired at high temperatures, making it nonporous regardless of its vitrification status. It is different from porcelain in that it is more opaque and usually only partially vitrified. Stoneware clay often has impurities that give it a gray or brownish tint, and it is typically glazed. For extrusion technologies, Ceramica Collet Sio-2 provides custom materials, while Tethon 3D offers a specific Tetonite powder for binder jetting.

Porcelain is produced by heating materials such as kaolin, mullite, and feldspar in a kiln between 1200°C and 1400°C. Its toughness, strength, and translucence primarily result from vitrification and the creation of the mineral mullite at these temperatures. Porcelain has several characteristics, including low permeability, elasticity, strength, whiteness, resonance, translucence, and resistance to chemical and thermal shocks. Tethon 3D supplies porcelain in both paste (for deposition and pneumatic extrusion technologies) and powder (for binder jetting).

Other minerals can also be 3D printed via extrusion or binder jetting. Concrete is the most common and is increasingly used in large-format extrusion processes for constructing buildings. While these applications are not detailed in this study, as they relate to a different distinct segment of 3D printing, similar concrete materials are used in some large extrusion and binder jetting systems to create decorative items, artwork, and furniture that fit within this analysis.

CONCR3DE, a binder jetting hardware manufacturer, enables 3D printing with recycled mineral powders such as marble, limestone, and granite, from small to extra-large sizes. CONCR3DE offers a range of materials that facilitate easy printing of complex shapes using stone and mineral materials. These materials have different properties, and the printed parts are robust and suitable for outdoor use when optionally sealed. CONCR3DE Marble offers sustainability and a waste-free process, along with a high-quality surface finish and excellent mechanical properties for complex designs. Similarly, CONCR3DE Granite provides a high-quality surface finish, cost-effective and scalable production capabilities, and the ability to print complex designs with excellent mechanical properties. CONCR3DE Limestone also offers high-quality surface finish, cost-effectiveness, scalable production, and the ability to print complex designs with superior mechanical properties. All of these materials are sustainable and involve a waste-free process.