Johnson Matthey lead the way in ceramic 3D printing
Johnson Matthey, a global leader in science that makes the world cleaner and healthier, has combined its technical expertise with state-of the-art facilities to become an industry leader in the additive manufacturing of ceramics.
Ceramic additive manufacturing (more commonly known as 3D printing) is a manufacturing process by which 3D objects are produced by depositing ceramic material in successive layers. With 3D printing, it is now possible to manufacture complex, previously impossible geometries for markets where higher performance is needed. JM can print tailored products with feature sizes down to just 400 µm.
New product ideas may be printed within days of conception, with changes to the design made quickly and easily without the need for bespoke tooling or other equipment. Traditional manufacturing techniques, such as extrusion or injection molding, have longer lead times to adapt the process to a new design, and will often require investment in new tooling.
The 3D printing capability within JM was developed as a step-out technology for a number of markets. Having tested several different processes, JM focused on binder-jetting, a 3D printing process in which a binder is selectively jetted on top of successive layers of ceramic powder to bind the powder particles together, forming a 3D object. After removing excess powder, printed shapes are fired to sinter the ceramic powder together and give strength to the final ceramic parts.
Binder-jetting provides a faster, more scalable solution when compared with other 3D printing technologies, making it the most sustainable 3D printing solution for industrial applications.
A large build area, superior to many other ceramic 3D printing methods (such as stereolithography), enables several complex parts to be produced during the same print run. JM’s ceramic parts can range in size from only a few millimeters up to 50-100mm.
Since this is a powder-based manufacturing method, the object being printed is self-supported within the powder bed and no support structures need to be added to the 3D model. When the printing process is complete, unbound powder is removed so it can be reused in the process. The fact that excess powder can be recycled with extremely low losses is a crucial factor that makes this process sustainable and financially viable at industrial scale.
Sintered ceramic powder will inherently produce porous parts. Ceramics with tailored porosity are promising materials for a number of functional and structural applications where filtration, thermal insulation or lightweight properties are required. Density is one of the features that can be tuned by varying process parameters. Relative densities in the range of 45% to 70% can easily be achieved. Details of surface structure and porosity can be seen in Figure 1.
The surface features of these 3D-printed parts make them particularly suitable for coating and surface activation as they can hold more active material. An example of surface activation with a catalytic material can be seen in Figure 2.
Despite being porous, these printed parts retain the high-strength characteristic of ceramic materials. Compression strength tests have been performed comparing 3D printing with parts manufactured via pelletization (see Figure 3). Results show that a similar performance is observed for both techniques.
JM has focused research on a process that is safe and environmentally friendly by using inert binders during manufacturing. Standard binder-jet methods usually use resins such as furan or phenolic binders as the binder agent. These resins have an acute toxicity and, during the firing stage, can release hazardous volatile organic compounds. JM’s new binder formulations have a very low environmental impact and toxicity.
JM has invested in different scales of equipment to allow flexibility in development and to enable fast design prototyping and optimization. The company uses adapted 3D printing machines from Voxeljet within its 3D printing processes. Voxeljet is a German manufacturer of 3D printing systems for industrial applications, specializing in binder-jetting. JM has worked closely with Voxeljet to jointly develop these ceramic 3D printers, tailoring the German firm’s large-format printers to JM’s specific requirements.
Production at scale
JM has recently commissioned its first pilot plant for ceramic 3D printing. This plant was installed in 2017 and is now one of the world’s most advanced facilities for ceramic 3D printing, allowing the manufacturing of ceramic 3D-printed parts at scale (Figure 4).
This new pilot plant is capable of handling multiple materials with ton capacities, and benefits from being integrated within JM’s supply chain of ceramic material powders.
Furthermore, state-of-the-art machinery was co-developed to accelerate and automate the post-printing stages of the process, which also increases product consistency.
With the construction of this pilot plant, JM is now able to deliver a wide range of ceramic products, from conception, through rapid prototyping using its R&D printers, to an end product.
Application areas for ceramic 3D printing
Ceramic 3D printing can be applied to a wide range of applications where lightweight, complex ceramic parts are required for high-performance applications (Figure 5).
For instance, the ability to produce optimized ceramic parts with reduced material volumes makes this technology particularly interesting to the automotive and aerospace markets, as it can increase overall efficiency or reduce energy demands. Since these ceramic 3D-printed parts are porous, they are also permeable and therefore can be applied to filtration systems or used in adsorption processes. The insulation capability and thermal stability of these ceramic materials are also attractive properties for the aerospace, automotive and electronics markets.
Ceramics’ chemical stability and low reactivity to chemical and biological media make these 3D-printed components particularly suited to medical and pharmaceutical applications. As they can be treated at higher temperatures, these parts can also be sterilized for multi-use applications.
One of the main ceramic 3D printing research areas within JM is catalytic applications and the design of the next generation of catalyst supports, which have been trademarked as Structal supports (Figure 6). Catalyst supports are commonly used in the chemical industry for heterogeneous catalytic reactions in fixed-bed reactors. These ceramic supports are coated with a catalytic material and then loaded into tubular reactors. A gas stream of reactants is forced to flow through and reacts on the catalytic surface. The conversion of reactants into the desired product is usually linked to the amount of reactive surface area available.
With 3D printing, it is now possible to design more complex shapes with considerably more available surface area. This can be applied to the design of smaller reaction units. Replacing conventional catalyst supports with Structal supports means that fewer are needed to deliver the same amount of surface area for a given reaction. Alternatively, if the same vessel volume is kept, the process could operate at a higher throughput. This is due to the increase in the total amount of surface area that Structal supports introduce into the system.
Moreover, 3D-printed catalyst supports can also be designed to reduce the pressure drop inside a fixed-bed reactor, while still delivering high surface area. This translates into benefits to the overall operational efficiency and energy demands of the process.
The future is now
In a world of change, JM’s continued growth comes from the ability to turn scientific expertise and creative thinking into compelling new products that create real value. With these recent advances in the ceramic 3D printing field, JM is at the forefront of Industry 4.0, which will inevitably change the way we make new products and make use of our resources.
Johnson Matthey will be exhibiting at Ceramics Expo 2019 in Booth 339