Additive Manufacturing for Chemical Sciences and Engineering

Science and engineering have been instrumental in advancing the progress of humanity and are the key enablers that are shaping our very present and the future, improving our health and living standards, allowing humanity to leave the planet, walk on the moon, and explore distant stars and galaxies. Additive manufacturing (AM) or 3D printing is the latest technological marvel in manufacturing that is compelling us to think differently about how we design and manufacture parts and components, the location where the parts are being manufactured, the supply chains, environmental impact of manufacturing and sovereign capability. AM is now being perceived as a disruptive technology because of the benefits and opportunities it offers over the long-established traditional manufacturing technologies. It is a relatively young technology, some 30 years since the invention of the first 3D printer, compared to conventional subtractive technologies that have been around for centuries. Mainstream AM has in fact only been around the last 5 to 10 years as both the 3D printing technology and feedstock materials have evolved and become more robust, cheaper, and reliable giving manufacturers the necessary level of confidence to adopt them in serial production. The level of activity in AM is at an all-time high as various stake holders, company executives, investors, researchers, and government agencies try to predict its trajectory. Global organizations of all types are attempting to understand the role they can play in the AM space. This chapter presents an overview of AM and its enormous potential in the advancement of chemical sciences and engineering. In-depth discussion of fundamental and applied aspects of each individual AM technology and how they relate to chemical sciences and engineering are presented in subsequent chapters. To date AM has seen greater adoption by the aerospace, defense, and biomedical industries and to somewhat lesser degree in the chemical manufacturing and processing industries. Introduction of AM practices in this sector can improve the efficiencies of existing chemical processing technologies, allow sophistication of existing processes for manufacturing of new products, improve process economics, and address complex challenges and demands of our modern society such as environmental compatibility, reduction in wastes and emissions and localized production. AM in chemical sciences has enormous potential in process intensification which enables efficient heat and mass transfer, large reduction in the footprint of chemical manufacturing and processing and reduce environmental pollution.

Since its first use to build sculptures, additive manufacturing has come a long way to become a prominent and prolific modern technology with wide acceptance due to significant benefits and advantages arising from its adoption and implementation in different industrial and consumer sectors. AM is rapidly paving a path towards an intensified technological society by facilitating unprecedented accomplishments ranging from digital storage of production data and on-demand manufacturing to repair and maintenance of malfunctioning machines, tools, and even human’s anatomy. This chapter presents a state-of-the-art review on the history and evolution of additive manufacturing technologies along with the emerging paradigm for the incorporation of AM in major industrial and research sectors. Overall, the chapter provides all the necessary insights essentially required by young researchers to understand where AM came from and where it is going.

The additive manufacture (AM) of plastic components can be accomplished by a variety of methods which are classified according to how material layers are consolidated layer-by-layer to create physical objects from digital data. Two of the most widely used methods include Material Extrusion (MEX) and Vat Photopolymerization (VP). These methods include a range of commercialized AM processes often referred to by various trademarked terms such as Fused Deposition Modelling (FDM) and Stereolithography (SLA). Compared to conventional subtractive or formative manufacturing process, MEX and VP are able to manufacture complex parts with high ability for customization, as they impose few constraints on part geometry, and require low setup effort with no custom tooling. Furthermore, MEX and VP are both well-established additive manufacturing processes and through ongoing refinement have achieved compatibility with a broad range of materials and part geometries, and comparatively low operating costs. Due to their high versatility, MEX and VP have been widely used in a broad range of industries including applications in chemical sciences, biotechnology, aerospace, defense, and automotive engineering. However, despite their high versatility, AM processes such as MEX and VP are subject to unique technological characteristics associated with the manufacturing process, the material properties, part design and suitable application areas. This chapter provides an overview of MEX and VP processes characteristics critical to the effective application of these additive manufacturing technologies to high performance products.

Laser Powder Bed Fusion (L-PBF) is an additive manufacturing process which uses a scanning laser beam to selectively melt metal powder in a layer-wise manner to produce solid metal parts. In comparison to conventional subtractive or formative manufacturing processes, L-PBF imposes few design constraints on part geometry and requires low setup effort without the requirement for custom tooling. These unique capabilities enable the manufacture of complex parts that are highly customizable. A broad range of metals can be processed provided they are in a specific powdered form, and that they meet the process compatibility requirements associated with laser weldability. L-PBF provides an exciting opportunity for the manufacture of novel devices for chemical engineering applications, previously difficult or infeasible with conventional manufacturing processes including, cellular materials, high-efficiency heat exchangers, and reactors with highly optimised geometry. To utilize this technology to its maximum potential, it is necessary to understand the practical technological benefits as well as the operational constraints associated with L-PBF materials, process characteristics, part design, and suitable application areas. Particularly, as the final part quality is determined by many influential parameters. The following chapter provides an overview of L-PBF to assist designers in optimizing the functional performance, manufacturability, reliability, and cost of additively manufactured products.

Functional ceramic materials with magnetic, electronic, piezoelectric, superconducting and other dielectric properties constitute an important field of materials research. Indeed, their broad potential enables them to be applied in various applications and are hence considered to be ‘smart materials’. However, ceramics are one of the more difficult materials to fabricate into complex morphologies and are challenging to employ for fine surface robocasting. Robocasting is as an emerging AM process, and despite its challenges, is currently the most viable candidate for the printing of complex ceramic structures and morphologies, of which, traditional manufacturing processes are incapable of in their current state. Robocasting differs from other AM techniques as it is capable of printing a precursor ceramic structure, which can be post-processed to produce dense ceramic structures with complex morphologies. As a result, this technique has a unique advantage over other AM technologies, with the freedom to print complex 3D ceramics given that the ceramic formulation (i.e., the ink), is workable. Excitingly, this technique and its applicable scope can be modified to print multi-ceramic functions, and shapable ceramic structures. This chapter explores the current state of robocasting technology and the wide range of potential materials that may be employed with this for fabrication purposes. Expert opinion is provided as to the emerging and future potential of this technology, with an appropriate discussion of the current challenges and drawbacks that may currently limit widespread application.

The emergence of additive manufacturing (AM) as an industry standard has brought unprecedented opportunity to many fields. Some examples of areas that particularly benefit from this technology include biological implantation, biomedicine, aerospace, advanced materials, automotive, tooling, and many chemical industries. This vast and growing sphere of application has prompted the need for specialised technology that enables tailor-made products. Nonetheless, the majority of printable materials currently available on the market are restricted to proprietary polymers, metal powders and ceramics, which are quickly proving to be inadequate for many applications. Typical AM processes build monofunctional structures with single materials. Hence, post-processing and surface chemical modification of AM printed materials are critical in providing a range of new functional and diverse chemical functionalities. Surface functionalization of 3D printed materials is quickly gaining significant traction as a sub-discipline, as this approach can address the technical challenges associated with optimizing the performance of AM end-user products. This chapter presents an overview of the novel post-physical treatments and surface chemical functionalization required to customize AM printed materials for a wide variety of applications. This chapter further gives indication as to the challenges associated with this field of study, including the status of research and the future avenues that may be able to exploit the true potential of this technology.

Once considered to be a field specific to mechanical sciences, additive manufacturing has now proliferated into all streams of science and swiftly becoming a true global phenomenon. Moving well beyond printing of customized prototypes and trinkets, many enterprises now manufacture using 3D printing at moderate to large scale. Massive improvements in precision, quality and reliability of additive manufacturing have triggered rapid uptake of this technology in the research and development sector especially in fields such as chemical engineering, electronic engineering, materials engineering, biochemistry, optics, analytical sciences, industrial chemistry, and environmental sciences. This chapter highlights some interesting applications of additive manufacturing in chemical processes such as catalysis, separation, and high throughout experimentation, sensing devices such as microfluidics, electrochemical, optical, optoelectronic, and electrical sensors, and energy systems such as batteries and capacitors. The advantages of AM porous catalysts and adsorbents materialize from their high catalytic and separation efficiencies, hierarchical porosity, suitable flow properties, superior mass and energy transfer, novel composite formulations, enhanced product selectivity and high throughput processing of reactants. On the other hand, additively manufactured sensor and energy systems gain the benefits of high performance, better cycling performance (charging/discharging), multifunctionality, geometric shape complexity, customized design, shaping of amorphous materials, better integration of device components and in three dimensions, portability, device flexibility, self-powering capability, and automatic operation. In all such applications the chemical reactivity of the 3D printed construct governs its primary functionality in addition to the shape derived basic function. Clearly this is an ascension from the simple use of printed constructs as 3D objects of complex shapes and geometry. Starting with a brief discussion on the rise of additive manufacturing in chemical sciences, this chapter mainly focusses on the applications of additive manufacturing while building on the knowledge gained in the previous chapters. The applications have been classified as surface sensitive chemical processes which are confined to the first few hundred microns of the surface of a 3D printed construct, bulk sensitive chemical processes which depend on the bulk properties of 3D constructs and high throughput experimentation applications. A summary and outlook section conclude the chapter with a perspective and viewpoint on the future frontiers for additive manufacturing in chemical processes and a knowledge test has been provided for the young learners in the last section.

Chemical sciences and engineering have made outstanding contributions in fulfillment of the needs of our technological society and upliftment of the quality of human life by enabling critical technologies for processing and manufacturing of high-volume essential commodities such as detergents, creams, sanitizers, pharmaceuticals, textiles, plastics, rubbers and so on. The global models of chemical manufacturing have been continuously evolving since the colonial rule to adapt to the socio-economic and political climate. In the face of the twenty-first century, chemical manufacturing is experiencing global challenges of different kinds ranging from depletion of natural resources, climate change and growing population to sustainable living, environmental compliance, and personalized healthcare. Thus, a great need has been felt for reinvigoration of the chemical processing and manufacturing industry in response to which the philosophies of industry 4.0 and smart manufacturing have seen global acceptance and recognition. However, this transcendence from the existing state of chemical manufacturing to smart manufacturing heavily relies on the availability and development of advanced manufacturing and sophisticated equipment, process intensification and efficient micro reaction technologies. Study, design, and engineering of equipment to manipulate chemical and physical phenomenon is at the heart of chemical engineering since equipment and reactor design directly governs process and energy efficiencies, performance, and process economics. Conventional subtractive and casting based manufacturing technologies are proving inadequate to meet the needs of modern chemical engineering demanding capabilities to fabricate sophisticated equipment with complex internal geometries, rapid prototyping, and performance testing. These manufacturing related issues can be effective phased out with the adoption and integration of additive manufacturing with chemical processing and manufacturing industries. While the automotive, aerospace, engineering and biomedical industries have hastily adopted AM technologies for associated benefits, the chemical industries have been lagging behind in the uptake due to lack of agility and adaptability in industrial chemical processes. Integration of AM with chemical industry is anticipated to bring widespread process automation, improved feedstock and product inventories, digital process control and process intensification. Future chemical reactors will be complex tailor-made devices with design optimized for fluid and particle flow, heat and mass transport and reaction thermodynamics. When reactions are catalytic in nature, the performance of the reactor becomes critically dependent on several of the catalyst properties, both physical and chemical. While the intrinsic chemical properties in terms of selectivity and activity are dependent on the choice of catalyst, other important considerations related to reactor efficiencies and design, are related to the structural properties of the catalyst, i.e., on how the active phase of the catalyst is dispersed in the support, that influences the available surface area, porosity, heat, and mass transfer characteristics as well as the hydrodynamic pressure dissipations. This aspect of structured catalytic reactor design, that is based on a functional integration of the catalytic as well as reactor design steps, is also receiving increasing focus from an advanced manufacturing viewpoint towards achieving higher efficiencies and lower energy consumption. In this chapter the role of additive manufacturing in chemical reactor and equipment design ranging from simulation and reactor modelling to demonstrated examples of additively manufactured micro mixers, micro heat exchanges and microreactors are elaborated which distinctly project additive manufacturing as the future of green chemical engineering.