Hi, I’m Dr. Billy will. And in this video, I’ll be talking about electrochemical additive manufacturing, which is a low-cost way to achieve metal 3d printing. This work is mostly based on two papers we published in advanced materials technologies and scientific reports. So if you’d like to find out more, please do check these out where the links can be found in the descriptions below. Firstly, let’s start with what 3d printing is. This is an additive manufacturing technique where we make an object layer by layer through the selective deposition of material, which is defined by a 3d digital model. What you see in this video is a plastic 3d printing process called fuse deposition modeling, but there’s many different types of 3d printing, which we’ll talk about later. The advantages of this process include the fact that you can make extremely complex geometries, which you wouldn’t be able to do with traditional subtractive manufacturing. Furthermore, this approach also helps to localize manufacturing, reduce lead times and lower material waste whilst at the same time being flexible and thus allowing for mass customization. However, the drawback of this approach is the fact that this is still relatively slow when making items at scale, and the cost of the items can be higher than traditional manufacturing as mentioned before there’s a number of different 3d printing technologies. Powder bed fusion is one of the main methods for making metallic structures and works through the selective fusion of powder-based material, with something like a laser directed energy deposition is a little bit More niche, however, can be used to make very large metallic structures and works via diffusion of metal powders, which are directed into a melt pool formed by a laser material jetting systems can enable high resolution prints and work through the jetting of material in a similar way to inkjet printers. The most common form of material jetting is the polymer jetting system, but there are more emerging ceramic and metal based systems coming online, binder jetting systems have parallels with powder bed fusion and material jetting systems in that they jet out a binder material which fuses powders together to form an object here colour can be added material. Extrusion is perhaps the most commonly found 3d printing process, where the vast majority of plastic 3d printers use fuse deposition modeling where plastic is extruded through a hot end and selectively deposited onto a build plate sheet. Lamination is another niche 3d printing process where sheets of material are cut and then fused together, either by gluing welding or some other joining method. And finally, that photo polymerization or stereo lithography is another common 3d printing process for polymers, where monomers are polymerized through the selective application of UV radiation. Most stereolithography systems work through a single point polymerization system, But there are some new systems that do 2d layers or even volumetric printing in the case of metals. Selective laser melting is the most common form of 3d printing here. Metal powder is spread from a dosing chamber to a build plate. A laser then selectively melts the metal powder in specific regions to consolidate this. And once this is complete, the build platform lowers by a small amount A new layer is spread over the build platform and the process is repeated until the component is complete afterwards. The excess powder is removed and a part is removed from the build platform, however, whilst this approach can make impressive components. The cost of a selective laser melting machine can often be in excess of one hundred thousand pounds due to the expensive lasers, inert gases and other supporting systems. Thus, there’s a need to develop lower-cost metal additive manufacturing systems. Now, in order to find such a process, our exploration started with the electroplating process, which has been used for many years. The general premise here is that metal coatings can be applied to conductive surfaces through the application of electricity with the help of an ionically conductive electrolyte. In this general example, Solid metal is oxidized into a metal ion and electrons. This happens for many different metals, with the example of copper shown here, which converts from solid copper to a CU2 plus ion and two electrons at the other electrode. These metal ions are then reduced to form solid metal again. In the case of copper, this would convert copper ions into solid copper, with the addition of the electrons and ionically conductive electrolyte, then allows the ions to move from one electrode to the other in the case of copper. This would normally be something like copper sulfate. These processes have already been used in a range of applications such as gold plating jewelry and also chrome plating automotive parts. So this is a very well established technique. So with the electrochemical 3d printing process, we take this well established deposition technique and localize it. This is done by having a syringe filled with an electrolyte and an electrode of the material we want to deposit in the case of copper printing. We use copper sulfate and a copper bar where the nozzle of the syringe touches the conductive substrate. An ionic pathway is established, which if a voltage is applied allows us to localize the deposition of metal, This then moves around to make our 3d object. The advantage of this approach is that its extremely low cost, but it can also be used in a subtractive manner to remove material. If we flip the voltage or multiple materials can be printed through the use of different printing solutions and electrodes, this is something which traditional selective laser melting would find difficult to do and a clear advantage of the electrochemical 3d printing approach. Here you can see a render of the setup. We had with the working and counter electrodes for the deposition and the syringe filled with the electrolyte. A reference electrode is used to better control the printing process. The nozzle of the syringe is filled with a sponge to balance the hydraulic back pressure of the electrolyte, allowing for the formation of a stable meniscus which you can see on the right. In this case, we printed the letters ICL from copper to demonstrate the process now, while this is a very powerful printing technique compared to other printing approaches, this is relatively slow. Typically, the amount of plated material is related to voltage applied with higher voltages, leading to faster rates of deposition, however, if we go too fast, then we start to form dendrites of material instead of ideal dense structures so this remains a barrier for further development of this technology. Now we previously also mentioned that electrochemical 3d printing can also be multi-material. So here you can see how this can be achieved. In the first instance, we might print a base layer of material, say copper from copper sulfate. Then we might use a second syringe filled with a different material in this case, nickel and nickel sulfate, allowing us to print directly on top of the first deposited copper layer. Here you can see how we designed a system through the modification of a simple fuse deposition modeling 3d printer, highlighting the low cost nature of this system now with this ability to print in multiple materials, this allows us to make bimetallic structures, which if we intelligently place, the material allows us to have firmly responsive materials in the first case you can see with a bi-metallic structure. Since the thermal expansion coefficient of copper is higher than that of nickel, this causes a bending in the structure when heated and depending on where the material is deposited, we can achieve a range of different motions. In this example, we create self-assembling structures with the letters ICL very useful. If we take a look at the cross-section of the two-layer system and perform elemental analysis, we can clearly see the deposited layers of copper and nickel, which are well adhered. This is equally true for the tri-layer copper nickel copper system where a tie interface can be seen in the micrograph and again with the elemental compositions being confirmed with the energy dispersive spectroscopy measurements. In terms of applications. This programmability allows us to make electrical circuits, which are firmly activated or have a range of other smart functionalities, so to summarize additive manufacturing is a technique which allows us to make complex 3d objects with selective laser melting being the main metal additive manufacturing technique. Now whilst this is useful. Unfortunately, the machines are very expensive. Electrochemical 3d printing therefore, has the potential to be a lower cost solution to metal 3d printing and works through the localized deposition of metals. This shift, in the way we deposit material means that the systems can more easily be multi-material, which allows for the creation of self-assembling structures, which are firmly responsive. This was demonstrated with the multi-metal copper nickel system, but other metals are also possible, so hopefully this video was a useful introduction into what electrochemical additive manufacturing is and how it could potentially be a low-cost metal 3d printing method again. If you’d like to find out more about our work, please do check out our two papers on the topic in advanced material technologies and scientific reports, which are linked in the description below.