Binder jet additive manufacturing method to fabricate near net shape crack-free highly dense Fe-6.5 wt.% Si soft magnets

Abstract

High silicon (Si) electrical steel has the potential for efficient use in applications such as electrical motors and generators with cost-effective in processing, but it is difficult to manufacture. Increasing the Si content beyond 3 wt.% improves magnetic and electrical properties, with 6.5 wt.% being achievable. The main goal of this research is to design, develop, and implement a scalable additive manufacturing process to fabricate Fe with 6.5 wt.% Si (Fe–6Si) steel with high magnetic permeability, high electrical resistivity, low coercivity, and low residual induction that other methods cannot achieve because of manufacturing limitations. Binder jet additive manufacturing was used to deposit near net shape components that were subsequently sintered via solid-state sintering to achieve near full densification. Here, it is shown that the use of solid-state sintering mitigates cracking since no rapid solidification occurs unlike fusion-based additive technologies. The Fe–6Si samples demonstrated an ultimate tensile strength of 434 MPa, electrical resistivity of 98 μΩ cm, and saturation magnetization of 1.83 T with low coercivity and high permeability. The results strongly supports to replace the only available 0.1 mm thick chemical vapor deposition (CVD) produced Si steel using the cost effective AM method with good mechanical and magnetic properties for motor applications.

Additive Manufacturing of Micro-Electro-Mechanical Systems (MEMS)

“…The result of the first phase of the process is a 3D object called the "green part". The green part is then subjected to extensive post-processing, including debinding, sintering and, eventually, infiltration and hipping (hot isostatic pressure) to remove the binder solution and increase the mechanical strength by reducing porosity [76,77,79,[81][82][83][84][85]. In the case of ceramics, the resolution of PBBJ is largely variable in the range 22-500 µm [86,87], while in the case of metals and polymers the typical feature size is about 100 µm [13], with variations related to the powder grains dimension [86].…”

Porosity, cracks, and mechanical properties of additively manufactured tooling alloys: a review

“…The use of these materials allows for the generation of parts for different applications. Figure 9 shows some examples of parts fabricated using BJ and different powder materials [71][72][73].…”

“…A vast amount of research is available in the literature focused on analyzing the machinability of different Fig. 9 Examples of the different materials processed by BJ printing suited for various applications a compression samples for lattice designs [71], b hollowed components to save weight, c internal channels for efficient cooling [72] and d magnetic part [73] materials and alloys. Many studies [79,80] have conducted an experimental tests of the material machinability based on different measurements, such as the cutting forces, surface roughness generated by a specific cutting pressure, tool wear, and cutting temperature.…”

Powder-Based 3D Printing for the Fabrication of Device with Micro and Mesoscale Features

“…However, the post-processing (e.g., debinding) of green parts could be time-consuming, and the green parts often are not suitable for designed applications. Generally, sintering is required to reduce porosity and improve mechanical preformation of the 3D-printed green part, and infiltration is sometimes required ( Figure 3 a) [ 82 , 91 , 92 , 93 , 94 , 95 , 96 ]. After fabrication, hot isostatic pressing could be used to increase the density of the green parts [ 63 , 66 , 82 , 83 , 93 ].…”

“…( a ) Computer-aided design image to sintered part. Reproduced with permission from [ 92 ]; ( b ) PBBJ 3D-printed mesh structures with powder size < 20 µm. The designed width is 400 µm, and the measured width ranges from 650–770 µm.…”