Binder Jet Additive Manufacturing Research Articles

Additive manufacturing of high-performance SiO2-Al2O3-K2O (Na2O) ceramic components via binder jetting technology

To resolve issues such as high sintering temperatures and relatively low relative densities and bending strengths of sintered bodies during the preparation of ceramic parts using binder jetting (BJ) additive manufacturing (AM) technology. In this study, high-performance SiO2-Al2O3-K2O (Na2O) ceramics were fabricated using quartz, kaolin, potassium feldspar, and sodium feldspar as raw materials through BJ technology. Initially, the sintering process of the BJ ceramics was studied by adjusting the ratio of potassium feldspar to sodium feldspar and the sintering temperature, which enhanced the relative density and bending strength of the silicate ceramics. Subsequently, using response surface methodology (RSM), the effects of print layer thickness (A), scraper speed (B), and ink volume per unit area (C) on the performance of the ceramics after sintering were investigated. Results indicated that the optimal parameters of the BJ printing process were determined using RSM: A was 250 μm, B was 3.44 mg cm−3, and C was 35 mm s−1. Under these conditions, the sintered ceramics achieved optimal relative densities, closed porosities, and flexural strengths of 89.05 %, 10.85 %, and 69.19 MPa for relative density, closed porosity, and flexural strength, respectively.

Fabrication of Cu-Infiltrated Journal Bearing by Binder Jetting Additive Manufacturing

In this study, considering the economic feasibility of products that can be produced through the binder jetting additive manufacturing process, 316L stainless steel, a widely used material with a wide particle size ranging from 15 to 106 μm, was used. The lubrication effect was increased by internal patterning through design for additive manufacturing, and journal bearing parts with excellent load resistance and wear resistance were implemented by using wear-resistant Cu as an infiltration material. In addition, to investigate the amount of Cu infiltrated as a function of porosity, the parts were pre-sintered from 1423 K to 1573 K, and the best performance was obtained when Cu was infiltrated after pre-sintering at 1473 K. As a result of rig testing of Cu-infiltrated journal bearings, mechanical properties were obtained that were more than 50% improved compared to those of mass products.

Achieving biomimetic porosity and strength of bone in magnesium scaffolds through binder jet additive manufacturing

Magnesium (Mg) alloys are a promising candidate for synthetic bone tissue substitutes. In bone tissue engineering, achieving a balance between pore characteristics that facilitate biological functions and the essential stiffness required for load-bearing functions is extremely challenging. This study employs binder jet additive manufacturing to fabricate an interconnected porous structure in Mg alloys that mimics the microporosity and mechanical properties of human cortical bone types. Using scanning electron microscopy, micro-computed tomography, and mercury intrusion porosimetry, we found that the binder jet printed and sintered (BJPS) MgZnZr alloys possess an interconnected porous structure, featuring an overall porosity of 13.3 %, a median pore size of 12.7 μm, and pore interconnectivity exceeding 95 %. The BJPS MgZnZr alloy demonstrated a tensile strength of ~130 MPa, a yield strength of ~100 MPa, an elastic modulus of ~21.5 GPa, and an ultimate compressive strength of ~349 MPa. These values align with the ranges observed in human bone types and outperform those of porous Mg alloys produced using the other conventional and additive manufacturing methods. Moreover, the BJPS MgZnZr alloy showed level 0 cytotoxicity with a greater MC3T3-E1 cell viability, attachment, and proliferation when compared to a cast MgZnZr counterpart, since the highly interconnected 3D porous structure provides cells with an additional dimension for infiltration. Finally, we provide evidence for the concept of using binder jet additive manufacturing for fabricating Mg implants tailored for applications in hard tissue engineering, including craniomaxillofacial procedures, bone fixation, and substitutes for bone grafts. The results of this study provide a solid foundation for future advancements in digital manufacturing of Mg alloys for biomedical applications.

Fabrication of porous Ni-Ti shape memory alloy via binder jet additive manufacturing and solid-state sintering

This paper explores the additive manufacturing of nickel-titanium (Ni-Ti) shape memory alloys (SMAs) using binder jetting and subsequent solid-state sintering under an Ar atmosphere. The consolidated 3D-printed Ni-Ti parts exhibit a correlation between pore morphology, pore fraction, and phase formation at different solid-state sintering temperatures. At a sintering temperature of 1175 °C, NiTi grains with TiC precipitates along grain boundaries are observed, accompanied by irregular, interconnected pores constituting ∼15 % of the volume. Increasing the sintering temperature to 1185 °C leads to the formation of a minor phase of Ni4Ti3 within NiTi grains, along with grain boundary TiC precipitates, and isolated pores with a volume fraction of ∼5 %. The higher sintering temperature corresponds to a higher average nanohardness value (8.1 GPa or 763 Hv compared to 6.9 GPa or 654 Hv), indicating the presence of a greater abundance of secondary phases and higher densification at the elevated sintering temperature. While the transformation temperatures (TTs) were undetectable in the bulk-printed samples, a different structure featuring designed channels and thin struts, sintered under similar conditions, exhibited detectable TTs, with a martensite start temperature of 34 °C. Biocompatibility tests demonstrated cell spreading and attachment on both sintered Ni-Ti samples. These findings offer valuable insights into the potential use of binder jetted Ni-Ti for medical implants and tissue engineering applications.

Denoising diffusion probabilistic models for generative alloy design

Inverse material design is an extremely challenging optimization task made difficult by, in part, the highly nonlinear relationship linking performance with composition. Quantitative approaches have improved significantly owing to advances in high throughput experimentation and computational thermodynamics. However, existing physics-based tools are mostly forward models; input a chemistry and obtain a prediction. More recently the materials community has leveraged advances in the machine learning community to establish novel inverse design frameworks. Very recently denoising diffusion probabilistic models have been shown to be extremely powerful generators producing synthetic data of various modalities e.g. images, text, audio, tables, etc.. In this work a novel framework for alloy design and optimization is proposed leveraging these class of models. Five key generative tasks are demonstrated (1) unconditional generation (2) composition conditioned generation (3) property conditioned generation (4) multi-feedstock conditioned generation and (5) generative optimization. These methods were tested on three case studies: high entropy alloy design, superalloy binder jet additive manufacturing, and in-situ dual-feedstock wire-arc additive manufacturing. Results indicate that the established models are extremely flexible, expressive, and robust. The architecture’s flexibility and training procedure empower the model to learn complex intra-compositional and composition-property relationships. Furthermore, the probabilistic nature of these models makes them well suited for addressing solution non-uniqueness and tackling uncertainty quantification tasks. While the fidelity and quantity of the underlying training data is paramount, we envision that future alloy design frameworks will make extensive use of these kinds of machine learning models as “search” tools bolstering the utility of experimental and computational approaches.

Spreading anomaly semantic segmentation and 3D reconstruction of binder jet additive manufacturing powder bed images

Variability in the inherently dynamic nature of additive manufacturing introduces imperfections that hinder the commercialization of new materials. Binder jetting produces ceramic and metallic parts, but low green densities and spreading anomalies reduce the predictability and processability of resulting geometries. In situ feedback presents a method for robust evaluation of spreading anomalies, reducing the number of required builds to refine processing parameters in a multivariate space. In this study, we report layer-wise powder bed semantic segmentation for the first time with a visually light ceramic powder, alumina, or Al2O3, leveraging an image analysis software to rapidly segment optical images acquired during the additive manufacturing process. Using preexisting image analysis tools allowed for rapid analysis of 316 stainless steel and alumina powders with small data sets by providing an accessible framework for implementing neural networks. Models trained on five build layers for each material to classify base powder, parts, streaking, short spreading, and bumps from recoater friction with testing categorical accuracies greater than 90%. Lower model performance accompanied the more subtle spreading features present in the white alumina compared to the darker steel. Applications of models to new builds demonstrated repeatability with the resulting models, and trends in classified pixels reflected corrections made to processing parameters. Through the development of robust analysis techniques and feedback for new materials, parameters can be corrected as builds progress.

Evaluating the sintering behaviors of ceramic oxide powders processed via binder jet additive manufacturing

AbstractBinder jet additive manufacturing is well suited for fabricating large (order of cm) and geometrically complex ceramic preforms. However, the main challenge in producing ceramic oxide parts via binder jetting is the high‐temperature postprocess tasked with eliminating internal porosity to achieve full densities. In this work, we demonstrate the ability to produce oxide ceramic parts with desirable densities by sintering binder jetted preforms. We investigate the sintering behavior of binder jetted preforms composed of three oxide powders with distinct morphologies: ball‐milled alumina, gas‐atomized silica, and sintered‐agglomerated zirconia. We fabricate the preform samples using a commercial binder jetting system and a conventional die‐pressing technique to understand the effect of starting densities. Furthermore, we parametrize the heating profiles to understand the effect of sintering temperature, sintering duration, and heating rate on each powder's densification behavior, microstructure, and phase composition. Results show the relatively low starting densities within the binder jetted preforms caused the onset sintering temperature to be higher than what is documented in conventional sintering studies. As expected, we observed sintered densities increase with respect to sintering temperature and duration. These findings were utilized to downselect sintering parameters capable of achieving high densities (>96%). Herein, this study validates the sintering of binder jetted preforms as a suitable way to manufacture ceramic parts, regardless of powder morphologies, thereby increasing the robustness of the supply chain involved in additive manufacturing of ceramic oxides.

Preparation of high-strength ZrO2 ceramics by binder jetting additive manufacturing and liquid glass infiltration

Binder jetting (BJ) additive manufacturing of zirconia (ZrO2) ceramics presently encounters the challenges of achieving high relative density, dimensional precision, and superior mechanical properties of the prepared ceramics. This study extensively investigates the impacts of BJ processing parameters—namely, binder saturation, layer thickness, roller speed, and printing layout—on the dimensional accuracy, density, and mechanical strength of the resulting green parts. The identification of optimal BJ processing parameters is pivotal in the fabrication of ZrO2 ceramic green bodies with superior dimensional precision and mechanical strength. The study shows that while solid-phase sintering alone can result in a relative density of 50.99%–54.27 % for BJ-processed ZrO2 ceramics, glass infiltration after sintering substantially elevates the relative density and flexural strength. Specifically, infiltration at an optimal temperature of 800 °C increases the relative density of the sintered ceramic to 94.49 % and flexural strength to 76.48 ± 3.25 MPa, which represent a significant improvement of 40.22 % in density and a 35-fold increase in strength of the sintered ZrO2 ceramics, respectively. These findings underscore the potential of BJ printing and subsequent glass infiltration as a synergistic approach to achieve high-performance ZrO2 ceramics through additive manufacturing.

Influence of CaCO3 on Density and Compressive Strength of Calcium Aluminate Cement-Based Cementitious Materials in Binder Jetting.

We investigated the impact of CaCO3 addition on the density and compressive strength of calcium aluminate cement (CAC)-based cementitious materials in binder jetting additive manufacturing (BJAM). To confirm the formation of a uniform powder bed, we examined the powder flowability and powder bed density for CaCO3 contents ranging from 0 to 20 wt.%. Specifically, powders with avalanche angles between 40.1-45.6° formed a uniform powder bed density with a standard deviation within 1%. Thus, a 3D printing specimen (green body) fabricated via BJAM exhibited dimensional accuracy of less than 1% across the entire plane. Additionally, we measured the hydration characteristics of CAC and the changes in compressive strength over 30 days with the addition of CaCO3. The results indicate that the addition of CaCO3 to CAC-based cementitious materials forms multimodal powders that enhance the density of both the powder bed and the green body. Furthermore, CaCO3 promotes the formation of highly crystalline monocarbonate (C4AcH11) and stable hydrate (C3AH6), effectively inhibiting the conversion of CAC and showing compressive strengths of up to 5.2 MPa. These findings suggest a strong potential for expanding the use of BJAM across various applications, including complex casting molds, cores, catalyst supports, and functional architectural interiors.

Pressure-less melt infiltration characteristics of Mg melt into Ti powder preforms with various pore structures: Toward the application to the binder jetting additive manufacturing

Binder jetting (BJT) additive manufacturing enables the fabrication of complex-shaped metallic parts but requires sintering as post-processing to obtain dense parts. The sintering inevitably causes the shrinkage from green body to dense products, resulting in low dimensional accuracy. In contrast, pressure-less melt infiltration (PMI) fills pores in the green body with a liquid metal driven by capillary pressure and fabricates a dense metal matrix composite without severe shrinkage. To consider the applicability of pressure-less melt infiltration to the post-processing of binder jetting additive manufacturing, it is required to clarify the relationship between pressure-less melt infiltration process conditions and the relative density of the composites. In this study, the liquid Mg/solid Ti system was selected because of good wettability and absence of Mg-Ti intermetallic, and the conditions of Ti powder preforms (corresponding to the green body) were focused on. Ti powder preforms with various powder sizes (2300, 410, 140, and 20 μm) and different shapes (irregular and spherical) were cold-pressed at 76, 102, 127, 153, and 178 MPa to fabricate preforms with various relative densities, pore sizes, and pore morphologies to response the similar characteristics in BJT preforms. Mg melt infiltrated into the preforms under constant conditions to fabricate Mg/Ti composites. The structures of the preforms and composites were characterized by sample size measurement, optical and scanning electron microscopy, and X-ray computed tomography. It was revealed that the relative density of the composite increased with decreasing Ti powder size and using spherical Ti powder, whereas the compact pressure exhibited a slight effect. Furthermore, defect volume increased with increasing infiltration height but decreased around the top surface of the sample. Minute observations around defects in the composites revealed that defects were formed at larger pores, and Mg melt was infiltrated into pores above the defects. These results indicated that infiltration velocity varied depending on the flow channel structure, and gas was trapped at larger pores (far from the outside of the sample) where infiltration velocity was low. Using smaller Ti powder decreased the variation in pore size in the preform, resulting in improving the relative density of the composites by suppressing the gas trapping. This study provides a new insight into the pressure-less melt infiltration process as a post-processing of binder jetting additive manufacturing.

Enhancing mechanical properties and density of WC-Co with pressureless sintering via shell structure binder jetting additive manufacturing

The binder jetting (BJT) additive manufacturing (AM) process is suitable for producing complex WC-Co cemented carbide parts. To achieve near-full-density in the final parts, the hot isostatic pressing (HIP) sintering process is typically employed to enhance densification. However, HIP sintering requires high equipment specifications and is relatively more costly compared to conventional pressureless sintering. To improve the density of WC-Co parts printed by BJT AM under the pressureless sintering environment, the shell structure printing method was used in this study. The shell structure printing only jets binder to the model's outer profile, creating a shell that encapsulates the central powder, mitigates binder pyrolysis and residual effects on particle densification, and enhances post-sintering density. In this work, the effect of shell thickness, binder type, and printing layer thickness on the density and mechanical properties of the WC-12Co parts under pressureless sintering conditions were investigated. The results show that the density and mechanical properties of the WC-12Co parts significantly improved with the decreasing shell thickness. Specifically, the WC-12Co printed using shell structure achieves a relative density of over 98% and a transverse rupture strength (TRS) of 1954 MPa after pressureless sintering, a result comparable to BJT printed samples treated with HIP sintering. Moreover, the results indicate using a binder with lower residual carbon content and smaller printing layer thickness has a more positive effect on improving density and mechanical strength when employing the shell structure printing method. Microstructure morphology and phase analysis results indicate that the shell structure printing method does not affect the growth of WC grains in the shell and center regions, nor does it influence its phase composition. The shell structure printing method offers a new approach to the manufacturing of near-full-dense WC-Co materials using the BJT process.

Effects of Layer Thickness and Compaction Thickness on Green Part Density in Binder Jetting Additive Manufacturing of Silicon Carbide: Designed Experiments

This paper reports on an experimental investigation that used a full factorial design to study the main effects and the interaction effect of layer thickness and compaction thickness on the green part density in the binder jetting additive manufacturing of silicon carbide. A two-variable, two-level full factorial design was employed. The results show that the green part density was higher at the low level of layer thickness and at the high level of compaction thickness. These results can be useful in selecting the values of printing variables, enabling the fabrication of green parts with a desirable density that is crucial for advanced ceramic applications.

Surface functionalization of binder jetted steels through super-solidus liquid phase sintering and electro-spark deposition

This study proposed a surface functionalization strategy for porous binder jet additive manufacturing (BJAM) steels. The methodology involves a sequential process of super-solidus liquid phase sintering (SLPS) followed by electro-spark deposition (ESD). SLPS with varying liquid fractions was used to modify the initial surface quality of BJAM steels, creating a range of surface roughness and bulk porosity. The ability of ESD to address substrate surface roughness and porosity variation was investigated using lower (Inconel 625) and higher (WC-Co) melting point coating materials. The results revealed a clear correlation between substrate surfaces and the surface finish, uniformity, and thickness of ESD deposits. Inconel 625, with its lower melting point, showcased an infiltration behavior and high tolerance to substrate conditions. Conversely, achieving high-quality WC-Co coating necessitated prior SLPS treatment to attain substrates with minimal roughness and sub-surface porosity. This investigation provides insights into optimizing surface modifications for porous BJAM metal parts, considering different coating materials and their compatibility with substrate conditions.

Preparation of high-density green body based on binder jetting 3D printing using spheroidized SiC powder

Silicon carbide (SiC) ceramic stands as a critical material in the realm of high-performance engineering ceramics. However, Crafting SiC ceramics with intricate structures and superior mechanical properties presents notable challenges in shaping, sintering, and processing. Binder jetting (BJ) additive manufacturing has the outstanding advantages of high forming efficiency and no thermal deformation, especially suitable for printing complex structure SiC components.; however, BJ printed green bodies often exhibit low density, resulting in high residual silicon content and diminished strength of the final components. In this work, we introduce a novel strategy to fabricate high-strength SiC components with complex geometries by improving the density of printed SiC green bodies. This method involves modifying the morphology of SiC powder through the molten salt method to increase the density of BJ 3D printed green bodies from 1.24 ± 0.13 g/cm³ to 2.01 ± 0.03 g/cm³, followed by a reactive melt infiltration process. The resulting RB-SiC ceramics display exceptional flexural strength, averaging 280.60 ± 33.05 MPa, and an elastic modulus of 294.67 ± 4.90 GPa. These values represent some of the highest for flexural strength and elastic modulus reported among 3D-printed SiC composites. With its robust mechanical performance and streamlined fabrication process, this strategy holds substantial promise for the production of structural SiC ceramics.

High-speed X-ray imaging of droplet-powder interaction in binder jet additive manufacturing

Binder jetting (BJ) is an additive manufacturing process that uses a powder feedstock in a layer wise process to print parts by selectively depositing a liquid binder into the powder bed using inkjet technology. This study presents findings from high-speed synchrotron imaging of binder droplet-interaction during the BJ printing process. A custom laboratory-scale BJ test platform was used for testing which enabled control of relevant process parameters including powder material, print geometry, spacing between droplets, powder bed density, and powder moisture content. Powder ejection was observed above the powder bed surface and powder relocation due to droplet impact was observed below the powder bed surface. Powder relocation was observed to be sensitive to powder material, powder bed density, powder bed moisture, droplet spacing, and print geometry. Increasing powder bed density was found to increase particle ejection velocity but reduce the total number of particles ejected. Process parameters that increase binder / moisture content in the powder bed were found to reduce powder ejection. The number of ejected powder particles was reduced for lower droplet spacings. Both powder ejection and powder relocation below the powder bed were reduced by treating the surface of the powder bed with a water/triethylene glycol (TEG) mixture before printing. Results from this study help to build understanding of the physical mechanisms in the BJ printing process that may contribute to formation of defects observed in final parts.

Dynamic shear resistance and its dependence on geometrical imperfection of high entropy Cantor alloy and BJAM 316L stainless steel

This paper examines the adiabatic shear resistance of recently popular Cantor alloy and Binder Jetting Additive Manufacturing (BJAM) 316L, with emphasis on their dependence on geometrical imperfection. A series of shear tests were conducted by using the long Split Hopkinson bar and shear compression specimen (SCS). Both alloys present strain rate dependent shear behaviour with the large dynamic shear failure strain of about 104 %–132 %. Microstructural characterizations reveal that both Cantor and BJAM 316L alloys fail by adiabatic shear band. Introduced by the varying notch root radius, the sharpness significantly affects the dynamic shear resistance of the Cantor and BJAM 316L alloys. The linear functions are proposed to describe the drop of critical strain and energy density with the designed inverse root radius.

Enhancing Quality Control: Image-Based Quantification of Carbides and Defect Remediation in Binder Jetting Additive Manufacturing.

While binder jetting (BJ) additive manufacturing (AM) holds considerable promise for industrial applications, defects often compromise part quality. This study addresses these challenges by investigating binding mechanisms and analyzing common defects, proposing tailored solutions to mitigate them. Emphasizing defect identification for effective quality control in BJ-AM, this research offers strategies for in-process rectification and post-process evaluation to elevate part quality. It shows how to successfully process metallic parts with complex geometries while maintaining consistent material properties. Furthermore, the paper explores the microstructure of AISI M2 tool steel, utilizing advanced image processing techniques like digital image analysis and SEM images to evaluate carbide distribution. The results show that M2 tool steel has a high proportion of M6C carbides, with furnace-cooled samples ranging from ~2.4% to 7.1% and MC carbides from ~0.4% to 9.4%. M6C carbides ranged from ~2.6% to 3.8% in air-cooled samples, while water-cooled samples peaked at ~8.52%. Sintering conditions also affected shrinkage, with furnace-cooled samples showing the lowest rates (1.7 ± 0.4% to 5 ± 0.4%) and water-cooled samples showing the highest (2 ± 0.4% to 14.1 ± 0.4%). The study recommends real-time defect detection systems with autonomous corrective capabilities to improve the quality and performance of BJ-AM components.

Silicon carbide ceramics formed by binder jetting: A study focusing on the printing layer thickness and the PIP densification process

Binder jetting (BJ) additive manufacturing has the advantages of high precision, fast forming speed, and no need for supporting structure, which is especially suitable for the forming of metallic and ceramic components with complex structures. In this paper, SiC ceramic parts were obtained by BJ additive manufacturing and precursor impregnation pyrolysis (PIP) cycles. It has been observed that the thickness of the printing layer significantly affects the strength of the SiC green body. The SiC green body exhibited the highest bending strength (3.1 ± 0.2 MPa) and lower dimensional deviation (0.47–1.64 %) when printed with a layer thickness of 50 μm. However, the bending strength of the SiC ceramics (after densification) had little variations when different printing layer thicknesses were utilized. In the subsequent densification process, the density, hardness, and bending strength of SiC ceramics increase as the number of PIP cycles increases obviously, and the flexural strength reached 228.7 ± 14.2 MPa after 9 PIP cycles, while the shrinkage rates in the X, Y, and Z direction were 1.9 %, 2.8 %, and 1.2 %, respectively. In addition, the influence mechanism of printing parameters on the strengths of the green bodies and SiC ceramics was also discussed. Specifically, it was found that with the layer thickness increase, the strengths of SiC ceramics also increase.

Bimodal powder optimization in SiC binder jetting for mechanical performance

Binder jetting (BJ) additive manufacturing has emerged as a promising technique for batch production of complex silicon carbide (SiC) ceramic components. However, the utilization of coarse powder in BJ often leads to lower density and strength in green parts and final composites compared to conventional fabrication methods. This study aims to enhance the mechanical performance of SiC ceramics through a novel bimodal SiC powder formulation for BJ, complemented by phenolic resin impregnation and pyrolysis (PRIP) and liquid silicon infiltration (LSI). The optimal ratio of bimodal powder, comprising 75 % coarse and 25 % fine powder, was determined through a comprehensive analysis of the microstructure and properties at various stages of the preparation process. The bimodal powder achieves a packing density of 48.3 % and exhibits satisfactory flowability. Notably, the density of the green part reaches 1.78 g/cm3, which is 31 % and 4.7 % higher than that of unimodal fine and coarse powders, respectively. Following the LSI process, the final Si-SiC composites display a high flexural strength of 276.6 ± 13.3 MPa and fracture toughness of 3.52 ± 0.12 MPa·m1/2. These values represent increases of 42.4 % and 25.3 %, respectively, compared to the composites derived from unimodal coarse powder. The material compositions and fabrication strategies proposed in this work offer an effective pathway for creating high-performance SiC ceramic composites via binder jetting.

Adhesive and alloying properties of dual purpose polyfurfuryl alcohol binder for binder jet additive manufacturing of steel

In-situ alloying in steel can be achieved in the binder jet additive manufacturing process by incorporating alloying elements into the binder. However, using binders with nanoparticle suspensions often leads to challenges with particle dispersion uniformity and nozzle clogging. To circumvent these limitations, we investigated the feasibility of using a particle-free binder based on poly(furfuryl alcohol) (PFA) for binder jet 3D printing of steel. The PFA binder serves dual purposes – (i) imparting structural integrity to the as-printed green part and (ii) providing carbon upon pyrolysis to alloy the printed iron parts into steel. The PFA binder was first dispensed layer-by-layer into a low alloy steel powder bed to produce green parts with a storage modulus of 3360 MPa and a compressive strength of up to 9 MPa. Compared to the control, a commercial carbon binder ink, the present particle-free PFA formulation offered better green part rigidity (+18%) and strength (+18.5%) for the same amount of carbon alloying. The green parts were then subjected to debinding and sintering to consolidate the steel powder particles. During vacuum sintering, the PFA was pyrolyzed and left behind a carbon residue which diffused into the steel part to form a hard and strong ferrite-carbide aggregate phase that significantly enhanced the hardness, yield strength and ultimate tensile strength of the sintered steel parts. Furthermore, by varying the amount of this particle-free binder formulation at different locations, components with site-specific microstructures and mechanical responses, confirmed through hardness tests and digital image correlation, were also demonstrated.