Surface Treatment Of Particles Research Articles

Technical cleanliness of additively manufactured Inconel 718: a comparative study of surface treatment methods

PurposeMetal laser-powder-bed-fusion using laser-beam parts are particularly susceptible to contamination due to particles attached to the surface. This may compromise so-called technical cleanliness (e.g. in NASA RPTSTD-8070, ASTM G93, ISO 14952 or ISO 16232), which is important for many 3D-printed components, such as implants or liquid rocket engines. The purpose of the presented comparative study is to show how cleanliness is improved by design and different surface treatment methods.Design/methodology/approachConvex and concave test parts were designed, built and surface-treated by combinations of media blasting, electroless nickel plating and electrochemical polishing. After cleaning and analysing the technical cleanliness according to ASTM and ISO standards, effects on particle contamination, appearance, mass and dimensional accuracy are presented.FindingsContamination reduction factors are introduced for different particle sizes and surface treatment methods. Surface treatments were more effective for concave design features, however, the initial and resulting absolute particle contamination was higher. Results further indicate that there are trade-offs between cleanliness and other objectives in design. Design guidelines are introduced to solve conflicts in design when requirements for cleanliness exist.Originality/valueThis paper recommends designing parts and corresponding process chains for manufacturing simultaneously. Incorporating post-processing characteristics into the design phase is both feasible and essential. In the experimental study, electroless nickel plating in combination with prior glass bead blasting resulted in the lowest total remaining particle contamination. This process applied for cleanliness is a novelty, as well as a comparison between the different surface treatment methods.

Development and Characterization of the Shale Stratum Well Wall Stabilized with Nanosomal Sealing Agent.

The development of micro cracks in shale formations can easily lead to wellbore instability caused by liquid phase invasion. In order to effectively seal the shale micropores, the surface treatment of nano-SiO2 particles was developed using the silicane coupling agent A-1891. Then, the temperature-sensitive polypenic acrylamide polymer was modified onto the surface of the nanoprocal particle through reaction to obtain the nanosomal blocking agent ASN. The infrared spectrum shows that there are chemical bonds between the generated polymer chains, rather than simple physical composites, indicating the successful synthesis of the temperature-responsive nanosealing agent ASN. The particle size analysis showed that the synthesized nanoparticles in ASN have a uniform particle size distribution and display no agglomeration phenomenon. Applying ASN as a sealing agent in drilling fluid effectively fills the nanoscale micropores and microcracks in shale, making shale denser and significantly improving the wellbore stability of shale formations. In addition, it has good temperature resistance, can adapt to reservoirs at different temperatures, is non-toxic and environmentally friendly, and has good prospects for stable applications in shale formation wellbore.

Tunable coffee-ring patterns of sessile suspension droplets through silica particle encapsulation with thermo-responsive block copolymers

Silica (Si) particles coated with poly(methyl methacrylate-b-N-isopropylacrylamide) (PMMA-b-PNIPAM) block copolymers (Si-PM-PN particles) were engineered to mitigate the coffee-ring effect (CRE) frequently encountered during the drying process of particulate suspensions. Leveraging the thermo-responsive transition between the hydrophilic and hydrophobic states of PNIPAM, with its lower critical solution temperature (LCST) around 32 °C, enabled precise adjustment of the CRE. Through microrheological analysis using multi-speckle diffusing wave spectroscopy and observation under an optical microscope, the dynamic behaviors of Si-PM-PN particles in sessile suspension droplets during drying were scrutinized both below and above the LCST. Above the LCST, the Si-PM-PN particles exhibited hydrophobic characteristics, with some migrating toward the center along the droplet interface, resulting in a more uniform particle distribution post-drying. Conversely, below the LCST, the homogeneously dispersed Si-PM-PN particles displayed rapid Brownian motion, contributing to a pronounced CRE. This approach, involving the surface treatment of particles with thermo-responsive polymers, effectively altered the droplet pattern by modulating particle interactions with the air–water interface.

Organic-inorganic core-shell materials as reinforced fillers of UHMWPE to improve its tribological and mechanical properties

Generally, modification of materials by adding multiple types of nano particles could cause dispersion problems, generally limited the performance improvement effect. Herein, we report the modification of UHMWPE materials by organic-inorganic core-shell particles with PTFE as the core and Al(OH)3 as the shell, which prepared by in-situ polymerization of sodium bicarbonate and aluminum sulfate solution. Core-shell particles were filled in UHMWPE matrix and sintered into composite by spark plasma sintering (SPS). The mechanical and tribological properties of the composites were characterized by tensile compression testing machine, universal micro tribometer (UMT-5), three-dimensional white light interferometer and scanning electron microscope (SEM). The results showed that the addition of core-shell structural materials effectively improved the tribological properties (friction coefficient decreased by 40%, wear rate decreased by 30%) and mechanical properties (compression strength increased by 2.4 times) of the composites. It was demonstrated that the inorganic framework provided strength to improve the mechanical properties and wear resistance of materials, and the organic phase was used as a lubricating phase to reduce the friction coefficient of materials. Surface treatment of core-shell particles both improved the binding between particles and matrix and decreased the formation of agglomerations, thus significantly reducing ploughing phenomena’s effect produced by abrasive wear of agglomeration

A comprehensive review on polystyrene/waste rubber blends: Effective parameters on mechanical properties

AbstractPolystyrene (PS), as a commercial thermoplastic polymer, suffers from brittleness at low temperatures. Blending with elastomers can resolve this defect. In this regard, waste rubbers from tires, shoes, and other sources are promising candidates for some applications. This approach of waste rubber recycling is an environmental‐friendly and economical method to produce value‐added products. This work aims to comprehensively review all reported cases regarding PS (or high‐impact polystyrene, HIPS, and expanded polystyrene, EPS)/waste rubber blends. The influences of different parameters on the mechanical properties were carefully summarized, including mixing conditions (temperature, mixing time, rotor speed, and mixing sequence), rubber content, rubber particle size, compatibilizer addition, rubber devulcanization, and surface treatment of rubber. Some parameters had a negligible effect on the mechanical properties, such as the rotor speed in the mixing process, while significant influences were observed for some parameters, such as rubber content. The effect of some parameters was remarkable only at low or high rubber loading, such as particle size and solvent‐inducing surface treatment of rubber, respectively. Finally, the effects of aforementioned parameters on tensile and impact strengths were compared and recommendations for future research in this field were suggested.Highlights All reported research regarding PS/waste rubber blends was comprehensively reviewed. All different factors influencing mechanical properties were carefully summarized. The effects of different factors on tensile and impact strengths were compared.

Effect of rubber surface treatment on damping performance of rubber-mortar ITZ in rubberized concrete

The reduction of the mechanical properties of rubberized concrete can be alleviated by surface treatment of rubber particles, which changes the interface between cement and rubber particles. The dynamic properties of the rubber-mortar interface under different bonding states were explored by performing four-point bending tests on the rubberized concrete beams. The free decay method was used to test the damping ratios of rubberized concrete beams with different interfaces and damage states. Isight was used to build an inversion analysis platform to determine the damping ratios of the rubber-mortar interfaces with different bonding states. The results show that: (1) Compared with the water treatment, the damping ratio of rubberized concrete modified by sodium hydroxide decreased by 3.01 %, while zinc stearate modification increased the damping ratio by 15.37 %; (2) The average increase in the damping ratio of zinc stearate rubberized concrete was 14.51 % for each damage level. Sodium hydroxide resulted in a 75.4 % decrease in the rubber-mortar interfacial damping ratio, while zinc stearate increased the interfacial damping ratio by 381.9 %; (3) The relationship among the normal bond strength, fracture energy and interface damping ratio was fitted by a planar relation formula.

Surface modification of particles in a photochemical fluidized bed

Different techniques have been recently studied to promote the surface modification of materials. Surface modifications are used to improve the performance of materials in diverse areas, such as chemical processes, pharmaceutical industry and agriculture. Despite the considerable work in the literature on the subject, the experiments carried out were always conducted with small samples of the materials, and the performance of the treatment on a larger scale has yet to be evaluated. This work aimed to make the surface modification of particles of different materials by UV-assisted treatment in a photochemical fluidized bed. The purpose was to verify the feasibility of treating particles with UV radiation on a larger scale, something not yet found in the literature. The analyzed materials were two polymers and four types of forage seeds. The effect of UV radiation on the surface was checked using the water contact angle (WCA) and FTIR analysis. The treated seeds were also submitted to the Standard Germination Test (SGT) to verify eventual physiological damages and possible beneficial effects of the treatment. The results indicated a significant decrease in the contact angle of the treated particles of all materials because of the incorporation of oxygenated groups on their surface. In turn, the SGT pointed out not only that the seeds were not damaged by radiation but also that there was a significant increase in the agronomic index for two of the species studied. The data obtained in this work showed that the photochemical fluidized bed proved a viable way to carry out the surface treatment of particles with UV radiation, making it possible to conduct the process on a larger scale.

Spherical CaCO3: Synthesis, Characterization, Surface Modification and Efficacy as a Reinforcing Filler in Natural Rubber Composites

Natural rubber (NR), an important natural polymer derived from the Hevea brasiliensis tree, has been widely used in the rubber industry owing to its excellent elastic properties. However, it requires reinforcing fillers to improve its mechanical properties for the manufacturing of rubber products. Generally, calcium carbonate (CaCO3) is employed as a non-reinforcing filler. This work aimed to synthesize spherical-shaped CaCO3 at a submicrometric scale without and with surface treatment and explore its utilization as a reinforcing filler in NR composites. The morphological shape and polymorphic phase of CaCO3 were investigated using SEM, TEM, XRD, ATR-FTIR and Raman techniques. The mechanical properties of various amounts (0 to 60 phr) of CaCO3-filled NR composites were explored. As a result, the NR/treated CaCO3 composites provided higher tensile strength than the NR/untreated CaCO3 composites and pure NR at all filler loadings. This may have been due to the improved interfacial interaction between NR and CaCO3 with the improved hydrophobicity of CaCO3 after treatment with olive soap. The optimal filler loading was 20 phr for the highest tensile strength of the rubber composites. In addition, the elongation at break of the NR/treated CaCO3 was slightly decreased. Evidence from SEM and FTIR revealed the vaterite polymorph and shape stability of CaCO3 particles in the NR matrix. The results demonstrate that the particle size and surface treatment of the filler have essential effects on the mechanical property enhancement of the rubber composites. Synthesized spherical CaCO3 could be a potential reinforcing filler with broader application in polymer composites.

Improvement of thermo‐mechanical and dielectric properties of poly(lactic acid) and thermoplastic polyurethane blend composites using a graphene and BaTiO3 filler

AbstractThis study focuses on the development of composite materials using thermoplastic polyurethane (TPU) and poly(lactic acid) (PLA) with fillers such as barium titanate (BaTiO3) and graphene. Suitable surface treatment of filler particles is applied to activate the fillers to enhance the compatibility between the fillers and polymer matrix. Specifically, the BaTiO3 particles are hydroxylated and treated with glycidyl methacrylate (GMA), which acts as a compatibilizer between the two matrix polymers. On the other hand, the graphene particles are hydroxylated and treated with isophorone diisocyanate (IPDI), which reacts with the TPU soft segment chains during composite fabrication. The composite samples are fabricated via melt‐blending at 190°C, followed by mini molding at the same operating temperature for subsequent analysis. The results demonstrate a three‐fold improvement in the dielectric constant of 40 wt.% BaTiO3 and graphene–TPU–PLA blends composites relative to that of the neat TPU, along with an improved tensile strength. The tensile strength improvement is attributed to the support of the TPU matrix against the low ductility of the PLA. The thermal conductivity was doubled as compared with the neat TPU–PLA matrix for the 40 wt.% BaTiO3 and graphene–TPU–PLA blends.Highlights Composites of TPU–PLA–graphene and BaTiO3 filler particles were fabricated. The melt blending technique was employed to fabricate the composite. The dielectric constant was analyzed at both constant and variable frequencies. Thermal conductivity was doubled (40 [graphene + BaTiO3])

The Impact of Particle Size and Surface Treatment of Zirconia Suspension for Photocuring Additive Manufacturing.

To prepare a photocurable ceramic suspension for use in commercialized additive manufacturing equipment, the effects of the rheological properties of zirconia particles added to a binder, and the presence or absence of a silane coupling agent on the particles was evaluated. To this end, three experimental groups (ZSs, ZMs, ZLs) and three control groups (ZS, ZM, ZL) were designed depending on the size of the underlying zirconia particles. The test-group zirconia suspensions were prepared through silanization, which was not applied to the control-group suspensions. Depending on the particle size, viscosity differences between the test and control groups were 16,842, 18,623, and 12,303 mPa·s, respectively. Compared to the other groups, the viscosity of the ZLs group suspension decreased by 70.98-88.04%. This confirmed that the viscosity of the suspensions was affected by the particle size and the presence of silane coating. The dispersion stability of the zirconia suspensions was evaluated over 20 days. A sedimentation test confirmed that the sedimentation rate of the ZLs group was slower than those of the other groups. This study aimed to optimize the suspension manufacturing method to effectively be utilized in further commercializing zirconia three-dimensional (3D) printing and could also help to develop various medical applications.

Fabrication of thermoplastic polyurethane composites with a high dielectric constant and thermal conductivity using a hybrid filler of CNT@BaTiO3

Thermoplastic polyurethane composites with an excellent dielectric constant and high thermal conductivity were obtained using CNT@BaTiO3 as a filler through a low-speed melt extrusion method. Before preparing the hybrid filler for the composite, the filler particles were surface modified to ensure that the outer surfaces could facilitate the reaction among particles to form the hybrid and ensure complete dispersion in the thermoplastic polyurethane matrix. After confirming the proper surface treatment of the filler particles using infrared spectroscopy, thermal degradation analysis and field emission scanning electron microscopy, they were used to prepare the composite materials at a processing temperature of 200 °C. The thermal stability, thermomechanical properties, mechanical properties, thermal conductivity, and dielectric properties of the composites were investigated. Compared to the neat thermoplastic polyurethane matrix, the prepared composite exhibited a higher thermal stability, approximately 300% higher storage modulus, higher tensile strength and elongation at break values, approximately three times higher thermal conductivity (improved from 0.19 W/(m.K) to 0.38 W/(m.K), and approximately five times larger dielectric constant at high frequencies (at 1 MHz a dielectric constant of 19.2 was obtained).

Aqueous Manufacturing of Ni-Rich Cathodes Using Polyacrylic Acid As Binder for Lithium-Ion Batteries

In the field of secondary batteries, the lithium-ion battery (LIB) is one of the most promising candidates for future electric vehicle (EV) applications, due to its high specific energy and good specific power [1]. However, to meet the demands in large scale storage, not only higher energy and power density and lower cost are needed, but environmentally friendly processing of LiBs is getting more in the focus of research.To meet the desirable requirements, one necessity is to tune the cathode in terms of sustainable production and materials. Ni-rich layered LiNi x Mn y Co1−x−y O2 (NMCs, x ≥ 0.8) cathodes are poised to be the dominating cathode materials for lithium-ion batteries for the foreseeable future due to its high energy density [2]. The state-of-the-art NMC based cathode production in both industrial and lab scale is with polyvinylidene fluoride (PVDF) in organic solvent N-methyl-2-pyrrolidone (NMP). NMP is a toxic, expensive, and highly flammable organic solvent [3]. Replacing NMP with water in the production of LiB cathodes is critical in terms of process cost savings and environmental concerns. Aqueous processes of NMC based cathodes are highly favorable as well as challenging due to the high reactivity of NMC particles. During the slurry preparation, the surface of Ni-rich particles undergoes Li leaching via exchange between H+ from water and Li+ from the active material which leads to increase in pH of the slurry. Li leaching leads to capacity fade and reduces the specific capacity of the cathode. The high pH of the slurry causes corrosion on the aluminum current collector. Surface treatment of NMC particles is a way to prevent Li leaching as well as using carbon coated Al current collector to resist the corrosion, but in terms of production cost these methods are not favorable.In this study, our fundamental aim is to demonstrate the manufacturing of large scale water based NMC811-PAA cathodes. We therefore employ a well-known binder material, polyacrylic acid (PAA), which is water soluble and an anionic polymer. During the mixing processes of the slurry, H+ from PAA can drive Li+ leaching, the leached Li+ reacts with carboxylic groups of PAA and binds to the PAA backbone. Thus, the reaction of H+ and OH- neutralizes the pH of the slurry. Bonded Li+ on PAA creates an active binder in which these Li ions can participate as an additional Li source to aid to prevent capacity decrease. This method has been successfully implemented in the lab scale [4]. Our main target is to investigate the slurry behavior and scalability of the cathodes with a PAA binder. Herein, we report high solid content of slurry behavior of NMC with PAA and the comparison to the conventionally produced slurry for the first time. Also, we show how the slurry behavior is affected by the mixing techniques from lab scale to pilot scale, which is an important parameter for later transfer to industrial production. The electrodes and successfully formed LiPAA as binder are shown by Fourier transformed infrared (FTIR) and Raman spectroscopy. The electrochemical tests are performed both in half and full cell configuration for NMC811-PAA and NMC811-PVDF cathodes.

Effect of fine particle shot peening on surface friction of stainless steel and ceramic bracket slots

This study aims to compare the static friction of untreated and fine particle shot peening (FPSP) treated stainless steel and ceramic bracket slots. A total of 60 pieces of stainless steel and 60 pieces of ceramic brackets (Roth prescription, 0.022×0.028 in2) were divided into 3 groups: control (n=20), silica glass bead particle surface treatment (n=20) and stainless steel (SUS316L) particle surface treatment (n=20). Ten brackets of each group were combined with 0.019×0.025 in2 orthodontic stainless steel arch wires and were analyzed for static friction. The remaining 10 brackets of each group were tested for slot surface roughness and hardness. The result shows that stainless steel brackets treated with FPSP exhibited lower static friction, with smoother and harder surfaces than the control group (p<0.05). In contrast, treated ceramic brackets showed no difference from the control group in terms of static friction, roughness, and hardness (p>0.05).

Method for Manufacturing Corn Straw Cement-Based Composite and Its Physical Properties.

This paper introduces an innovative method for making cement-based composites from corn straw plants, and investigates the strength, thermal conductivity, and hydration characteristics of the composites. Corn straw is a natural, renewable, and breathable thermal insulation composite that contains cellular sealed pores. Corn straw contains a large amount of soluble cellulosic sugar, which hinders the hydration reaction of Portland cement and affects the use of corn straw as a building material. In this study, a 3 wt.% siliceous solution was used for surface treatment of corn straw particles to prevent cellulosic sugar from affecting the hydration performance of Portland cement. The composition of added cement-based composite materials with treated corn straw at the dosage of 11–20 wt.% was investigated. The test results showed that the corn straw cement-based composite (CSCC) had an optimal thermal conductivity of 0.102–0.112 (W/(m·K)) and a minimum compressive strength of above 1 MPa. The hydration performance of four typical CSCCs was examined using XRD, SEM, and EDS. The experimental results of this study may help to increase the comprehensive utilization of corn straw. The manufacturing method of the composite materials is simple, effective, and convenient for popularization and application, and it provides a new important technical measure to solve the problem of high energy consumption in rural houses.

InGaAs/InP Schottky barrier diode with submicron T-shaped contact and Cut-Off frequency above 9 THz

A high-performance terahertz InP Schottky Barrier Diode (SBD) with a submicron T-shaped contact structure featuring a high theoretical cut-off frequency of 9.0 THz is reported in this paper. The Schottky contact with a minimum diameter of 0.2 μm was achieved by photoresist laminate and gradient exposure process, exhibiting a minimum zero-bias junction capacitance is 0.15 fF. The quality of Schottky contact was improved by surface treatment of particles and high-temperature passivation of the edge with a polymer film, with an ideal factor of between 1.2 and 1.4. The high-frequency performance of the diode is further improved due to the small parasitic capacitance contributed by the polymer film dielectric bridge. The terahertz monolithic integration circuit based on this T-shaped contact submicron Schottky has better performance in reducing the circuit dielectric loss, exhibiting a remarkable potential for high-frequency applications.

Assessing the similarity of nanoforms based on the biodegradation of organic surface treatment chemicals

A substance may have one or more nanoforms, defined for regulatory purposes under EU chemicals legislation REACH based on differences in physicochemical properties such as size, shape, specific surface area and surface chemistry including coatings. To reduce the burden of testing each unique nanoform for the environmental risk assessment of nanomaterials, grouping approaches allow simultaneous assessment of multiple nanoforms. Nanoforms with initially different intrinsic properties, could still be considered similar if their environmental fate and effects can be demonstrated to be similar. One hypothesis to group nanoforms with different organic surface modifications is to use parameters linked to biodegradation of the organic surface. The hypothesis contends that nanoforms with a similar core chemistry, but different organic surface treatments may be grouped, if the surface treatment is likely to be lost through biodegradation rapidly upon entering an environmental compartment, such that it no longer modulates fate, exposure and toxicity of the nanoform.To implement grouping according to surface treatment biodegradability, a robust approach to measure the breakdown of particle surface treatments is needed. We present a tiered testing strategy to assess the biodegradation of organic surface treatments used with nanomaterials that can be implemented as part of an Integrated Approach to Testing and Assessment (IATA) for grouping based on surface treatment stability. The tiered approach consists of an initial pre-screening MT2 colorimetric carbon substrate utilisation assay, to provide a rapid assessment of coating degradation, and a second tier of testing using OECD Test Guideline 301F for assessing organic chemical biodegradability. Six common surface treatment substances are assessed using the tiered testing strategy to refine rules for escalating between tiers. Similarity assessment using absolute Euclidean distances and x-fold difference concluded that the Tier 1 assessment can be used as conservative binary screening for biodegradability (no false positive results in Tier 1), whilst for substances showing intermediate biodegradation (10–60% in OECD 301F, Tier 2), similarity assessments can be informative for grouping surface treatments not considered readily biodegradable. Further validation using higher tier tests (e.g., mesocosms) is needed to define acceptable limits of similarity between intermediately biodegradable substances, where differences in biodegradability of the surface coating lead to negligible differences in fate, behaviour and toxicity of the nanoforms, and this is critically discussed.

Particle-resin systems for additive manufacturing of rigid and elastic magnetic polymeric composites

Fiber-reinforced polymeric composites (FRPCs) with selective fiber orientations are finding applications in building biological constructs, smart materials and energy devices. Field-assisted additive manufacturing (AM) has emerged as one of the promising methods for creating FRPC structures. Compared to other AM processes and due to the liquid form of the raw materials, vat photopolymerization has shown higher potential in building FRPCs with selective fiber orientation. Compared to other methods of controlling the fiber orientation during AM processes, magnetic field-assisted fiber reorientation, is a relatively easy-to-use contactless method that has been effectively paired with vat photopolymerization. One of the major issues in magnetic field-assisted vat photopolymerization is the dispersion instability of the particles in resin system, which leads to separation between the resin components and dispersed particles and results in non-uniform particle distribution during the printing process. In this study, ferromagnetic particle-loaded photocurable resins are developed through surface modification of the particles to achieve more uniform particle dispersion, more dispersion-stable resins systems and enhanced mechanical properties of FRPCs. Magnetite particles were functionalized under silanization reactions and mixed with two photocurable resins. Fourier-transform infrared spectroscopy (FTIR) analysis was used to select the matching composition of silane compounds and verify the functionality of the treated magnetite particles for each resin mixture. Dispersion stability of the developed resin system was verified by visual observation of the resin mixture and image analysis of microscope images. To provide a better guideline for 3D printing the developed resin system, cure depth of each resin system containing different particle fractions is studied. Tensile tests are devised to understand the effects of particle content, orientation, and surface treatment on mechanical properties of the 3D printed FRPCs. Results of this study suggest that an optimized particle-resin system can be developed through surface treatment of magnetite particles with functional groups.

Surface treatment of clayey soil particles for reducing water loss through evaporation

To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200–500 µm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobic-treated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.

Surface Treatment of Industrial-Grade Magnetite Particles for Enhanced Thermal Stability and Mitigating Paint Contaminants.

Pigments can retain their color for many centuries and can withstand the effects of light and weather. The paint industry suffers from issues like aggressive moisture, corrosion, and further environmental contamination of the pigment materials. Low-cost, long-lasting, and large-scale pigments are highly desirable to protect against the challenges of contamination that exist in the paint industry. This exploratory study reinforces the color and thermal stability of industrial-grade (IG) magnetite (Fe3O4). IG Fe3O4 pigments were further considered for surface treatment with sodium hexametaphosphate (SHMP). This metaphosphate hexamer sequestrant provides good dispersion ability and a high surface energy giving thermal and dust protection to the pigment. Various physicochemical characterizations were employed to understand the effectiveness of this treatment across various temperatures (180–300 °C). The X-ray diffraction, Raman, and X-ray photoelectron spectroscopy techniques signify that the SHMP-treated Fe3O4 acquired magnetite phase stability up to 300 °C. In addition, the delta-E color difference method was also adopted to measure the effective pigment properties, where the delta-E value significantly decreased from 8.77 to 0.84 once treated with SHMP at 300 °C. The distinct color retention at 300 °C and the improved dispersion properties of surface-treated Fe3O4 positions this pigment as a robust candidate for high-temperature paint and coating applications. This study further encompasses an effort to design low-cost, large-scale, and thermally stable pigments that can protect against UV-rays, dust, corrosion, and other color contaminants that are endured by building paints.

Binder Jetting of Custom Silicone Powder for Direct Three-Dimensional Printing of Maxillofacial Prostheses.

Recent advances in digital workflow have transformed clinician's ability to offer patient-specific devices for medical and dental applications. However, the digital workflow of patient-specific maxillofacial prostheses (MFP) remains incomplete, and several steps in the manufacturing process are still labor-intensive and are costly in both time and resources. Despite the high demand for direct digital MFP manufacturing, three-dimensional (3D) printing of colored silicone MFP is limited by the processing routes of medical-grade silicones and biocompatible elastomers. In this study, a binder jetting 3D printing process with polyvinyl butyral (PVB)-coated silicone powder was developed for direct 3D printing of MFP. Nanosilica-treated silicone powder was spray dried with PVB by controlling the Ohnesorge number and processing parameters. After printing, the interconnected pores were infused with silicone and hexamethyldisiloxane (HMDS) by pressure-vacuum sequential infiltration to produce the final parts. Particle size, coating composition, surface treatment, and infusion conditions influenced the mechanical properties of the 3D-printed preform, and of the final infiltrated structure. In addition to demonstrating the feasibility of using silicone powder-based 3D printing for MFP, these results can be used to inform the modifications required to accommodate the manufacturing of other biocompatible elastomeric materials.