Ceramic Binder Research Articles

Preparation of Ti3Si0.8Al0.2C2 Bonded Diamond Composites and Their Friction Properties Coupled with Different Counterfaces

Polycrystalline diamonds were sintered with the binder of Ti3Si0.8Al0.2C2 to solve the shortcomings of conventional metal binders and ceramic binders. Ti3Si0.8Al0.2C2 bonded polycrystalline diamond composites have been synthesized from a mixture of Ti3Si0.8Al0.2C2 powder (40 wt%) and diamond powder under 4.5–5.5 GPa at 1050–1300°C by high press and high-temperature technology. The characteristic peaks of TiC were observed at 4.5 GPa and above 1100°C. From the microstructure analysis, the diamond particles are equally dispersed throughout the Ti3Si0.8Al0.2C2 matrix and firmly bound to the matrix. The effects of the sintering conditions, test parameters, and counterparts on the friction properties of diamond composites were systematically analyzed. The friction coefficient between diamond composite and glass counterpart is between 0.18 and 0.33 and increases significantly at the speed of 400 rpm/min. SEM and EDS analysis show Ti3Si0.8Al0.2C2 has a strong holding force on the diamond particles. The wear mechanism is mainly abrasive, and there are obvious grooves on the surface of the glass ball. The friction coefficient of diamond composite sintered at 1050°C with POM decreases monotonically with increasing load and reaches the minimum value of 0.42 at 12 N. The higher sintering temperature (1150°C) resulted in lower friction coefficient for diamond/POM pairs. The friction coefficient of diamond/PP pairs decreases first and then increases with increasing load, reaching a minimum value of 0.431 at 10 N. The wear mechanism of PP and POM is a combination of abrasive wear and adhesive wear, while the abrasive chips of POM are small salt-like particles and the abrasive chips of PP are long flocs. The wear track of PP balls has a smoother surface than that of POM balls. For an Al pair, the friction coefficient of diamond composite sintered at 1150°C is higher than that of the composite sintered at 1050°C except for the 10 N load. The friction coefficient of the diamond composites with Cu pairs varies slightly with increasing load, with values ranging from 0.443 to 0.518 and decreases with increasing speed, reaching a minimum value of 0.396 at 600 rpm/min. The wear mechanism of Cu and Al is mainly based on adhesive wear. The presence of the diamond second phase improves the stability of Ti3Si0.8Al0.2C2 compared to the high-pressure treatment of single phase Ti3SiC2. The analysis of friction properties indicates that Ti3Si0.8Al0.2C2 bonded diamond composites are promising candidates for superhard tool materials.

Damage formations of ramie fiber composites multilayer armour system under high-velocity impacts

Multilayer armour system (MAS) becomes the best choice in reinforcing protection for military officers against projectile attack which has a high velocity of up to 7.62×51 mm NATO ball lead core (projectile level III NIJ standard) or AP 7.62×51 mm hard steel core (projectile level IV NIJ standard). This study aimed to analyze the damage formation of wolfram carbide (WC) ceramic and ramie fiber composites. The frontmost MAS uses WC ceramic and is enveloped by a back layer of ramie fiber composites with epoxy resin reinforcing material as the matrix. Ballistic testing was carried out in this study using a long-barreled rifle to determine the resistance of the MAS from projectile impact. The speed meter in ballistic testing uses a velocity sensor type light screen B 471 and clay witness is used to measure back face signature (BFS). The results show that 7.62 lead core and hard steel core projectiles were unable to penetrate the 3-layer ceramic MAS in the front. The results are marked by a relatively low BFS value of 1.45 and 1.17 mm, so that the energy in the MAS with 3 ceramic layer is absorbed efficiently but with the phenomenon of rupture ceramic failure. Ceramic rupture failure needs to be overcome by bonding several layers of ramie so that MAS can be used in the next stage. MAS with 1 and 2 ceramic layers are unable to withstand projectile level III and level IV NIJ standard. From these results it is known that the MAS limit can withstand the projectile level III and IV NIJ standard, namely MAS with 3 ceramic layers. The damage formation of ceramic was rupturing ceramic failure. Therefore, it is necessary to design a ceramic binder by placing some ramie fibers in front of the ceramic

Spherical indentation of polycrystalline cubic boron nitride (PcBN): Contact damage evolution with increasing load and microstructural effects

The extremely severe conditions at which cutting tools are exposed in hard machining operations require tool materials with outstanding mechanical properties. Excellent combinations of high hardness and fracture toughness are aimed to enhance wear and contact damage resistance; and thus, reliability of the tool. Here, spherical indentation is used to induce controlled damage, under monotonic loads, and to assess the resulting damage scenario of polycrystalline cubic boron nitride (PcBN). In doing so, two grades with different content of cBN particles as well as chemical nature of the binder are investigated. Systematic and detailed inspection of residual imprints, by means of optical and scanning electron microscopy, is conducted to document critical loads for damage emergence and evolution through different stages, as a function of increasing load and microstructural assemblage. It is found that H-PcBN grade, with higher content of cBN particles and a metallic binder, exhibits higher resistance to crack nucleation as well as a more gradual transition between distinct damage scenarios. This enhanced response is linked to the concomitant increase of hardness and fracture toughness observed for that grade, as compared to the L-PcBN one, consisting of a significantly lower amount of superhard particles bound by a binder of ceramic nature. In-depth inspection of interaction between fissures and microstructure indicates the existence of four different crack paths for both PcBN grades - transgranular through cBN particles, across the binder phase, and intergranular along either cBN/cBN or cBN/binder interfaces. Relative frequency of these crack paths as well as operative toughening mechanisms define the effective crack growth resistance of each PcBN grade. In this regard, a higher fracture toughness is assessed for H-PcBN, as a result of crack bridging by metallic ductile ligaments together with the effective barrier-like role played by substructural features within cBN particles. Meanwhile, L-PcBN grade shows a rather low crack growth resistance, in direct correlation with the intrinsic brittle nature of the contiguous ceramic binder through which crack extension predominantly takes place. These relative differences in resistance to crack nucleation and growth become key for understanding the enhanced contact damage behaviour determined for the grade with higher content of cBN particles in this study.

Strong, Lightweight, Thermally Stable, Hydrophobic Coal-Based Composites Using Polysiloxane Polymer as Ceramic Binder: Potential as a Sustainable Building Material

Strong, Lightweight, Thermally Stable, Hydrophobic Coal-Based Composites Using Polysiloxane Polymer as Ceramic Binder: Potential as a Sustainable Building Material

Geopolymer-based grinding stones utilizable in metal machining

This article presents partial results of a project focused on the Research and development of new grinding tools fixed with hybrid binder based on inorganic polymers. The clay-slag geopolymer with corundum abrasive grains was first time used to prepare novel abrasive tools for metal grinding. The effect of brown and white corundum grains of different grain sizes and content has been investigated. The experiments performed on a rusted steel tube on a lathe along with subsequent scanning electron analysis (SEM) have confirmed the grinding properties of geopolymer grinding stones. The grinding traces detected by SEM analysis correspond to the incorporated amount of the abrasive and the size of the grain used. The results have proven that, in case of metal grinding, a geopolymer matrix can substitute for ceramic binder in grinding tools. The geopolymer grinding stones are an opportunity to sustainable development of a new generation of abrasive materials which utilize waste materials, save primary raw material resources and energy consumption and has a minimum impact on the environment.

A Study on the Reliability of Mass, Density, and Fire Performance of Recycled Wastepaper Building Finishing Material Made with Large Wet Cellulose 3D Printers

The impact of non-face-to-face contact following the COVID-19 pandemic has emerged as a social problem and has increased the amount of wastepaper, mainly in home delivery boxes. The appropriate recycling of paper waste is an area where sustainable growth is required in terms of the net environment system and carbon neutrality practice. Therefore, in this study, a specimen of building finishing material using wastepaper was produced using a custom-made large wet cellulose (LWC) 3D printer, and the site applicability of the fire performance was evaluated. The specimen of the building finish material was a mixture of wastepaper and ceramic binder, and the molding of the specimen was uniformly produced by a cylinder injection-type LWC 3D printer. The production reliability of the 3D printer was analyzed by measuring the mass and density of the specimen. The uniformity of the mass and density of the manufactured building finishes were confirmed to have standard deviations of ±0.05 g and ±0.01 g/cm3, respectively. The uniformity of the fire performance of specimens was confirmed by checking the relative standard deviation (RSD) value of ±3% under the same ceramic addition conditions from ISO 5660-1. Through the mass and density analysis and fire performance analysis of the building finishing materials, it was confirmed that the same mass, density, and fire performance can be produced simultaneously, and manufacturing using LWC 3D printers has been confirmed to be effective in developing uniform semi-non-combustible and retardant building materials.

Safety-Enhanced Polyethylene Separator with Thermally Conductive Ultra-Thin Ceramic Coating Layer for Advanced Libs

Lithium-ion batteries (LIBs) are widely used from small electronic devices to large-format electric vehicles and energy storage systems. However, as the energy density of LIBs increases, ensuring safety becomes more important to battery manufacturer. [1] As a result, battery engineers are reluctant to use bare polyethylene separators without the ceramic coating layer, which is generally fabricated from the slurry containing ceramic particles, binder, and solvent. Thus, the ceramic-coated separator (CCS) becomes a must-have item for state-of-the-art LIBs. However, since an additional ceramic layer not only reduces the energy density of LIBs, but also increases the cell resistance, there are previous works to reduce those resistive ceramic layers without compromising the thermal or mechanical properties of CCSs. [2] The key process they utilized was the deposition, which can coat the SiO2, Al2O3, or TiO2 ceramic layers of tens of nanometer on the surface of separators. [3,4,5,6] Thus, without ceramic coating layer of a few micrometers, they could show both improved electrolyte affinity and thermal stability comparable to the conventional slurry-based CCSs. However, except for oxide-based ceramics, other ceramics like nitride, which has a good thermal conductivity, have not been tried for this ultra-thin ceramic coating layers.Thus, herein, we attempt to deposit nitride on polyethylene separators using RF sputtering method. After the CCS was prepared, its physical properties such as thickness, mass per area, permeability, and morphological change were evaluated with a control CCS with Al2O3 layer. Also, not only thermal stability but also thermal conductivity was compared between nitride- and oxide-based CCSs. Furthermore, their electrochemical properties such as cyclability and rate capability were also investigated with large-area pouch-type full cells. Through these comparative study, pros and cons of ultra-thin nitride layer would be reported for advanced LIBs.[1] John B. Goodenough et al., J. Am. Chem. Soc. 2013, 135, 1167−1176.[2] Karun Kumar Jana et al., ChemBioEng Reviews, 2018, 5, 346-371[3] Taejoo Lee et al., Macromolecular Research, 2014, 22, 1190–1195[4] Min Kim et al., Journal of Power Sources, 212, 2012, 22-27 [5] Yoon Seok Jung et al., Adv. Energy Mater. 2012, 2, 1022–1027[6] Kun Peng et al., RSC Adv., 2015, 5, 81468

Alumina-based ceramic mold with integral core and shell for hollow turbine blades fabricated by laser powder bed fusion

Alumina-based ceramic molds are extensively applied in investment casting processes of hollow turbine blade due to their outstanding high-temperature chemical stability and creep resistance. Herein, laser powder bed fusion ( L -PBF) method was utilized to fabricate an alumina-based ceramic mold with integral core and shell (CMCS). The influences of the component contents in the composite powder on fluidity and packing density were comprehensivley studied, and the optimized formulation for the composite powder was consequently determined as 88 wt% mixed spherical alumina (coarse: fine = 9:1), 12 wt% epoxy resin E12, and 0.1 wt% fumed silica. The vacuum infiltration process was adopted to improve mechanical properties of alumina ceramic after the sintering, where the solid loading of ceramic slurry was investigated. The CMCS was divided into two parts for fabrication, i.e., the core&shell and the base with a spiral grain selector, which could facilitate convenient of cleaning residual powder due to enlarged openings. After the first infiltration and pre-sintering, the separated two parts were bonded by a ceramic binder and then underwent second infiltration and final-sintering to obtain a complete CMCS. The alumina-based ceramic fabricated through L -PBF and post-treatment possessed low sintering shrinkage (1.51–2.03%), adequate apparent porosity (30.82 ± 0.01%), and room-temperature strength (13.03 ± 2.90 MPa for unbonded specimen, 9.72 ± 1.34 MPa for bonded specimen). Strikingly, the subsequent casting experiment has proved that the method proposed in this paper is promising to fabricate superior alumina-based CMCSs.

Distinguishing contributions of metal binder and ceramic phase to mechanical performance of cermets at different temperatures

It is crucial to clarify the effects of the ceramic phase, the metal binder, and temperature on the mechanical properties of WC-Co cermets, as a typical representative of cermet materials, due to highly demanded excellent high-temperature properties under harsh service conditions. Based on uniaxial compression tests and detailed microstructural characterization, this study quantified the deformation characteristics of the ceramic phase and the metal binder at room temperature and high temperatures applying multiple analysis methods. It distinguished different contributions of the ceramic phase and metal binder to the plasticity of the cermets during deformation, and proposed the mechanisms for the plastic deformation of cermets. The results indicated that the dislocation plasticity is the dominant deformation mechanism of the cermets, and the ceramic matrix is mainly responsible for the fracture strength and contributes significantly to the plasticity of the cermets both at room temperature and high temperatures. At high temperatures, grain boundary slip and phase boundary sliding also contribute to the plastic deformation of cermets.

Fracture behaviors of Ti(C, N)-based cermets with different contents of metal binder

Ti(C0.7,N0.3)-Mo2C–Ni cermets are fabricated by powder metallurgy methods. We systematically investigate the microstructure, fracture morphology, crack propagation mechanism, and interface characteristics of Ti(C, N)-based cermets with different Ni binder contents.The increased dissolution of carbides and carbonitrides leads to a large amount of (Mo,Ti)(C,N) solid solution precipitates, which then spontaneously nucleate, resulting in a significant increase in the content of white core-gray rim grains in the cermets with a high binder content. The increased Ni binder largely improves the flexural strength and fracture toughness of the Ti(C,N)-based cermets because of the ductile dispersion toughening. The rim-core interfaces have a superior atomic coherent relationship in all Ti(C,N)-based cermets owing to the small lattice mismatch. The lattice mismatch of the interface between the rim phase and metal binder is remarkably decreased with the increase in the binder content to construct an atomic coherent relationship. Thus, the increased Ni binder promotes atomic ordering at the interface between the ceramic grains and binder and strengthens the grain boundary. The characteristic (111) peak of nickel shifts to a larger angle due to the reduction in the Ni-based solid solution lattice distortion. Therefore, the effect of solid solution strengthening is diminished with the increase in binder content, which results in a decreased binder strength. In the Ti(C,N)-based cermets with low metal binder contents, the fracture of the grain boundary between the ceramic grains and binder is the predominant failure mechanism. The intergranular crack accompanied by crack branching is the main characteristic of crack propagation. A hybrid fracture mode of intergranular and transgranular cracks is observed in the Ti(C,N)-based cermets with a moderate binder content. As the binder content further increases, the plastic yield deformation and subsequent tearing of the metal binder are the main fracture characteristics because of grain boundary strengthening and decreased strength of the binder.

Simulation of shrinkage during sintering of additively manufactured silica green bodies

Green bodies with ceramic particles and polymer binders can be shaped with additive manufacturing (3D-printing) techniques without the need for a mold. The dimensions and properties of the final ceramic part produced from printed green bodies depend on the porosity created from polymer burn-off and the densification of the ceramic particles during the post-printing steps. Predictions of the part dimensions and the internal stress states of the final ceramic part can assist the designers in properly sizing and shaping the green body. In this paper, the SOVS model was implemented in a three-dimensional finite element software as a user-defined creep model. The parameters required for the SOVS model, namely viscosity and surface energy, were calibrated by minimizing the error between predicted and experimental relative densities. The parameters were obtained using an error measure definition and minimizing the error with the well-known Differential Evolution global optimization. The dimensional changes of selected additively manufactured green bodies through the polymer burn-off and sintering process are analyzed. Density changes are tracked through the time-temperature cycles typically used to create ceramic parts from their green bodies.

Material extrusion for ceramic additive manufacturing with polymer-free ceramic precursor binder

Additive manufacturing of dense ceramic products has been challenging because of the high polymeric content of the ceramic feedstock materials. Several studies have been conducted to increase the ceramic content in the feedstock, but the binder and additives in it have remained in the polymeric content. A novel strategy for highly dense additive manufacturing using a sol-gel-based ceramic slurry without polymeric additives is presented. Alumina, which is the most widely used fine ceramic, was chosen as a representative ceramic material. The proposed sol-gel solution enabled a high solid loading of approximately 50 vol% without any polymeric dispersant while satisfying the requirements for material extrusion process, such as extrudable viscosity (<100 Pa.s) and self-sustainable yield stress. This novel sol-gel binder system evolves into aluminum oxide nanoparticles during the sintering process, eventually fusing to the alumina particles. The as-printed green body possessed high alumina content and 66% of theoretical density, which was higher than that obtained via the conventional molding methods. A reduced linear shrinkage of less than 16% and a high density of 99.5% of the theoretical value were also achieved. This research would present a practical strategy for ceramic additive manufacturing as an emerging fabrication process.

Mechanically robust superamphiphobic ceramic coatings with releasable nanoparticle-capsules

Superamphiphobic surfaces that can keep surface clean even in severe oil pollution environments are attractive for many practical applications. Existing surfaces could achieve good environmental durability, but rarely anyone has demonstrated that coatings with mechanical robustness and superamphiphobicity were fabricated by simple fabrication processes. In this work, a new design of component phase separation on nanoparticle-capsules is proposed to generate durable superamphiphobic coatings by spray-coating the suspension of fluorinated nanoparticle powders and ceramic binders. During the process of film formation, the micro/nano composite structures appear on the surface by the stacking of agglomerates and nanoparticles. Meanwhile, the particles in the suspension can be reunited to produce plentiful particle-agglomerates in longitudinal direction driven by the difference of surface tension. And the agglomerates acted as particle-capsules are able to release the embedded fluorinated silica nanoparticles to the surface to regenerate superamphiphobicity instantaneously during physical wear. Moreover, the coatings are durable against physical abrasion of 500 Taber abrasion cycles under a load of 250 g, maintaining super-repellency to oils under comprehensive harsh conditions such as oil immersion, oil mist impact, and sand water stirring. This strategy is supposed to offer a new insight to development durable superamphiphobic coatings that can endure harsh operation environments for mechanical abrasion and chemical erosion.

Experimental investigation on the effect of roller traverse and rotation speeds on ceramic binder jetting additive manufacturing

The objective of this experimental investigation is to identify the effect of roller traverse and rotation speeds on ceramic binder jetting additive manufacturing. Green and sintered densities were found decreasing with increasing roller traverse speed, and this decrease was more significant at a low roller rotation speed. A high roller traverse speed led to more cavities on the powder bed surface after spreading a new layer on a printed layer. Furthermore, a high roller traverse speed caused more cracks on the powder bed surface after jetting the binder. These defects observed during printing were inherited by the green and sintered parts, which were confirmed by X-ray computed tomography and scanning electron microscopy, respectively. Finally, the sintered flexural strength of the parts printed at a high roller traverse speed was more than 30% higher than that of the parts printed at a low roller traverse speed.

Influence of microstructural assemblage of the substrate on the adhesion strength of coated PcBN grades

Coated polycrystalline cubic boron nitride (PcBN) tools are increasingly used for industrial applications with stringent requirements. However, information on the mechanical integrity of these systems is quite limited. Within this context, the adhesion strength of two TiN/TiAlN-coated and microstructurally different PcBN substrates – high- and low-cBN content grades with metallic and ceramic binders, respectively – is investigated by means of Rockwell C indentation testing. In doing so, special attention is paid to substrate microstructure effects on emergence and evolution of damage as applied load is increased. For both coated systems, it is found that damage scenario evolves from early adhesive delamination within the contact area towards radial cracking and spalling outside the residual imprint. However, critical loads for transition between damage stages are discerned to depend on microstructural assemblage of the substrate. Higher resistance to radial cracking and delamination is exhibited by the high cBN-content grade, in agreement with its higher hardness and toughness. Failure micromechanisms associated with cracking and spalling are similar for both coated-PcBN systems. Very interesting, delamination outside the residual imprint is determined to be of cohesive nature within the substrate, an experimental fact resulting from interaction among indentation-induced radial, cone-like and lateral fissures in PcBN.

A Study on the Flame-Retardant Performance of Recycled Paper Building Materials Manufactured by 3D Printer

The increase in non-face-to-face lifestyles due to COVID-19 worldwide have shown an increase in delivery services. The number of parcels in 2020 was 3.373 billion, an increase of 20.9% from 2.788 billion in 2019. This phenomenon increased delivery box waste. Against this background, this study attempted to develop building materials from the recycling of delivery boxes. In this study, the self-developed WC (wet cellulose) 3D printer confirmed the standardization and uniform performance of the sample by filling the material supply cylinder with cellulose filaments and spraying the composite material through a 10 mm nozzle. The cellulose filament for a WC 3D printer is based on cellulose extracted from wastepaper, and a cellulose filament composite material is used by mixing additives. After manufacturing a specimen using the WC 3D printer, a reliability test for the flame-retardant performance of the material was conducted according to the ISO 11925-2 test method. As a result of the experiment, flame-retardant performance was confirmed at a 40 wt% or greater ceramic binder content. In addition, the WC 3D printer achieved accurate test results by producing specimens with uniform physical properties. In addition, we confirmed that 3D-printed WC can be used to develop customized building materials that can prevent fire spread.

Highly improved thermal stability of the ceramic coating layer on the polyethylene separator via chemical crosslinking between ceramic particles and polymeric binders

• The PD layer on ceramic particles and binder can form crosslinking points during drying condition. • The crosslinked CCL improves both adhesion and thermal stability of a thin separator at 160 °C. • Chemical crosslinking points are electrochemically stable and structurally robust for cycling. The ceramic coating layer (CCL) on a polyolefin separator plays a pivotal role in securing the safety of lithium-ion batteries (LIBs) by suppressing the thermal shrinkage of the separator even under abnormal circumstances. However, an additional CCL inevitably leads to energy density loss and electrochemical performance degradation. To mitigate these weaknesses, we designed a new chemical crosslinking between ceramic particles and polymeric binders to minimize the thickness of the CCL while maintaining its thermal stability. For this purpose, a polydopamine (PD) nanolayer is preliminarily introduced on the surface of ceramic particles using a simple solution polymerization method. Then, a poly(acrylic acid) binder, which can react with the amine groups in the PD, is chosen for the aqueous ceramic coating slurry. Thus, this combination can create a number of crosslinking points within the CCL, which leads to higher adhesion within the CCL after electrolyte impregnation. As a result, the crosslinked PD ceramic-coated separator (xPD-CCS) can maintain its original dimension even at 160 °C for 1 h with a 9-μm polyethylene base film. In addition, a full cell (LiNi 0.8 Co 0.1 Mn 0.1 O 2 /graphite) with the xPD-CCS can show a comparable cycle performance (capacity retention of 89.2% after 400 cycles) to those of bare polyethylene and non-crosslinked PD-CCS cases.

Effect of impact angle on wear behavior of Mo2NiB2–Ni cermets with different Ni content

Herein, the influence of the impact angle and Ni content on the wear behavior of Mo2NiB2–Ni cermets was studied using an erodent-carrying slurry comprising artificial seawater and SiO2 sands. The results reveal that the material loss may be attributed to the wear damage caused by SiO2 sands because cermets are expected to exhibit good corrosion resistance in artificial seawater. The relative density of cermets markedly influences their resistance to wear damage, and the material loss experienced by cermets with poor relative density is 2–4 times higher than that of cermets with good relative density; this occurs because a higher relative density can markedly enhance the mechanical properties and reduce the defects in the cermets. Moreover, the results indicate that as the impact angle increases from 0° to 60°, the manifestation of the wear mechanism changes from damaging the Ni binder phase (caused by single cutting wear) to damaging both the Mo2NiB2 ceramic and Ni binder phases due to the combination of cutting wear and impact wear. The wear damage is dominated by the cutting wear and impact wear from SiO2 sand at the low and high impact angles, respectively. Furthermore, the severe deterioration of the single ceramic skeleton at high impact angles indicates that the synergistic influence of the Mo2NiB2 ceramic and Ni binder phases on enhancing the wear resistance of the cermets intensifies at high impact angles.

Research on selection of abrasive grain size and cutting parameters when grinding of interrupted surface using aluminum oxide grinding wheel with ceramic binder

In this article, a study on intermittent surface grinding using aluminum oxide grinding wheel with ceramic binder is presented. The testing material is 20XH3A steel (GOST standard – Russian Federation). The testing sample has been sawn 6 grooves, with the width of each groove of 10 mm, the grooves are evenly distributed on the circumference of sample. The testing sample resembles a splined shaft. An experimental matrix of nine experiments has been built by Taguchi method, in which abrasive grain size, workpiece speed, feed rate and depth of cut were selected as input variables. At each experiment, surface roughness (Ra) and roundness error (RE) have been measured. Experimental results show that the aluminum oxide and ceramic binder grinding wheels are perfectly suitable for grinding intermittent surface of 20XH3A steel. Data Envelopment Analysis based Ranking (DEAR) method has been used to solve the multi-objective optimization problem. The results also showed that in order to simultaneously ensure minimum surface roughness and RE, abrasive grain size is 80 mesh, workpiece speed is 910 rpm, feed rate is 0.05 mm/rev and depth of cut is 0.01 mm. If evaluating the grinding process through two criteria including surface roughness and RE, depth of cut is the parameter having the greatest effect on the grinding process, followed by the influence of feed rate, workpiece speed, and abrasive grain is the parameter having the least effect on the grinding process. In addition, the effect of each input parameter on each output parameter has also been analyzed, and orientations for further works have also been recommended in this article

Combining powder bed compaction and nanopowders to improve density in ceramic binder jetting additive manufacturing

This paper reports a new approach to density improvement in ceramic binder jetting additive manufacturing: combining powder bed compaction and nanopowders. Samples were printed on a commercially available binder jetting 3D printer using an alumina nanopowder. Compaction thickness was varied across 0, 5, 10, 15, 20, and 60 μm at a layer thickness of 5 μm, and across 0, 100, and 200 μm at a layer thickness of 30 μm. Sintered density, as well as powder bed density, was measured. Furthermore, microstructure of sintered samples, with a focus on number and size of pores, was investigated to substantiate the density results. It was shown that at the same layer thickness, higher compaction thickness resulted in higher powder bed density, higher sintered density, and smaller number and size of pores in sintered samples. The highest sintered density (72.0%) achieved in this study was on par with the highest density reported in the literature on binder jetting of alumina without involving unusual liquid feedstocks or special post-processing techniques, demonstrating the effectiveness of this new approach to density improvement.