Preparation Of Powders Research Articles

Preparation of additive manufacturing powder by external field–enabled: a comparative assessment

Preparation of additive manufacturing powder by external field–enabled: a comparative assessment

Research progress in quality control of Bufonis Venenum in preparations

Bufonis Venenum, an animal medicinal material, is widely used for treating cardiovascular diseases and pain induced by rheumatics or malignant tumors. In view of the high activity and high toxicity, it is of great significance to pay attention to the quality control of Bufonis Venenum to ensure the safety and effectiveness of its preparations. China's drug standards involve 102 preparations(474 batch numbers) containing Bufonis Venenum approved for sale, including 14 preparations in the Chinese Pharmacopoeia(2020 edition) and 68 preparations in the standards issued by the Ministry of Health Drug Standard of the People's Republic of China. Bufonis Venenum is mostly used in pill and powder preparations in the form of raw powder, with the main functions of clearing heat, removing toxin, relieving swelling and pain, replenishing qi, activating blood, opening orifice, and awakening brain. Except the high level of quality control for Bufonis Venenum in the preparations in the Chinese Pharmacopoeia(2020 edition), the quality control standards of Bufonis Venenum in other preparations are low or even absent. Therefore, it is urgent to conduct research on the improvement of quality standards for the preparations containing Bufonis Venenum. This study retrieved the reports focusing on the quality evaluation and quality control of the preparations containing Bufonis Venenum from CNKI, PubMed, and Web of Science. Qualitative and quantitative analysis methods for 64 preparations containing Bufonis Venenum have been reported, mainly including thin-layer chromatography, HPLC fingerprint, and multi-component content determination. The index components mainly involved bufadienolides, such as gamabufalin, arenobufagin, bufotalin, bufalin, cinobufagin, and resibufogenin. According to the literature information, this paper suggests that attention should be paid to the correlations between the analysis methods and detection indexes of medicinal materials, decoction pieces and preparations, the monitoring of indole alkaloids, and the content uniformity inspection for further improving the quality standards for the preparations containing Bufonis Venenum.

Optimization of pectin extraction from cacao pods using microwave assisted extraction (MAE) as a sustainable method for on-farm waste utilization

Cacao pods are the main waste of cacao on-farm processing that contains pectin. Generally, it is utilized for culinary purposes due to its gel-forming characteristic. Cacao pod pectin extraction was conducted by the MAE method using citric acid as a solvent. This study aims to determine the most appropriate optimum conditions from determined parameters of solvent pH and solvent-to-substrate (S/S) ratio using Response Surface Methodology (RSM) with yield as a response. There are two phases in this research, namely the preparation of cacao pod powder and pectin extraction from cacao pod powder with variations in the pH and S/S ratio of each 1.0; 1.5; 2.0 and 15:1; 20:1; 25:1 (v/w). This research confirmed that optimal conditions were reached at S/S ratio 21.57:1 (v/w) and pH 2.0 with a yield of 3.51%. Then, it was evaluated by comparing to commercial pectin for its degree of esterification (DE) and moisture content (MC). This experiment concluded that MAE technique is a potential method for sustainable pectin extraction. It can be applied on a larger scale due to shorter extraction time with fewer requirements for solvent and industrially more acceptable regarding the environmentally friendly.

Bowel preparation efficacy and safety of compound polyethylene glycol electrolyte powder combined with linaclotide for colonoscopy: A randomized controlled trial.

Adequate bowel preparation is essential for colonoscopy, which is important for detecting colon polyps and preventing colorectal cancer. Linaclotide is approved for irritable bowel syndrome with predominant constipation (IBS-C) symptoms. The main objective of this study was to explore the quality of bowel preparation by low-volume compound polyethylene glycol (PEG) combined with linaclotide. A total of 266 patients who underwent colonoscopy in Shangrao People's Hospital from June 2021 to June 2022 were randomized to 1 of 3 split PEG regimens: 4LPEG, 2LPEG, and 2LPEG + L (linaclotide). The primary end point was adequate bowel preparation (Boston Bowel Preparation Scale [BBPS] total score of ≥6, with each of three colonic segments subscores ≥2). Secondary outcomes were polyp detection rates and the incidence of adverse reactions. Over 12 months, 266 subjects were randomized into 2LPEG (n = 12), 4LPEG (n = 112), or 2LPEG + L (n = 142). There were no significant differences between the 4LPEG and 2LPEG + L groups in achieving adequate bowel preparation (P > 0.05). The mean BBPS score of the total colon, left hemi-colon, right hemi-colon, and transverse in the 2LPEG + L group was higher than that in the 2LPEG group (P < 0.001). Patient's sleeping quality and the incidence of adverse reactions of 2LPEG + L group were compatible with 2LPEG group, but it was significantly lower than that in 4LPEG group. There was no statistically significant difference in the detection rate of colon polyps between each group. The quality of bowel preparation of the compound polyethylene glycol electrolyte powder combined with linaclotide is approximately the same as that of 4LPEG, and it can reduce the adverse reactions in the process of bowel preparation, and its intestinal cleansing effect is also better than that of 2LPEG.

A Simple Preparation of Electrolyte Powder for Stoichiometric Electrolyte in Protonic Ceramic Cells

Among various eco-friendly energy conversion technologies, solid oxide cells (SOCs) exhibit superior energy conversion efficiency and performance owing to the kinetic and thermodynamic advantages. Recently, protonic ceramic cells (PCCs) have begun to attract attention with expectation that the operating temperature of SOCs can be lowered around 500oC, thereby achieving better durability with maintaining higher conversion efficiency. However, the promising proton conducting electrolytes in PCCs are mostly Ba-containing perovskites exhibiting highly refractory property, thus substantially have challenges associated with barium volatilization during high-temperature sintering process. At the same time, Ni-containing transient phases generated at the electrode and supplied to the electrolyte during sintering of electrode/electrolyte bilayer not only facilitate the sintering of electrolyte, but also induce the compositional change owing to the residue thereof. Such off-stoichiometry indeed degrades the electrical properties, and thus most of all reported performance of PCCs could not fully reflect the intrinsic property of electrolytes.Here, we describe a simple but effective strategy to realize the highly conductive electrolyte in PCCs via suppression of barium volatilization as well as minimization of supplied amount of transient phases; a low-temperature calcination process. The electrolyte powder calcined at the relatively lower temperature, which is high enough to react all the precursors without residue, but low enough to suppress the Ba volatilization. The PCCs fabricated using this low-temperature calcined electrolyte powder shows the reduced ohmic resistance, and in turn, enhanced electrochemical performance. While the research on PCCs, up to now, have mainly been focused on processing technique or new materials for the better performance, the result of this study implies that the status of initial electrolyte powder can significantly influence the overall cell characteristics.

Fabrication of High-Entropy Alloys Using a Combination of Detonation Spraying and Spark Plasma Sintering: A Case Study Using the Al-Fe-Co-Ni-Cu System

The use of pre-alloyed powders as high-entropy alloy (HEA) coating precursors ensures a predetermined (unaltered) elemental composition of the coating with regard to the feedstock powder. At the same time, it is interesting to tackle a more challenging task: to form alloy coatings from powder blends (not previously alloyed). The powder-blend-based route of coating formation eliminates the need to use atomization or ball milling equipment for powder preparation and allows for the introduction of additives into the material in a flexible manner. In this work, for the first time, a HEA was obtained using detonation spraying (DS) followed by spark plasma sintering (SPS). A powder mixture with a nominal composition of 10Al-22.5Fe-22.5Co-22.5Ni-22.5Cu (at.%) was detonation-sprayed to form a multicomponent metallic coating on a steel substrate. The elemental composition of the deposited layer was (9 ± 1)Al-(10 ± 1)Fe-(20 ± 1)Co-(34 ± 1)Ni-(27 ± 1)Cu (at.%), which is different from that of the feedstock powder because of the differences in the deposition efficiencies of the metals during DS. Despite the compositional deviations, the deposited layer was still suitable as a precursor for a HEA with a configurational entropy of ~1.5R, where R is the universal gas constant. The subsequent SPS treatment of the substrate/coating assembly was carried out at 800–1000 °C at a uniaxial pressure of 40 MPa. The SPS treatment of the deposited layer at 1000 °C for 20 min was sufficient to produce an alloy with a single-phase face-centered cubic structure and a porosity of &lt;1%. Interestingly, the hardness values of the as-sprayed and SPS-treated coatings were close to each other (~320 HV0.3). The hardness of the coatings measured in two perpendicular directions did not differ significantly. The features of the DS–SPS route of the formation of HEA coatings and its potential applications are discussed.

Spicy Shiro flour and Berbere powder (an ethnic, indigenous food of Ethiopia)

Ethiopia is a multiethnic nation with a wide range of cultural traditions, as well as ancient indigenous culinary skills that have made a significant contribution to national and religious holidays, family get-togethers, community celebrations, funeral rites, and economical progress. The most extensively produced and consumed traditional meals in various regions of Ethiopia are Shiro flour and Berbere powder. The significance and reputation of Shiro flour and Berbere powder in Ethiopian culture cannot be overstated. Shiro flour and Berbere powder are consistently the most well-liked and essential components in Ethiopian cuisine. However, research on Shiro flour and Berbere powder was limited, and there was no scientifically compiled data on these food products. As a result, this study was undertaken to collect indigenous knowledge, practices, mode of preparations, and skills, as well as to generate baseline data on Shiro flour and Berbere powder at the national level by examining the physicochemical qualities, this study was conducted. A cross-sectional study design was used, and 220 respondents with prior experience preparing Spicy Shiro flour and Berbere powder took part. The findings of this study will use for interventions such as food supplementation, importing to international markets for revenue generation, setting national and international standards, formulating products, providing students and researchers with reference material, and creating jobs, particularly for young people and women. The bioavailability and recommended amount/dosage of herbs and spices to be added during Shiro flour and Berbere powder preparation, however, has not been studied in Ethiopia. Furthermore, the current study did not address the analysis of antioxidants, aflatoxins content from Berbere powder, amino acid profiles, value addition, and shelf life of both products.

Preparation of (ZrTiCoNiNb)Ox high-entropy oxide powders by microwave heating with thermal field modulation

High entropy oxide powders (ZrTiCoNiNb)Ox were successfully synthesised using microwave heating with a TE666 resonant mode at temperatures ranging from 700 °C to 900 °C. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) techniques were carried out to characterize the samples, and the behavior of the samples when they undergo microwave heating was investigated. The mechanism of thermal field modulation (TFM) was explored to reduce the temperature gradients and improve heating efficiency. The temperature field distribution was simulated using COMSOL software. The process of synthesising (ZrTiCoNiNb)Ox using microwave heating was found to comprise four stages: thermal accumulation, local solid-phase reaction, synchronous reaction and grain growth. A phase transition from multi-phase mixing to a fixed high entropy phase was observed. The effectiveness of the mechanism of thermal field modulation was confirmed via analogue computation and experimentation.

Additive manufacturing and spark plasma sintering as effective routes for manufacturing of AISI 316L austenitic stainless steel - WC composites

Metal matrix composites (MMCs) are lightweight, high-performance materials with continuous expansion in industrial applications. In this study, Laser Powder Bed Fusion (LPBF), Binder Jetting (BJ), and Spark Plasma Sintering (SPS), were used to produce AISI 316L austenitic stainless steel (SS316L)-WC composite with different compositions and powder preparations. In the present study, the products manufactured with these different technologies and material compositions were compared in terms of final density, microstructure, and mechanical property. Results show a significant difference in the microstructure of the parts produced by these different manufacturing techniques with microstructural analysis showing that samples processed by LPBF exhibit the finest grain size, while the BJ processed samples exhibit the coarsest grain size. Furthermore, analysis of the micrographs and the XRD patterns obtained for all processing routes suggest that there was some level of WC dissolution followed by inter atomic diffusion occurring between the WC inclusions and the SS316L matrix, involving dissolved W and C atoms from the inclusions and Cr and Fe atoms from the steel matrix, with the final structure and microhardness of the composite system depending on the kinetics of the manufacturing process.

Cost-effective preparation of high-quality silicon nitride powders from silicon scrap through direct nitridation

This work reports a cost-effective and environmentally friendly method for preparing high-quality and highly-crystalline silicon nitride (Si3N4) powders from silicon (Si) scrap through direct nitridation. With Si scrap from semiconductor manufacturing processes being a critical and imperative global issue in recent times, an efficient methodology is essentially required to recycle it. For this purpose, ball milling parameters for Si scrap were optimized using different solvents to obtain homogeneous and fine-micron sized silicon powders for efficient nitridation. Ethanol was found to be the most effective in producing the required conditions of Si powders. Direct nitridation was performed at 1450 °C in an atmosphere of nitrogen and hydrogen gas flow to prepare Si3N4 powders. Various characterization techniques were used to analyze particle sizes, phase compositions, and morphologies of raw Si scrap, ball-milled Si powders, and Si3N4 powders. Results indicated that the nitridation reaction resulted in 90.1% conversion of Si into Si3N4 and the α-Si3N4 phase accounted for 85% of the total Si3N4 produced. This study provides a fundamental perspective from both industrial and environmental standpoints on the recycle of Si waste and production of cost-effective and high-quality Si3N4 powders. This novel approach of using Si scrap as a silicon source for Si3N4 powder preparation has the potential to significantly reduce the large volumes of Si waste generated from semiconductor industries.

Preparation and 3D printability study of bio-based PBAT powder for selective laser sintering additive manufacturing

Additive Manufacturing (AM) has been recognized as a highly versatile manufacturing method with high potentiality. Polymers are materials of central importance for AM specifically for fabrication of original and customized parts. However, most of the polymers currently in use derive from fossil sources, which extensive use represents a critical issue for the environment. This scenario encourages the use of sustainable and biodegradable biopolymers. The present paper focuses on the study of the printability of a bio-based powder, starting from an aromatic‐aliphatic biodegradable polyester, poly (butylene adipate-co-terephthalate) (PBAT), as sustainable alternative for Selective Laser Sintering (SLS) conventional materials. Bio-based polymers represent environmentally friendly materials that can be suitable for AM, although several problems still need to be solved for SLS applications. In fact, it is challenging to produce polymeric powders with specific particle size and size distribution, spherical shape, good flowability and processability. From this point of view, PBAT powder was prepared by means of an emulsion solvent evaporation method, characterized from morphological and thermal points of view, and then successfully used for SLS process, with the aim to obtain novel 3D printed objects using for the first time this biodegradable polymer.

Influence of powder properties and mixing technique under different conditions, on the densification and thermal conductivity of AlN for solar thermal applications

In this study, a novel approach is presented which can be utilized to enhance the thermal conductivity and densification of sintered AlN pellets. AlN pellets with a CaO additive were produced by spark plasma sintering. The influence of CaO powder properties such as particle size (micron-, submicron- and nano-scale), dispersion, flowability and structural characteristics, on the mixing behavior of AlN and CaO mixed powders, and on the porosity and thermal conductivity of AlN pellets, were investigated. Additionally, the influence of mixing conditions, including additive content and rotational speed in a novel high-shear mixer (Picomix), were studied and various mixing techniques were compared. The results indicate that when the CaO content of the AlN pellets is increased to 3 wt%, their thermal conductivity rises from 48.1 W/m·K to 112.9 W/m·K. This increase can be attributed to the formation of a liquid phase, and to a reduction in pellet porosity during sintering. Furthermore, when the rotational speed of the mixer is increased to 5000 rpm, the pellets’ thermal conductivity further rises to 126.2 W/m·K. This improvement is a result of the enhanced dispersion of CaO in the mixed powder. The shearing forces in the Picomix facilitate the coating of AlN particles with submicron- or nano-scale CaO particles, thereby improving the flowability of the mixed powder and narrowing the particle size distribution. This further improves the liquid phase distribution, thus enhancing the thermal conductivity of the AlN pellets (135.3 W/m·K). The novel high-shear mixer (Picomix) has demonstrated enhanced performance when compared with traditional mixing techniques (ball milling and manual mixing), since it involves a solvent-free process, is faster, has a lower energy consumption, causes less powder-oxidation and leads to a higher value of thermal conductivity, making it an excellent choice for the preparation of mixed powders for solar thermal applications.

Synergistic regulation of the formation of yttrium oxyfluoride layer on yttrium oxide substrate by fluoride-chloride molten salts

Fluoride molten salt (KAlF4) can modify Y2O3 to form YOF, but the reaction degree of this process is difficult to control and tends to form a large amount of yttrium fluoride (YF3) with low-strength. The reaction degree of the modification process of fluoride molten salt with Y2O3 can be suppressed by the synergistic effect of chlorides (KCl-CaCl2), which is mainly determined by the diffusion of fluorine-containing complex ions (AlF4-) in the fluoride-chloride mixed molten salts (FCMMS). The low diffusion rate of AlF4- in FCMMS directly leads to the decrease of the fluorination reaction rate and delays or even prevents the deeper fluorination process. After the synergistic modulation of Y2O3 by FCMMS, only YOF is formed, and the formation of YF3 is completely avoided. The strategy and mechanism may be applied to the economical preparation of YOF protective layer or YOF powder on low-cost Y2O3 template.

Spark plasma sintering of graphite-chromium carbide composites: Influence of the sintering temperature and powder synthesis method

Carbon-metal carbide composites are a novel family of materials with potential application in heat dissipation due to the lightness and thermal-mechanical properties. Within these composites, those of graphite-chromium carbide have been still few studied. Therefore, this research focuses on both the influence of the powder preparation method (mechanical mixing (MM) and colloidal synthesis (CS)) and the spark plasma sintering (SPS) temperature (1600, 1700, 1800, 1900 and 2000 °C) in the properties of the composite graphite-7 vol. Cr. Results indicate that the composites sintered from powders processed by CS exhibit better properties, which can be explained by the better dispersion of the chromium carbide, formed during the sintering process, in the matrix of composite. Apart from the powder preparation method, sintering temperature has influence on the properties of the composite: 1900 °C is the best in the case of the route CS + SPS, while 2000 °C is the best option in the route MM + SPS. The thermal conductivity in-plane is 1.75 times greater in the CS than in the MM route, which suggests a better performance in the composite processed by colloidal route in heat dissipation applications.

Exploring the Possibility of Enriching Fermented Milks with Young Barley Leaves Powder Preparation

Barley (Hordeum vulgare L.) is one of the first cereals that humans began to cultivate. This study aimed to investigate the possibility of enriching fermented dairy products, using fermented milk as an example, with young barley leaves powder (YBLP) preparation including different starter cultures of lactic acid bacteria (LAB). The addition of YBLP did not affect the maximum rate of acidification and the time at which the maximum acidification rate was achieved. However, it did impact the time required to reach the desired pH level (4.6) for specific starter cultures. Over a 28-day storage period, gradual acidification of the fermented milk was observed. The addition of YBLP has a limited effect on the pH of the fermented milk, with the pH value primarily dependent on the type of starter culture and storage time. The addition of YBLP may have a positive effect on the survival of bacterial cells during the storage of the fermented milk; however, a gradual decrease in the number of LAB cells was observed during refrigerated storage. Furthermore, the addition of YBLP had a significant effect on the hardness, adhesion, and water-holding capacity of some fermented milk immediately after fermentation, depending on the specific starter culture used.

Preparation of ultrafine Mo powder by the H2 reduction of MoO2: Parameter optimization, reaction kinetic, and its reduction mechanism

The influences of different parameters, such as reaction temperature, yttrium (Y) content, and H2 concentration, on the particle size and morphological structure of Mo powder prepared via the H2 reduction of MoO2, were investigated in the work. TG, XRD, FE-SEM, laser particle size analysis, model fitting, and orthogonal design experiment methods were adopted to analyze the reaction kinetic and reduction mechanism. The results showed that the optimum conditions for preparing ultrafine Mo powder were recognized as 1073 K, 1 mass% Y content, and a H2 concentration of 0.000576 mol·cm−2·min−1, which enabled the as-prepared Mo powder with a particle size as small as 107 nm. A new interfacial chemical reaction model with the consideration of reaction temperature, H2 concentration, and sample thickness, was proposed to analyze the reaction kinetic. It was found that the curves predicted by the model agreed well with the experimental data, with the apparent activation energy extracted to be 94.686 kJ/mol. The effect of different individual parameter on the reaction rate and the possible reduction mechanism were also elucidated.

Powder Preparation by Vacuum Atomization and 3D Printing Forming Performance of 316 Stainless Steel

This work describes the process of preparing 316 L stainless steel powder by vacuum atomization, then a 3D print sample of 316 L stainless steel is prepared by selective laser melting (SLM) experiments. Over 77% of the powder particle size distribution ranges from 15 to 45 μm. The prepared sample shows a smooth surface with few satellite globules and high sphericity with the 4.5 Mpa atomization pressure. Under these atomization pressure conditions, the tensile strength can reach 798 Mpa and the elongation up to 32.3%. This work demonstrated that 3D printing metal materials with high tensile strength and good plasticity could be obtained under appropriate atomization pressure conditions.

Preparation of granulated powders via freeze drying at different levels of slurry solid loading and comparison of their powder bed quality in roller-compaction-assisted binder jetting

Granulation can improve the flowability of nanopowder and the density of resultant parts printed by binder jetting. Forward-rotating roller compaction has the potential for further improving the density. In this study, for the first time, powder recoating tests of different granulated alumina powders were conducted on a commercially available binder jetting printer equipped with a forward-rotating roller compaction system. Freeze drying was used to prepare the granulated powder. Four different granulated powders were prepared from slurries with different levels of solid loading: 2, 5, 10, and 15 vol%, respectively. Powder bed quality, including defects on powder bed surface and maximum powder bed density without defects, was compared among the granulated powders. When the compaction ratio was too high, granulated powders with low solid loading levels of 2 and 5 vol% showed much fewer compaction-induced defects (including surface ridges and edge ridges) on powder bed surface than those with high solid loading levels of 10 and 15 vol%. As the solid loading level increased from 2 to 15 vol%, the maximum powder bed density without defects decreased from 19.5% to 16.0%. This study showed that a granulated powder prepared from a low level of slurry solid loading could reduce the compaction-induced defects on powder bed surface and enhance the powder bed density in roller-compaction-assisted binder jetting.

Preparation and properties of different azide polymer-modified nitrocellulose spherical powder

Preparation and properties of different azide polymer-modified nitrocellulose spherical powder

Preparation of High Water-Soluble Trichoderma Co-Culture Metabolite Powder and Its Effects on Seedling Emergence Rate and Growth of Crops.

Trichoderma spp. are widely used beneficial microbes in agricultural production; however, the improper carrier choice for Trichoderma agent preparation can alter the effectiveness of Trichoderma fungicides. In this study, the co-culture of four Trichoderma strains produced a large amount of free amino acids, with a content of 392.8414 ug/mL, and significantly improved the production level of γ-aminobutyric acid. A greenhouse experiment further showed that the co-culture of Trichoderma synergistically improved the female flower development and bacterial angular leaf spot resistance. The effects of ten kinds of carriers were compared in terms of water absorption and heat generation, as well as their effects on the seedling emergence rate and the plant growth promotion of maize, cucumber, and pakchoi cabbage. Each carrier was screened to mix with four strains of co-culture metabolites to prepare highly soluble and quality powders. The results showed that there were different effects of the carriers themselves and Trichoderma strain co-culture metabolite powder prepared with the carriers on seedling emergence rate and seedling growth. Β-cyclodextrin performed best in high solubility and low heat generation upon absorbing water and in easy drying in processing operations. Trichoderma strains co-culture metabolite powder with β-cyclodextrin as a carrier provided the most obvious promotion effects on seedling emergence rate and seedling growth. Therefore, β-cyclodextrin was determined to be an ideal carrier to prepare a highly water-soluble Trichoderma agent. Taken together, the study successfully developed a new type of highly soluble powder containing Trichoderma co-culture metabolites that is expected to benefit farming drip irrigation and spraying systems for the promotion of crop growth and disease control.