Powder Blends Research Articles

In situ Alloyed Medium Entropy Alloy Fabricated by Laser Powder Bed Fusion: Microstructure and Cryogenic Performance

An investigation is conducted into the feasibility to produce in situ alloyed medium entropy alloy containing four principal elements by laser powder bed fusion of the blended elemental powders. The effect of scan strategy, layer thickness, and laser power on in situ alloying is examined. It is revealed that the melting of Cr particles could be enhanced by increasing the remelting times of each building layer through the re‐scan strategy or reducing the powder layer thickness and by increasing the melting pool depth via large laser power. Besides, the combination of elemental uniformity and the low porosity in the printed alloy can be achieved. The accuracy of the nominal composition in the as‐printed sample could be ensured by the large remelting times combined with middle laser power, while an excessively large laser power could cause the loss of Cr element. Based on the high repetitive remelting process, the mechanism of pores elimination during in situ alloying is discussed. After the optimization, the as‐printed Fe60Co15Ni15Cr10 alloy fabricates with the re‐scan strategy or high laser power shows a tensile strength of ≈1140 MPa and an elongation of ≈0.39 under cryogenic loading. The as‐printed alloy overcomes the strength–ductility trade‐off at cryogenic temperature through the transformation‐induced plasticity.

Microbial Growth Dynamics in Minced Meat Enriched with Plant Powders

Plant powders with antimicrobial properties can be used in food manufacturing and must comply with the demands of consumers regarding microbiological safety, nutritional value, and sensory properties of foods. The present study aimed to assess the microbial growth inhibitory ability of different plant powders, including by-products of horticultural primary processing (e.g., pomace) in raw and cooked minced pork. The total counts of aerobic mesophilic bacteria, pseudomonads, yeasts, and moulds were studied to assess the microbial growth dynamics in meat samples. Additionally, for the plant powders, which were able to suppress the microbial growth in a total counts dynamics study, the growth potential of Listeria monocytogenes in ready-to-eat (RTE) minced meat samples was estimated by challenge testing. The results showed that the most effective combinations of plant powders in raw minced pork, in relation to the total counts of microorganisms, were 3% apple+1% onion+2% blackcurrant berries (Apple+On+BCber); 3% apple+1% garlic+2% tomato (Apple+Ga+Tom); and 3% apple+2% tomato+1% rhubarb petioles (Apple+Tom+Rhub). However, challenge tests revealed that some plant powders were unable to inhibit the growth of L. monocytogenes. The lowest L. monocytogenes growth potential (δ = 2.74 log cfu/g) was determined for cooked minced pork samples enriched with 2% rhubarb petioles, followed by Apple+On+BCber (δ = 3.63 log cfu/g) and Apple+Tom+Rhub (δ = 3.74 log cfu/g). In minced pork samples without plant additives, the L. monocytogenes growth potential was 7.30 log cfu/g. In conclusion, blends of plant powders may have good potential for developing meat products with acceptable microbiological quality.

In vitro toxicity assessment of polyethylene terephthalate and polyvinyl chloride microplastics using three cell lines from rainbow trout (Oncorhynchus mykiss)

The RTgill-W1 (gill), RTG-2 (gonad), and RTL-W1 (liver) cell lines derived from a freshwater fish rainbow trout (Oncorhynchus mykiss), were used to assess the toxicity of polyethylene terephthalate (PET) and two forms of polyvinyl chloride (PVC). Two size fractions (25-μm and 90-μm particles) were tested for all materials. The highest tested concentration was 1 mg/ml, corresponding to from 70 000 ± 9000 to 620 000 ± 57 000 particles/ml for 25-μm particles and from 2300 ± 100 to 11 000 ± 1000 particles/ml for 90-μm particles (depending on the material). Toxicity differences between commercial PVC dry blend powder and secondary microplastics created from a processed PVC were newly described. After a 24-h exposure, the cells were analyzed for changes in viability, 7-ethoxyresorufin-O-deethylase (EROD) activity, and reactive oxygen species (ROS) generation. In addition to the microplastic suspensions, leachates and particles remaining after leaching resuspended in fresh exposure medium were tested. The particles were subjected to leaching for 1, 8, and 15 days. The PVC dry blend (25 μm and 90 μm) and processed PVC (25 μm) increased ROS generation, to which leached chemicals appeared to be the major contributor. PVC dry blend caused substantially higher ROS induction than processed PVC, showing that the former is not suitable for toxicity testing, as it can produce different results from those of secondary PVC. The 90-μm PVC dry blend increased ROS generation only after prolonged leaching. PET did not induce any changes in ROS generation, and none of the tested polymers had any effect on viability or EROD activity. The importance of choosing realistic extraction procedures for microplastic toxicity experiments was emphasized. Conducting long-term experiments is crucial to detect possible environmentally relevant effects. In conclusion, the tested materials showed no acute toxicity to the cell lines.

Microstructural engineering of a dual-phase Ti-Al-V-Fe alloy via in situ alloying during laser powder bed fusion

When Ti-6Al-4V is processed by laser powder bed fusion (L-PBF), acicular martensitic α’-Ti grains are formed within the columnar prior β-Ti grains, resulting in inferior mechanical properties. The application of blended powders in L-PBF enables to tailor the microstructures and obtain a mixture of α’ + β phases. In this work, we demonstrate an effective method to engineer the phase fraction of an L-PBF manufactured Ti alloy using blended powders consisting of Ti-6Al-4V and 3 wt% Fe particles. By varying laser parameters, the as-built microstructures transit from α’ dominated microstructure to a nearly complete β-dominant microstructure. High-speed operando X-ray diffraction during L-PBF processing combined with X-ray fluorescence and EBSD characterization allows for relating microstructure to the spatial distribution of the β-stabilizer Fe under the high cooling rates typical for L-PBF. The as-built microstructure containing large amounts of β phase achieves high strength and enhanced ductility without post-processing heat treatments.

Functional Beverages from Blends of Ficus Deltoidea Leaves and Brown Rice Powders: Physico-Phytochemical Properties, Antioxidant Activities, Sensory Evaluation and Acute Toxicity Study

Functional Beverages from Blends of Ficus Deltoidea Leaves and Brown Rice Powders: Physico-Phytochemical Properties, Antioxidant Activities, Sensory Evaluation and Acute Toxicity Study

Effect of combined lean additions of isomorphous and eutectoid beta stabilisers on the properties of titanium

Reduction of the manufacturing cost of titanium and the development of new alloys are crucial to effectively harvest the benefits derived by the use of titanium in industrial applications. Therefore, we considered the creation of new Ti-2X-2Z alloys via the combined lean additions of isomorphous (i.e. Nb) and eutectoid (i.e. Cu, Mn, and Fe) beta stabilisers, and systematically analysed their effect on the manufacturability and mechanical response of titanium produced via powder metallurgy. It is found that the addition of the alloying elements reduces the compressibility of the powder blend but enhances the densification. The microstructure of titanium is transformed into a Widmanstätten structure composed of α grain boundaries and α+β lamellae where the stronger the beta stabilisers the more refined the microstructural features, and no intermetallic phases are precipitated despite the use of eutectoid stabilisers. Consequently, the combined addition of isomorphous and eutectoid beta stabilisers has a significant effect on the mechanical response with the material becoming stronger, harder and less tough with the increment of the potency of the added beta stabilisers; however, the Ti-2X-2Z alloys share similar strengthening mechanisms. A more accurate theoretical equation for developing titanium alloys through the molybdenum equivalent parameter should be developed.

Investigation of granular dynamics in a continuous blender using the GPU-enhanced discrete element method

Continuous powder blending is an essential operation during continuous pharmaceutical manufacturing. However, the complex granular dynamics in the blender is still poorly understood. This study employs a graphic processor unit (GPU) enhanced discrete element method (DEM) to analyse the granular dynamics in a continuous blender. Numerical results indicate that only a small fraction of powder distributes in the upper region of the blender, while most of that distributes in the middle and lower regions. Besides, a higher impeller speed leads to a smaller hold-up mass and a shorter mean residence time. Interestingly, the maximum number of blade passes is achieved at an intermediate impeller speed. There are two distinct regimes during continuous blending: i) a shearing regime at low impeller speeds; and ii) a dynamic regime at high impeller speeds. This study demonstrates that the GPU-enhanced DEM can be a robust tool for analysing powder flow during continuous pharmaceutical manufacturing. • GPU-enhanced DEM analysis on the full-scale continuous blending is performed. • Impeller speed has a significant impact on the powder flow in the inclined blender. • At steady-state, powder mainly distributes in the middle and bottom zones of blender. • Maximum number of blade passes can be achieved at an intermediate impeller speed.

Molecular‐level composition design for efficient synthesis of SiAlON ceramics

AbstractSiAlONs are a class of liquid‐phase sintered ceramics with excellent room‐temperature strength and toughness, but whose residual grain boundary glass softens at high temperatures, limiting use in extreme environments. For this reason, efforts are made to minimize the volume of the grain boundary glass while still facilitating full densification. This work describes a potential route for the densification of SiAlONs with very low concentrations of liquid‐phase sintering additive (e.g., rare‐earth oxides such as yttria) by using an organometallic precursor. Solid solution of Al and O in the Si3N4 lattice was accomplished through the incorporation of solute atoms via liquid organic precursor aluminum sec‐butoxide (ASB). Al2O3 powder is conventionally used for this purpose, and the subsequent lattice softening associated with the solid solution helps to facilitate densification. However, a liquid‐phase additive is still essential for the full densification of SiAlONs. Higher densities were obtained from SiAlON powder blends utilizing organometallic ASB than those utilizing alumina powder, allowing for greater densification at very low Y2O3 concentrations. The thermal decomposition of the organic precursor was investigated by high‐temperature scanning electron microscopy, thermogravimetric analysis, and various X‐ray diffraction experiments. Immersion density measurements and lattice parameter refinements were performed for samples sintered with varying Y2O3 concentrations and/or dwell times. Results indicate that ASB‐containing powder blends favor SiAlON formation more strongly than Al2O3‐containing powder blends and favor densification at very low Y2O3 concentration.

3D-Powder-Bed-Printed Pharmaceutical Drug Product Tablets for Use in Clinical Studies.

Printing of phase 1 and 2a clinical trial formulations represents an interesting industrial application of powder bed printing. Formulations for clinical trials are challenging because they should enable flexible changes in the strength of the dosage form by varying the active pharmaceutical ingredient (API) percentage and tablet mass. The aim of this study was to investigate how powder bed 3D printing can be used for development of flexible platforms for clinical trials, suitable for both hydrophilic and hydrophobic APIs, using only conventional tableting excipients. A series of pre-formulation and formulation studies were performed to develop two platform formulations for clinical trials using acetaminophen and diclofenac sodium as model compounds and lactose and starch as excipients. The results showed that the type of starch used as the formulation binder must be optimized based on the type of API. Moreover, powder blend flow and liquid penetration ability proved to be critical material attributes (CMAs) that need to be controlled, particularly at high drug loading. Optimization of these CMAs was performed by selecting the appropriate particle size of the API or by addition of silica. A critical process parameter that had to be controlled for production of tablets of good quality was the quantity of the printing ink. After optimization of both the formulation and process parameters, two platform formulations, that is, one for each API, were successfully developed. Within each platform, drug loading from 5 up to 50% w/w and tablet mass from 50 to 500 mg were achieved. All 3D-printed tablets could be produced at tensile strength above 0.2 MPa, and most tablets could enable immediate release (i.e., >80% w/w within 30 min).

Resistance against Abrasive Wear and Corrosion of Laser Powder Bed Alloyed High Chromium Tool Steels

Additive manufacturing by laser-based powder bed fusion of metals (PBF-LB/M) enables the production of complex shaped components. High-carbon tool steels tend to cracking during PBF-LB/M due to internal stresses caused by the rapid solidification. Expensive atomization and long lead times for powder generate high costs in this processing route. In situ alloying during PBF-LB/M of powder blends from conventionally available powders enables a more flexible approach of alloy design. For industrial use, the mechanical properties of in situ alloyed parts must be comparable to those of conventionally manufactured parts. In some cutting and forming applications, high wear resistance and corrosion resistance are required simultaneously. High alloyed cold work tool steels with sufficient chromium solved in the metal matrix fulfill these demands. Herein, AISI H13 has been modified by Cr3C2 and elemental Cr to suit these requirements. Two novel alloys are modeled thermodynamically and processed by PBF-LB/M. In-depth microstructural investigations by backscatter electron imaging and diffraction in combination with abrasive wear tests and potentiodynamic polarization curves allow microstructure property correlations for different heat-treated conditions. Partial crack-free processing, hardenability, formation of Cr-rich carbides, and residual Cr-rich inclusions are observed and their influence on the wear and corrosion resistance is discussed.

Manipulating the strength and tensile ductility of a PM near α titanium alloy by adjusting the morphologies and volume fractions of α and βt domains

Powder metallurgy (PM) near α Ti−6Al−2Sn−4Zr−2Mo−0.1Si−0.5Y (wt.%) alloy with a low oxygen content and fabricated by thermomechanical powder consolidation of an elemental powder blend with a trace amount of Y addition was subjected to two heat treatments to obtain different microstructures which were free of grain boundary α (αGB) layers. One heat treatment (960°C/1h/AC, AC = air cooling) led to the formation of an α/βt microstructure consisting of 75.3 vol% primary α (αp) domains with globular and platelike morphologies, 21.5 vol% β transformed structure (βt) domains comprising ultrafine secondary α (αs) lamellae in a β matrix and 3.2 vol% thin β strips. The other heat treatment (960°C/1h/WQ+580°C/6h/AC, WQ = water quenching) led to the formation of a microstructure consisting of 38.2 vol% isolated αp plates, slabs, and globules dispersed in a βt matrix comprising nanometer-sized αs lamellae and residual β strips. The first microstructure rendered the alloy with high tensile strength of 1128 MPa and excellent tensile ductility of 15.6%, thanks to the activation of abundant <a> and <c+a> slips in all α grains and tensile twinning in the “hard” <0001> micro-textured α grains with the c-axis parallel to the tensile force direction which mitigated the strain localization and enhanced strain hardening. On the other hand, the harder nanostructure of the βt matrix in the second microstructure resulted in a significantly increased tensile strength of 1351 MPa while maintaining an excellent tensile ductility of 10.5%. This can be attributed to the activation of abundant <a> and <c+a> slips in thin α plates and a limited degree of tensile twinning in the “hard” α domains, as well as a large number of statistically stored dislocations (SSDs) within the micron-scaled α slabs/globules. Both microstructures rendered the alloy with favorable ductile fracture.

Machine Learning-Enabled NIR Spectroscopy in Assessing Powder Blend Uniformity: Clear-Up Disparities and Biases Induced by Physical Artefacts

NIR spectroscopy is a non-destructive characterization tool for the blend uniformity (BU) assessment. However, NIR spectra of powder blends often contain overlapping physical and chemical information of the samples. Deconvoluting the information related to chemical properties from that associated with the physical effects is one of the major objectives of this work. We achieve this aim in two ways. Firstly, we identified various sources of variability that might affect the BU results. Secondly, we leverage the machine learning-based sophisticated data analytics processes. To accomplish the aforementioned objectives, calibration samples of amlodipine as an active pharmaceutical ingredient (API) with the concentrations ranging between 67 and 133% w/w (dose ~ 3.6% w/w), in powder blends containing excipients, were prepared using a gravimetric approach and assessed using NIR spectroscopic analysis, followed by HPLC measurements. The bias in NIR results was investigated by employing data quality metrics (DQM) and bias-variance decomposition (BVD). To overcome the bias, the clustered regression (non-parametric and linear) was applied. We assessed the model’s performance by employing the hold-out and k-fold internal cross-validation (CV). NIR-based blend homogeneity with low mean absolute error and an interval estimates of 0.674 (mean) ± 0.218 (standard deviation) w/w was established. Additionally, bootstrapping-based CV was leveraged as part of the NIR method lifecycle management that demonstrated the mean absolute error (MAE) of BU ± 3.5% w/w and BU ± 1.5% w/w for model generalizability and model transferability, respectively. A workflow integrating machine learning to NIR spectral analysis was established and implemented.Graphical Impact of various data learning approaches on NIR spectral data

Optimization of biocorrosion resistance and mechanical properties of PM Ti–XAl–2Fe–3Cu alloys by response surface methodology

In the current study, the biocorrosion resistance and mechanical properties of the Ti–XAl–2Fe–3Cu (wt%) (X = 6, 4, 2 wt%) alloy produced by powder compact extrusion of blended elemental powders were optimized by using the response surface methodology in order to gain the best combination of processing parameters. To run the optimization process, central composite design with three equal levels of oxygen, hydrogen and aluminum was used and, by employing ANOVA, the analysis of variance was implemented. The results showed that the content of aluminum has a significant effect on the microstructure, mechanical properties, biocorrosion resistance and fracture behavior of the extruded rods. The highest aluminum content corresponds to the highest alloy strength and biocorrosion resistance. This was due to the reduction of the lamella thickness and of the material colonies as the aluminum content increases. Also, by running the experimental and optimization tests, the mechanical properties resulted 1245 MPa in yield strength and 1340 MPa in ultimate tensile strength with 0.1 µAcm−2 in corrosion current.

Laser powder bed fusion of an Al-Cr-Fe-Ni high-entropy alloy produced by blending of prealloyed and elemental powder: Process parameters, microstructures and mechanical properties

High-entropy alloys in the Al-(Co)-Cr-Fe-Ni system have been designed along several pathways to obtain tailored microstructures with remarkable mechanical properties, such as high strength and ductility. Additive manufacturing techniques, such as laser powder bed fusion, have been utilized and aim towards further optimization of their mechanical properties. However, processing challenges exist for these promising alloys, mainly due to their crack susceptibility as recently shown in the Co-free Al-Cr-Fe-Ni alloy. In this study, gas atomized prealloyed powder of a baseline Al-Cr-Fe-Ni high-entropy alloy was mixed with Fe and Ni elemental fine powder particles, to produce a powder blend with a modified composition. It was aimed to improve the alloy processability via designing the solidification path by reducing the Al content. The synthesized novel alloy composition was processed by laser powder bed fusion and crack-free material with a metastable, near single-phase face-centered cubic microstructure was obtained. Process parameters for minimum porosity were identified and net-shape tensile specimens were produced. Heat treatment led to a refined dual-phase microstructure consisting of face-centered cubic and body-centered cubic phases with promising mechanical properties, such as high tensile strength, reasonable elongation and notable strain hardening.

Enhancement in Crystallizability of Poly(L-Lactide) Using Stereocomplex-Polylactide Powder as a Nucleating Agent.

High-molecular-weight poly(L-lactide) (HMW-PLLA) is a promising candidate for use as a bioplastic because of its biodegradability and compostability. However, the applications of HMW-PLLA have been limited due to its poor crystallizability. In this work, stereocomplex polylactide (scPLA) powder was prepared by precipitation of a low-molecular-weight poly(L-lactide)/poly(D-lactide) (LMW-PLLA/LMW-PDLA) blend solution and investigated for use as a fully-biodegradable nucleating agent for HMW-PLLA compared to LMW-PLLA powder. The obtained LMW-PLLA and scPLA powders with a nearly spherical shape showed complete homo- and stereocomplex crystallites, respectively. HMW-PLLA/LMW-PLLA powder and HMW-PLLA/scPLA powder blends were prepared by melt blending. The LMW-PLLA powder was homogeneously melted in the HMW-PLLA matrices, whereas the scPLA powder had good phase compatibility and was well-dispersed in the HMW-PLLA matrices, as detected by scanning electron microscopy (SEM). It was shown that the enthalpies of crystallization (ΔHc) upon cooling scans for HMW-PLLA largely increased and the half crystallization time (t1/2) dramatically decreased as the scPLA powder content increased; however, the LMW-PLLA powder did not exhibit the same behavior, as determined by differential scanning calorimetry (DSC). The crystallinity content of the HMW-PLLA/scPLA powder blends significantly increased as the scPLA powder content increased, as determined by DSC and X-ray diffractometry (XRD). In conclusion, the fully biodegradable scPLA powder showed good potential for use as an effective nucleating agent to improve the crystallization properties of the HMW-PLLA bioplastic.

In Situ Alloying of Fe-Cr-Co Permanent Magnet by Selective Laser Melting of Elemental Iron, Chromium and Cobalt Mixed Powders

Fe-25Cr-15Co (wt.%) permanent magnets were fabricated via selective laser melting (SLM) and in situ alloying from a blend of Fe, Cr and Co elemental powders. Under the optimal laser scanning process, the as-built Fe-25Cr-15Co alloy has a homogeneous composition distribution without defects such as holes or un-melted particles, and presents a single α phase with the bcc crystal structure. The density of as-built samples was 7.705 g/cm3 (the relative density is 99.32%). The preferred magnetic properties of the sample in the isotropic state were obtained as Hc = 22.84 kA/m, Br = 0.86 T and (BH)max = 7.98 kJ/m3. The hardness and yield strength of Fe-25Cr-15Co permanent magnets are above 331.5 HV and 800 MPa, respectively. The results of this study verified the feasibility of fabricating Fe-Cr-Co permanent magnets by SLM in situ alloying and can be extended to a wide range of applications that require complex shapes with variable magnetic circuit characteristics or gradient structures.

NIR Spectroscopy as an Online PAT Tool for a Narrow Therapeutic Index Drug: Toward a Platform Approach Across Lab and Pilot Scales for Development of a Powder Blending Monitoring Method and Endpoint Determination.

An online near-infrared (NIR) spectroscopy platform system for real-time powder blending monitoring and blend endpoint determination was tested for a phenytoin sodium formulation. The study utilized robust experimental design and multiple sensors to investigate multivariate data acquisition, model development, and model scale-up from lab to manufacturing. The impact of the selection of various blend endpoint algorithms on predicted blend endpoint (i.e., mixing time) was explored. Spectral data collected at two process scales using two NIR spectrometers was incorporated in a single (global) calibration model. Unique endpoints were obtained with different algorithms based on standard deviation, average, and distributions of concentration prediction for major components of the formulation. Control over phenytoin sodium's distribution was considered critical due to its narrow therapeutic index nature. It was found that algorithms sensitive to deviation from target concentration offered the simplest interpretation and consistent trends. In contrast, algorithms sensitive to global homogeneity of active and excipients yielded the longest mixing time to achieve blending endpoint. However, they were potentially more sensitive to subtle uniformity variations. Qualitative algorithms using principal component analysis (PCA) of spectral data yielded the prediction of shortest mixing time for blending endpoint. The hybrid approach of combining NIR data from different scales presents several advantages. It enables simplifying the chemometrics model building process and reduces the cost of model building compared to the approach of using data solely from commercial scale. Success of such a hybrid approach depends on the spectroscopic variability captured at different scales and their relative contributions in the final NIR model.

Microstructural Characteristics of Ti‐Based Composites with Various Ceramic Reinforcements Manufactured via Hydrogen‐Assisted Blended Elemental Powder Metallurgy

The manufacturing of in situ reinforced titanium matrix composites by the sintering of titanium hydride and ceramic powder blends is an attractive and cost‐efficient process. Herein, a novel two‐stage (double‐compaction/double‐sintering) hydrogen‐assisted powder approach is suggested to produce uniform highly dense Ti‐based composites reinforced with TiB, TiC, and dual TiC + TiB phase particles. In this approach, the hydrogenation and milling of presintered products enable the initial porous materials to transform into hydrogenated prealloyed (PA) powders of controlled sizes, and a second press‐and‐sinter process further converts the PA powders into nearly dense composite microstructures with evenly distributed fine reinforcements. The adverse effect of the raw reinforcing powder size on microstructure uniformity, porosity, and mechanical characteristics of the presintered in situ composites becomes negligible in final sintering stage. The reduction of the porosity and enhancement of the hardness indicate that the hydrogen‐assisted double‐compaction and double‐sintering blended elemental powder metallurgy (BEPM) + PA approach enables the low‐cost fabrication of Ti‐based composites with suitable mechanical characteristics.

Reactive spark plasma sintering of SiC-TiC-diamond composites

SiC-TiC-diamond composites were fabricated via spark plasma sintering at hold temperatures of 1600 °C, 1625 °C, and 1650 °C from a powder blend containing by weight 30 % Si, 30 % Ti, and either 40 % uncoated or TiC-coated diamond. Due to the sintering conditions, sp3-diamond decomposed into thermodynamically favorable sp2‑carbon, reacting with Si and Ti to form SiC and TiC at T ≥ 1600 °C. As the hold temperature increased, the composite density reduced due to excess graphite formation for the uncoated diamond composites. However, at too low of a temperature the porosity fraction increased in the SiC-TiC matrix for the TiC-coated diamond composites. Overall, the results revealed that composites with ~97 % theoretical density and minimal (up to 5 vol%) graphite can be achieved by sintering Si-Ti-uncoated diamond at 1600 °C and Si-Ti-TiC-coated diamond at 1625 °C. X-ray diffraction, electron and x-ray microscopies with imaging analyses were carried out to quantify the volume fractions of each composite phase and used to explain the composite densification behavior. Conventional and energy filtered transmission electron microscopy, in addition to electron energy loss spectroscopy, were conducted to understand the nature of diamond graphitization with respect to the nucleation and growth of SiC, TiC, and nanoscale graphite.

Formulation and Evaluation of Posaconazole Bilayer Delayed Release Tablets Using Solid Dispersion Technique

The aim of present investigation to formulate bilayer tablets of posaconazole by using solvent evaporation technique. Posaconazole belongs to BCS class 2 which has high permeability and low solubility. In order to enhance the solubility of posaconazole solvent evaporation technique was applied where HPMC AS was used as carrier. This tablet consist of two layers of which first layer serves as loading dose which produce immediate release of drug and second layer serves as maintenance dose that provide controlled release of drug. The whole bilayer tablet is coated with Eudragit L30D55 to produce delayed release and protect drug from acid environment in stomach. The drug excipient compatibility study was performed by FTIR and no interaction was found. Croscaramellose was used in immediate release layer as superdisintegrant. Methocel K100M and Methocel E5M are used for sustain drug release in control release layer. The powder blend for evaluated for flow properties like angle of repose, bulk density, tapped density, Carr’s index and Hausner’s ratio which showed good results. Invitro dissolution studies was performed with USP dissolution apparatus 2- Paddle type. Invitro dissolution was performed for 2 hours in 0.1N HCl which showed no drug release followed by 6.8 phosphate buffer for 12 hours. The bilayer tablet showed initial release to provide loading dose of drug followed by controlled release up to 12 hours. Change in concentration of polymer and superdisintegrant showed impact on drug release profile. Increase in concentration of superdisintegrant in immediate release layer showed increased % drug release. Whereas increase in sustain release polymers in controlled release layer showed decrease % drug release. F9 batch showed satisfactory release up to 100% for 12 hours and was selected as best formulation. Reproducible batch for F9 was formulated and called F10 which also showed satisfactory results.