Deposition Of Materials Research Articles

Data-driven optimization of additive composite manufacturing using automated fibre placement: A study on process parameters effects and interactions

The influence of process parameters and their interactions on the interlaminar shear strength (ILSS) of additively manufactured CF-PEEK composites was investigated. The composites were made using a hot gas torch (HGT)-based automated fibre placement (AFP) process. Experimental short beam shear (SBS) tests and FEA numerical simulations with bonding models were conducted to generate data. Various process parameter combinations were analyzed using full-factorial statistical assessment. Results show that ILSS increases with decreasing deposition speeds and increasing HGT temperatures, with consolidation forces having a milder effect. A strong interaction effect between parameters was observed, and the effect of HGT temperature on ILSS depends on material deposition speed. The optimum ILSS were at low deposition speeds (76 mm/s) with high HGT temperatures (900 °C or 950 °C), also evident in the fracture surfaces. This database can aid smart production planning in additive manufacturing of composites by optimizing process parameters for maximum interlaminar strength.

The Formulation and Evaluation of Customized Prednisolone Gel Tablets Prepared by an Automated Extrusion-Based Material Deposition Method

The Formulation and Evaluation of Customized Prednisolone Gel Tablets Prepared by an Automated Extrusion-Based Material Deposition Method

Multimaterial inkjet printing of mechanochromic materials

AbstractInkjet printing technology achieves the precise deposition of liquid-phase materials via the digitally controlled formation of picoliter-sized droplets. Beyond graphical printing, inkjet printing has been employed for the deposition of separated drops on surfaces or the formation of continuous layers, which allows to construct materials gradients or periodic features that provide enhanced functionalities. Here, we explore the use of multinozzle, drop-on-demand piezoelectric inkjet technology for the manufacturing of mechanochromic materials, i.e., materials that change their color or fluorescence in response to mechanical deformation. To accomplish this, suitable polyurethane polymers of differing hardness grades were tested with a range of organic solvents to formulate low-viscosity, inkjet-printable solutions. Following their rheological characterization, two solutions comprising “soft” and “hard” polyurethanes were selected for in-depth study. The solutions were imbibed with a mechanochromic additive to yield fluorescent inks, which were either dropcast onto polymeric substrates or printed to form checkerboard patterns of alternating hardness using a laboratory-built, multimaterial inkjet platform. Fluorescence imaging and spectroscopy were used to identify different hardness grades in the dropcast and printed materials, as well as to monitor the responses of these gradient materials to mechanical deformation. The insights gained in this study are expected to facilitate the development of inkjet-printable, mechanochromic polymer materials for a wide range of applications.

Effect of Substrate Temperature on Bead Track Geometry of 316L in Directed Energy Deposition: Investigation and Regression Modeling

The optimization of process parameters in powder Directed Energy Deposition (DED) is essential for achieving consistent, high-quality bead geometries, which directly influence the performance and structural integrity of fabricated components. As a subset of additive manufacturing (AM), the DED process, also referred to as laser metal deposition (LMD), enables precise, layer-by-layer material deposition, making it highly suitable for complex geometries and part repair applications. Critical parameters, such as the laser power, feed rate, powder mass flow, and substrate temperature govern the deposition process, impacting the bead height, width, contact angle, and dilution. Inconsistent control over these variables can lead to defects, such as poor bonding, dimensional inaccuracies, and material weaknesses, ultimately compromising the final product. This paper investigates the effects of various process parameters, specifically the substrate temperature, on bead track geometry in DED processes for stainless steel (1.4404). A specialized experimental setup, integrated within a DED machine, facilitates the controlled thermal conditioning of sample sheets. Using Design of Experiments (DoE) methods, individual bead marks are generated and analyzed to assess geometric characteristics. Regression models, including both linear and quadratic approaches, are constructed to predict machine parameters for achieving the desired bead geometry at different substrate temperatures. Validation experiments confirm the accuracy and reliability of the models, particularly in predicting the bead height, bead width, and contact angle across a broad range of substrate temperatures. However, the models demonstrated limitations in accurately predicting dilution, indicating the need for further refinement. Despite some deviations in measured values, successful fabrication is achieved, demonstrating robust bonding between the bead and substrate. The developed models offer insights into optimizing DED process parameters to achieve desired bead characteristics, advancing the precision and reliability of additive manufacturing technology. Future work will focus on refining the regression models to improve predictions, particularly for dilution, and further investigate non-linear interactions between process variables.

Post-mortem analysis of material deposition and fuel retention on the plasma-facing materials after the 2021 campaign in EAST

Plasma-wall interaction (PWI) is a critical concern in tokamaks because of its significant impact on the lifetimes of plasma-facing materials (PFMs), fuel retention, and plasma performance. In 2020, the Experimental Advanced Superconducting Tokamak (EAST) PFMs were upgraded to predominantly metallic walls. Following the 2021 experimental campaign, the deposition distribution and fuel retention on the surfaces of the PFMs along both the poloidal and toroidal directions were analyzed. The poloidal tests commenced at the high-field side (HFS), proceeded to the lower divertor, then to the low-field side (LFS), and finally to the upper divertor. The toroidal tests were performed at the midplane of the HFS, beginning from port A and ending at port P. The distributions of the deposits in the poloidal and toroidal directions were clearly asymmetrical. Mo and Fe particles sputtered from the first wall and inner stainless steel (SS) components were prone to deposition in the lower divertor region, as evidenced by the fact that the elemental content in the far-SOL region of the inner divertor exhibited Mo and Fe peaks, as did both the near- and far-SOL regions of the outer divertor. In addition, quick re-deposition of W and Fe was observed, as demonstrated by the fact that their contents near the erosion sources were higher than those farther away along the toroidal first wall on the HFS. This tendency was stronger for W than for Fe. Further analysis indicated that the deposits consisted of Li, C, O, W, Mo, Fe, Cu, and Ni. The Li and Fe contents were much higher than those of other metal impurities, with peak values of 8.17 μg/mm2 and 7.78 μg/mm2, respectively. The Li content decreased along the HFS first wall from 8.17 μg/mm2 at P-2 to 1.82 μg/mm2 at P-22, and then increased to 2.72 μg/mm2 at P-32 in the divertor, while the Fe content was higher around the top side and the midplane of the HFS. The deposited Li originated from routine wall conditioning and existed primarily in the form of Li2CO3. Additionally, other metal impurities deposited on the Li2CO3 surfaces exhibited various irregular shapes, often appearing as aggregated and recrystallized small particles. Furthermore, significant deuterium (D) retention on the order of 1021 atoms/m2 was measured on all the analyzed SiC-coated graphite tiles on the HFS. The D content at location P-10 at the midplane was the highest along the poloidal direction of the HFS because it was directly facing the NBI beam.

Mitochondrial and Microtubule Defects in Exfoliation Glaucoma.

Exfoliation Syndrome (XFS) is an age-related systemic condition characterized by large aggregated fibrillar material deposition in the anterior eye tissues. This aggregate formation and deposition on the aqueous humor outflow pathway are significant risk factors for developing Exfoliation Glaucoma (XFG), a secondary open-angle glaucoma. XFG is a complex, multifactorial late-onset disease that shares common features of neurodegenerative diseases, such as altered cellular processes with increased protein aggregation, impaired protein degradation, and oxidative and cellular stress. XFG patients display decreased mitochondrial membrane potential and mitochondrial DNA deletions. Here, using Tenon Capsule Fibroblasts (TFs) from Normal (No Glaucoma) and XFG patients, we found that XFG TFs have impaired mitochondrial bioenergetics and increased reactive oxygen species (ROS) accumulation. These defects are associated with mitochondrial abnormalities as XFG TFs exhibit smaller mitochondria that contain dysmorphic cristae, with an increase in mitochondrial localization to lysosomes and slowed mitophagy flux. Mitochondrial dysfunction in the XFG TFs was associated with an increase in the dynamics of the microtubule cytoskeleton, decreased acetylated tubulin, and increased HDAC6 activity. Treatment of XFG TFs with a mitophagy inducer, Urolithin A, and a mitochondrial biogenesis inducer, NAD + precursor, Nicotinamide Ribose, improved mitochondrial bioenergetics and reduced ROS accumulation. Our results demonstrate abnormal mitochondria in XFG TFs and suggest that mitophagy inducers may represent a potential class of therapeutics for reversing mitochondrial dysfunction in XFG patients.

Evaluation of hydrogen peroxide diffusion in the pulp chamber, bleaching efficacy, and physicochemical properties of an experimental in-office bleaching gel containing a hydroxyapatite-capsaicin composite.

This study assessed the hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE), surface roughness (Ra), and Knoop microhardness (KHN) of an experimental bleaching gel containing a hydroxyapatite-capsaicin composite (HAp-CAP). Human premolars were randomly assigned to three groups (n = 9) based on the dental bleaching gel used (50min; one session): only 35% HP, 35% HP + HAp-CAP, and not exposed to bleaching (negative control; NC). HP diffusion (µg/mL) into the pulp chamber was assessed using UV-Vis spectrophotometry, and BE (ΔEab, ΔE00, and WID) was evaluated using a digital spectrophotometer. Human molars were used to determine Ra and KHN before and 7days after the bleaching procedure, and for Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses. A paired t-test or t-test was used for statistical analysis (α = 0.05). A higher amount of HP into the pulp chamber and significant BE (ΔEab, ΔE00, and WID) were observed for 35% HP and 35% HP + HAp-CAP compared to NC (p < 0.001), with no significant difference between them (p > 0.05). SEM and EDS demonstrated material deposition on the enamel surface after bleaching for 35% HP + HAp-CAP, which helped maintain the KHN (p > 0.05). Furthermore, Ra increased for both groups (p < 0.05). The 35% HP + HAp-CAP did not decrease HP diffusion into the pulp chamber, reduced KHN values, and increased Ra. Material deposition on the enamel surface was observed, and BE was effective.

Controlled Formation of Porous Cross-Bar Arrays Using Nano-Transfer Printing.

Nano-transfer printing (nTP) has emerged as an effective method for fabricating three-dimensional (3D) nanopatterns on both flat and non-planar substrates. However, most transfer-printed 3D patterns tend to exhibit non-discrete and/or non-porous structures, limiting their application in high-precision nanofabrication. In this study, we introduce a simple and versatile approach to produce highly ordered, porous 3D cross-bar arrays through precise control of the nTP process parameters. By selectively adjusting the polymer solution concentration and spin-coating conditions, we successfully generated discrete, periodic line patterns, which were then stacked at a 90-degree angle to form a porous 3D cross-bar structure. This technique enabled the direct transfer printing of PMMA line patterns with well-defined, square-arrayed holes, without requiring additional deposition of functional materials. This method was applied across diverse substrates, including planar Si wafers, flexible PET, metallic copper foil, and transparent glass, demonstrating its adaptability. These well-defined 3D cross-bar patterns enhance the versatility of nTP and are anticipated to find broad applicability in various nano-to-microscale electronic devices, offering high surface area and structural precision to support enhanced functionality and performance.

Magnetic Nanoparticle Aggregation and Complete De-encapsulation of Such Aggregates from a Liquid Drop Interior.

Magnetic nanoparticles (MNPs) have been extensively used for drug delivery, on-demand material deposition, etc. In this study, we demonstrate the capability to extract such MNPs on-demand from a magnetic nanoparticle-laden drop (MNLD) (i.e., a drop of a stable aqueous dispersion of MNPs), suspended inside a highly viscous polymer (poly(dimethylsiloxane) or PDMS) medium in the presence of an externally applied magnetic field. The phenomena involve the aggregation of the MNPs inside the drop and the consequent extraction of the MNP aggregate out of the drop, with the drop retaining its original shape after the MNP aggregate extraction. We define this latter phenomenon as de-encapsulation. This is the first study that, to the best of our knowledge, demonstrates such precise, controlled, and on-demand removal of the NPs from the interior of a drop (where the NPs, which were originally inside the drop, breach the drop interface and get completely separated from the drop as an aggregate) without any permanent deformation of the drop. We quantify the effect of the changes in the MNP concentration and the drop volume in determining the de-encapsulation distance, which refers to the distance between the drop and the location of the magnet at the time instant when the MNP aggregate leaves the drop. We further identify the volume of the aggregates extracted from the drop and the mechanisms causing such de-encapsulation. We propose a theory to describe the process, and our theoretical predictions capture the experimental trends well. In addition, we also demonstrate multiple, back-to-back MNP aggregate extractions from a single MNLD at different sites, indicating the possibility that the MNLD can be used as an on-demand carrier and depositor of materials. Overall, our results, in addition to demonstrating the first-of-its-kind de-encapsulation of NPs (in the form of an aggregate) from the drop interior, demonstrate a method to control the dynamics, extraction, and targeted deposition of the MNPs.

Controlled Delivery of Ketoconazole an Antifungal Agent from Uncemented Titanium Using a Layer-by-Layer Technique.

This study aims to evaluate the effectiveness of a layer-by-layer (LbL) technique for delivering ketoconazole to prevent fungi prosthetic joint infection (PJI) LbL assembly is a versatile technique for functionalizing biomaterial surfaces and engineering objects such as capsules and films through electrostatic attraction. This method involves the cyclic deposition of various materials onto substrates, allowing for the controlled growth of thin films. One of the key advantages of LbL assembly is its ability to create stable, nanoscale films with organized structures and customizable compositions on a range of substrates, which only need to carry electrostatic charges. Furthermore, the scalability and ease of fabrication of LbL coatings are significant advantages. For example, the deposition of drugs using LbL allows for a prolonged release of these drugs. In the in vivo study, ketoconazole release continued for 60 days, while in vitro release persisted for over 20 days. Moreover, 14 days after surgery, the study group showed a quicker reduction in inflammation and experienced fewer complications The evidence indicates that the LbL coating method positively affects cell viability, suggesting the potential for enhanced patient outcomes and significantly improving prophylactic strategies against fungal PJIs in joint replacement surgeries by preventing and treating fungal infections in prosthetic joints. Future research should explore the use of various antifungal agents to evaluate this approach further.

Laser power modulation between disturbed and undisturbed material removal regime in laser chemical processing

Laser chemical machining (LCM) is a method for removing material by thermally induced chemical dissolution of self-passivating metals. However, the process window is limited by disrupted material removal due to gas bubble formation and metallic salts and oxides deposition at higher energy input. Since the temperature increases, and therefore gas bubble growth takes time, it is hypothesized that the temporal modulation of laser power can remove the metal homogeneously, i.e., without disrupted material removal, while achieving a higher removal rate. Based on this, the dynamic process behavior of material removal is investigated for the LCM of titanium in phosphoric acid, using a rectangular modulation of the laser power with varying irradiation durations. As a result, however, high-speed videos show that gas bubbles are consistently generated, regardless of the applied laser power and power modulation, although the quantity of bubbles varies with different parameters. Even with short power durations (10 ms), the material deposition occurs after multiple irradiations. When the duration is longer, the material deposition increases in height along the laser scan direction. For the studied process parameters, a Fourier analysis in the spatial domain further indicates the correlation between the material removal frequencies and the modulation frequencies. In conclusion, the laser power modulation cannot prevent the disturbed material removal at high laser powers. Nevertheless, the material deposition can be utilized to generate periodic surface structures with a depth below and above the initial surface.

Study of optimization features of gas-powder jets created by a coaxial nozzle with divided powder supply during direct laser deposition of materials

A comparative analysis of the dynamics of gas-dispersed flows created by a coaxial nozzle (with divided powder supply) used in laser cladding in the additive manufacturing of metal products and 3D printing has been carried out. A new analytical method for calculating the optimization of the coaxial nozzle geometry to improve the focusing of converging single jet powder flows is proposed. Numerical modeling showed that, being repeatedly reflected from the walls of the transport channel, powder particles can fly out with a wide range of angles of deviation of trajectories from its axis. It has been revealed that one of the main reasons for poor particle focusing is an increase in the transverse component of the particle velocity relative to the tube axis, while a decrease in the transverse component of the particle velocity stabilizes the powder jet, reducing the maximum divergence angle of the trajectories. For the first time, it has been experimentally shown that polishing the internal channel of copper tubes or using smooth quartz glass tubes significantly improves the transport properties and focusing of powder jets, providing a significant reduction in the particle scattering angle. The results of optical diagnostics and visualization using a high-speed camera are consistent with the data of numerical modeling. Recommendations are formulated to improve the efficiency of using a coaxial nozzle with divided powder supply in laser gas-powder cladding.

On the electrohydrodynamic jet printing of two-dimensional material-based inks for printed electronics

Electrohydrodynamic (EHD) jet printing is a well-known advanced manufacturing technique that uses electric fields to generate and control fine jets of fluid for high-precision deposition of materials. This method enables the printing of extremely fine features, making it ideal for applications such as printed electronics. However, little is known about the optimal conditions for achieving consistent jet stability and droplet formation, especially when dealing with complex and volatile fluids laden with two-dimensional (2D) nanoparticles. In this work, we study the electrohydrodynamic printing process of 2D material-based inks using toluene as the main carrier fluid. Adding ethyl cellulose to toluene allows us to increase the stability of the suspensions and establish the steady cone-jet mode of electrospray. A small amount of ethanol increases the fluid conductivity, stabilizing the steady cone-jet mode and reducing the jet diameter. The inks behave as leaky-dielectric, weakly viscoelastic liquids. For this reason, the jet diameter and minimum flow rate obey the scaling laws for electrospray of Newtonian liquids. We determine the optimal parameter conditions for the EHD printing of our inks directly onto a non-conductive substrate. The influence of the substrate's velocity on the width of the printed lines is analyzed. These findings enlarge the knowledge about how to increase the throughput in the EHD jet printing process while controlling the resolution of the printed lines when using volatile solvents, 2D nanomaterials, and non-conductive substrates.

ESTRATEGIAS DE DEPOSICIÓN Y PROGRAMACIÓN PARA ABORDAR LA FABRICACIÓN DE PIEZAS DE GEOMETRÍA COMPLEJA MEDIANTE WAAM (WIRE AND ARC ADDITIVE MANUFACTURING)

This work analyzes the factors that affect the manufacture of complex geometry parts by WAAM (Wire and arc additive manufacturing) with the aim of minimizing the material used, improving the Buy-to-Fly ratio (ratio of raw material weight divided by the weight of the final component) and avoiding part distortions. A study of the different material deposition strategies to manufacture the parts (straight beads, circular path beads, serpentine, overlapping beads...) has been carried out to obtain the desired geometry. Depending on the deposition strategy to be used and the geometry of the part, the best option for the definition of robot trajectories has been analyzed, which can be done by direct programming of the robot or in a CAD-CAM design environment. Another aspect to be considered in manufacturing is the time between layers. This time affects the growth of the parts, since the accumulated heat can cause the growth to be inconsistent and generate distortions. To see the effects of different waiting times, simulation tools have been used. Finally, in order to control the deviations of the real part with respect to the theoretical one, the option of using profilometry has been analysed. This paper aims to analyse the development of new methodologies that respond to the different challenges mentioned above.) Keywords: WAAM, Buy-to-Fly, deposition strategies, robot trajectories, simulation

Genesis of the Qingchayuan Flake Graphite Deposit in the Huangling Dome of Yangtze Block, South China

The Qingchayuan flake graphite deposit is located in the Huangling Dome, which represents a part of the Yangtze Block in South China. This deposit is a major and highly typical flake graphite deposit within this metallogenic region. The graphite ores are found within graphite-bearing mica schist and graphite-bearing biotite–plagioclase gneiss. The fixed carbon content varies from 3.52 to 13.78% with an average of 7.83%. The major element analysis shows that the main chemical components of the Qingchayuan flake graphite ore are SiO2, Al2O3, TFe2O3, and K2O. The carbon isotope study of the graphite ore indicates light carbon values ranging from −22.80 to −26.72‰, suggesting that it has a biogenic origin. In addition, the sulfur isotope values of the graphite samples range from −10.67 to −14.58‰, indicating the formation of the graphite deposit is related to biological processes. The presence of traces of migmatization around the graphite deposit indicates that the graphite has undergone ultra-high temperatures during the formation process. The origin of the Qingchayuan flake graphite deposit is explained by a two-stage genetic model, which involves material deposition and regional metamorphism (including migmatization). Firstly, after the deposition of carbonaceous material and its conversion into graphite by regional metamorphism, the graphite might have undergone recrystallization, resulting in the development of big flakes due to migmatization. This model is supported by previous studies and newly collected information.

Characterization and simulation of AlSi10Mg reinforcement structures by direct energy deposition by means of laser beam and powder

Among metal additive manufacturing technologies, direct energy deposition (DED) processes have the advantage to be easily integrable in a manufacturing chain with other conventional technologies. This characteristic can be exploited by designing reinforcement structures to be added by DED onto pre-existing subcomponents to tailor the part’s mechanical properties while keeping the part lightweight. This study focuses on DED by means of laser beam and powder process optimization to improve material quality and geometrical accuracy of AlSi10Mg reinforcement structures while preventing excessive thermal deformations and material dilution into the substrate. These results are compared with finite elements numerical simulations of the deposition process, comprising thermo-elastic deformation and material deposition, to predict the bending and reinforcement of the processed substrate. In particular, the model includes the deterministic prediction of the deposition profile as a function of the process parameters and a few condition-specific coefficients: once calibrated, the model was used to compare the numerical and experimental residual deformation of the reinforced sample, obtaining promising agreement. The reinforcement provided to a 1.5 mm thick substrate by a single wall of deposited materials, with cross-sectional dimensions of 2 mm in width and 2.5 mm in height, was evaluated by three points bending. With the reinforcement on the tensile side of the stresses, the energy absorbed by the material plastic deformation increased by 2.4% as compared to the substrate alone, while with the reinforcement on the compression side of the stresses the energy absorption increased by 75.8% on average.

Evaluating Benchtop Additive Manufacturing Processes Considering Latest Enhancements in Operational Factors

With the evolution of additive manufacturing technologies, concerning their material processing techniques, range of material choices and deposition speed, 3D printers are extensively employed in academia and industry for a number of purposes. It is no longer uncommon to have a portable, desktop 3D printer and build specific designs in a matter of minutes or hours. The functionality, costs, materials and applications of desktop 3D printers differ. Among the several desktop 3D printers with a variety of characteristics, it might be challenging to choose which one is optimal for the intended applications and uses. In this study, a variety of commercially available thermoplastic and photopolymer resin desktop 3D printers are presented and compared for user selection. This article intends to provide end-users of desktop 3D printers with fundamental information and guidelines via a comparison of desktop 3D-printing technologies and their technical characteristics, enabling them to assess and select appropriate desktop 3D printers for a variety of applications.

Process development and heat flow analysis for thin walls made of aluminum using extreme high-speed laser material deposition (EHLA3D)

Extreme high-speed laser material deposition (EHLA) is an adapted variant of directed energy deposition (DED-LB-P/M), also known as laser material deposition, and has been developed for the efficient manufacturing of thin layers with high deposition speeds. With precise control of the energy input into the powder gas jet and the substrate, EHLA allows deposition speeds of up to 200 m/min and weld beads as thin as 25 μm. Advantages include a smaller melt pool and a heat-affected zone, allowing the processing of difficult-to-weld material combinations. The development of EHLA for additive manufacturing (EHLA3D) aims to produce highly customized components with improved structural accuracy compared to standard LMD at increased build rates compared to laser powder bed fusion (PBF-LB/M). A promising application is complex lightweight structures for the aerospace industry. However, there is a lack of systematic investigation on lightweight materials processed with EHLA3D at feed rates &amp;gt;20 m/min. In this work, a specially designed tripod machine (maximum feed rate 200 m/min) was used to investigate the buildup of aluminum in process regimes at 30 m/min. After confirming the existing single-track parameters, the tracks were metallographically examined and checked for pores, cracks, and bonding defects. The process was applied to thin-wall geometries and line energies as well as return-times that were varied. To gain an understanding of process-induced heat development, the process was monitored using thermography. Since the process shows geometry-specific heat flow patterns, guidelines have been developed that enable the buildup using different process adaptions.

Characterization of Ceramic Tile Bodies Prepared From Clays Collected from Four

Sierra Leone has high potentials for the setting-up of ceramic industry because of its huge virgin deposits of raw materials, chiefly clay, but lacks the technological know-how to utilize these materials to an economically sound level. Tile body offers a foundation for the performance of a glaze. The chemical and mineralogical composition of these clay bodies coupled with some physical properties, such a plasticity, bulk density, porosity, and water absorption, play significant role in determining the quality of the glazed surface.This is attested by certain glaze defects like pinholes, crazing and crawling on the glaze surface resulting mainly from bubble development within the body matrix during firing. The study aims at contributing to the promotion and use of appropriate ceramic building materials technology in Sierra Leone, by providing relevant research data to guide the production of quality ceramic products. The three key objectives, were to determine (1) the physical properties (2) chemical properties (3) mechanical properties of the clay samples investigated for their suitability in clay tile bodies production. Clay samples were collected from four sites in Sierra Leone namely Matankay (C-M) in the Western Rural District, Bo (C-B) in Bo District, Koribondo (C-K) in Pujehun District and Yele (C-Y) in Tonkolili District. Based on their plasticity index values, grain size distribution, bulk density, porosity and dry-fired shrinkage results obtained from this study, the four clay samples investigated are suitable for clay tile body production provided grog, frits, fluxes and other components are added proportionately and fired at temperatures above 1100oC to improve vitrification of the clay tile body during biscuit firing before application of the glaze.

Growth of copper single crystal using cone die Czochralski method

Copper (Cu) and other metal single crystals are useful as substrates for the deposition of atomic layer materials for many electronic applications, but the growth of large-sized single crystals is difficult to achieve. Characteristics of the metal material, namely seed elongation and intense cooling radiation at high temperatures during crystal growth, are the main challenges encountered when growing ingots with large diameters. These problems can be resolved by optimizing the crystal growth parameters. By adjusting the shoulder formation angle of the ingot shape to approximately 20° to 40°, we are able to grow a large (1-inch diameter, 30 mm length) single crystal of metal Cu using the Czochralski (CZ) method. However, the generation of suspended solids and film impurities such as reactants and precipitates and their nucleation, growth, and solidification, limited the further increase in size of the Cu crystal. Using the cone-shape die CZ (CD-CZ) method solves this problem and a 2-inch diameter Cu single crystal is successfully grown. This is the world’s largest single crystal metal grown using this method and it paves the way for the growth of other metal crystals.