Journal of Composites and Compounds
Volume:3 Issue: 6, Apr 2021

Ni/Co-modified aluminide coatings were prepared on the Hastelloy-X superalloy by a combined process of elec-trodeposition and slurry aluminizing. In this regard, pure layers of Ni and Ni-50wt.%Co were initially applied via electrodeposition process and successive aluminization was carried out by a slurry technique. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the microstructural and chem-ical composition characterization of the specimens. The results of these analyses revealed that a compact and dense aluminide coating was formed with a two-layered structure containing the outer Al-rich β phase and inner interdiffusion zone. Moreover, the presence of pre-electrodeposited layers inhibited the outward diffusion flux of elements from the substrate and effectively suppressed the formation of Kirkendall pores. The hot corrosion studies of the obtained coatings indicated that the addition of a pre-electrodeposited layer could enhance the high-temperature corrosion performance of the coatings when exposed to sulfate salt.©2021 jourcc

Metallic MCrAlY coatings have been widely utilized to protect the high-temperature materials operating in ag-gressive conditions of gas turbines. However, with more demands on the turbine inlet temperature rise for efficien-cy gains, there is a need to further improve the high-temperature performance of the MCrAlY coatings. A possible way to meet this challenge is by microstructure modification. The aim of this study is to produce nanocrystalline MCrAlY powders via wet and dry mechanical milling techniques and deposit the obtained feedstock powders by the high-velocity oxygen fuel (HVOF) spraying method. Comprehensive characterization and comparison of the different powder processing techniques and the corresponding coatings were studied. It was established that the nano-scaled MCrAlY feedstock powder with low contamination levels could be achieved by mechanical milling. Moreover, the powder samples were well-deposited by the HVOF process and the correlation between powder properties and coating characteristics was investigated

Silicone rubber (SR) and ethylene-propylene-diene monomer (EPDM) are widely-used polymers as housing for high voltage insulators. In this work, SR/EPDM/clay nanocomposites were obtained by two-roll mill mixing for outdoor polymeric insulators. Morphology, dielectric properties, dielectric breakdown strength (DBS), and sur-face and volume resistivity of different weight contents of nanoclay (Cloisite 15A) incorporated in SR, EPDM, and SR/EPDM hybrid nanocomposites were characterized. In addition, the distribution of breakdown voltages was fit to the distribution of Weibull and estimated the scale and shape parameters. The polar groups of the clay particles enhanced the polarization capability of the nanocomposites. Moreover, DBS results showed an enhance-ment of the dielectric strength proportional to clay content. Finally, the surface and volume resistance of all nano-composites decreases but maintains very high electrical resistance. The experimental data presented in this study will be useful for designing and manufacturing the outdoor insulators.

TiO2 as a photocatalyst has been widely investigated and applied in many fields such as fuel cells, sterilization, and environmental decontamination. Some efforts, such as operation pa-rameters, synthesis techniques, and improve-ments by doping have been made to improve its performance. To have a photocatalyst with high photocatalytic activity for environmental purification, the most important step is to know about the synthesis methods and the pa-rameters and conditions that lead to preparing a highly photocatalytic active photocatalyst. This article paves the way in selecting the best synthesizing technique. In this article, the most common synthesis techniques of TiO2-based photocatalysts, including sol-gel, hydro-thermal, solvothermal, chemical vapor deposition, and phys-ical vapor deposition have been reviewed. The most important results that have been achieved in the field of synthesis were collected.

The manufacturing, application, and design of chemical processes and products that minimize or remove waste and the use of dangerous and toxic reagents are referred to as green chemistry. Green chemistry is made up of twelve principles, one of which is catalysis. The role of catalysis is to accelerate the reaction by introducing a substance called a catalyst. Because of their high efficiency, productivity, activity, and selectivity, nanocatalysts have recently received many interests. Nanocatalysts are characterized by their high surface area to volume ratio, as well as their nanoscale forms and sizes. One of the significant applications of nanocatalysts is wastewater and wastewater purification. Green and bio-synthesized nanocatalysts could be used efficiently to remove heavy metals, medicinal, organic, and inorganic pollutants from the wastewater systems. This paper reviews nanocata-lysts based on noble and magnetic nanocatalysts, as well as metal catalysts supported by organic polymers, and discusses their industrial effluent treatment mechanisms.

Drug delivery is known as an approach for transporting a pharmaceutical compound in animals and the human body to achieve effective therapy. Drug carriers are usually based on nanoparticles synthesized by several meth-ods. The sol-gel method is an inexpensive and simple process to prepare drug carriers that can produce particles with a high degree of homogeneity and purity. The process of sol-gel involves hydrolysis, polymerization/conden-sation of monomers, particle growth, and gel formation. The properties of materials including composition and morphology are affected by several factors and can be controlled by the process parameters. Due to the advantages of this method, it is widely used for drug carriers’ preparation. In this study, the definition and advantages of the sol-gel process are discussed. Moreover, drug carriers such as organic-inorganic, silica, and calcium composites, as well as bioactive glass synthesized by this method are reviewed

Magnesium based materials are considered promising biodegradable metals for orthopedic bone implant applica-tions as they exhibit similar density and elastic modulus to that of bone, biodegradability, and excellent osteogenic properties. The use of Mg based biomaterials eliminates the limitations of currently used implant materials such as stress shielding and the need for the second surgery. Recently, the development of Mg-based implants has attracted significant attention. Additive manufacturing is one of the effective techniques to develop Mg based implants. Ad-ditive manufacturing which could be named 3D printing is a transformative and rapid method of producing indus-trial parts with in the acceptable dimensional range. Therefore, recent investigations have tried to apply this meth-od for the development of Mg-based implants. This state-of-the-art review focuses on the additive manufacturing of Mg biodegradable materials and their in-vitro corrosion and degradation, and mechanical properties. The future directions to develop Mg biodegradable materials are reported through summarization of current achievements.