Mohamed Mitwally Amer

Bio: Mohamed Mitwally Amer is an academic researcher. The author has contributed to research in topics: Materials science & Ceramic. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

High-Entropy Coatings (HEC) for High-Temperature Applications: Materials, Processing, and Properties

Abstract: High-entropy materials (HEM), including alloys, ceramics, and composites, are a novel class of materials that have gained enormous attention over the past two decades. These multi-component novel materials with unique structures always have exceptionally good mechanical properties and phase stability at all temperatures. Of particular interest for high-temperature applications, e.g., in the aerospace and nuclear sectors, is the new concept of high-entropy coatings (HEC) on low-cost metallic substrates, which has just emerged during the last few years. This exciting new virgin field awaits exploration by materials scientists and surface engineers who are often equipped with high-performance computational modelling tools, high-throughput coating deposition technologies and advanced materials testing/characterisation methods, all of which have greatly shortened the development cycle of a new coating from years to months/days. This review article reflects on research progress in the development and application of HEC focusing on high-temperature applications in the context of materials/composition type, coating process selection and desired functional properties. The importance of alloying addition is highlighted, resulting in suppressing oxidation as well as improving corrosion and diffusion resistance in a variety of coating types deposited via common deposition processes. This review provides an overview of this hot topic, highlighting the research challenges, identifying gaps, and suggesting future research activity for high temperature applications.

A Review on In Situ Mechanical Testing of Coatings

Abstract: Real-time evaluation of materials’ mechanical response is crucial to further improve the performance of surfaces and coatings because the widely used post-processing evaluation techniques (e.g., fractography analysis) cannot provide deep insight into the deformation and damage mechanisms that occur and changes in coatings’ material corresponding to the dynamic thermomechanical loading conditions. The advanced in situ examination methods offer deep insight into mechanical behavior and material failure with remarkable range and resolution of length scales, microstructure, and loading conditions. This article presents a review on the in situ mechanical testing of coatings under tensile and bending examinations, highlighting the commonly used in situ monitoring techniques in coating testing and challenges related to such techniques.

Cracking Behavior of Gd2Zr2O7/YSZ Multi-Layered Thermal Barrier Coatings Deposited by Suspension Plasma Spray

Abstract: A new multi-layered thermal barrier coating system (TBCs) containing gadolinium zirconate (GZ, Gd2Zr2O7) and yttria-stabilized zirconia (YSZ) was developed using suspension plasma spray (SPS) to improve the overall thermal cycling performance. This study focuses on the cracking behavior of the GZ/YSZ TBC after thermal exposure to find out the key factors that limit its lifetime. Different cracking behaviors were detected depending on the thermal treatment condition (i.e., horizontal cracks within the ceramic layer and at the thermally grown oxide (TGO)/YSZ interface) which can be related to stresses developed through thermal expansion mismatch and increased TGO thickness beyond a critical value, respectively. A reduction in hardness of bond coat (BC) was measured by nanoindentation and linked with the thermally activated grain growth mechanism. The hardness and elastic modulus of ceramic layers (GZ and YSZ) showed an increased trend after treatment that contributed to the interfacial cracks.

Contemporary view for upholstery and curtain jacquard fabrics matching with woven hanging design

Abstract: Fabric designing process in general and upholstery and curtain jacquard fabrics designing in particular is the complete plan for structuring a whole weaved product which can compete in internation ...

Isolation of asparaginase-producing microorganisms and evaluation of the enzymatic antitumor activity

Abstract: Background L-asparaginase is an enzyme with very high biological activity owing to its activity on several tumor cells. It is mainly used to treat acute lymphoblastic leukemia. The complicated immunogenic adverse effects of present microbial sources present a need for switching to natural novel sources that have no immunogenic effect and better activity of L-asparaginase, so screening for other sources of L-asparaginase, like marine bacteria, may result in an enzyme having fewer adverse effects. Objective To screen and identify marine eco-friendly and potent L-asparaginase-producing bacteria, having a novel immunological property that possibly will avoid hypersensitivity. Materials and methods In the present study, bacterial strains were screened for extracellular L-asparaginase production from marine isolates, identified by 16 s rDNA technology, and L-asparaginase productivity was assessed using semiquantitative and quantitative enzymatic assays. The antiproliferative effect of the partially purified enzyme on different tumor human cell lines [HepG-2 (human hepatocellular carcinoma cell line), MCF-7 (breast cancer cell line), and PC-3 (prostate carcinoma cell line)] was assessed by the mitochondrial-dependent reduction of yellow MTT. Results and conclusion Bacillus safensis was established as the bacterial strain (Gene Bank accession number: MK541039). The extracellular enzyme-yielding capacity of the isolate B. safensis (518 IU/ml) was found to be 4.18 times higher than Bacillus pumilus (157.03 IU/ml) and higher than Bacillus circulans species (85 IU/ml). The marine isolate is environmentally friendly and can be used to produce significant quantities of extracellular L-asparaginase for the treatment of a variety of tumors and preparation of acrylamide-free fry food.

A Review on the Enhancement of Mechanical and Tribological Properties of MCrAlY Coatings Reinforced by Dispersed Micro- and Nano-Particles

Abstract: The application of metal-matrix composite coatings for protecting and improving the service life of sliding components has demonstrated to have the potentials of meeting the requirements of a diverse range of engineering industries. Recently, a significant body of research has been devoted to study the mechanical and tribological performance of dispersion-strengthened MCrAlY coatings. These coatings belong to a class of emerging wear-resistant materials, offering improved properties and being considered as promising candidates for the protection of engineering structural materials exposed to tribological damage, especially at elevated temperature regimes. This paper attempts to comprehensively review the different reinforcements used in the processing of MCrAlY-based alloys and how they influence the mechanical and tribological properties of the corresponding coatings. Further, the major fabrication techniques together with their benefits and challenges are also reviewed. Discussion on the failure mechanisms of these coatings as well as the main determining factors are also included. In addition, a comprehensive survey of studies and investigations in recent times are summarized and elaborated to further substantiate the review.

A Review on the Enhancement of Mechanical and Tribological Properties of MCrAlY Coatings Reinforced by Dispersed Micro and Nanoparticles

Abstract: The application of metal-matrix composite coatings for protecting and improving the service life of sliding components has demonstrated to have the potential of meeting the requirements of a diverse range of engineering industries. Recently, a significant body of research has been devoted to studying the mechanical and tribological performance of dispersion-strengthened MCrAlY coatings. These coatings belong to a class of emerging wear-resistant materials, offering improved properties and being considered as promising candidates for the protection of engineering structural materials exposed to tribological damage, especially at elevated temperature regimes. This paper attempts to comprehensively review the different reinforcements used in the processing of MCrAlY-based alloys and how they influence the mechanical and tribological properties of the corresponding coatings. Furthermore, the major fabrication techniques together with their benefits and challenges are also reviewed. Discussion on the failure mechanisms of these coatings as well as the main determining factors are also included. In addition, a comprehensive survey of studies and investigations in recent times are summarized and elaborated to further substantiate the review.

Layered sound absorptive non-woven fabric

Abstract: The invention relates to the layered sound absorptive non-woven fabric containing the resonance membrane and at least one another layer (1, 3) of the fibrous material at which the resonance membrane is created by a layer (2) of nanofibres having diameter to 600 nanometers and of surface weight 0,1 to 5 g/m^2, at the same time the resonance membrane together with at least one layer (1, 3) of fibrous material is formed by cross laying to the required thickness and surface weight.

Recent advances and outstanding challenges for implementation of high entropy alloys as structural materials

Abstract: The review summarizes some achievements of materials scientists in designing high entropy alloys (HEAs) and developing production routs for their industrial implementation, as well as highlights and discusses outstanding challenges in this way. Initially, the generally accepted concept of HEAs and its criticisms have been matched. Then, suggestions for their possible application have been agglomerated. After that, typical designing algorithms for metal products and structures have been considered, focusing on the rational selection of materials. Finally, correspondence of the reported data on both characteristics and properties of HEAs, as well as procedures for their heat treatment, processing and surface engineering, has been correlated with the content of recent reference books on those for conventional metals, steels and alloys. Based on the analysis of these results, some conclusions have been drawn, including generalized knowledge gaps and challenges. Also, further research directions have been proposed.