Qamar Hayat

Bio: Qamar Hayat is an academic researcher from Coventry University. The author has contributed to research in topics: Materials science & Ultimate tensile strength. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

Multiscale modelling for fusion and fission materials: the M4F project

Abstract: This work has received funding from the Euratom research and training programme 2014-2018 under grant agreement No. 755039 (M4F project).

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.

Reinforcement of Silica Particles in Bentonite Clay Based Porous Geopolymeric Material

Abstract: Positive effect of silica reinforcement in bentonite clay based geopolymer has been observed in the present investigation. In this research, heat treated bentonite clay with varying percentages of silica reinforcing particles (low, medium and high concentration) were used to prepare geopolymer mortars. While a constant quantity (25%) of sodium hydroxide and sodium silicate mixture was used. The effect of reinforcing silica particles on the physical and mechanical integrity of heat treated bentonite clay based geopolymer mortar has been elaborated in this research. After geopolymerization and de-hydroxylation, density (bulk and apparent) and porosity were measured for the all geopolymeric samples. Various techniques like FTIR (to confirm degree of geopolymerization), XRD (to determine the mineral phases), TGA (to measure the weight loss), and SEM (to study the microstructure) were used for the characterization of samples. The sample with low percentage of silica particles showed higher degree of polymerization. A compressive strength upto 57 MPa was achieved for the sample having high concentration (90%) of silica. The evaluation of various samples demonstrated that heat-treated bentonite-silica particles reinforced geopolymers were viable and eco-friendly alternative to fly ash geopolymers.

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.

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.

Materials for Sustainable Nuclear Energy: A European Strategic Research and Innovation Agenda for All Reactor Generations

Abstract: Nuclear energy is presently the single major low-carbon electricity source in Europe and is overall expected to maintain (perhaps eventually even increase) its current installed power from now to 2045. Long-term operation (LTO) is a reality in essentially all nuclear European countries, even when planning to phase out. New builds are planned. Moreover, several European countries, including non-nuclear or phasing out ones, have interests in next generation nuclear systems. In this framework, materials and material science play a crucial role towards safer, more efficient, more economical and overall more sustainable nuclear energy. This paper proposes a research agenda that combines modern digital technologies with materials science practices to pursue a change of paradigm that promotes innovation, equally serving the different nuclear energy interests and positions throughout Europe. This paper chooses to overview structural and fuel materials used in current generation reactors, as well as their wider spectrum for next generation reactors, summarising the relevant issues. Next, it describes the materials science approaches that are common to any nuclear materials (including classes that are not addressed here, such as concrete, polymers and functional materials), identifying for each of them a research agenda goal. It is concluded that among these goals are the development of structured materials qualification test-beds and materials acceleration platforms (MAPs) for materials that operate under harsh conditions. Another goal is the development of multi-parameter-based approaches for materials health monitoring based on different non-destructive examination and testing (NDE&T) techniques. Hybrid models that suitably combine physics-based and data-driven approaches for materials behaviour prediction can valuably support these developments, together with the creation and population of a centralised, “smart” database for nuclear materials.

Improved Water Retention and Positive Behavior of Silica Based Geopolymer Utilizing Granite Powder

Abstract: This research aims to study the behavior of silica based geopolymeric material (22–28%Si) from granitic waste. Granitic waste in powder form was used as main precursor in combination of activating alkaline-solution (18% Na2SiO3, 7% NaOH and 75% distilled water). The ratio between Na2SiO3 and NaOH was kept constant (2.57) in all experiments to achieve appropriate geopolymerization but solid to liquid ratio was varied. Five different compositions of geopolymeric material were prepared with varying proportions of granite waste in the range of 70–78%, combined-alkaline-solution in range of 28–20% and 2% water. Curing of the samples was done in a heating oven at 70 °C for 24 h. After that samples were de-moulded and placed in a heating furnace for further curing at 220 °C for 2 h. After curing, compressive strength, density (bulk, apparent and true) and porosity (open, close and total) were measured. Phase analysis, degree of geopolymerization and microstructural analysis were evaluated by XRF (X-ray Fluorescence), FTIR (Fourier Transform Infrared Spectroscopy) and SEM (Scanning Electron Microscopy), respectively. XRF analysis revealed 28.38% Si and 5.96% Al which are the main constituents for the synthesis of geopolymer. Maximum achieved compressive strength was 22 MPa with minimum porosity of 19.487% in 78% granite based geopolymer. Minimum bulk density of 1.441 g/cm3 was achieved using 70% granite waste. FTIR results confirmed geopolymerization and optimized composition in the resultant samples which is 78% granite and 20% combined-alkaline-solution. Further, SEM results revealed most homogenous and dense structure in the same composition. The durability of the geopolymeric samples was evaluated by water absorption index. Maximum water absorption index of 3.09 was found in 72% granite based sample having 26.79% Si while minimum 2.018 in 78% granite based geopolymeric material having 22.97% Si. Positive compositional effect on various construction properties has been achieved in this study.

On the equivalence of irradiation conditions on present and future facilities for fusion materials research and qualification: a computational study

Abstract: We performed a computational study to assess the suitability and equivalence of the irradiation conditions on several test irradiation facilities (either currently operating or planned to deploy in the future) aimed at the qualification of materials for nuclear fusion reactors such as ITER and DEMO. The degradation of the material's properties is driven by the changes in its microstructure and chemistry (transmutation). The primary objective of this study is thus to perform a comparison of the microstructural pattern as predicted by means of simulations. The focus of the study is put on two materials: Eurofer97 steels and tungsten. We considered operation conditions in fusion reactors (i.e. ITER and DEMO) and in test irradiation facilities such as material test reactors (fast and mixed neutron spectrum), IFIMIF-DONES, ESS and proton accelerators. Typical irradiation conditions are addressed according to the currently available design (for DEMO) and expected operation modes (for ITER). The study is realized by means of object kinetic Monte Carlo which is parameterized and configured using state-of-the-art knowledge on irradiation spectra, neutron cross-sections, primary damage states, lattice defects mobility/cohesion and interaction of the material's microstructure with lattice defects. The irradiation defects are singled out using a dedicated post-processing tools to enable a comparison with expected findings in transmission electron microscopy (TEM) and atom probe tomography (APT). The results are discussed in terms of the equivalence of the emerging irradiation microstructure predicted to occur in test irradiation facilities if compared with the one simulated in the nuclear fusion reactors. The summary and discussion provide information on the equivalence and deviations of the microstructural patterns suggesting the suitability of the test irradiation facilities for certain irradiation regimes, as well as pointing at some limitations, e.g., originating from the difference in the neutron spectra or flux.