Journal of Environmental Friendly Materials
Volume:7 Issue: 2, Summer-Autumn 2023

Hybrid composites are a kind of composite produced with two or more different reinforce. One of the production technologies is using metal-fiber layers in a hybrid composite. In the present study, for the production of Hybrid composite, samples were prepared from glass fiber (S glass), aluminum alloy sheet (2024), and epoxy resin (F grade) using Resin Transfer Molding (RTM) process. Thus, three samples were considered, not strengthened matrix samples, samples with two layers of glass and samples with two layers of glass and two layers of aluminum. Then amounts of rigidity, strength and density of the samples were calculated considering fibers volume fraction. The results indicate that the presence of aluminum layer leads to an increase in toughness and plasticity of the composite, and thus causes more resistance to damage. Besides ultimate strength and strain, Natural frequency of the samples also increases by addition of the aluminum layer.

One of the most attractive and widely used alloys in the industry and field of implants is titanium and titanium alloys, including Ti6Al4V. The outstanding properties and application of this with the attractive capabilities of additive manufacturing technology have increased the inclination towards additive manufacturing of titanium parts. In this research, the effect of surface treatment and heat treatment on the microstructure and mechanical properties of Ti6Al4V alloy manufactured by selective laser melting was investigated. For this purpose, Ti6Al4V alloy produced by selective laser melting was subjected to annealing heat treatment at 1050 degrees Celsius and surface treatment of surface ultrasonic mechanical stimulation. Then, the microstructure and phases of Ti6Al4V alloy, which included α and β phases, were investigated with optical microscopy and X-ray diffraction analysis. The mechanical properties of the samples were also checked by Vickers hardness, tensile and uniaxial compression tests. The results showed that annealing heat treatment and then aging decreases the strength properties but increases the flexibility and toughness. By performing surface treatment, the hardness of Ti6Al4V alloy increases. In general, it can be said that the desired properties of this alloy, produced by selective laser melting, can be obtained by performing suitable surface and thermal treatments.

Light-expanded clay aggregates (LECA) is an alternative material which widely used in building materials and many other applications. This paper investigates the permeability, compressive, and splitting tensile strength of concrete specimens produced with ordinary coarse aggregate or LECA. Eight concrete mixes with the partial replacement of cement by steel slag powder were prepared to get an appropriate mix design for ordinary coarse aggregate or LECA concrete. The variables in the current study include steel slag content (0% to 60%) and curing time (7, 28, or 90 days). This study finds out that 40% of cement can be replaced by steel slag powder, which causes the compressive and splitting tensile strength to increase. The steel slag content has no important effect on the permeability coefficient of specimens. Furthermore, the compressive and splitting tensile strength of coarse aggregate concrete specimens is more than that of LECA concrete specimens for a given steel slag content and curing time. In general, increasing curing time results in an increase in both the compressive and splitting tensile strength of specimens.

Surface coating on metal substrates has remained a difficult challenge for researchers due to the conflicting requirements for different properties. In recent years, due to their mechanical, thermal, electrical, and tribological properties in many advanced engineering applications, functionally graded coatings (FGCs) have become fascinating materials for researchers worldwide to obtain coatings with specific requirements. FGCs are a novel type of traditional composites in which phases are not equally distributed to form a smooth gradient structure; thus, gradient coatings have shown a new research path.The present paper tries to describe briefly major thermal spray techniques used to spray functionally graded coatings such as atmospheric plasma spraying, high velocity oxy-fuel spraying, suspension and solution precursor plasma spraying, and finally low and high-pressure cold gas spray methods. The examples of combined spray processes as well as some examples of post-spray treatment including laser and high temperature treatments or mechanical ones, are described.

Functionally graded materials (FGMs) revealed an immense growth with worldwide demand. This paper describes a brief review of the feasibility of production methods (solid, liquid, and gaseous methods) chosen for FGMs, with the aid of schematic diagrams. Advanced FGM fabrication techniques such as additive manufacturing and laser deposition, which have been gaining importance are also explored. The evolution of fabrication techniques is correlated to the industrial requirements along with their merits and limitations. This review article also highlights some advanced engineering applications observed for FGMs. Comparing various fabrication technologies employed for FGMs, centrifugal casting was the most established and economically feasible method that met vast industrial product demands like hybrid and double-graded FGMs. Powder metallurgy was preferred for bulk gradation in spite of their sharp transitions across layers. Advanced FGM fabrication techniques like additive manufacturing, electrochemical gradation, and laser deposition techniques improved critical production parameters like precision, gradation control, etc. Thermal spraying successfully improved the heat insulation performance of FGMs.

One of the main challenges in advanced industries in the field of future technologies is the existence of materials that can maintain their integrity at temperatures above 2000 degrees Celsius. Ultra-high temperature ceramics (UHTCs) are among the attractive options for meeting this industrial need. Resistance to oxidation and linear and mass erosion is one of the most important and influential properties of these high-temperature ceramics. Hf and Zr diborides are the most important materials among high-temperature ceramics for these components, showing the best resistance to oxidation up to a temperature of 1500 degrees Celsius. Especially ZrB2 has received more attention due to its low density and low cost. However, two important factors hinder its application: firstly, it contains a high amount of boron. Boron oxides quickly vaporize at temperatures above 1200 degrees Celsius, resulting in severe material loss due to hot gases. Secondly, due to its brittleness and low thermal shock resistance, it is prone to sudden fracture. In order to reduce the evaporation of boron oxides and improve the erosion resistance of ZrB2, significant attention has been given to adding silicides (such as SiC, MoSi2, etc.) and carbides (such as ZrC) to ZrB2 to form multiphase ceramics. On the other hand, relatively little attention has been paid to the development of single-phase ceramics with multiple elements. Although ZrC is less prone to evaporation at high temperatures due to the absence of boron, it has lower oxidation resistance compared to diborides (such as ZrB2) and is weaker. This makes it less suitable for anti-erosion applications. The mentioned factors indicate that high-temperature ceramics are limited in their application in environments with very high temperatures, and new single-phase ceramic materials with lower evaporation rates and better oxidation resistance need to be developed. This research focuses on recent studies on increasing the oxidation resistance of ZrB2 composites in detail.

From ancient civilizations using gold and silver for healing to the metal surgical instruments of the Renaissance, the introduction of anesthetic and antiseptic treatments in the 19th century, and the 20th century medical device revolution, the history of medical materials is an inventive one. Today, modern healthcare is being shaped by materials like bioglass.Dr. Larry Hench invented bioglass in 1969, and it has since been used extensively in biological and medical application. This brief study covers composition, bioactivity mechanisms, and healthcare applications of bioglass. Bioglass has a wide range of applications, including bone regeneration, tissue engineering, implantable devices, and more thanks to its remarkable bioactivity, biocompatibility, and tissue bonding properties. The sol-gel synthesis method, offering lower processing temperatures and uniform compositions, has gained prominence. Although there are still issues with optimizing bioglass for various biomedical uses, current research and innovation show promise for the material's future advancement in healthcare.

Along with material science progress, many new high-quality and cost-effective engineering materials have been introduced in various fields. Smart materials are the new generation of materials superior to construction and commonly used materials. With their inherent intelligence, these materials can adapt to external stimuli such as loads or the environment. Smart materials refer to those materials that understand and react to their environment and surrounding conditions. The crystal structure of these materials responds to applied force (mechanical, electrical, magnetic, etc.). According to NASA's definition, smart materials remember positions and can return to them with certain stimuli. Smart materials are used in systems whose inherent properties can be changed to achieve the required performance. In this article, while introducing the application and development of memory metal smart materials, the relationship between the development of advancing technologies and the development and application of this class of material is discussed.