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The urban violence and the different types of global armed conflicts demand efficient protective systems against high energy ammunition. Multilayered Armor Systems (MAS) provide efficient protection by making use of lighter and more efficient materials. A typical MAS may be composed of three layers: a front ceramic followed by a composite, backed by a ductile metal. Polymer composites reinforced with natural fibers have proven to be effective second layers, being also lighter, low-cost and environmentally friendly as compared to conventional composites like KevlarTM. The present work evaluates MAS using as second layer polyester composites reinforced with 10, 20, and 30 vol. % of sisal fibers. Ballistic tests were performed using class III 7.62x51 mm ammunition, based on the NIJ 0101.06 backface signature methodology. Both the 30 vol.% sisal fiber composite and the conventional aramid laminates were equally efficient in terms of MAS second layer. The explanation might be the similar capacity of the different composites to retain the fragments generated by the interaction of the projectile with the front ceramic, independently of the percentage of sisal fibers.

For personal protection against high kinetic energy projectiles, multilayered armor systems (MAS) are usually the best option. They combine synergistically the properties of different materials such as ceramics, composites and metals. In the present work, ballistic tests were performed to evaluate multilayered armor systems (MAS) using curaua non-woven fabric epoxy composites as second layer. A comparison to a MAS using aramid (Kevlarâ¢) fabric laminates was made. The results showed that the curaua non-woven fabric composites are suitable to the high ballistic applications, and are promising substitutes for aramid fabric laminates. Keywords: Composite, Natural fiber, Curaua fiber, Non-woven fabric, Aramid laminate, Ballistic test

The domains of the existence of deformation mechanisms in a map associated with phase transformation and mechanical effects related to aging processes were investigated in austenitic stainless steels. It was also discussed the participation of grain boundary sliding, both as an additional deformation mechanism and a damage accumulation process. A prediction analysis for two typical high temperature engineering systems was attempted based on the map information. This prediction indicates the possibility of grain boundary sliding and creep strain jumps to interfere with the expected operational life of components in these systems operating at high temperatures.

The cracking susceptibility of a WSTE-51 steel for pressurized container of a nuclear power plant was evaluated. This evaluation was performed by means of the Controlled Thermal Severity Test and the Cold Cracking TEKKEN Test, as well as the VINCKIER Test for reheating cracking. Conventional mechanical tests and metallographic examinations were performed to characterize additional properties of the welding. The results indicated that the weldment has susceptibility to crack formation. Procedures to avoid this susceptibility were discussed.

Aluminum nitride, AlN, and titanium diborite,TiB2, are covalent-based ceramics with wide technological applications. However, sintering of these ceramics using conventional methods of high pressure requires not only elevated temperatures but also long processing time. This causes excessive grain growth, which impairs strength and hardness. In the present work, 70%AlN-30%TiB2 ceramic composites were sintered to relatively higher density and hardness by means of the Spark Plasma Sintering (SPS) at temperatures in the interval from 1500 to 1900°C in order to improve the properties of both compounds and decrease the processing time. The SPS was applied for different sintering temperatures and the effects on density, hardness and surface structure were evaluated. Maximum values obtained for density and hardness were 98.8% of the theoretical value and 13.7 GPa, respectively.

The residue obtained from sugarcane juice extraction, in sugar and ethanol production, is known as bagasse. At the industrial mill, bagasse is either incinerated for steam and power generation or discarded as a waste. The incorporation of bagasse waste into polymeric composites for ballistic resistant materials was investigated in this study. Plates of epoxy composites reinforced with either raw bagasse or extracted bagasse fibers were characterized. The 30 vol% bagasse composites were selected as a second layer, backing a front ceramic, in multilayered armors against 7.62 mm ammunition. Ballistic performance of composites was compared to Kevlar™ plates used in commercial multilayered armor systems. Results of ballistic tests indicated that multilayered armors with Kevlar™ and bagasse fiber composites satisfied the National Institute of Justice (NIJ) norm, and displayed similar depths of indentation in a clay witness. By contrast, the armor with raw bagasse composite demonstrated worse performance, with nearly two times deeper indentations, some of which exceeded the NIJ limit. Economical analysis revealed that armor with bagasse fiber composite is nearly 180% less expensive than a corresponding armor with Kevlar™. Therefore, it is shown for the first time that composites reinforced with fibers extracted from sugarcane bagasse (a large scale worldwide generated waste) could replace Kevlar™ in multilayered armor systems making them cheaper and more sustainable.