In this study, kinetic examinations on boronized X45NiCrMo4 (DIN 1.2767) and 90MnCrV8 (DIN 1.2842) steel samples are described. Samples were boronized in indirect heated fluidized bed furnace at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h. Morphologically and typically examinations of borides formed on the surface of the steel samples were studied by optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD). Boride layer thickness formed on the steel X45NiCrMo4 ranges from 45 μm to 382 μm and for the material 90MnCrV8 ranges from 33 μm to 471 μm. The hardness of the boride layer formed on the steel X45NiCrMo4 varied between 1713 HV0.1 and 2111 HV0.1 and for the steel 90MnCrV8 between 1716 HV0.1 and 2761 HV0.1. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature. The kinetics of the reaction has been determined with K = Ko exp (-Q/RT) equation. Activation energy (Q) of the borided steel X45NiCrMo4 was determined as 156 kJ/mol and that of the steel 90MnCrV8 was determined as 179 kJ/mol.

In this study, the fracture toughness of Fe2B boride layer on boronized AISI 304 stainless steel was investigated. Samples were boronized in an indirect heated fluidized bed furnace with Ekabor 1™ boronizing agent at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h, respectively. The boride phases were investigated by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indentation. With increasing boriding temperature and time the fracture toughness values were reduced. The boride layer thickness formed on the boronized samples ranged between 12 μm and 176 μm. The hardness of the borides ranged between 1709 HV0.1 and 2119 HV0.1 and fracture toughness was in the range of 2.19–4.47 MPa × m1/2 depending on the layer thickness and hardness.

Energy requirements in the design, construction and use of buildings have a major impact on the consuming of energy resources. For this reason, it is important to build buildings in a way that is least harmful to the environment and energy efficient. The façade, which is the first surface where the building communicates with the external environment, is the part that affects energy usage the most. Figure A. Basic principles for energy efficiency in building facadesPurpose: The main aim of this study is to find the answer of the question; "Can solutions for providing energy efficiency in building facade systems be designed by taking inspiration from the systems in nature?" Theory and Methods: The methods of providing these energy efficient solutions (efficiency, protection, production, etc.) of biomimetic façade systems inspired by nature have been examined through the sample projects identified. Following the required literature review, five examples of projects with different features were examined. At each project inspired by different organisms; firstly, it has been analyzed how organisms develop air, water/moisture, heat, and light regulation strategies through structure, skin, surface or layer. It was determined that these strategies are transferred to the facade systems at which level and approach of biomimicry. In biomimetic façade systems, it was determined at which level these strategies are used in the system and what type of façade system was used. After the energy efficient solutions provided by the system in line with the determined principles were analyzed one by one, the projects were evaluated with a comparative table in line with these principles.Results: As a result of the evaluation, it has been determined that energy efficient facade systems can be designed with sustainable, innovative and alternative solutions offered by the biomimetic approach. In addition, it has been observed that energy efficiency is achieved by producing solutions for air and water regulation with especially heat and light regulation, in biomimetic facade systems. Conclusion:When designing energy efficient facade systems, biological solutions should be well defined and integrated into the design according to the problems experienced in the creation of facade designs. In addition, in order to obtain more reliable and clear data, it is recommended that biomimetic project analysis be performed with energy simulation programs and energy performance calculation methods.