No abstract

Anodic zinc oxide (AZO) layers are attracting interdisciplinary research interest. Chemists, physicists and materials scientists are increasingly devoting attention to fundamental and application‐related research on these layers. Research work focuses on the application as semiconductor, corrosion protector, adhesion promoter, abrasion protector, or antibacterial surfaces. The structure and crystallinity essentially determine the properties of the AZO coatings. The type and concentration of the electrolyte, the applied current density or voltage as well as the duration time enable layer structures of structural variety. The article gives an overview of the different possibilities of anodic treatment, whereby the voltage and the current type are the main distinguishing criteria. Presented is the electrolytic oxidation (anodizing) and the electrolytic plasma oxidation (EPO). The electrolytic etching is also a process of anodic treatment. However, it does not produce AZO layers, but rather a degradation of the zinc layer. The review article shows the parameters used so far (electrolyte, current type, current density, voltage) and points out the influence on the formation of AZO structures in dependency to the used electrolyte.

Характер руйнування армувальної стальної сітки під час зварювання прокаткою композиційного матеріалу на основі алюмініюFlat roll-bonded aluminum 6060 composite materials with reinforcing steel inlets made of woven wire mesh (AISI 321) and expanded mesh (AISI 304) have been produced at 20 % and 30 % reduction. The roll bonding process has been performed at 400 and 500℃. After the process the composites were peeled and their interfaces were subsequently studied via SEM microscopy. In all cases the fracture of mesh inlets has been observed. The analysis of the failure mode has shown that the fracture of woven wire mesh corresponds to that described by other researchers. At the same time, the failure mode of expanded mesh inlet was presented in this study is characterized by a significant amount of brittle fracture at the region between strands and knuckles of expanded mesh. In order to analyze a stress state in these regions, the simulation using the finite element method (FEM) was set up by means of QForm software. The thermal and deformational conditions corresponded to experimental ones. It was shown that the von Mises stress reaches a significant magnitude up to the strength of austenitic steel. At the same time, a study of initial micro hardness of expanded mesh was conducted. The study revealed a significant work-hardening in the region of knuckles due to manufacturing procedure of expanded mesh and this seems to be the most important cause of destruction. In order to avoid such fracture, the annealing of expanded mesh was proposed. Presented results show a significant decrease of hardness and therefore an opportunity plastic deformation of expanded steel mesh.

Laser surface treatment of metals is one option to improve their properties for adhesive bonding. In this paper, a pulsed YVO4 Laser source with a wavelength of 1064 nm and a maximum power of 25 W was utilized to increase the surface area of the steel HCT490X in order to improve its bonding properties with a carbon fibre reinforced polymer (CFRP). Investigated was the influence of the scanning speed of the laser source on the bonding properties. For this purpose, the steel surfaces were ablated at a scanning speed between 1500 and 4500 mm/s. Afterwards the components were bonded with the adhesive HexBond™ 677. After lap shear tests were carried out on the specimen, the surfaces were inspected using scanning electron microscopy (SEM). The experiments revealed that the bonding quality can be improved with a high scanning speed, even when the surface is not completely ablated.

No abstract