This paper shows results of a study on the corrosion behavior of micro-arc oxidation (MAO) coatings sampled from the AlMg6 alloy. The alloy was simultaneously subjected to a corrosive environment and static tensile stress. For comparative purposes, the tests were run for both coated samples and samples without coatings. The research was conducted at a properly prepared stand; the samples were placed in a glass container filled with 3.5% NaCl aqueous solution and stretched. Two levels of tensile stress were accepted for the samples: σ1 = 0.8R0.2 σ2 = R0.2, and the tests were run for two time intervals: t1 = 480 h and t2 = 1000 h. Prolonged stress corrosion tests (lasting up to 1000 h) showed that the samples covered with ceramic coatings demonstrated significantly higher corrosion resistance than the samples without the coatings. Protective properties of the coating could be explained by its structure. Surface pores were insignificant, and their depth was very limited. The porosity level of the main coating layer was 1%. Such a structure of coating and its phase composition provided high protective properties.

Composites are increasingly being modified with various types of fillers and nanofillers. These materials have attracted much attention due to the improvement in their properties compared to traditional composite materials. In the case of advanced technologies, adding additives to the matrix has created a number of possibilities for use in many industries, from electronics to mechanics. Mechanical recycling of composites allows them to be reused as a filler in new composite materials; however, a decrease in their strength parameters is observed, and hence, new possibilities of their use are sought. The main objective of this research was to analyze the effect of the graphite content on the tribological and structural properties of composites with polyester–glass recyclate. Composite materials with 10% polyester–glass recyclate and an additive in the form of graphite in the amounts of 0%, 2%, 5%, 10% were made using the hand lamination method and their mechanical properties were verified. Then, using a universal tribometer operating in rotational motion with friction without lubrication, the influence of nanoadditives on the change in the coefficient of friction (µ) and the change in the coefficient K (the rate of a mass wear) of the obtained composites was investigated. This study showed that adding graphite in the amount of 2%, 5%, and 10% changes the nature of tribological wear of the obtained composite material. The coefficient K (mass wear rate) also changes. The addition of 10% graphite significantly changes the coefficient of friction without lubrication in a pair with a steel counter-sample.

This paper investigates the structure and mechanical characteristics of a coating based on an AlSi12 alloy, obtained by centrifugal induction surfacing as an alternative to a bronze sliding bearing. To provide for the adhesion of an aluminum layer to the inner surface of a steel bearing housing, a sublayer of low-melting metals was formed, while the formation of the main layer and the sublayer was done in a single processing cycle. The low-melting metals had higher density, which ensured that the sublayer was created at the interface with the steel bearing housing under the action of centrifugal forces. It is shown that the low-melting sublayer forms a strong bond both with the aluminum alloy and with the steel base. Lead and tin are used as low-melting additives. It has been established that lead or tin used in a sublayer are indirectly involved in the structural formation of boundary layers of steel and aluminum claddings, acting as a medium for diffuse mass transfer. Thus, lead is not included in the composition of the main coating and does not change the chemical composition of the aluminum layer. After the addition of tin, the aluminum develops a dendritic structure, with tin captured in the interdendritic space. In this case, the deposited layer is saturated with iron with the formation of intermetallic (Fe, Al, Si) compounds, both at the interface and in the coating volume. This paper offers an explanation of the mechanism through which Pb and Sn act on the structure formation of the coating, and on the boundary layer of the steel bearing housing. Tribological tests have shown that the resulting materials are a promising option for plain bearings and highly competitive with the CuSn10P bronze.

The results of the study of the crack resistance of the microarc oxidation coating (MAO) after laser doping with zirconium oxide are presented. The crack resistance was determined by an indentation method with microhardness prints visualization by atomic force microscopy. It was established that laser doping with zirconium oxide leads to a significant hardening of the MAO coating. The stress intensity factor increases by a factor of 2.7 and the damage to the surface decreases by a factor of 2 compared with the initial MAO coating.

This article presents a comparative study of mechanical properties and stress corrosion cracking (SCC) resistance of bare AW-5083 aluminum alloy and the same alloy coated by plasma electrolytic oxidation (PEO). Although Al–Mg alloys of the 5XXX series have been extensively studied with respect to SCC behavior, data concerning their performance after PEO treatment under mechanical loading in chloride-containing environments remain scarce. Prior to SCC testing, potentiodynamic polarization measurements were performed to assess the barrier properties of the PEO coating against general corrosion. The results demonstrate that the PEO coating significantly modifies the electrochemical response of the alloy and improves its resistance to corrosion processes in the presence of chloride ions. SCC tests revealed that the application of the PEO coating leads to enhanced resistance to stress-assisted degradation of the AW-5083 alloy, while distinct features of coating cracking under tensile loading were observed and discussed. The study provides new experimental insight into the combined mechanical and electrochemical behavior of PEO-coated AW-5083 alloy exposed to chloride environments.