Today, the relative wear of parts of marine equipment (the proportion of the decrease in the mass of the part to its initial mass) is very low but nevertheless can cause failure of the mechanism as a whole. The expenses due to wear in shipbuilding and in the service of the fishing fleet are quite high.For this reason the problem of obtaining diffusion wear-resistant coatings on metallic parts remains urgent. In order to solve it the department of metal technology and ship repair of the Murmansk State Technical University has performed a study of wear-resistant diffusion coatings on steel parts. Specimens of carbon steels were subjected to diffusion saturation in powderlike mixtures at various temperatures.The wear resistance of the diffusion coatings was studied under conditions of dry sliding friction in an SMTs-2 machine for steel 45 and St3 at a speed of 8.3 m/sec and a load of 400 N. The tests were performed at room temperature; the roll and the shoe were weighed in every 500 m of the path in order to determine the decrease in the mass caused by wear.The specimens of carbon steels with diffusion wear-resistant coatings only lap to each other on the 500-m friction path. The coated specimens had a glittering surface with good sliding, no traces of scoring or flattening were observed, and the color did not change.The performed study of the wear resistance of parts from carbon steel with diffusion coatings has shown that the method of deposition of protective coatings used can be recommended for increasing the service life of parts operating under the conditions of friction. The use of wear-resistant diffusion coatings on carbon steel 45 and St3 not only increases the service life of parts of marine equipment but can be used in some cases for replacing high-nickel steels and alloys of the 12Khl8N9TL type.

For the development of standards of timing and amount of shipboard equipment maintenance and repair it is important to study and improve the theory and practice of evaluation of endurance of such friction pairs as sliding bearings. In the diagnosis of rolling bearings vibroacoustic methods are widely used, but, as for sliding bearings, these methods are still at the stage of research with respect to friction. Thereby, the results of testing different types of tribounit samples on friction test machines have been studied. There have been done vibration measurements for given conditions (rotation speed and load), where the root mean square values (RMS) of vibrational acceleration a in m/s2 or dB for acceleration were used as main diagnostic parameters. The authors have investigated dependencies of vibration levels for each band of tri-band spectrum on rotational speed, load, lubrication, surface roughness with respect to temperature, coefficient of friction and wear resistance. It has been proved that the source of VHF vibration of RMS is friction in coupling, depending on the surface condition and lubrication type of the friction pair. Dependency of acceleration RMS level on rotational speed and load of the sample has been stated. The results allow to infer about the effectiveness of the proposed tri-band vibroacoustic characteristics of the tribounits using vibrometer CM-21. This method can be used for diagnostics of sliding bearings, which can require standardization of modes and conditions of measurement and the establishment of zones of maximum permitted levels of the object state.

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Operation of mechanisms and equipment under significant temperature changes can cause brittle destruction not only of metal structures. In the process of research of high pressure hose of camber mechanism there was revealed violation of the tightness of the outer rubber layer, which led to further penetration of acid-alkaline environment (moist sea air) into the formed voids in winding layers. In the damaged segments the torn filament ends of metal coiling of flexible hydraulic connection seem typical of brittle damage. Further study of macro-and microstructure of the material of metal filaments of the wire and detailed analysis of the near-surface layer revealed violation of the technology of protective coating of the filaments. The low quality of brass coating of the metal coiling of DN20 wire of the hydraulic connection resulted in the rapid corrosion attack. The presence of structural defects in the near-surface layer led to the formation of discontinuities of brass coating, to a decrease of adhesion characteristics of the metal coiling. Iron oxide being a product of corrosion of metal filament coiling in the formed voids between the layers slashed under bending effected by friction contact and alternating loads. The research results can be used for developing effective anti-corrosion methods for flexible hydraulic connections.