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The kinetics of plasma-electrolytic oxidation (PEO) coating growth on AZ31 alloy in an alkaline–phosphate–aluminate electrolyte was studied. The structure, elemental composition and corrosion resistance of obtained PEO coatings were studied as a function of thickness. It was established that formation of the coating layers takes place in the following sequence: anodic, external and internal layers. Their formation occurs due to: 1) dielectric layer formation due to anodic conversion of surface; 2) ignition of powerful microdischarges in the transversal pores of the initially formed coating, forming the main part of its outer layer in case of increasing duration of the PEO process; 3) etching of magnesium alloy as a result of electrolyte penetration through the transversal pores to the metal substrate, followed by its anodizing; 4) ignition of microdischarges under the coatings outer layer, leading to formation of an inner layer. Existence of the coating inner layer causes a significant increase in corrosion resistance; however, it is still insufficient for long-lasting standalone corrosion protection. It was shown that sodium oleate (SOl) is the best inhibitor for the AZ31 substrate, therefore it was selected for impregnating PEO coatings. Impregnation of the coatings in 10 mM SOl solution increases their protective ability. Corrosion tests of PEO coated AZ31 samples in a climate chamber showed that the effect of impregnating is most pronounced for thin PEO coatings (20 μm). Under more corrosive conditions of salt spray test, impregnating the PEO coating with SOl increased the time until the appearance of the first corrosion marks. It also significantly slowed down the development of the corrosion marks compared with the samples coated by PEO without impregnation.

© Published under licence by IOP Publishing Ltd. The article describes a fuel system of a diesel engine with a construction tractor multistage heating, allowing the use of pure rapeseed oil as a diesel engine fuel. The paper identified the kinematic viscosity depending on the temperature and composition of the mixed fuel, supplemented by the existing recommendations on the use of mixed fuels based on vegetable oils and developed the device allowing use as fuel for diesel engines of biofuels based on vegetable oils.

© Published under licence by IOP Publishing Ltd. The main structural and technological factors of electric arc metallizers, which significantly affect the quality of their operation, are considered. The results of experimental studies on the adhesion strength, porosity, microhardness and comparative wear resistance of coatings obtained by electroarc metallization are presented. Optimal modes of coating with electroarc metallization are determined. It is established that the use of aerosol fluxing during electric arc metallization provides an increase in adhesion-cohesive strength by 25 ⋯ 30%, an increase in microhardness to 40%, a decrease in porosity by 20 ⋯ 25%.

The transverse and longitudinal magnetic relaxation of solutions of cellulose nitrate (CN) with nitrogen contents of 13·5 and 11·9% have been studied in deuterated acetone in the temperature range from -100 to +70°C al two concentrations (34 and 50 wt. %). The two-component nature of the decay of the transverse magnetization points to the structural non-uniformity of CN in solution. The observed minima on the temperature dependence of the spin-lattice relaxation time in the laboratory system of coordinates, T1, and in a rotating system of coordinates are caused by segmental movement in open-packed regions of the solution. The contribution of slow movements to the spectrum of correlation times at the temperatures of the minimum T1 has been assessed. The values obtained for the activation energy for segmental motion in the unordered regions show that a vibrational-rotational mechanism predominates in the segmental motion of CN. © 1983.

This paper proposes a strategy for the classification of codimension-two discontinuity-induced bifurcations of limit cycles in piecewise smooth systems of ordinary differential equations. Such nonsmooth transitions (also known as C-bifurcations) occur when the cycle interacts with a discontinuity boundary of phase space in a nongeneric way, such as grazing contact. Several such codimension-one events have recently been identified, causing for example, period-adding or sudden onset of chaos. Here, the focus is on codimension-two grazings that are local in the sense that the dynamics can be fully described by an appropriate Poincaré map from a neighborhood of the grazing point (or points) of the critical cycle to itself. It is proposed that codimension-two grazing bifurcations can be divided into three distinct types: either the grazing point is degenerate, or the grazing cycle is itself degenerate (e.g. nonhyperbolic) or we have the simultaneous occurrence of two grazing events. A careful distinction is drawn between their occurrence in systems with discontinuous states, discontinuous vector fields, or that with discontinuity in some derivative of the vector field. Examples of each kind of bifurcation are presented, mostly derived from mechanical applications. For each example, where possible, principal bifurcation curves characteristic to the codimension-two scenario are presented and general features of the dynamics discussed. Many avenues for future research are opened.