Effect of Rare Earth Element La on Corrosion Resistance of Powder Zinc Coating: Experiment and First Principle Calculation

Using a combination of first-principles calculations and experimental studies to study the effect of La on the corrosion resistance of Powder sherardizing layer in metal structures. Compared to other sherardizing rare earth elements (Re), La has better adsorption with the iron matrix and has the lowest binding energy on the adsorption surface (111) of the Fe matrix. Therefore, the rare earth element La is added to the powder sherardizing process for the rare earth chemical heat treatment to reduce the defects of the powder sherardizing faults formed, improve the surface uniformity and the quality of the permeation layer. On the basis of calculation, La element was added in the process of powder sherardizing, and the corrosion performance of the formed powder galvanizing layer was studied. After alternating salt spray experiments, the degree of corrosion of the layer is relatively small and the corrosion products are predominantly layered and spherical. Electrochemical tests of the layer show that the corrosion resistance of the layer after the rare earth chemical heat treatment has improved.

Analysis of the stress-strain state in carburized gearwheels

This article studies the static strength, static fracture and stiffness of the teeth of a wheel made of structural alloy steel of 12KhN3А grade before and after the carburizing of the working surface. The results of the analysis show that the static strength and static destruction of the part before and after chemical heat treatment are approximately equal, however, the gear wheel, strengthened by this method, has a higher hardness. The study and simulation of the applied loads were carried out using a 3D-model in the SolidWorks 2018 Simulation software.

Comparative Analysis of Novikov and Involute Gearing in the ANSYS Workbench Software Package

The paper introduces the results of studying the stress-strain state of the Novikov gearing in comparison with the involute gearing, similar in geometric parameters. In both versions, the wheel and gear are selected in size and gear ratio in accordance with the most common recommendations without additional hardening by chemical heat treatment. The zone of multiple contact of mated profiles is analyzed: changes in the geometry of contacts, pressure in the contact and stresses in various phases of gearing.

Chemical-heat treatment influence on thermal stability of microstructure, mechanical properties and fracture features of V-Cr-Ta-Zr alloy

A study of the features of structural-phase state, thermal stability, mechanical properties characteristics and fracture features of V-Cr-Ta-Zr alloy after chemical-heat treatment by the method of nonequilibrium internal oxidation has been carried out. It has been established that, in contrast to chemical-heat treatment in a defect state, the effect of oxygen when introduced into a material with a stabilized structure is observed only at high concentrations. At such oxygen concentrations, which ensure the maximum binding of Zr into particles based on ZrO2, the alloy under study demonstrates a high level of thermal stability and strength properties. These effects are associated with the implementation of disperse strengthening according to the Orowan mechanism by nanosized ZrO2 particles characterized by high thermal stability. The concentration and nature of the distribution of oxygen predetermine the spatial distribution of nanosized ZrO2 particles formed during chemical-heat treatment, which manifests itself in fracture features of the material at different temperatures.

ANALYSIS OF METHODS FOR CALCULATING SPUR GEAR FOR DEEP CONTACT STRENGTH

Spur gear is an integral part of transport and technological machines structure. To increase the load ability of the spur gear, chemical heat treatment of the working cogs surfaces is used. Spur gear with chemical heat treatment must be checked for deep contact strength. The article analyzes various methods (according to GOST 21354-87, methods using the generalized criterion of the limit state for structurally inhomogeneous material by Lebedev-Pisarenko, methods from the handbook describing reducers of power machines etc.) for calculating spur and helical gearing for deep contact strength. The author presents all necessary formulas and graphs for the implementation of each methods, and compares the calculations results of these methods with the results of experimental studies of cemented cylindrical rollers for deep contact destruction.

Chemical-heat treatment of 08Kh18N10T steel to improve its performance

Effect of liquid boriding on the structure and properties of 08Kh18N10Т steel is studied by metallographic studies. The dependence of the phase ratio in the boride layer on holding time is established. Corrosion resistance tests in 5 % saline solution and in salt spray chamber are performed. It is shown that the corrosion resistance of 08Kh18N10Т steel practically does not deteriorate after liquid boriding.