Increasing of working properties of the industrial components surfaces by applying modified nano-formation coatings

Increasing of operational properties, especially wear-resistant surface of industrial components may be achieved by modifying the surface layers of nano forms through the providing of nanopowders into the molten pool at electric-arc surfacing and coating during thermal spraying.

The basis of the weld and the surface layers were deposited by materials with different doping systems, which are recommended for conditions of abrasion and the dry friction of metal on metal. As modifiers were used nanopowders of alumina, titania and silicon fraction of 5-50 nm, whose providing in small amounts can significantly affect the nucleation and physico-mechanical properties of the coating material. Providing of nanoparticles into the weld pool and the coating is carried out at special circuits, which leads to a change in the conditions of crystallization and the formation of a fine-grained microstructure with a certain amount of hardening constituents which is responsible for strength values and wear resistance of the surface layers.

The relationship between the structural and phase composition and properties of modified surface layers, depending on the content and type of nanopowder. Providing of nano-powder silicon dioxide contributes to the formation of acicular ferrite, a structural component of high strength and toughness, which has a positive effect on endurance and leads to the formation of nonmetallic inclusions predominantly oxide type increasing the wear resistance of the weld deposited metal in 3–4 times. When surfacing low alloy steels it is found a positive effect of aluminum oxide nanopowder additives on wear resistance under abrasive wear with an increase of it more than 6 times.

Rational modes mechanochemical synthesis to create a powder mixture of nano and microparticles using a planetary ball mill is developed. Modes set spraying powder mixtures are obtained using a laminar plasma jet, thereby transferring nanopowder coating. The range of optimum content of nanopowders is within 0,5–1,0%. It is shown that the presence of aluminum oxide nanoparticles in the coating in an amount established by coating enhances the wear resistance 2,5–3 times and reduce the friction coefficient and improve the hardness by 25–40%.

The technological recommendations arc weld surfacing and plasma spray coatings modified nanostructures are presented.

Мікроструктура плазмового покриття системи NiCrFeBSi  модифікованого нанопорошком Al2O3 до оплавлення
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