Page 7 - дисертація Головчук

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SUMMARY

Holovchuk M. Ya. Influence of the Diameter of High-alloyed Powder Wires

on the Structure and Physicо-Mechanical Properties of Electric-Arc Coatings –

Qualification scientific work on the rights of manuscript.

Thesis for the degree of a Candidate of Technical Sciences in specialty

05.02.01 – Materials Science – Karpenko Physico-Mechanical Institute of National

Academy of Sciences of Ukraine, Lviv, 2020.

Formation regularities of wear resistant electric-arc coatings made of PW with

the increased content of alloying elements of the Fe – Cr – B – C system were

investigated in the thesis.

PW of larger diameter may contain more charge materials, and therefore allow

to obtain alloyed coatings with high physico-mechanical and tribological

characteristics, wear resistance and gas-abrasive resistance both at room and

elevated temperatures.

Model PW of three alloying systems of martensitic class, austenite of carbide

class and martensite with borides inclusions were studied in the work. In order to

identify the effect of the diameter on physico-mechanical properties a series of

model PW 1.6 and 2.4 mm in diameter with the same chemical composition were

prepared.

It was established that by increasing the PW diameter and arc current, the

volume of melted metal at the ends of the PW rises and therefore the air flow

disperses it into drops of larger diameter. As a result, the thickness of the lamellae

(as a structural feature of coatings) in the coatings of all alloying systems increases

as well.

It was found that the content of the oxide phase in the coatings doubled with

increasing spray distance from 80 to 120 mm and with increasing the time of the

drops presence in the air stream. Coatings made of PW with a diameter of 2.4 mm

contained 40… 100% more oxide phase than ones made of PW with a diameter of

1.6 mm. This is due to the larger volume of the charge in the PW of larger diameter,