Page 12 - НАЦІОНАЛЬНА АКАДЕМІЯ НАУК УКРАЇНИ

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layers decreases during friction tests with a rigidly fixed abrasive by 48 ... 93 times

due to an increase in the volume content of Al 4SiC 4 particles with globular

morphology and high hardness. Since the maximum effect of the laser modification

was manifested in the wear resistance of the surface on the B95 alloy, it was further

investigated.

It was revealed that the abrasive wear resistance increases in proportion to the

volume content of SiC particles in the modified alloy.

The speed of movement of the laser beam (linear energy of the beam) over the

surface affects the structure and wear resistance of laser-modified layers as well as

the heating of the substrate. In particular, with an increase in heat input from 740 to

1100 J/cm, the concentration of SiC particles in the modified layer increases by 25%,

and the wear resistance during friction tests with a rigidly fixed abrasive by

1,7...2 times.

It was found that the wear resistance of the modified layer is almost not

affected by the direction of friction (along or across the laser processing tracks),

however, the ratio of adjacent tracks overlap significantly affects. So, when rubbing

with a rigidly fixed abrasive, with an increase in the width of the overlapping zone of
laser tracks from 25 to 50%, obtained at a linear energy of 740 and 1100 J/cm, the

wear of the reinforced layer is reduced by half. An increase in wear resistance was
associated with an increase in the volume content of SiC particles in the modified

layer.
Thus, the wear resistance of the modified layer under friction by a rigidly fixed

abrasive increases with an increase in the size of SiC particles and their volume

content, an increase in the linear energy of the laser beam and the tracks overlap ratio.

When testing with a non-fixed abrasive, the trends in wear resistance remained,

however, the influence of the factors analyzed above is much weaker. Depending on

the processing conditions, it increased only by 10...35% in comparison with an

unchanged surface.

After analyzing the worn surfaces, the wear mechanism of the laser-modified

layer on the B95 alloy is revealed, and it was found that during friction with a rigidly