In order to find alternative hard oxide particles to increase friction coefficient as well as adhesive materials to reduce damage to wheel rail surface,the effects of Cu,Fe and SiO2 powders on the friction coefficient,wear and surface hardness were compared and tested using a pin-on-disk friction testing machine by adding powder to the wheel rail friction surface,and the morphology of the friction surface were analyzed under the testing pressure of 0.5 MPa and the rotational speed of 100,200,350 and 500 r·min-1.The results showed that the effect of Cu and Fe powder on increasing the friction coefficient between wheel and rail is greater than that of hard SiO2 powder.The friction coefficient increased by 0.2-0.3 after Cu powder was added to the friction surface,0.1-0.2 after Fe powder was added.When the rotational speed was less than 200 r/min,the increase in friction coefficient by adding SiO2 powder was below 0.1.While the friction coefficient did not increase when the rotational speed exceeded 200 r·min-1.In terms of low rotational speed conditions,SiO2 and Fe powder increased wear by over 40％.When the rotational speed was greater than 200 r·min-1,Cu powder reduced the wear by 50％.The reason was that high hardness particles intensified the plowing of the friction surface,leading to a doubling of wear.Under the action of shear force,Cu powder is prone to significant plastic deformation,so as to adhere to the friction surface,which could increase friction and reduce wear.Under low rotational speed conditions,the hardness of Fe and SiO2 powder was high,which formed an bite effect with the friction surface,leading to an increase in friction coefficient.As the increase of rotational speed,Fe and SiO2 powder were crushed and refined,and the fine particles have a rolling effect,weakening the shear force between the surfaces and making it difficult to increase the friction coefficient.
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