Surface Topography and Roughness Parameters of Electrospark Coatings on Titanium and Nickel Alloys

Abstract

This paper examines the topography and roughness of coatings of hard alloyed materials deposited by electrospark deposition (ESD) on titanium and nickel alloys with different initial roughness. The influence of the electrode materials and the energy parameters of the ESD process on the roughness parameters Ra, Rt, Rq, Rz, Rmax, on the depth of waviness Wt, the asymmetry Rsk, the excess Rku, on the depth of core roughness Rk and the depth of the reduced picks roughness Rpk was established. The conditions for ESD are indicated, under which the traces of the previous treatment are erased and the characteristics of the initial substrate surface are improved. The numerical values of the roughness parameters for electrospark coatings from five types of hard alloys and one type of TiB2 based electrode with nanosized additives have been established.

Study of the Influence of Coating Roughness on the Properties and Wear Resistance of Electrospark Deposited Ti6Al4V Titanium Alloy

“…The results of our present and previous studies [12,15,16,[22][23][24]26] and the literature data [10,13,25,27,30,32] show that the following approaches are possible to obtain on titanium surfaces uniform ESD coatings with reduced roughness higher thickness:…”

“…-As the pulse energy (I, C, Ti) increases the amount of anode material transferred to the cathode increases [10,12,16,[22][23][24], and the thickness, roughness and microhardness of the coatings monotonically increase, but their specific values under the same ESD conditions are different for different electrodes (Tables 3-5, Figs. 1-4).…”

“…-The amount of solid phases carried by the electrode, the newly formed compounds and the degree of dispersity and amorphousness also increase [16,[22][23][24][25][26]. The coatings of KW and NW electrodes, whose thickness is the highest, and the lowest values -of the coatings of TN, KNT16 and AlSi12 electrodes, show the highest values of the roughness parameters.…”

“…A main disadvantage of ESD coatings on titanium surfaces is their relatively high roughness, which reduces the effect of their application. It is known [16][17][18] that surface roughness and texture play an important role on the coefficient of friction values and the wear characteristics. In tribology, rough surfaces typically have higher coefficients of friction and wear out more quickly [18][19][20][21].…”

“…The influence of texture and roughness on the wear resistance of ESD coatings is too complicated to be study because the change in roughness is always accompanied by a change in the thickness, phase composition and structure of the coatings. It is widely known [10][11][12][14][15][16]22] that as the pulse energy increases, the amount of electrode material transferred to the substrate increases. The roughness, the thickness, microhardness, and the amount of wear-resistant phases in the formed layer increase accordingly.…”