OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 25 No. 2 2023 a b Fig. 7. The specimens with coatings after bend test: a – 170/140; b – 250/200 that the cracks in the coatings are almost straight without any branching. The distance between cracks increases with increasing arc current and spraying distance. The obtained data indicate a high adhesion of the coatings. Conclusions 1. In this paper, a range of high-quality WC-Co coatings were formed with using of HV-APS. These coatings are characterized by high density, absence of cracks and oxide films. 2. All coatings consist of WC and W2C particles uniformly distributed in the metal matrix. The matrix is an amorphous or nanocrystalline supersaturated Co(W,C) solid solution. 3. It has been shown that the spraying distance, as well as the arc current, has a significant effect on the volume fraction of carbides. The maximum amount of carbides (49%) is observed in coatings obtained by the 170/140 mode, the minimum ones (25%) — in coatings obtained by the 250/200 mode. 4. The maximum microhardness of coatings is 1,284 and 1,287 HV0.1 (modes 170/140 and 250/140), the minimum microhardness is 1,153 and 1,140 HV0.1 (modes 170/ 200 and 250/200). 5. The maximum wear resistance is typical for samples with coatings obtained by the 170/140 mode (relative wear resistance 0.21), the minimum value has coatings obtained by the 250/200 mode (relative wear resistance 0.14). 6. All coatings are characterized with high adhesion. It cracked in the bending area, but did not peel off. References 1. Afzal M., Ajmal M., Nusair Khan A., Hussain A., Akhter R. Surface modification of air plasma spraying WC-12% Co cermet coating by laser melting technique. Optics Laser, 2014, vol. 56, pp. 202–206. DOI: 10.1016/j. optlastec.2013.08.017. 2. Wu Y., Hong S., Zhang J., He Z., Guo W., Wang Q., Li G. Microstructure and cavitation erosion behavior of WC-Co-Cr coating on 1Cr18Ni9Ti stainless steel by HVOF thermal spraying. International Journal of Refractory Metals and Hard Materials, 2012, vol. 32, pp. 21–26. DOI: 10.1016/j.ijrmhm.2012.01.002. 3. VenterA.M., LuzinV.,MaraisaD., Sacks N., Ogunmuyiwa E.N., Shipway P.H. Interdependence of slurry erosion wear performance and residual stress in WC-12wt%Co and WC-10wt%VC-12wt%Co HVOF coatings. International Journal Refractory Metals and Hard Materials, 2020, vol. 87, p. 105101. DOI: 10.1016/j.ijrmhm.2019.105101. 4. Wu X., Guo Z.M., Wang H.B., Song X.Y. Mechanical properties of WC-Co coatings with different decarburization levels. Rare Metals, 2014, vol. 33, iss. 3, pp. 313–317. DOI: 10.1007/s12598-014-0257-8.
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