Microgeometrical characteristics of electrospark coatings in the initial state
DOI:
https://doi.org/10.31891/2079-1372-2020-98-4-33-39Keywords:
elektrospark alloying, discrete coating, Abbott curve, stress-strain stateAbstract
Microgeometric parameters of the effect of discrete electrospark coatings on their stress-strain state have been evaluated for the case of using a combined technology of modification of duralumin D16, which includes the technique of electrospark alloying with subsequent surface plastic deformation of coatings formed. According to the profilograms of discrete electrical coatings, the curves of the bearing surface (Abbott curves) were constructed and the parameters that drastically affect tribological characteristics of the coatings were determined. It was shown that modification of duralumin D16 with a combined electrospark coating VK-8 + Cu reduces the arithmetic mean height of peaks in the top portion of the profile by 4.4 and 3.2 times, doubles the arithmetic mean depth of the profile core irregularities, increases the arithmetic mean depth of profile valleys by 1.8 and 1.1 times, in comparison with electrospark coatings from hard alloy VK-8 and copper, respectively. These parameters help to reduce the period of running-in of the contact surfaces strengthened by the combined electrospark coating VK-8 + Cu, increase their bearing capacity, contact durability and specific oil consumption. On the basis of the finite element analysis method of the Nastran software complex, a model of the stress-strain state of a discrete coating/base was designed and distribution of the main normal stresses was determined for a coating compactness of 60% under a normal load of 600 N. The performed modeling revealed advantages of a combined technology for formation of wear-resistant electrospark coatings, which consists in turning residual tensile stresses into compressive ones. When modifying the duralumin D16 with a VK-8 + Cu coating, on the coating surface and in the base material, compressive stresses (-93 MPa and -20 MPa, respectively) are formed, which provides a decrease in wear of the modified surface by two times compared to unmodified duralumin D16.
References
2. Ljashenko B. A., Volkov Ju. V., Solovyh E. K., Lopata L. A. (2015) Povyshenie iznosostojkosti detalej sudovyh mashin i mehanizmov pokrytijami diskretnoj struktury. Tehnologicheskoe obespechenie pokrytij diskretnoj struktury jelektrokontatnym pripekaniem [Improving wear resistance details of ship and machinery coatings discrete structure. Technological provide coverage discrete structure elektrocont sintering]. Problemi tertja ta znoshuvannja, 2 (67), 110-126.
3. Mihajljuk A.I., Rapoport L.S., Gitlevich A.E. i dr. (1991) Vlijanie poverhnostno-plasticheskoj deformacii na harakteristiki iskrovyh pokrytij na osnove zheleza. Soobshhenie 1 [Effect of surface plastic deformation on the characteristics of iron-based spark coatings]. Jelektronnaja obrabotka materialov,1, 16-19.
4. Anohin A.A. (2003) Nekotorye progressivnye tehnologii vosstanovlenija kachestva poverhnostej detalej [Some advanced techniques for restoration of quality of part surfaces]. Vostochno-Evropejskij zhurnal peredovyh tehnologij, 5 (5), 10-16.
5. Tarel'nik V.B. (1998) Kombinirovannye tehnologii jelektrojerozionnogo legirovanija i poverhnostnoj plasticheskoj deformacii. Soobshhenie 3. Issledovanie fiziko-mehanicheskih svojstv izdelij, uprochnennyh jelektrojerozionnym legirovaniem i poverhnostnoj plasticheskoj deformaciej [Combined techniques for electroerosion alloying and surface plastic deformation. Report 3. Investigation of physical-mechanical properties of workpieces hardened by electroerosion alloying and surface plastic deformation]. Jelektronnaja obrabotka materialov, 3-4, 31-37.
6. Okin M.A. (2010) Povyshenie mezhremontnogo resursa vosstanovlennyh jelektroiskrovoj obrabotkoj detalej optimizaciej fiziko-mehanicheskih svojstv pokrytij. [Increase in overhaul period of parts restored by electrospark processing due to optimization of physical-mechanical properties of coatings]. Avtoref. Dis. Na soisk.uch.step. k.t.n. po spec.05.20.03, GOUVPO Mordovskij gosudarstvennyj un-t im. N.P. Ogareva, Saransk, 20 s.
7. Nikolenko S.V., Verhoturov A.D., Sjuj N.A. i dr. (2006) Vlijanie parametrov jelektroiskrovogo razrjada na sherohovatost' i mikroabrazivnyj iznos poverhnosti stali 45 posle JeIL jelektrodami na osnove TіS [Effect of electrospark discharge parameters on the roughness and microabrasive wear of steel 45 surface after ESA with TiC based electrodes]. Jelektronnaja obrabotka materialov, 52(4), 30-37.
8. Nikolenko S.V., Verhoturov A.D., Sjuj N.A. i dr. (2015) Sozdanie i issledovanie jelektrodov na osnove karbidov vol'frama i titana dlja mehanizirovannogo jelektroiskrovogo legirovanija [Production and investigation of electrodes based on tungsten and titanium for electrospark alloying]. Jelektronnaja obrabotka materialov, 51(1), 38-44.
9. Minakov A.P., Il'jushina E.V. (2006) Issledovanie vlijanija pnevmovibrodinamicheskoj obrabotki na jekspluatacionnye svojstva obrabotannoj poverhnosti [Study of the effect of pneumovibrodynamic processing on the operation properties of surface processed]. Vestnik Mogilevskogo gosudarstvennogo tehnicheskogo universiteta, 1(10), 172-176.
10. DIN 4776-1990 Determination of surface parameters Rk, Rpk, Ruk, Mr1, Mr2 serving to describe the material component of the rougness profile. MCS 17.040.20, 5p.
