Roumen Zlatev Iankov

Prof. Roumen Zlatev Iankov

Bulgarian Academy of Sciences, Institute of Mechanics

Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
1 April 2014 in Materials Science and Engineering: B
Verified
Journal Article
Closed access
Sabina ChernevaSabina Cherneva
Sabina Cherneva
RIRoumen Zlatev Iankov
Roumen Zlatev Iankov
NRNenad Radic
Nenad Radic
BGBosko Grbic
Bosko Grbic
DSDimitar Stoychev
Dimitar Stoychev

18 July 2018 in Journal of Engineering Materials and Technology
Verified
Journal Article
Closed access
PDF file
Sabina ChernevaSabina Cherneva
Sabina Cherneva
DGDesislava Guergova
Desislava Guergova
RIRoumen Zlatev Iankov
Roumen Zlatev Iankov
DSDimitar Stoychev
Dimitar Stoychev
Important from exploitation point of view mechanical properties of single-layer, double-layer, and mixed alumina and ceria films and their stainless steel (SS) substrate were investigated by means of nanoindentation experiments. As a result, we obtained the experimental load–displacement curves and calculated the indentation hardness (HIT) and indentation modulus (EIT), by means of Oliver and Pharr approximation method. Numerical simulations of the process of nanoindentation by means of finite element method were performed as well, in order to obtain more information about the plastic properties of the investigated films. The obtained results show that the mixed Al2O3+Ce2O3 film, obtained at dominant concentration of cerium ions in the working electrolyte, has the highest indentation hardness and modulus, followed by the single Ce2O3-CeO2 film, the mixed Al2O3+Ce2O3 film, obtained at dominant concentration of aluminum ions in the working electrolyte, the double Ce2O3-CeO2/Al2O3 layer, and single Al2O3 layer.

28 June 2020
Verified
Report
Closed access
MCMikhail Chebakov
Mikhail Chebakov
APAlexei Poddubny
Alexei Poddubny
EKElena Kolosova
Elena Kolosova
AAAlexsander Alexiev
Alexsander Alexiev
RIRoumen Zlatev Iankov
Roumen Zlatev Iankov

25 February 2022 in Materials
Verified
Journal Article
Open access
PDF file
COCarlos Alberto Monesi Oliveira
Carlos Alberto Monesi Oliveira
KGKorneli Grigoriev Grigorov
Korneli Grigoriev Grigorov
ATAleksandar Tsanev
Aleksandar Tsanev
AJArmstrong Godoy Junior
Armstrong Godoy Junior
ACAntonio augusto Couto
Antonio augusto Couto
MMMarcos Massi
Marcos Massi
Hexagonal boron-nitride nanoparticle coating was deposited on AISI 1045 steel surface. The deposition process included a transformation of B-containing thin organic film into nanocrystalline BN using two methods: thermal annealing at 450–850 °C and reactive ion etching in Ar/N2 plasma. The film structure, phases, and film morphology of deposited nanoparticles of boron nitride on AISI 1045 steel were characterized by XPS, XRD, and EDS. Post-annealing at 450 °C does not lead to the formation of a BN phase in the layer. A non-stoichiometric BN phase with nitrogen deficiency appears at 650 °C. At 850 °C annealing, the formed BN phase is completely stoichiometric. The effects of deposited and incorporated BN on the friction and hardness properties of AISI 1045 steel were also studied. The post-annealing process improved the hardness from 5.35 to 11.4 GPa, showing a pronounced linear temperature dependence. An original approach was adopted to quantify the energy-dependent growth constants based on the indentation load-discharge curves measured on samples treated under different conditions. Those constants describe the rate of the reactions and the type of interdiffusion process characteristic for each material used. This approach can partially fulfill the role of the Rutherford backscattering spectrometry profile, which is an expensive and time-consuming process, mainly when light elements such as boron and nitrogen are used.

14 February 2017 in Materiali in tehnologije
Verified
Journal Article
Closed access
Sabina ChernevaSabina Cherneva
Sabina Cherneva
RIRoumen Zlatev Iankov
Roumen Zlatev Iankov
NRNenad Radic
Nenad Radic
BGBosko Grbic
Bosko Grbic
MDMaria Datcheva
Maria Datcheva
DSDimitar Stoychev
Dimitar Stoychev

15 October 2024 in Tehnicki vjesnik - Technical Gazette
Verified
Journal Article
Open access
PDF file
DMDarko Mihajlov
Darko Mihajlov
MPMomir Praščević
Momir Praščević
MRMiomir Raos
Miomir Raos
RIRoumen Zlatev Iankov
Roumen Zlatev Iankov
The ISO 1996 series harmonize the methods for the description, measurement and assessment of environmental noise from all source types. In addition, the standards contain the guidelines for estimating the uncertainty of environmental noise measuremen...