Staff

Activities

Publications

Projects

    

    

	Name:	Phone: (+359 2) 979 XXXX	E-mail: ....@ie.bas.bg
HEAD:	Prof. P.I. Petrov, Dr.Sc.	5869	pitiv
RESEARCH SCIENTISTS:	Assoc. Prof. I. Martev, Ph.D.	5874	inmartev
	D.A. Dechev
	N.P. Ivanov
	N.K. Lutakova

    

    

    

RESEARCH ACTIVITIES

    

1. Nanolaminated TiN/W₂N hard multilayer coatings

Multilayer coatings consisting of successively deposited thin films of nanometric thickness of homologous compounds of transition metals are characterized generally by better mechanical properties compared to those of single film coatings from the respective compound. Such type of monolayer coatings, termed as nanolaminated structures (or super-lattices), are often formed on the basis of transition metal nitrides that are characterized on their own by good mechanical properties (hardness, wear-resistance). A generally accepted physical model for explanation of this effect is the blocking of dislocations in the interfaces of single layers. The thickness of the interfaces usually increases due to the effect of interdiffusion of the elements involved. Forming high-quality coatings requires suppressing the interdiffusion processes, which can be achieved through decreasing the growth temperature and, to some extent, the thickness of the single layers. The activities on this topic were a continuation of the work on a previous stage related to optimizing the deposition of TiN/W₂N thin films and investigating their characteristics, mechanical properties and adhesion. The work was performed in the framework of research project "Physical Characteristics and Mechanical Properties of Monolayer Nanostructures of Complex Nitrides of Transition Metals", funded by the Bulgarian National Science Fund. Nanolaminated TiN/W2N multilayer structures were synthesized by alternative deposition of TiN и W₂N thin films using DC magnetron sputtering. The deposition was preceded by a process of ion treatment of the substrate surfaces in an argon gas discharge at high pressure for enhancing the coating adhesion to substrates of different types (tool steel, hard alloyed materials). The deposition was performed in a process gas mixture of nitrogen and argon in different ratios for the two types of films. Special attention was paid to decreasing the deposition temperatures so as to make it suitable for the synthesis of polycrystalline TiN и W2N with the desired phase. The thickness of the films was significantly reduced to about 6−6.5 nm. Twenty pairs of TiN и W₂N films were grown for analysis and characterization. 105 pairs (2x105 TiN/W₂N NLMLS) of the same films were synthesized for the investigation of their mechanical properties. The structural characteristics were analyzed by transmission electron microscopy (TEM) and cross-section scanning electron microscopy (CSSEM) with very high resolution. The results showed that the growth of the structures at the initial stages is smooth, uniform and homogenous. Further, a small deviation from the planarity is observed as a result of stress accumulated by defects presumably generated in the interface zones. For the complex characterization of the structures, some investigations and analysis are foreseen, namely, Rutherford back scattering (RBS) and X-ray Diffraction (XRD). The mechanical properties namely, hardness, Young's modulus, energy of plastic deformation, etc., of the 2x105 TiN/W₂N NLMLS were investigated by a FISHERSCOPE H100 nanotester. The results showed that these structures possess extremely high hardness (50−60 GPa) comparable with the best examples of super lattices based on transition metal nitrides. The adhesion was tested qualitatively by Rockwell-C Indent Test and was evaluated as acceptable. The wear resistance was tested by the so called "KALO - Test" (erasing the film by a rotating metal sphere). The morphology was observed by a Minicon Optiphot metallographic microscope.

    

    

    

PUBLICATIONS

During year 2011, 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002, 2001.

    

2011

1. Lambov S I, Krastev P G, Ilieva N I, Dechev D A, Ivanov N P, Chobanov P N and Raichev V P 2010

   Study of some mechanical characteristics of NiCr alloys thin films deposited by magnetron sputtering on dielectric substrates

   Bulletin of the Union of Scientists in Bulgaria, Sliven Branch 17 37-9 ISSN 1311 2864 (In Bulgarian)

2. Slavova V, Petrov St, Lambov S, Ivanov N and Ivanova N 2011

   Operating characteristics of composite ultrafiltration membranes prepared by magnetron sputtering of NiCr alloys on polymer substrates

   Machine building and machine science 2 88-91 (ISSN 1312 8612) (In Bulgarian)

3. Krastev P G, Ilieva N I, Lambov S I, Dechev D A and Ivanov N P 2011

   Preparation of sample electric heating elements and study of their operating cgharacteristics - possibilities for research learning in a group

   Bulletin of the Union of Scientists in Bulgaria, Sliven Branch 19 236-40 (ISSN 1311 2864) (In Bulgarian)

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2010

1. Martev I N, Dechev D A, Ivanov N P and Kashchieva E P

   Nanolaminated TiN/MO₂N hard multilayer coatings

   J. Phys.: Conf. Series 223 012019 (ISSN 1742 - 6588)

2. Milusheva P, Uzunov T and Ivanov N

   Research on the surface char-acteristics of Ti and Fe-Cr-Ni alloy thin films on polymeric substratum

   J. Balkan Tribological Association 3 16 564-569 (ISSN 1310-4772)

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2009

1. I. N. Martev, D. A. Dechev, N. P. Ivanov, Ts. D. Uzunov and E. P. Kashchieva

   Nanolaminated TiN/Mo₂N hard multilayer coatings,

   Sixteenth Int. Summer School on Vacuum Electronic and Ion Technologies 28 Sept.-02 Oct. 2009, Sunny Beach, Bulgaria.

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2008

1. Martev I N, Dechev D A, Ivanov N P, Uzunov T D, Kashcjieva E P,

   Characterization and properties of highly adhesive titanium nitride and tungsten nitride thin films,

   J Phys: Conf Series 2008;113:012025.

2. Dechev D A, Ivanov N P, Uzunov Ts D, Martev I N, Lutakova N K,

   Adhesion and hardness investigation of TiN/MoN multilayer nanostructures deposited by magnetron sputtering,

   Issue of Union of Scientists 2008;13:16-9.

3. Dechev D A, Ivanov N P, Ivancheva V M, Uzunov Ts D, Krustev P G,

   Investigation of evolution of the properties of TiN/WN coatings as a result of vacuum annealing at moderate temperatures,

   Issue of Union of Scientists 2008;13:24-7.

4. Krustev P G, Ivancheva V M, Ivanov N P, Dechev D A, Uzunov Ts D, Lutakova N K, Ivanov N P,

   Development of methodic for laboratory teaching on deposition of coatings in vacuum and study of microhardness and sheet resistance,

   Issue of Union of Scientists 2007;12:115-20.

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2007

1. Uzunov Ts D, Dechev D, Martev I N, Ivanov N,

   Deposition and mechanical properties of titanium nitride (TiN) and tungsten nitride (W₂N) coatings,

   Proc FEP TU Anniversary Conf 2007;11/2:17-19.

2. Dechev D, Uzunov Ts D, Milusheva P. Ivanov N P, Lutakova N K,

   Adhesion of metal coatings deposited by ion sputtering on polymers,

   Proc FEP TU Anniversary Conf 2007;11/2:20-23.

3. Uzunov Ts D, Nikolov S,

   Physics teaching in engineering education,

   Proc FEP TU Anniversary Conf 2007;11/4:5-7.

4. Krustev P, Uzunov Ts D, Ivanov N, Parashkevov D,

   Sheet resistance of thin films deposited by ion sputtering,

   Proc FEP TU Anniversary Conf 2007;11/4:35-36.

5. Guerassimov N, Ghelev Ch, Martev I, Petrov P I (Eds),

   Abstract Book of the 15th International Summer School on Vacuum, Electron and Ion Technologies,

   126 pages, 2007, Sozopol, Bulgaria.

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2006

1. Radeva EI, Martev IN, Dechev DA, Ivanov NI, Tsaneva VN, Barber ZH,

   Sensitivity to humidity of TiO₂ thin films obtained by reactive magnetron sputtering,

   Surface and Coatings Technology 2006;201:2226-2229.

2. Slavova B, Petrov S, Uzunov Ts D,

   Performance and selectivity investigation of ultrafiltering polymer membranes coated by chrome-nickel in vacuum,

   Union of Scientists Issue, Bulgaria 2006;10;20-22.

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2005

1. Djakov B, Enikov R, Oliver D,

   Production and diagnostics of plasma jets,

   J Bulg Acad Sci 2005;5:18-25.

2. Dechev D, Uzunov T, Krastev P, Ivanov N,

   AlN coatings deposited by reactive sputtering,

   Proc Univ Sliven, Bulgaria 2005;9:51-54.

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2004

1. Jordanov M, Uzunov T,

   Adhesion and cohesion tensions in magnetron sputtered coatings determined by the scratch test method,

   Machine technique and technology 2004;2:24-28.

2. Djakov B, Oliver D, Enikov R, Vasileva E,

   Optical monitoring geometrical properties of plasma jets by chromaticity methods,

   Proc 12^th Int. Workshop Plasma Technology, Ilmenau, Germany, 2004, pp 111-118.

3. Ivancheva V, Uzunov T, Krastev P, Yordanov M, Ivanov N, Dechev D,

   Fabrication of electrically-resistive Al-Si films by magnetron sputtering in vacuum,

   Proc Nat Conf "Science, Engineering, Technologies, Education", Yambol, Bulgaria, 2004, 2004;2:59-61 (In Bulgarian).

4. Uzunov T, Yordanov M, Ivancheva V, Krastev P, Ivanov N, Dechev D,

   Mechanical characteristics of magnetron-deposited Al-Si thin films,

   Proc Nat Conf "Science, Engineering, Technologies, Education", Yambol, Bulgaria, 2004, 2004;2:123-126 (In Bulgarian).

5. Uzunov T, Kashchieva E, Nikolov S,

   The inter-disciplinary links of physics with the engineering sciences - a key factor determining the level of engineering education,

   Proc ХХХІІ Nat Conf "The interdisciplinary approach to the education in physics", Blagoevgrad, Bulgaria, 2004, pp 30-36 (In Bulgarian).

6. Uzunov T, Ilieva N, Krastev P,

   A possibility for integrating the academic curricula in chemistry anf physics of metals in the engineering universities,

   Proc ХХХІІ Nat Conf "The interdisciplinary approach to the education in physics", Blagoevgrad, Bulgaria, 2004, pp 360-363 (In Bulgarian).

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2003

1. Ivanov N, Uzunov T,

   Thermal studies of a wide-surface-area electric heating element fabricated by magnetron ion sputtering in vacuum,

   Bulletin of the Sliven Branch of the Technical University of Sofia 2003;5:63-65 (In Bulgarian).

2. Uzunov T, Yordanov M,

   MATLAB processing of CrN coatings UV transmission and absorption data,

   Bulletin of the Sliven Branch of the Technical University of Sofia 2003;5:96-99 (In Bulgarian).

3. Krastev P, Uzunov T,

   Flat electric IR emitters - a low-cost efficient heating alternative,

   Bulletin of the Sliven Branch of the Technical University of Sofia 2003;5:73-76 (In Bulgarian).

4. Ivanov N, Vladimirova M,

   Deposition of thin coatings of Al and Fe–Cr–Ni on wine and liquor bottles,

   Bulletin of the Sliven Branch of the Technical University of Sofia 2003;5:60-62 (In Bulgarian).

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2002

1. Tz. Uzunov, D. Dechev,

   W₂N and Mo₂N coatings deposited by reactive sputtering in vacuum

   Proceedings Anniversary scientific meeting of the Russe University 2002, Russe, Bulgaria.

2. M. Yordanov, Tz. Uzunov,.

   Some optical properties of the magnetron sputtered CrN coatings

   Proceedings Anniversary scientific meeting of the Russe University 2002, Russe, Bulgaria.

3. Z. Parashkevov, Tz.Uzunov, N. Ivanov, S. Kasarova,

   Thin film heating elements on enameled steel samples

   Proceedings Anniversary scientific meeting of the Russe University 2002, Russe, Bulgaria.

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2001

1. M. Yordanov, Tz. Uzunov,

   Influence of the substrate temperature on the adhesion and wear resistance of CrN–coatings deposited by reactive ion sputtering

   Proceedings of the University of Sliven, 3, (2001), pp. 39-43.

2. D. Dachev, N. Ivanov, Tz. Uzunov,

   Optical characteristics of one-layer TiN coations deposited by reactive dc sputtering

   Proceedings of the University of Sliven, 3, (2001), pp. 44-46.

    

    

    

ONGOING RESEARCH PROJECTS:

    

Financed by the Bulgarian Academy of Sciences

• Working characteristics of metal-nitride coatings obtained in vacuum.

Financed by the Technical University of Sofia

• Working characteristics of Cr-Ni allow coatings obtained by ion sputtering in vacuum.

    

COLLABORATIONS:

• Deposition and investigation of mechanical properties of nanostructured multilayer systems of transition metal nitrides,
  Nanotechnology Centre for PVD Research, Materials and Engineering Research Institute, Sheffield Hallam University, UK