Chavdar Ognyanov Pashinski

Dr. Chavdar Ognyanov Pashinski

orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

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

Representative Publications

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30 April 2025 in Coatings
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Journal Article
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SKStefan Kolchev
Stefan Kolchev
Dr. Lilyana KolaklievaDr. Lilyana Kolaklieva
Dr. Lilyana Kolaklieva
Daniela KovachevaDaniela Kovacheva
Daniela Kovacheva
GAGenoveva Atanasova
Genoveva Atanasova
TCTetiana Cholakova
Tetiana Cholakova
CPChavdar Ognyanov Pashinski
Chavdar Ognyanov Pashinski
TiAlSiN/AlSiN coatings, with 3 and 30 periods, were successfully deposited by cathodic-arc evaporation technology. The composition, structure, mechanical, and tribological properties were studied at thermal treatment from 700 °C to 900 °C. The SEM observation and EDS analysis verified the dense structure and stable element composition in the coating depth at increased temperatures. A limited surface oxidation was identified at 800 °C, which increased moderately at a higher temperature of 900 °C. The coating period displays a nanocomposite structure of TiAl(Si)N and AlN nanograins incorporated in an amorphous Si3N4 matrix obtained by XRD and XPS analyses. The coatings exhibit high hardness of 41.1 GPa and 36.4 GPa for the 3- and 30-period coatings, respectively. The coatings with higher modulation periods demonstrate an excellent high temperature hardness and resistance to elastic and plastic deformations up to 900 °C. The hardness of the coatings with a smaller modulation period reduces to 29.7 GPa at the same temperature, causing a decrease in the H/E and H3/E*2 ratios. The tribological tests found that the high-temperature wear resistance depends strongly on the coating composition and architecture. An oxidation wear mechanism dominates the coatings with a large modulation period, and the wear rate decreases with a temperature increase. Abrasive wear is predominant in coatings with a lower modulation period, leading to an increasing wear rate. Wear rate values of 7.27 × 10−6 mm3/N·m and 8.53 × 10−6 mm3/N·m were determined after annealing at 900 °C for the 3- and 30-period coatings, respectively.

1 March 2014 in Journal of Nano Research
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TCT. Cholakova
T. Cholakova
VCV. Chitanov
V. Chitanov
DCDimitrios Chaliampalias
Dimitrios Chaliampalias
LKLilyana Kolaklieva
Lilyana Kolaklieva
RKR. Kakanakov
R. Kakanakov
Efstathios MeletisEfstathios Meletis
Efstathios Meletis
A study of the structural and mechanical properties of nanocrystalline TiAlSiN gradient coatings deposited by cathodic arc deposition techniques at 500 °C and post-annealed at 525 °C is presented. Analysis of the coatings, chemical composition and microstructure revealed that the coatings have a structure based on (Ti, Al)N nanocrystals with an average size of 10 nm embedded in an amorphous Si3N4 phase. The study of the mechanical properties showed that post-annealing causes improvement and increase of the coatings hardness. A maximum hardness of 48 GPa and elastic modulus of 560 GPa were measured. Also, excellent adhesion to the WC-Co substrate was observed in the post-annealed coatings.

3 February 2012 in Journal of Nano Research
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LKLilyana Kolaklieva
Lilyana Kolaklieva
RKRoumen Kakanakov
Roumen Kakanakov
DCDimitrios Chaliampalias
Dimitrios Chaliampalias
GVG. Vourlias
G. Vourlias
TCT. Cholakova
T. Cholakova
EPEfstathios K. Polychroniadis
Efstathios K. Polychroniadis
Multilayered, Gradient Tialsin-Based Nanocomposite Coatings Have Been Developed and Investigated with Respect to their Applicability in the Machining Industry. the Main Coating Layer Was Composed of 5-8 Nm Tin and Aln Nanograins. the Coating Possessed Hardness as High as 40 GPA, which Allows it to Be Classified as Superhard. during Heating up to 900oC in Air in Steps of 100oC for 6 H at each Temperature, the Coating Showed Good Stability up to 700oC. Thermal Treatment over this Temperature Caused a Decrease in the Hardness to Values Characteristic for Tialn Multilayered Coatings, while the Adhesion to the Substrate Remained Steady.

28 February 2017 in IOP Conference Series: Materials Science and Engineering
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VRVelko Rupetsov
Velko Rupetsov
GMGeorgi Mishev
Georgi Mishev
SDStefan Dishliev
Stefan Dishliev
VKViktor Kopanov
Viktor Kopanov
VCVassiliy Chitanov
Vassiliy Chitanov
CPChavdar Ognyanov Pashinski
Chavdar Ognyanov Pashinski
Injection molds used in production of plastic components are subject of heavy abrasion wear. The increase of their wear resistance significantly reduces the production cost. In the current work are presented research results of the wear resistance of injection molds made of steel 1.2343, coated with Ti/TiN/TiCN/nc-TiCN: a-C/nc-TiC:a -C/a-C. The study of the wear rate was done using the volumetric method and the influence of the trace length was investigated. The coating thickness, nanohardness, elastic modulus and adhesion were also tested. The coating was applied on unhardened ground specimens, hardened ground specimens and hardened polished specimens.

27 July 2024 in Coatings
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VCVasiliy Chitanov
Vasiliy Chitanov
Dr. Lilyana KolaklievaDr. Lilyana Kolaklieva
Dr. Lilyana Kolaklieva
RKRoumen Kakanakov
Roumen Kakanakov
TCTetiana Cholakova
Tetiana Cholakova
CPChavdar Ognyanov Pashinski
Chavdar Ognyanov Pashinski
KHKurt Hingerl
Kurt Hingerl
A preliminary investigation of the optical properties of complex Cr-based hard coatings and their connection with the compound structure of the coatings is presented. Cr/CrN, Cr/CrN/CrAlN, Cr/CrN/CrTiAlN, and Cr/CrN/CrAlTiN coating structures were deposited through unbalanced magnetron sputtering. Their mechanical properties, especially nanohardness, coefficient of friction, and adhesion, were measured. The structure and composition of the coatings were characterised through SEM, FIB, XPS, and TEM. Their optical properties were investigated by UV-VIS ellipsometry. The optical parameters’ phase difference Δ, the amplitude ratio Ψ, the frequency-dependent real (ε1(ω)) and imaginary (ε2(ω)) part of the dielectric function, and the corresponding refractive and extinction indexes n(ω) and k(ω) were measured and modelled via regression analysis implemented using the WVASE© software version 3.686. Satisfactory coincidence was achieved between the measured optical data and the corresponding fitting models. The physical polycrystalline optical constants of the industrial samples were extracted from modelling data with roughness. The analysis of the data showed that ellipsometric characterisation can be used in order to determine the physical properties of Cr-based hard coatings with complex structure and composition, as well as for repeatability control of the deposition process. However, more detailed research is needed to predict the composition based on measured optical properties.

1 October 2019 in IOP Conference Series: Materials Science and Engineering
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VRVelko Rupetsov
Velko Rupetsov
LKLilyana Kolaklieva
Lilyana Kolaklieva
VCVassiliy Chitanov
Vassiliy Chitanov
MAMilko Angelov
Milko Angelov
Raycho Petrov RaychevRaycho Petrov Raychev
Raycho Petrov Raychev
CPChavdar Ognyanov Pashinski
Chavdar Ognyanov Pashinski
The application of Physical Vapor Deposition (PVD) hard coatings is one time-tested practice in the modern industry. Two of the main tendencies that promise a progress in this area are the combination of more chemical elements in one coating and the creation of nanolaminate structures. Since many combinations are possible in the design of the coatings, it could be expected they would have many different properties which are difficult to predict. In an attempt to work simultaneously in both of these directions, one nanolaminate Ti/TiN/AlTiSiN/(AlTiSiN/TiAlSiN)n/AlTiSiN coating was developed and its mechanical properties were tested. The results obtained give a reason to believe that it could be widely practically applied.