Martinovs, Andris

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Preferred name
Martinovs, Andris
Alternative Name
Andris Martinovs
Martinovs, A
Main Affiliation
Email
andris.martinovs@rta.lv
ORCID
Scopus Author ID
57217029083
Researcher ID
GQW-2280-2022

Research Output

Now showing 1 - 2 of 2
  • Publication
    Mechanical and electrical properties of the solid sapropel
    (2015)
    Martinovs, Andris 
    ;
    Josef Timmerberg
    ;
    Tretjakova, Rasma 
    ;
    Paul Beckmann
    ;
    Valentina Popa
    ;
    Regina Wagner
    In this paper are explored the mechanical (ultimate compression strength, ultimate strain, Young’s modulus, hardness) and the electrical (relative permittivity, specific electrical resistance, quality factor, their dependence on the electric field frequency in the range till 1MHz) properties of the solid sapropel. For the researches are used samples from the solid, monolith sapropel (obtained in the drying process) and samples from the sapropel powder that are pressed with a different force; before the measurements, a part of these samples were heated. There is explored the dependence of the relative permittivity on temperature. Are explored the methods for the forming of the products from the solid sapropel powder.
    Scopus© Citations 1
  • Publication
    EFFECT OF HEAT TREATMENT ON ELECTRICAL AND MECHANICAL PROPERTIES OF THE SOLID SAPROPEL
    (2017)
    Martinovs, Andris 
    ;
    Tretjakova, Rasma 
    ;
    Rene Castro
    ;
    Vladimir Solovyev
    ;
    Josef Timmerberg
    ;
    Alexander Cvetkov
    ;
    Sergey Gango
    ;
    Angelika Borkenstein
    ;
    Paul Beckmann
    ;
    Helmut Schütte
    ;
    Nikolai Puchkov
    ;
    Sergey Trifonov
    In this work changes of electrical and mechanical properties (hardness) of the solid sapropel after its heat treatment were researched. Changes of real and imaginary parts of dielectric permittivity, dielectric losses and specific electrical resistance depending on electrical field frequency in the range 0.01Hz- 1MHz were observed. Temperature dependences of AC (at 1 kHz) and DC electrical conductivity were studied. Chemical sample composition, IR spectra and structure of the solid sapropel were investigated. Heat treatment has a noticeable effect on the electrical characteristics of solid sapropel due to the strong influence of water on the charge transfer in this complex material. Charge transfer occurs predominantly due to ion migration and demonstrates strong dependence upon hydration - dehydration processes. After the heat treatment of the solid sapropel at the temperature of 1000C its hardness doesn’t change. If the sample of the solid sapropel is subjected to 20 min heat treatment at the temperature of 1500C, its hardness decreases by 5.4%, the number of C=C bonds decreases by 6.3±0.1%, the number of C=N bonds decreases by 2.2±0.1%, the number of C-C bonds decreases by 1,7±0.1%, the number of C-H bonds increases by 18.5±0.3%. It shows that in the temperature range 100-1500C destructive processes of the solid sapropel start, although visually (with optical microscope and with SEM) changes of structure are impossible to observe yet.
    Scopus© Citations 2