TR Dizin İndeksli Yayınlar / TR Dizin Indexed Publications Collection

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Author: search.filters.author.Balkose, DevrimDepartment: search.filters.department.İzmir Institute of Technology

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  • Article
    Citation - Scopus: 3
    Zinc Borate Chemical Garden and Zinc Borate Powders From Tincal Mineral and Zinc Sulfate Heptahydrate
    (Turkish Energy Nuclear and Mining Research Institute, 2021) Gönen, Mehmet; Alp, Fatma Burcu; Savrık, Sevdiye; Balkose, Devrim
    The formation of the first membrane, the swelling of the crystal by incoming water from the semipermeable membrane and the formation of irregular shaped branches were observed by optical microscopy, when zinc sulfate heptahydrate crystals were immersed in saturated borax solution. The powders obtained by mixing dilute aqueous borax and zinc sulfate solutions had B, O, Na, S and Zn elements. Presence of $Na Zn_{1/2}B_4O_7.xH_2O$ was indicated by EDX analysis. The molar ratio of $B_2O_3/ZnO$ in powders was around 2. FTIR analysis indicated the ratio of absorbance values of asymmetric stretching vibrations of B(3)-O at 1351 cm-1 to that of B(4)-O at 1026 cm-1 increased with their heating time at 90ºC during their preparation. X-ray diffraction patterns indicated the presence of $Zn(OH)_2and Zn_4(OH)_6(SO_4)·4H_2O$. The zinc borate compounds in the powders were not crystalline since no sharp peaks related to zinc borates were present in x-ray diffraction diagram. There were two mass loss steps in TG curves of the powders. The first step at 150-350ºC and the second step at 700-950ºC were due to elimination of water and due to decomposition of sulfate ions respectively. The submicron powders were a mixture of zinc borate, $Zn(OH)_2, Zn_4(OH)_6(SO_4)·4H_2O and Na Zn_{1/2}B_4O_7.xH_2O$ and they could be used as lubricant additive due to their small particle size of 600 nm.
  • Article
    Lubricants Having Zinc Borate by Homogeneous Precipitation and Span 60 in Spindle Oil
    (Turkish Energy Nuclear and Mining Research Institute, 2021) Gönen, Mehmet; Alp, Burcu; Savrık, Sevdiye; Balköse, Devrim; Alp, Fatma Burcu; Balkose, Devrim
    Nano particles of zinc borate were obtained by homogeneous precipitation method which is based on dissolving zinc borate in ammonia and precipitating it as nano particles by slow evaporation of ammonia. The synthesized zinc borates were characterized by advanced analytical techniques. Zinc borate nano particles were used as a lubricant additive to spindle oil having Span 60 dispersant. The particles were well dispersed in spindle oil as shown by optical microscopy of the oils. Four ball tests of the lubricants indicated zinc borate lowered (61.8%) the wear scar diameter significantly. The hardness of wear surfaces of test balls was reduced from 688 HV to 618 HV and presence of zinc borate particles embedded on the surface indicated a flexible skin was formed. Therefore the pressure was decreased due to increase of the contact area of the balls. The surface roughness was also decreased from 35.63 nm to 27.60 nm by the addition of zinc borate to spindle oil having Span 60. Zinc borate prepared by homogeneous precipitation technique lowered the wear of the surfaces that rub to each other.