Characteristics of Plasma Sprayed TiO₂-NiCr Conductive Heating Roll Coatings

Kang, Tae-Gu; Jin, Min-Seok; Ko, Young-Bong; Kim, Tae-Hyung; Cho, Sang-Hum; Park, Jung-Sik; Kim, Jong-Chul; Park, Kyeung-Chae

Journal of KWJS 2007;25(4):28-34.
Published online September 21, 2007.

가열 롤에서 플라즈마 TiO₂-NiCr 용사피막의 특성

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Characteristics of Plasma Sprayed TiO₂-NiCr Conductive Heating Roll Coatings

Tae-Gu Kang, Min-Seok Jin, Young-Bong Ko, Tae-Hyung Kim, Sang-Hum Cho, Jung-Sik Park, Jong-Chul Kim, Kyeung-Chae Park

Abstract

  The heating unit of direct heating method manufactured as the plasma spray coating of TiO₂/NiCr conductive heating material on the surface of heating unit in order to improve the disadvantages of indirect heating method. TiO₂ and NiCr (80wt.%Ni-20wt.%Cr) that had the properties of conduction and heating was chosen for the conductive heating material. The compositions of the composite powders were studied TiO₂-30wt.%NiCr and TiO₂-10wt.%NiCr.
  As the heating temperature was increased, the hardness of heating layer was increased because of the fine microstructure and the decrease of porosity. The adhesion strength was decreased for coarsening and connection of voids in the insulation layer, and the electrical resistivity of heating layer was increased for fine crack formation and growth.
  In this study, the best efficient sprayed coatings with heating unit was concluded as the plasma sprayed TiO₂-10wt.%NiCr coatings that was heat treated at 300 ℃.

Key Words: APS (Atmospheric plasma spray), Heating unit, Adhesion strength, Electrical resistivity, Composite powders