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Thermal Plasma Coating Technologies

  • University of Minnesota High Temperature Lab

     

    The emphasis in this Thrust Area is on establishing and broadening the

    science and technology bases for high rate, economical coating processes,

    including plasma spraying, wire arc spraying and thermal plasma chemical

    vapor deposition (TPCVD). A combination of advanced diagnostics and

    modeling is used to enhance our understanding of the fundamentals of the

    interactions between plasmas and particles or liquid droplets and chemical

    precursors for the coatings. This understanding then provides the

    guidelines for developing new equipment and process designs, such as

    nozzles and shrouds to modify the fluid dynamics, and for developing

    sensors and control strategies for advanced process controls. These

    activities will lead to improved process tolerance against the influences

    of uncontrolled parameters.

     

    Specific activities which are presently being pursued are:

    A) Plasma spraying:

    * Nozzle and shroud development and evaluation for increased plasma jet

    stability, and improved deposition efficiency and consistency of coating

    quality.

    * Development of sensors and control algorithms for detecting and avoiding

    variations in plasma jet behavior and coating quality.

     

    B) Wire arc spraying:

    * Spray pattern control through different nozzle and shroud designs.

    * Development of fundamental process correlations using process models and

    advanced diagnostics with a novel torch.

    * Application of novel control algorithm based on computer analysis of arc

    voltage traces.

     

    C) Thermal plasma CVD:

    * Texture control during high rate diamond film deposition through

    detailed understanding of the boundary layer chemistry based on modeling

    and diagnostics using gas chromatography.

    * Arcjet deposition at high rates of hard, boron containing films.

     

    There are several complementary projects spanning a wide spectrum from

    fundamental studies in arc technologies, electrode attachment control and

    plasma heat transfer to specific industrial applications.

     

    Recent collaborations with industrial partners:

    * Plasma spray model for process control development.

    * High definition arc spray system development.

    * Torch cathode erosion mechanism investigation.

    * Barrier discharge characterization.

     

    Collaborations with other laboratories:

    Stanford University High Temperature Gas Dynamics Laboratory; SUNY Stony

    Brook Thermal Spray Laboratory, University of Limoges, France: Technical

    University of Ilmenau, Germany; University of Tokyo, Japan; University of

    Sherbrooke, Canada.

     

     

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