How to Repair Oil Pump Plunger by Gas Detonation Spraying

       The plunger of an oil pump is made of alloy steel, the surface is chrome-plated, and the hardness is 50HRC~55HRC. During use, the surface appears eccentric wear or deep 0.4mm scratches, how to repair?



    1) Spray material

    Use Al2O3+13%TiO2 to spray powder.

    2) Spraying method. Al2O3+13%TiO2 coatings can be prepared by gas detonation spraying or plasma spraying; in this example, the gas detonation spraying method is preferred for spraying.

    3) Spraying process

    (1) Cleaning. Clean and degrease the surface to be sprayed.

    (2) Preprocessing. Remove the chrome layer of the part to be processed, and the turning depth is 0.45mm~0.5mm.

    (3) Sandblasting. Use corundum sand with a particle size of 20 mesh to 40 mesh to sandblast the processing parts, and cover other parts, and spray them immediately after sandblasting.

    (4) Spraying. The process parameters are as follows:

        C2H2: =1.1:1.2

        Oxygen pressure 0.4MPa; Acetylene 0.2MPa

        Deflagration frequency: 4 times/s

        Powder spraying speed: 1.2kg/h~1.5kg/h

        Coating thickness: 450 υm ~500 υm

     (5) Post-processing. Diamond grinding; surface roughness Ra: 1.25 υm.

     (6) Coating properties. The bonding strength is greater than 50MPa; the porosity is less than 1.5%.

     (7) Use effect. Spraying Al2O3+13%TiO2 coating on the plunger of the oil pump increases its service life by 2 to 3 times.