What are the characteristics of "one-step method" and "two-step method" of oxy-acetylene flame powder spray melting process

       1) Process characteristics of "one-step method"



   (1) Powder spraying and remelting are performed alternately or at the same time, and the powder is directly sprayed into the molten pool, so the particle size and distribution of the powder are required to be finer.

   (2) The heat input to the workpiece is low, the influence on the base metal structure is small, and the deformation of the workpiece is small.

   (3) The thickness of the melt spray layer can vary within a wide range, generally 0.8mm~1.2mm, rarely more than 2mm.

   (4) The process is simple and the operation is flexible.

    Its disadvantage is that it is generally operated manually, with poor labor conditions and low productivity.

    2) Process characteristics of "two-step method"

   (1) "Two-step method" is to separate powder spraying and remelting, first spraying powder and then remelting; the powder spraying process is the same as that of flame powder spraying, the powder stays in the flame for a long time, and the too fine powder is easily oxidized. Therefore, the powder particle size used is coarser than that of the "one-shot" method. And the particle size distribution is required to be concentrated.

   (2) The workpiece is heated more, and the workpiece is deformed greatly after spray melting.

   (3) The thickness of one spray melting should not be too large, generally about 1mm, so that it is easy to obtain a high-quality spray melting layer.

   (4) The melt-blown layer is uniform and flat, with high productivity, and it is easy to realize mechanized operation.

    "Two-step method" spray melting is suitable for protective cladding and repair on the surface of cylindrical and rotating parts; workpieces requiring large-area protective cladding