Method for manufacturing a metallic functional part delimiting a porous filtering medium, using an additive manufacturing method, and obtained functional part

A manufacturing method enabling obtainment of a functional part essentially formed in a metallic material, all or part of the functional part delimiting a filtering medium permeable to a fluid and delimiting first and second main faces for a circulation of a gas through the filtering medium between the first and second main faces, the manufacturing method comprising a main phase consisting of an additive manufacturing method in successive passes from a support tray, each pass comprising a deposition of at least one layer of the metallic material, the deposited material adhering to the metallic material of at least one layer deposited before, the deposition of the metallic material at a level of each layer being controlled at each pass such that a stack of the metallic material deposited during the successive passes constitutes the functional part, whose filtering medium comprises a coalescent network of connecting strands interconnected according to a three-dimensional spatial distribution between the first and second main faces, the connecting strands of the network delimiting therebetween pores spatially distributed within the filtering medium in three dimensions between the first and second main faces,

• wherein each pass comprises a step of depositing at least one powder layer formed in the metallic material and then a step of selective melting of the powder deposited before through a local energy input by action of a laser beam, the selective melting of the powder being controlled using a pre-established computer database, which computer database controls at each pass, by a computer program controlling a spatial displacement of the laser beam relative to the powder deposited before, at least one of a parameter selected amongst:
• a relative path between the laser beam and the powder deposited before, a displacement velocity corresponding to a relative velocity between the laser beam and the powder deposited before, a laser beam power, a laser beam power density,
• wherein at each selective melting step, a porosity rate of the pores within the filtering medium is adjusted, for a given laser beam power and a given layer thickness, by adapting the laser beam power density and adapting the displacement velocity, the porosity rate increasing below an upper threshold of the laser beam power density, as the laser beam power density decreases and the porosity rate increasing above a lower threshold of the displacement velocity, as the displacement velocity increases,
• wherein the given laser beam power is 275 W and the given layer thickness is 50 μm, the upper threshold of the power density being comprised between 7 and 20 J/mm3 and the lower threshold of the displacement velocity being comprised between 1500 and 6000 mm/s.