Embedding and compacting particles in porous surfaces

In the process for preparing a metallic surface having pores in which particles are embedded therein which comprises:

• a. heating a porous metallic surface to at least 100.degree. F and not more than 650.degree. F to enlarge the pores thereof, said pores having an average width not greater than 100 microns;
• b. promptly thereafter depositing finely divided particles having an average size no greater than 50 microns onto said heated surface and working said particles into said pores, said particles being at a temperature at least 100.degree. below the temperature of said heated surface and being selected from the class consisting of perfluorocarbon polymers, elemental metals, metal oxides, metal nitrides, metal carbides and metal disulfides, whereby said metallic surface after said depositing is well above room temperature;
• the improvement comprising:
• c. applying to a surface produced according to steps (a) and (b) a fluid stream,
• said fluid stream having a temperature equal to or below room temperature, a pressure of 30-120 psi, and having suspended therein finely divided particles of an average size no greater than 50 microns, said stream being applied for a sufficient period to compact the embedded particles and cool the said surface so that the surface and particles reach a temperature equal to or below room temperature whereby the said embedded particles are locked into the said pores;
• d. thereafter heating said surface to a temperature of at least 100.degree. F.
• e. promptly thereafter depositing additional finely divided particles similar to those already embedded in said pores onto said heated surface and working said particles into said pores, said particles being at a temperature at least 100.degree. F below the temperature of said heated surface;
• and
• f. permitting said surface and particles to reach temperature equilibrium, thereby to lock said additional particles into said pores.