Cleaning Porous Sintered Metal
Cleaning of porous sintered metals can allow reuse in some applications where the cost savings can justify the cleaning expense. The cost of disposable of other types of paper or plastic media can be expensive. The lower strength, limited temperature capability and minimal corrosion resistance of most disposable media limits the practicality of cleaning. In order to extend the service life, blocked porosity can be opened with a variety of cleaning techniques and solutions, depending on the nature of the material in the pores. Thermal burn-off, ultrasonic cleaning, reverse flow and chemical processing are typical cleaning methods. Cleaning can often be accomplished with mild detergents, caustic solutions or diluted acids but testing is required to insure that the base metal is not affected. In order to avoid corrosion or cross contamination, the cleaning solutions must be flushed out under pressure and dried thoroughly before being returned to service. Test methods such as visual inspection using magnification, bubble point testing and permeability testing are often performed to determine the effectiveness of the cleaning method. Cleaning methods that mechanically close off or smear the pores, such as wire brushing or sand blasting should be avoided.