| 摘要 |
<p>A molten metal or molten metal alloy is filtered to remove contaminants. Filters may include imaging agents, especially those useful for N-ray radiography, X-ray analysis, and neutron activation. Currently preferred imaging agents include gadolinia and tungsten. Currently preferred refractory materials include yttria, zirconia, tantalum, tungsten and rhenium. A homogeneous distribution of refractory and imaging materials may be accomplished by vacuum impregnation, chemical vapor deposition, physical vapor deposition, chemical vapor infiltration, fusing, cocalcining, alloying, and physical mixing. Filters substantially resistant to chemical and mechanical degradation may be used. For example, filters may be constructed with at least an outer layer of the filter comprising yttria. Filters may define a porosity and mesh size for efficient filtration and to exclude the maximum allowed size of defects for the particular application. Castings may be analyzed for inclusions by X-ray analysis, neutron activation, and N-ray radiography. Preferred methods for filtering melts include providing a filter including an imaging agent and filtering the melt into a mold to cast a metal article. Filtration may include heating the filter during filtration. The melt may include any molten metal or metal alloy, particularly aluminum, steel, alloys of titanium, chromium, nickel, cobalt and alloys thereof.</p> |
