| 摘要 |
A shaped refractory body has a coating comprising a base composition and a getter finely distributed throughout the base composition. The body is of Mo; refractory alloys of Mo with at least one of Ti, Zr, Hf, Th, V, Nb, Ta, Pa, Cr, Mo, W, or V; SiC; or C. The base composition is formed in weight per cent, from: SiO2, 70-85; alkaline earth oxide, 0.9-6; alkali oxide, 0.1-5; and Al2O3, 14-29. Up to 60% of the Al2O3 may be replaced by oxide(s) of Ti, Zr, Nb, Ta and/or Th. Instead of the alkali metal oxide and alkaline earth metal oxides there may be provided oxides of Be, Ca, Zr, and/or Nb. The oxide mixture may comprise kaolin, feldspar, mica, beryl, zircon, monazite, or bentonite, and 0.1-5% fluoride as flux. The getter consists of the silicide of at least one of Ti, Zr, Hf, Th, V, Nb, Ta, Cr, Mo, W, or V. Preferably 10-80% of the getter is used, with grain-size preferably <25m . The coating may be applied by (a) forming an aqueous suspension of the constituents to which an organic bonding medium may be added, and applying by immersion, spraying or brushing, and firing at e.g. 1200-1650 DEG C. in an inert or reducing atmosphere; or (b) firing the components, pulverizing, and flame-spraying on to the surface which is at 400-1000 DEG C. If the shaped body is of carbon, e.g. graphite, it may first be coated with SiC and/or a silicide and/or carbide of one or more Group IV, V, or VI transition metals by direct deposition. An intermediate layer, comprising 90-99% getter and 10-1% base composition, may be interposed between the body and the coating. The bodies may be used: for nuclear fuel envelopes, in which case the coatings should posses low neutron absorption cross-sections, as crucibles; as rocket nose-cones; as heating elements; or electrodes for glass melts. |
