Coating material for flame or plasma spraying - uses mixt. of metal oxide(s) and silica to obtain hard, tough refractory mineral coatings contg. vitreous phase

摘要

The material consists of agglomerates formed by (wt.%) 50-99% of at least two oxides, esp. Al2O3, MgO, CaO, BaO, Cr2O3, TiO2, and/or ZrO2; plus 1-50% of at least one glass forming oxide, esp. SiO2, with a m.pt. which is 50-1100 deg.C lower than the other metal oxides. The pref. materials include (I) 50-80% CaO, 1-5% MgO, 18-45% SiO2; or (II) 50-90% MgO, 1-5% CaO, 5-45% SiO2, or (III) 90-95% Cr2O3, 2-8% TiO2, 1-3% SiO2; or (IV) 46-51% Al2O3, 33-41% ZrO2, 8-21% SiO2. The oxides are pref. fed through a plasma burner to obtain an agglomerate which can be collected in cooling system of water or air; or the plasma burner can be used to spray the agglomerate directly onto a substate to be protected. With powder mixts similar to (I) to (IV) above, coatings can be obtd. consisting of dicalcium silicate plus moticellite; forsterite and a vitreous phase; a mineral rich in Cr, plus a vitreous phase; or corundum plus baddeleyite and a vitreous phase. To provide a non-metallic refractory material as a protective coating applied in a single operation, and resisting mechanical- and thermal-shock and abrasion and with min. porosity.