摘要:
The invention relates to a sealing composition suitable for bonding yttria or alumina ceramic members, or bonding refractory metals to the ceramics. The sealing composition has, in mole percent, about 0.5 to 40 percent yttria, about 45 to 65 percent alumina, up to 10 mole percent strontia, and the balance substantially calcia.
摘要:
A method of forming polycrystalline rare earth oxide ceramic scintillators formed by dissolving a mixture of oxides of the scintillator in an aqueous hydrochloric or nitric acid solution to form a rare earth solution, precipitating oxalates from the rare earth solution, calcining the oxalates to form the respective oxides, cold pressing the oxides to form a compact, and sintering the compact in a reducing atmosphere or vacuum to form the scintillator, the method being improved by precipitating the oxalates by admixing the rare earth solution with an oxalic solution comprised of, oxalic acid and ammonium ions in an amount that disperses the oxalate precipitates.
摘要:
A high yield method of fabricating an ultrasound array having densely packed ultrasound elements with smooth surface finishes includes the steps of: 1) applying an acoustic matching material to opposites faces (or surfaces) of a piezo electric material ceramic block; 2) cutting the block in a plane perpendicular to the two faces of the block so as to form a plurality of wafers having the acoustic matching material disposed on opposite ends; 3) assembling the wafers to form a laminated body having respective portions of the matching layer on opposite surfaces and with the wafers each being separated from an adjacent wafer by a selected gap distance and bonded together by a polymeric adhesive material; 4) cutting the laminated body along a longitudinal axis so as to form a first laminate body subassembly and a second laminate body subassembly, each of the subassemblies having a front surface having the acoustic matching material disposed thereon and a back surface where the laminate body was cut; 5) applying a backing layer to each laminate body subassembly; and 6) removing the polymeric adhesive material disposed between the wafers, whereby each subassembly comprises an ultrasound array having transducer elements separated by the selected array gap distance.
摘要:
A phosphor comprising an effective amount of cerium to provide luminescence, and the balance substantially an oxide compound of hafnium and an alkaline earth from the group consisting of barium, strontium, calcium, and mixtures thereof, having substantially a perovskite crystal form.
摘要:
A phosphor is disclosed comprised of an effective amount of cerium to provide luminescence, and the balance substantially a gadolinium lutetium aluminate compound having the formula Gd.sub.x Lu.sub.1-x A10.sub.3, where x ranges from about 0.25 to 0.9.
摘要:
A simplified method of forming polycrystalline translucent-to-transparent yttria-gadolinia composition scintillators comprises forming an aqueous suspension of hydroxide coprecipitates of the yttria-gadolinia composition, and converting the hydroxides to oxalates. The oxalates are neutralized by washing, dried, and granulated to form a finely dispersed oxalate powder. The oxalate powder is calcined, cold pressed to form a compact, and sintered in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator.
摘要:
A titanium acylate solution is produced by adding glacial acetic acid to tetra-isopropyl titanate. Distilled water is then added until the solution clears, and a high grade alkaline-earth metal carbonate, such as BaCO.sub.3, SrCO.sub.3 or CaCO.sub.3, or a combination thereof, is added and agitated until the earth-metal dissolves and the solution again becomes clear. An alkaline hydroxide, such as NaOH, is added until the pH of the solution reaches 13 or 10 above, and causes crystals of an earth-metal titanate to form in the solution. The solution is thereafter filtered to produce an alkaline-earth metal titanate filter cake which is then dried and washed to produce the desired powder. At no time during the process is it necessary to apply any external heat to the solution. The heat of reaction is sufficient.