摘要:
In a method of preparing a boron carbide material, boron carbide powder is washed with essentially pure water at an elevated temperature to generate washed boron carbide powder. The washed boron carbide powder is combined with a sintering aid. The mixture of the boron carbide powder and the sintering aid is pressed to form a shaped material, and the shaped material is sintered. A sintered boron carbide material comprises a boron carbide component that includes boron carbide, elemental carbon, and not more than about 0.6 wt % of oxygen on the basis of the total weight of the boron carbide component. The sintered boron carbide material has a density of at least about 99% of the theoretical density. Another sintered boron carbide material comprises a boron carbide component that includes boron carbide, silicon carbide, elemental carbon, and not more than about 0.3 wt % oxygen on the basis of the total weight of the boron carbide component, and has a density of at least about 97% of the theoretical density.
摘要:
A method for forming a reinforced rigid anode monolith and fuel and product of such method. The method includes providing a solution of organic aerogel or xerogel precursors including at least one of a phenolic resin, phenol (hydroxybenzene), resorcinol(1,3-dihydroxybenzene), or catechol(1,2-dihydroxybenzene); at least one aldehyde compound selected from the group consisting of formaldehyde, acetaldehyde, and furfuraldehyde; and an alkali carbonate or phosphoric acid catalyst; adding internal reinforcement materials comprising carbon to said precursor solution to form a precursor mixture; gelling said precursor mixture to form a composite gel; drying said composite gel; and pyrolyzing said composite gel to form a wettable aerogel/carbon composite or a wettable xerogel/carbon composite, wherein said composites comprise chars and said internal reinforcement materials, and wherein said composite is suitable for use as an anode with the chars being fuel capable of being combusted in a molten salt electrochemical fuel cell in the range from 500 C to 800 C to produce electrical energy. Additional methods and systems/compositions are also provided.
摘要:
Spinel-type ferrimagnetic particles having a composition represented by the formula: (MO).n/2(Fe2O3) where M is a divalent metal and n is a molar ratio of Fe to M (n=Fe/M) which is from more than 2.05 to less than 2.5 (2.05
摘要翻译:具有由式(MO)n / 2(Fe 2 O 3)表示的组成的尖晶石型亚铁磁性颗粒,其中M是二价金属,n是Fe与M(n = Fe / M)的摩尔比,其来自更多 小于2.5(2.05
摘要:
A method is provided for heavy metal stabilisation comprising: mixing waste, comprising heavy metals, with molecular sieve with the proviso that carbon-based molecular sieve is excluded, and clay; and vitrifying the mixture. In particular, a method comprising the steps of: preparing a pre-stabilised mixture by mixing waste, comprising heavy metals, with the molecular sieve, and optionally other chemicals; mixing the pre-stabilised mixture with clay; and vitrifying the obtained mixture is provided. It also provides a product comprising heavy metals that have been stabilised into the structure of the clay-based ceramic matrix, wherein the product is a vitrified product of a mixture of at least waste, comprising heavy metals, molecular sieve (with the proviso that carbon-based molecular sieve is excluded) and clay.
摘要:
The invention relates to a method of preparing a stable sol-gel solution as precursor of an oxide ceramic based on lead, titanium, zirconium and one or more lanthanides, comprising, in succession, the following steps: a) a sol-gel solution is prepared by bringing a lead-containing molecular precursor, a titanium-containing molecular precursor, a zirconium-containing molecular precursor and a lanthanide-metal-containing molecular precursor into contact with a medium comprising a diol solvent and optionally an aliphatic monoalcohol; b) the solution obtained in step a) is left to stand for a sufficient time needed to obtain a solution having an approximately constant viscosity; and c) the solution obtained in step b) is diluted to a predetermined amount with a diol solvent identical to that of step a) or a solvent miscible with this solvent. Application to the preparation of an oxide ceramic material comprising lead, a lanthanide metal, titanium and zirconium.
摘要:
Dielectric particles including a main component including barium titanate and R oxide (where R is at least one element selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), wherein when defining the size of the dielectric particles as “D” and defining the region of a depth from the particle surface of 0% to 10% of said D as a surface region, a region of a depth from the particle surface of more than 10% to less than 40% of the D as an intermediate region, and a region of a depth from the particle surface of 40% to 50% of the D as a center region, in the surface region, the ratio of content of the R oxide decreases from the surface side toward the center of the dielectric particles and in the center region, the ratio of content of the R oxide increases from the surface side toward the center of the dielectric particles.
摘要:
The inventive composition, according to a first embodiment, consists essentially of a cerium oxide and a zirconium oxide. According to a second embodiment, said composition is based on cerium oxide, zirconium oxide and at least one rare earth oxide other than cerium. After a first 4-hour period of calcination at 900 .C followed by a second 10-hour period of at 1000 .C, the specific surface variation thereof is 20% maximum in the first embodiment and 15% maximum in the second embodiment. The inventive composition can be used as a catalyst, i.e. in the treatment of waste gases from internal combustion engines.
摘要:
Spinel-type ferrimagnetic particles having a composition represented by the formula: (MO).n/2(Fe2O3) wherein M is a divalent metal; and n is a molar ratio of Fe to M (n=Fe/M) which is from more than 2.05 to less than 2.5 (2.05
摘要:
A sol-gel process for producing dry porous gel monoliths, e.g., silica glass monoliths, in which the successive process steps of gelling, aging and drying all occur within a mold formed of a porous material, e.g., graphite. The mold is inert to the gel solution and it has sufficient strength to withstand the temperatures and pressures encountered during the process, yet it has sufficient porosity to facilitate the escape of liquid from the gel pores directly through the mold, itself. The mold and gel thereby can remain within a sealed autoclave during these process steps, and mechanical handling of the mold and the gel are minimized. This substantially enhances the process' efficiency. Alternatively, the mold can have a non-porous inner skin.
摘要:
A process for preparing a zirconia-alumina base composite ultra-fine powder is described, including the steps of: mixing an aluminum salt or an alumina hydrate with an aqueous zirconium oxychloride solution, with or without metal salt acting as a stabilizer; mixing urea or a substance capable of generating ammonia by hydrolysis with the resulting mixture; and allowing the mixture to react at a temperature of 140.degree. to 300.degree. C. and a pressure of 4 to 150 kg/cm.sup.2 in a high-temperature and -pressure vessel. The reaction product is further dried, calcined and crushed to obtain an ultra-fine powder.