摘要:
Provided is a crystalline TiO2 powder in the form of aggregated primary particles having a variable sintering stability at a BET surface area of 70-100 m2/g and a rutile content of greater than 10% but less than or equal to 40%, and a process for preparing the crystalline TiO2 powder, which involves: introducing a TiCl4 vapor and, separately therefrom, H2 and a primary air into a mixing chamber to produce a gaseous mixture; igniting the gaseous mixture in a burner to produce a flame, which is burned into a reaction chamber to produce the crystalline TiO2 powder and gaseous substances; and separating the crystalline TiO2 powder from the gaseous substances, wherein the relative amounts of TiCl4 vapor, H2 and primary air are selected to provide crystalline TiO2 powder having the aforementioned BET surface area and rutile content, with the proviso that factor A has a value of 0.1-0.4 g/m2 in accordance within the following formula: factor A=105{[(TiCl4 vapor×H2)/(amount of air×gaseous mixture)]/BET]}.
摘要:
A crystalline titanium dioxide powder, containing aggregated primary particles, wherein a BET surface area of the aggregated primary particles is from 30 to 65 m2/g, and a rutile content of a sum of crystalline modifications in the crystalline titanium dioxide is from of 50-70%.
摘要:
Surface-modified silicas Surface-modified, highly structured, potassium oxide-doped silicas, characterized by BET surface area, m2/g: 25-400 average primary particle size, nm: 5-50 pH: 3-10 carbon content, % by weight: 0.1-10 potassium oxide content, % by weight: 0.000001-40 are prepared by subjecting a potassium oxide-doped silica to surface modification. It can be used as a filler in silicone rubber compositions.
摘要:
Stable, aqueous dispersion containing silicon dioxide powder having a hydroxyl group density of 2.5 to 4.7 OH/nm2, which is obtained from a silicon dioxide powder produced by a flame hydrolysis process under acid conditions. The dispersion is produced by incorporating the silicon dioxide powder into an aqueous solution by means of a dispersing device. The dispersion can be used to produce glass articles.
摘要:
Flame-hydrolytically produced titanium dioxide powder that is present in the form of aggregates of primary particles, and has a BET surface of 20 to 200 m²/g, a half width (HW) [nm] of the primary particle distribution of HW = a×BETf where a = 670×10−9 m³/g and −1.3 ≤ f ≤ −1.0 and the proportion of particles with a diameter of more than 45 &mgr;m lies in a range from 0.0001 to 0.05 wt. %. The powder is produced by a process in which a titanium halide is vapourised at temperatures of less than 200°C., the vapours are transferred to a mixing chamber by means of a carrier gas of defined moisture content and, separately from this, hydrogen, primary air, which may optionally be enriched with oxygen and/or preheated, and steam are added to the mixing chamber, following which the reaction mixture is combusted in a reaction chamber sealed from the ambient air, secondary air is in addition introduced into the reaction chamber, the solid is then separated from gaseous substances, and following this the solid is treated with steam. The titanium dioxide powder may be used for the heat stabilisation of polymers.
摘要:
Surface-modified silicas Surface-modified, highly structured, potassium oxide-doped silicas, characterized by BET surface area, m2/g: 25-400 average primary particle size, nm: 5-50 pH: 3-10 carbon content, % by weight: 0.1-10 potassium oxide content, % by weight: 0.000001-40 are prepared by subjecting a potassium oxide-doped silica to surface modification. It can be used as a filler in silicone rubber compositions.
摘要:
Disclosed is a process for producing a substantially shell-shaped component, from substantially carbon-fiber-reinforced synthetic material having at least one local reinforcing zone and at least one stiffening element, in particular a fuselage shell, a wing shell, a vertical stabilizer shell or horizontal stabilizer shell of an aircraft or the like. The process according to the invention comprises the following steps: arranging at least one doubler which has already been cured, on an at most partially cured shell skin to form the local reinforcing zone, applying at least one stiffening element which has already been cured, and placing at least one at most partially cured connecting angle bracket against the at least one stiffening element at least in the region of the at least one doubler, and curing the shell skin and the connecting angle bracket.
摘要:
Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 150±15 m2/g, wherein the aggregates display an average surface area of 12000 to 20000 nm2, an average equivalent circle diameter (ECD) of 90 to 120 nm and an average circumference of 1150 to 1700 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a second silicon component comprising H3SiCl, H2SiCl2, HSiCl3, CH3SiCl3, (CH3)2SiCl2, (CH3)3SiCl and/or (n-C3H7)SiCl3 are mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1670 to 1730° C. is obtained. Silicone sealing compound containing the pyrogenically produced silicon dioxide powder.
摘要:
Use of titanium dioxide mixed oxide as a photocatalyst, wherein the titanium dioxide mixed oxide has the following features: BET surface area: 5 to 300 m2/g, mixed oxide component: one or several oxides from the group comprising aluminium, cerium, silicon, tungsten, zinc and zirconium, proportions: titanium dioxide more than 97.5 wt. %, mixed oxide component ≧0.1 to
摘要:
Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 300±25 m2/g, wherein the aggregates display an average surface area of 4800 to 6000 nm2, an average equivalent circle diameter (ECD) of 60 to 80 nm and an average circumference of 580 to 750 nm.It is produced by a pyrogenic process in which silicon tetrachloride and a maximum of up to 40 wt. % of a second silicon component comprising H3SiCl, H2SiCl2, HSiCl3, CH3SiCl3, (CH3)2SiCl2, (CH3)3SiCl and/or (n-C3H7)SiCl3 are mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1390 to 1450° C. is obtained.It can be used as a filler.