摘要:
Disclosed is a sol-gel process for making high-density monolithic alpha-alumina articles. Cracking problems caused by shrinkage of the gel during the drying and firing stages are minimized by controlling the temperature and humidity during the drying process and by using molds formed of prescribed polymeric materials, preliminarily coated with a silicone release agent. The process of the invention provides porous alpha-alumina articles having a controlled microstructure and a controlled pore size distribution, which are beneficial features when the material is used in practical applications, e.g., as substrates for gas sensors.
摘要:
A new method is disclosed for producing thin plates by sintering a thin gel plate (e.g., silica) made using a sol-gel process, which substantially eliminates warpage of the plate during the sintering step. Sintering a sol-gel based silica plate to a dense glass typically causes significant shrinkage, and this can cause the plate to curl, especially around its edges. This phenomenon is referred to as warpage. In the method of the invention, the sintering step is performed while the gel plate is mounted on a support surface, separated by a thin layer of refractory powder. At the high sintering temperature, the powder partially fuses and sticks to both the gel plate and the support surface, which prevents non-uniform stresses in the gel plate from warping the plate.
摘要:
A process which uses sol-gel to process oxide-based monoliths which are virtually free of cracks, without nullifying the desired attributes of the oxide-based monoliths. The method comprises substantially drying a wet porous gel monolith by removing a portion of the liquid from the pores of the gel monolith while the gel monolith remains wet, shrinking in size, and becoming correspondingly more dense, then removing the remaining portion of the liquid from the pores of the gel monolith such that the outer region of the gel monolith is not dried before the inner region of the gel monolith is dried. The gel monolith is substantially dried under conditions in which the liquid evaporation rate is no greater than the pore liquid diffusion rate.
摘要:
The present invention relates to a process for preparing silica-alumina carriers preferably under the form of extrudates. Further, the present invention also provides hydrogenation catalysts prepared thereof. These catalysts are used in an improved process for the reduction of the aromatic hydrocarbons content present in hydrocarbon streams.
摘要:
The present invention relates to a method for production of a metal oxide thin film and a method for production of an arrayed metal oxide functional device, comprising the steps of: preparing a sol containing a material and a solvent; gelating the sol to give a gel member; processing the gel member under a pressure of not less than 0.2 MPa at 100 to 400° C. in a water-vapor-containing atmosphere; and conducting a heat treatment on the water-vapor-processed gel member at 200 to 400° C.
摘要:
A method of a fabricating silica glass by sol-gel process is provided. The method includes mixing silica, a binder, a dispersing agent and a gelling agent, and forming a sol without air bubbles; injecting the sol into a mold, the injection of the sol into the mold being controlled by the pressure of an inert gas; gelating the sol injected into the mold and demolding the gel; and drying the demolded gel, and thermally-treating the dried gel. Therefore, incorporation of impurities and air bubbles during injection of a sol into a mold is minimized, and injection amount and injection rate of the sol can be controlled.