摘要:
Articles suitable for use as high-temperature machine components include a substrate and an environmental barrier coating disposed over the substrate, where the environmental barrier coating includes at least one hermetic self-sealing layer formed from a mixture including an alkaline earth metal aluminosilicate and a rare-earth silicate, and where the at least one hermetic self-sealing layer exhibits substantially no net remnant or residual expansion when subjected to high temperature heat treatment. The environmental barrier coating can further include a bondcoat disposed between the substrate and the hermetic self-sealing layer, a topcoat disposed over the hermetic self-sealing layer, and/or an intermediate layer disposed between the hermetic self-sealing layer and the bondcoat. The intermediate layer can include a barrier material that is substantially inert with respect to silica.
摘要:
The invention relates to a process of selectively treating parts of the surface of a porous dental ceramic comprising the steps of a) providing a composition and a porous dental ceramic having an outer surface, b) applying the composition to only a part of the outer surface of the porous dental ceramic, c) optionally drying the porous dental ceramic, and d) optionally firing the porous dental ceramic, wherein the composition comprises—a liquid being miscible with water, but not being water, —a whitening agent comprising nano-sized metal oxide particles, metal ion containing components or mixtures thereof which precipitate if the composition is adjusted to a pH above 5, —acid, complexing agent or mixture thereof. The invention also relates to a dental ceramic article obtainable by a process.
摘要:
A thermal barrier coating for a turbine engine component contains neodymia, optionally alumina, and zirconia. The thermal barrier coating has resistance to CMAS attack and a low thermal conductivity.
摘要:
A method of protecting a part made of carbon-including composite material against oxidation, the method including a) applying a coating composition on at least a portion of the outside surface of the part, the coating composition being in the form of an aqueous suspension including: a metallic phosphate; a powder of a compound comprising titanium; and a B4C powder; and b) applying heat treatment to the coating composition applied during step a) with a treatment temperature lying in the range 330° C. to 730° C. being imposed during the heat treatment in order to obtain a coating on the outside surface of the part, the coating including a first phase in which the metallic phosphate is in crystalline form and a second phase in which the metallic phosphate is in amorphous form.
摘要:
Disclosed is a ceramic honeycomb structure comprising a honeycomb body and a multilayered outer layer formed of a thick core layer applied and rapidly dried and a thin clad layer dried more gently to form a crack free dual skin layer. The core layer may have properties that are closer to those of the ceramic honeycomb body in service than the clad layer that may provide a tough outer shell to withstand handling and assembly.
摘要:
Slurry compositions for making an environmental barrier coating including from about 9 wt % to about 81 wt % water; from about 3 wt % to about 72 wt % primary material; and from about 0.1 wt % to about 18 wt % slurry sintering aid, and environmental barrier coatings including such compositions.
摘要:
A refractory material withstanding high temperatures in an oxidizing medium contains at least hafnium boride and tantalum boride, hafnium and tantalum being present in the refractory material exclusively in compound form.
摘要:
The method includes depositing on the entire surface of a substrate a refractory cement paste formed by a powder mainly constituted by silica and alumina and mixed with a liquid. The method includes filling the cement paste in hollow portions in a relief of the surface; performing a heat treatment to harden the cement paste after it has set to obtain a first coating layer of refractory cement; and depositing a slip on the first layer, and formed of a glass frit in suspension in a liquid. The method includes performing a heat treatment for glazing by softening and spreading the glass in order to obtain a second coating layer forming a glaze covering the first layer. The composition of the glass frit is selected to form a glass having a glazing temperature lower than 1100° C. and a glass transition temperature lower than 750° C.
摘要:
Organic solvent based slurry compositions for making an environmental barrier coating including from about 6.8 wt % to about 96.1 wt % solvent; from about 3.9 wt % to about 93.2 wt % primary material; and from about 0.01 wt % to about 20 wt % slurry sintering aid.
摘要:
The present inventions incorporate self-healing mechanisms into current and future EBC systems. Such approaches have the potential to form environmental protection materials (i.e. thermally grown silicate compositions) in-situ to enable the ability to provide environmental protection to SiC based ceramics even in the event that cracks or voids form from within the EBC layer. In this disclosure, novel, self-healing EBC systems are disclosed along with coating synthesis techniques required to deposit the materials, microstructures and architectures. This research is anticipated to result in a thermal/environmental barrier coating system (T/EBC) that provides improved durability over current coatings. These advancements will aid the use of Si-based ceramics in a range of high temperature applications such a gas turbine engines and heat exchangers. These advances will not only benefit military engines, but also commercial and industrial engines requiring greater performance.