摘要:
A reduced thermal conductivity thermal barrier coating having improved impact and erosion resistance for an underlying metal substrate of articles that operate at, or are exposed to, high temperatures. This coating comprises an inner layer nearest to the underlying metal substrate comprising a ceramic thermal barrier coating material, as well as a protective outer layer adjacent to and overlaying the inner layer and having an exposed surface. The outer layer has a thickness up to about 5 mils (127 microns) sufficient to impart impact and erosion resistance to the thermal barrier coating, and comprises a zirconia-containing ceramic composition having a c/a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by a stabilizing amount of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, ytterbia and mixtures thereof. This coating can be used to provide a thermally protected article having a metal substrate and optionally a bond coated layer adjacent to and overlaying the metal substrate. The thermal barrier coating can be prepared by forming the inner layer comprising the ceramic thermal barrier coating material, followed by forming on the inner layer the protective outer layer.
摘要:
A process of depositing a coating system suitable for use as an environmental barrier coating on various substrate materials, particularly those containing silicon and intended for high temperature applications such as the hostile thermal environment of a gas turbine engine. The process comprises depositing a first coating layer containing mullite, and preferably a second coating layer of an alkaline earth aluminosilicate, such as barium-strontium-aluminosilicate (BSAS), by thermal spraying while maintaining the substrate at a temperature of 800° C. or less, preferably 500° C. or less, by which a substantially crack-free coating system is produced with desirable mechanical integrity.
摘要:
An article protected by a thermal barrier coating system is fabricated by providing an article substrate having a substrate surface, thereafter depositing a bond coat on the substrate surface, the bond coat having a bond coat surface, and thereafter processing the bond coat to flatten the bond coat surface. A thermal barrier coating is deposited overlying the bond coat surface. The thermal barrier coating is yttria-stabilized zirconia having a yttria content of from about 3 percent by weight to about 5 percent by weight of the yttria-stabilized zirconia.
摘要:
Improved adhesion of thermal barrier coating systems to nonmetallic substrates using a layer of silica on an underlying nonmetallic substrate that includes a silicon containing material is described. The improved adhesion occurs because the improved thermal barrier system improves the temperature capability of the system by providing a layer adjacent the substrate that has improved thermal performance and that is not subject to deterioration. The application of a silica layer of predetermined thickness adjacent the substrate also forms a diffusion barrier for oxygen while eliminating the need to transform an external layer of the substrate by a pre-oxidation step. This diffusion barrier prevents any oxidizable component of the substrate from decomposing. The thermal/environmental barrier coating (T/EBC) system includes an intermediate layer containing YSZ and BSAS, mullite and/or alumina, which is preferably used in combination with a mullite layer that overlies the surface of the silica layer, a layer of BSAS between the mullite layer and the intermediate layer, and a thermal barrier coating of YSZ overlying the intermediate layer.
摘要:
A closed impeller has a base cover, which has a base interior surface, and a second cover. A vane, which has an inlet distal end and an outlet distal end, is on the base interior surface. The vane has low and high pressure side surfaces wherein they have a low or high pressure midpoint, respectively. A hard coating is on the low and high pressure side surfaces. The hard coating has a minimum low and high pressure coating thickness at their respective midpoints. The minimum low, as well as high, pressure coating thickness ranging between about 0.085 and about 0.8 of either one of the maximum outlet coating thickness at the outlet distal end or the maximum inlet coating thickness at the inlet distal end, respectively.
摘要:
A system for precision glass molding comprising a substrate and a coating. The substrate has less than 1.2 wt. % minor constituents. The coating comprises TiAlxNy, wherein x is about 0.7-1.5 and y is about 2.0-3.0. The coating is applied on at least a portion of the substrate.
摘要:
A protective coating for use on a silicon-containing substrate, and deposition methods therefor. The coating has a strontium-aluminosilicate (SAS) composition that is less susceptible to degradation by volatilization and in corrosive environments as a result of having at least an outer surface region that consists essentially of one or more stoichiometric crystalline phases of SAS and is substantially free of a nonstoichiometric second crystalline phase of SAS that contains a substoichiometric amount of silica. The coating can be produced by carrying out deposition and heat treatment steps that result in the entire coating or just the outer surface region of the coating consisting essentially of the stoichiometric celsian phase.
摘要:
A thermal barrier coating and deposition process for a component intended for use in a hostile thermal environment, such as the turbine, combustor and augmentor components of a gas turbine engine. The TBC has a first coating portion on at least a first surface portion of the component. The first coating portion is formed of a ceramic material to have at least an inner region, at least an outer region overlying the inner region, and a columnar microstructure whereby the inner and outer regions comprise columns of the ceramic material. The columns of the inner region are more closely spaced than the columns of the outer region so that the inner region of the first coating portion is denser than the outer region of the first coating portion, wherein the higher density of the inner region promotes the impact resistance of the first coating portion.
摘要:
An article comprising a substrate formed of a silicon-comprising material, such as an article exposed to the hostile thermal environment of a gas turbine engine. The article further comprises an environmental barrier layer, e.g., an alkaline earth metal aluminosilicate, and a physical barrier layer overlying the environmental barrier layer. The physical barrier layer comprises zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals; and a low CTE oxide selected from the group consisting of niobia and tantala; and mixtures thereof. A method for preparing an environmental barrier coating system on a substrate formed of a silicon-comprising material is also disclosed.
摘要:
An article comprising a silicon-containing substrate, a silicide-containing bond coat layer overlying the substrate, and typically an environmental barrier coating overlaying the bond coat layer. An article is also provided wherein the environmental barrier coating comprises: (1) an optional inner silica scale layer overlaying the bond coat layer; (2) intermediate layer overlaying the inner silica scale layer, or the bond coat layer in the absence of the inner silica scale layer, and comprising mullite, or a combination of mullite with a barium strontium aluminosilicate, a yttrium silicate, or a calcium aluminosilicate; and (3) an outer steam-resistant barrier layer overlaying the intermediate layer and consisting essentially of an alkaline earth silicate/aluminosilicate. Processes are also provided for forming the silicide-containing bond coat layer over the substrate, followed by forming the environmental barrier coating over the bond coat layer.