摘要:
A coating system for Si-containing materials, particularly those for articles exposed to high temperatures. The coating system exhibits improved resistance to corrosion from sea salt and CMAS as a result of using aluminate compounds to protect silicate-containing layers of the coating system. The coating system includes an environmental barrier coating, a thermal barrier coating overlying the environmental barrier coating and formed of a thermal-insulating material, and a transition layer between the environmental barrier coating and thermal barrier coating, wherein the transition layer contains at least one aluminate compound and/or alumina.
摘要:
An article comprising a silicon-containing substrate, an environmental barrier coating (EBC) overlying the substrate, wherein the EBC comprises an outer alkaline earth aluminosilicate barrier layer; and a corrosion resistant alumina/aluminate sealant for the outer barrier layer. A process is also provided for forming a corrosion resistant alumina/aluminate sealant layer over the outer barrier layer of the EBC. Also provided is an alternative process for treating a porous outer barrier layer with a liquid composition comprising an corrosion resistant alumina/aluminate sealant precursor to infiltrate the porous outer barrier layer with the alumina/aluminate sealant precursor in an amount sufficient to provide, when converted to the corrosion resistant alumina/aluminate sealant, protection of the environmental barrier coating against environmental attack; and converting the infiltrated alumina/aluminate sealant precursor within the porous outer barrier layer to the corrosion resistant alumina/aluminate sealant.
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:
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.
摘要:
An article comprising a silicon-containing substrate, an environmental barrier coating (EBC) overlying the substrate, wherein the EBC comprises a higher metal silicate-containing outer barrier layer; and a corrosion resistant alumina/aluminate sealant for the higher metal silicate-containing outer barrier layer. A process is also provided for forming a corrosion resistant alumina/aluminate sealant layer over the higher metal silicate-containing outer barrier layer. Also provided is an alternative process for treating a porous higher metal silicate-containing outer barrier layer with a liquid composition comprising an corrosion resistant alumina/aluminate sealant precursor to infiltrate the porous higher metal silicate-containing outer barrier layer with the alumina/aluminate sealant precursor in an amount sufficient to provide, when converted to the corrosion resistant alumina/aluminate sealant, protection of the environmental barrier coating against environmental attack; and converting the infiltrated alumina/aluminate sealant precursor within the porous higher metal silicate-containing outer barrier layer to the corrosion resistant alumina/aluminate sealant.
摘要:
An article comprising a silicon-containing substrate, a silicide-containing bond coat layer overlying the substrate, and an environmental barrier coating (EBC) overlying the bond coat layer, wherein the EBC comprises a corrosion resistant outer layer comprising a corrosion resistant metal silicate. A process is also provided for forming the corrosion resistant outer layer over the silicide-containing bond coat layer.
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 formed by chemical vapor deposition and comprising mullite and alumina, and a top coat comprising alumina, stabilized zirconia or stabilized hafnia, wherein the zirconia or hafnia is stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals, and mixtures thereof. The environmental barrier layer is compositionally graded and consists essentially of mullite at an interface of the environmental barrier layer with the substrate, and consists essentially of alumina at an interface of the environmental barrier layer with the top coat, the environmental barrier layer having a decreasing concentration of mullite and an increasing concentration of alumina in a direction away from the substrate. A method for preparing a thermal/environmental barrier coating on a substrate formed of a silicon-comprising material is also disclosed.
摘要:
In one aspect, tungsten carbide material systems are described herein which, in some embodiments, can provide desirable characteristics including chemical inertness, high hardness, reduced sensitivity to local compositional fluctuations and/or enhanced machining properties. In some embodiments, a tungsten carbide material described herein comprises 5.85-6.13 wt. % carbon, 0.85-1.05 wt. % chromium, less than 0.3 wt. % binder, less than 0.3 wt. % impurities and a balance being tungsten.
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:
Method for preparing reduced thermal conductivity thermal barrier coating having improved impact resistance for an underlying substrate for high temperature applications. An exemplary method includes depositing a first zirconia-containing ceramic composition having a c/a ratio of about 1.011 to about 1.016 and stabilized in the tetragonal phase by yttria, calcia, ceria, scandia, magnesia, india, lanthana, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof, and including about 0.3 to about 0.5% by weight lanthana, neodymia, gadolinia, and mixtures thereof The first material forms a high fracture toughness inner layer having a fraction of porosity of about 0.20 or less, and a thickness in the range of from about 0.5 to about 2 mils. The method includes depositing a ceramic material forming an outer thermal insulating layer overlying the inner layer and having a greater fraction of porosity than the inner layer.