A manufacturing process for the synthesis of environmental barrier coating system (EBC) which protect Si-based Ceramic Matrix Composite (CMC) material against oxidation and volatilization at high temperatures is disclosed. The manufacturing process is carried out in vacuum and includes steps of depositing a silicon bond coat and an oxygen containing barrier coating. The process is supported by plasma, preferably through and arc discharge, which lead to full dissociation of the gas precursors such as silane. Plasma is as well used for pre-treatment of substrates in an uninterrupted process chain. A deposition system with essential vacuum and plasma components is disclosed as well as EBC coatings manufactured by the process.

A technique may include controlling, by a computing device, a vacuum pump to evacuate a vacuum chamber to high vacuum. The technique also may include controlling, by the computing device, a coating material source to provide a coating material to a plasma spray device, the coating material having a first composition including a first amount of a metal oxide and a second amount of silica. The second amount of silica may be greater than an amount of silica in a metal silicate including the first amount of metal oxide. The technique further may include controlling, by the computing device, the plasma spray device to deposit an environmental barrier coating on a substrate in the vacuum chamber using plasma spray physical vapor deposition, wherein the coating comprises the metal silicate.

A technique may include controlling, by a computing device, a vacuum pump to evacuate a vacuum chamber to high vacuum. The technique also may include controlling, by the computing device, a coating material source to provide a coating material to a plasma spray device, the coating material having a first composition including a first amount of a metal oxide and a second amount of silica. The second amount of silica may be greater than an amount of silica in a metal silicate including the first amount of metal oxide. The technique further may include controlling, by the computing device, the plasma spray device to deposit an environmental barrier coating on a substrate in the vacuum chamber using plasma spray physical vapor deposition, wherein the coating comprises the metal silicate.

PURPOSE: To provide a method capable of detecting a large oxygen deposit existing in a silicon single crystal obtained by a CZ method with good sensitivity.

CONSTITUTION: A silicon single crystal is subjected to heat treatment for 30 to 300 minutes at 900 to 1050 deg.C in a dry O2 atmosphere, then, is subjected to heat treatment for 30 to 200 minutes at 1100 to 1200 deg.C in a wet O2 atmosphere. After this crystal is treated with a dilute hydrofluoric acid and an oxide film on the surface of the crystal is removed, the crystal is dipped in a seco solution for 1 to 30 minutes to etch selectively the face <100> and lastly, the number of pieces of OSFs, which appear on the silicon single crystal surface, is found by an optical microscope. Accordingly, by this two-stage heat treatment, as a large oxygen deposit in the crystal is turned into the selective OSFs and the OSFs appear on the crystal surface, an inspection of the quality of the silicon single crystal can be carried out with high sensitivity.

PURPOSE: To provide a method capable of detecting a large oxygen deposit existing in a silicon single crystal obtained by a CZ method with good sensitivity.

CONSTITUTION: A silicon single crystal is subjected to heat treatment for 30 to 300 minutes at 900 to 1050 deg.C in a dry O2 atmosphere, then, is subjected to heat treatment for 30 to 200 minutes at 1100 to 1200 deg.C in a wet O2 atmosphere. After this crystal is treated with a dilute hydrofluoric acid and an oxide film on the surface of the crystal is removed, the crystal is dipped in a seco solution for 1 to 30 minutes to etch selectively the face <100> and lastly, the number of pieces of OSFs, which appear on the silicon single crystal surface, is found by an optical microscope. Accordingly, by this two-stage heat treatment, as a large oxygen deposit in the crystal is turned into the selective OSFs and the OSFs appear on the crystal surface, an inspection of the quality of the silicon single crystal can be carried out with high sensitivity.

In some examples, a method including depositing a plurality of particles on a ceramic or ceramic matrix composite (CMC) substrate to form a barrier coating on the ceramic or CMC substrate, the plurality of particles including a silica-rich rare earth (RE) disilicate material and a second material, wherein the silica-rich RE disilicate material includes excess silica compared to a stoichiometric RE disilicate material, wherein the barrier coating includes a first domain including the silica-rich RE disilicate material and a second phase, the second phase being disposed at grain boundaries, splat boundaries, or both of the barrier coating.

A gas turbine engine component, comprising a substrate containing a ceramic matrix composite material, the ceramic matrix composite material includes at least one environmental barrier coating comprising at least hafnon and hafnium titanate.