Coating for refractory alloy part

Patent metadata

Field	Value
Publication number	US-11542586-B2
Application number	US-201917265835-A
Country	US
Kind code	B2
Filing date	Aug 7, 2019
Priority date	Aug 7, 2018
Publication date	Jan 3, 2023
Grant date	Jan 3, 2023

Abstract

A process for coating a part by chemical vapor diffusion is provided and includes placing a powder mixture in a chamber, immersing the part partially in the powder mixture, and applying a heat treatment to the part. The powder mixture includes a first component and a second component forming a gaseous compound during the heat treatment so as to allow deposition of the second component on the part. The part includes a metal refractory allow and the second component forms a solid diffusion alloy by solid diffusion with a metal species of the refractory metal alloy to generate a coating. The solid diffusion allow generates a passivating oxide layer when subjected to oxidizing conditions.

First claim

The invention claimed is:

1. A process comprising:
coating a part by chemical vapor diffusion;
placing a powder mixture in a chamber,
the powder mixture comprising at least one first component, at least one second component and an inert component;
the powder mixture including a mass proportion comprised between 6 and 8% of the first component and between 8 and 12% of the second component;

the first component comprising at least one halide species selected from NH4Cl, NH4F, AlCl3, CrCl2;
the second component comprising at least one species selected from silicon, aluminum, iron, copper, cobalt, nickel, lanthanum, germanium, zirconium, chromium, titanium, hafnium, rhenium and a mixture thereof;
immersing the part at least partially in the powder mixture,
the part comprising a metal refractory alloy,
the metal refractory alloy comprising molybdenum; and

heat treating the part, the first component and the second component forming a gaseous compound during the heat treating step so as to allow deposition of the second component on the part;
the second component forming a solid diffusion alloy by solid diffusion with at least one metal species of the metal refractory alloy so as to generate a coating;
the solid diffusion alloy generating a passivating oxide layer when subjected to oxidizing conditions;
wherein the process produces a coating on the part, the coating comprising a plurality of superimposed layers;
the superimposed layers comprising:
a first layer having a thickness comprised between 0.1 μm and 30 μm, a molar fraction of the second component in the first layer being comprised between 0 and 50%,
a second layer covering the first layer and having a thickness comprised between 1 μm and 50 μm, the second layer having a molar fraction of the second component less than 2%;
a third layer covering the second layer and having a thickness comprised between 0.5 μm and 50 μm, the third layer having a molar fraction of the second component comprised between 60 and 70%.

2. The process as claimed in claim 1 , wherein the powder mixture includes a mass proportion comprised between 1 and 20% of the second component and a mass proportion comprised between 1 and 10% of the first component based on the total mass of the powder mixture.

3. The process as claimed in claim 1 , wherein:
the second component is a mixture of a silicon powder and an aluminum powder, and
the first component is ammonium chloride.

4. The process as claimed in claim 1 , wherein the powder mixture further includes a mass proportion comprised between 80 and 86% of an inert component.

5. The process as claimed in claim 4 , wherein the powder mixture comprises between 82 and 84% by mass of inert component.

6. The process as claimed in claim 4 wherein the inert component is an alumina powder.

7. The process as claimed in claim 1 , wherein the powder mixture comprises:
a mass proportion comprised between 6 and 8% of the first component,
a mass proportion comprised between 8 and 12% of the second component, the second component being a mixture of aluminum and silicon powder, and
a mass proportion of inert component comprised between 80% and 86%, the inert component comprising one refractory mineral oxide powder or a combination of refractory mineral oxide powders.

Assignees

• Commissariat Energie Atomique
• Safran

Inventors

• Bechelany Mirna
• Jaquet Virginie
• Saboundji Amar
• Soulier Mathieu
• Boidot Mathieu
• Laucournet Richard

Classifications

• C23C28/023

  only coatings of metal elements only · CPC title

• C23C28/02

  only coatings {only including layers} of metallic material · CPC title

• C23C10/34 Primary

  Embedding in a powder mixture, i.e. pack cementation · CPC title

• C23C10/28

  using solids, e.g. powders, pastes · CPC title

• C23C28/021

  including at least one metal alloy layer · CPC title