Corrosion and wear resistant coating on zirconium alloy cladding

Patent metadata

Field	Value
Publication number	US-9844923-B2
Application number	US-201514826524-A
Country	US
Kind code	B2
Filing date	Aug 14, 2015
Priority date	Aug 14, 2015
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

The invention relates to compositions and methods for coating a zirconium alloy cladding of a fuel element for a nuclear water reactor. The composition includes a master alloy including one or more alloying elements selected from chromium, silicon and aluminum, a chemical activator and an inert filler. The alloying element(s) is deposited or are co-deposited on the cladding using a pack cementation process. When the coated zirconium alloy cladding is exposed to and contacted with water in a nuclear reactor, a protective oxide layer can form on the coated surface of the cladding.

First claim

What is claimed is:

1. A method of coating a zirconium alloy substrate for use in a nuclear water reactor, comprising:
obtaining the zirconium alloy substrate having a surface;
combining a master alloy comprising one or more elements selected from the group consisting of chromium, silicon and aluminum, a chemical activator and an inert filler powder to form a coating mixture;
obtaining a chamber having a heating zone and an inert or reducing gas atmosphere;
surrounding the zirconium alloy substrate with the coating mixture in the chamber;
heating the chamber to an elevated temperature;
reacting the master alloy with the chemical activator to form a gaseous compound;
diffusing the gaseous compound to contact the surface of the zirconium alloy substrate;
decomposing the gaseous compound;
depositing the one or more elements of the master alloy on the surface of the zirconium alloy substrate; and
forming a substantially uniform diffusion coating layer thereon comprising zirconium and the one or more elements of the master alloy.

2. The method of claim 1 , wherein the surrounding includes packing the zirconium alloy substrate in a bed of the coating mixture.

3. The method of claim 1 , wherein the diffusion coating layer is formed on one or both of an interior surface and an exterior surface of the zirconium alloy substrate.

4. The method of claim 1 , further comprising:
positioning the zirconium alloy substrate with the substantially uniform diffusion coating layer thereon in a nuclear reactor;
exposing and contacting with water the zirconium alloy substrate with the substantially uniform diffusion coating layer thereon; and
forming a protective oxide layer on the substantially uniform diffusion coating layer, which comprises one or more of the following Cr 2 O 3 , SiO 2 , and Al 2 O 3 when the one or more elements of the master alloy is chromium, silicon and aluminum, respectively.

5. The method of claim 1 , wherein the diffusion coating layer comprises a Zr—Cr phase, a Zr—Si phase and a Zr—Al phase when the one or more elements of the master alloy is chromium, silicon and aluminum, respectively.

6. The method of claim 1 , wherein the heating is conducted at a temperature from 600° C. to 1100° C.

7. The method of claim 1 , wherein the substrate has a thickness from 1 micron to 200 microns.

8. The method of claim 7 , wherein the coated zirconium alloy substrate is subjected to one or more cold working steps to reduce the overall thickness and achieve a final dimension.

9. The method of claim 8 , wherein the cold working comprises pilgering.

10. The method of claim 8 , further comprising intermediate annealing of the coated zirconium alloy substrate to release residual stress in the coating and cladding.

Assignees

• Westinghouse Electric Co Llc

Inventors

• Xu Peng
• Cai Lu

Classifications

• G21C3/20

  with coating on fuel or on inside of casing; with non-active interlayer between casing and active material {with multiple casings or multiple active layers} · CPC title

• G21C21/02

  Manufacture of fuel elements or breeder elements contained in non-active casings · CPC title

• B32B15/01 Primary

  all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)} · CPC title

• G21C17/0225

  Chemical surface treatment, e.g. corrosion (corrosion prevention in presence of water from scale removal or by modification of the properties of the liquid C02F5/00; inhibiting corrosion by adding corrosion inhibitors C23F11/00) · CPC title

• G21C3/06 Primary

  Casings; Jackets · CPC title