COATINGS AND SURFACE MODIFICATIONS TO MITIGATE SiC CLADDING DURING OPERATION IN LIGHT WATER REACTORS

A composite silicon carbide cladding for use in a light water nuclear reactor, the composite silicon carbide cladding comprising:

• an innermost a silicon carbide ceramic matrix composite (CMC) layer, wherein the silicon carbide CMC layer comprises a silicon matrix and silicon fibers;
• and
• a coating applied to an outer surface of the silicon carbide CMC layer, wherein the coating comprises:
• a first CrN layer applied to the outer surface of the silicon carbide CMC layer, a first chromium layer applied to the first CrN layer, a second CrN layer applied to the first chromium layer, and a second chromium layer applied to the second CrN layer;
• a YSi2 layer applied to the outer surface of the silicon carbide CMC layer;
• a Y2Si2O7 layer applied to the outer surface of the silicon carbide CMC layer;
• a ZrSi2 layer applied to the outer surface of the silicon carbide CMC layer;
• or
• a ZrSiO4 layer applied to the outer surface of the silicon carbide CMC layer.

A method of preparing a composite silicon carbide cladding for use in a light water nuclear reactor, comprising:

• providing a silicon carbide ceramic matrix composite (CMC) substrate, wherein the silicon carbide CMC substrate comprises a silicon matrix and silicon fibers;
• and
• depositing a coating on an outer surface of the silicon carbide CMC substrate, wherein depositing the coating, comprises:
• depositing a first CrN layer on the outer surface of the silicon carbide CMC substrate, depositing a first chromium layer on the CrN layer, depositing a second CrN layer on the first chromium layer, and depositing a second chromium layer on the second CrN layer;
• depositing a YSi2 layer on the outer surface of the silicon carbide CMC substrate;
• or
• depositing a ZrSi2 layer on the outer surface of the silicon carbide CMC substrate.