Synthesis of Al-Ni coatings by pack cementation and examination of their high temperature oxidation resistance

2019 ◽  
Author(s):  
Kourtidou Dimitra ◽  
Chaliampalias Dimitrios ◽  
Teknetzi Aikaterini ◽  
Karfaridis Dimitrios ◽  
Tarani Evangelia ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Pack Cementation ◽  
Temperature Oxidation

SiC/SiO2 Coating on Matrix Graphite Spheres of HTR Fuel Element Produced by a Two-Step Pack Cementation/High-Temperature Oxidation Process

2016 ◽  
Vol 852 ◽  
pp. 952-958 ◽  
Author(s):  
Ping Zhou ◽  
Zi Qiang Li ◽  
Hong Sheng Zhao ◽  
Kai Hong Zhang ◽  
Xiao Xue Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Reactor Core ◽  
Isothermal Oxidation ◽  
Pack Cementation ◽  
Temperature Oxidation ◽  
Matrix Graphite ◽  
Fuel Elements

Graphite is one of the most important material for the reactor core and fuel elements of high temperature gas-cooled reactor (HTR). Improving the oxidation resistance of graphite is very essential for the research of new fuel elements and the development of HTR. In this study, a gradient SiC layer of 500~700 μm was prepared on matrix graphite spheres by a two-step pack cementation, and the outer SiO2 layer prepared by the high-temperature oxidation process. The phases, microstructure, bonding strength and oxidation resistance of SiC/SiO2 coated matrix graphite spheres were investigated. The SiC/SiO2 coated matrix graphite spheres were carried on rapid thermal shocking tests from 1773 K to room temperature for 50 times without any cracks. The SiC/SiO2 coated matrix graphite spheres exhibits excellent anti-oxidation properties. No obvious weight loss was found after isothermal oxidation in air at 1273 K for 50 h and the weight gain was less than 1% at 1773 K in air for 50 h due to the oxidation of SiC layer.

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