Zirconium alloy under high temperature and high pressure water in the nuclear reactor environment is easy to react with water vapour Zr + 2H2O + 2 = ZrO2 h2 write, produce hydrogen gas in high temperature environment is easy to cause hydrogen explosion, nuclear safety accident caused by ceramic coating of high strength, high hardness, wear resistance, high temperature resistance, oxidation resistance, corrosion resistance and chemical character such as stable performance can resolve the situation. For example, silicon carbide ceramic coating has high temperature resistance, corrosion resistance and excellent nuclear reactor internal performance. Deposition of SiC coating on the surface of zirconium alloy can effectively isolate water and zircon coated tubes for hydrogen absorption and corrosion in the reactor environment. Wang meiling et al. prepared silicon carbide coating on the surface of zirconium alloy. The coating was closely combined with the substrate, and the interface was free of holes and cracks. The coating particles were fine and uniform.
The improvement of the comprehensive properties of zircon coated tubes depends on the properties of the coating such as high temperature oxidation resistance, corrosion resistance, high temperature structural stability, coating surface density, low porosity, good bonding properties of coating matrix and thermal expansion coefficient matching. Ti 3 SiC2 and Ti 2AlC coatings were prepared on the surface of zirconium alloy and the antioxidation experiments were carried out in 1100~1300 ℃. In the process of high temperature oxidation, the Si and Al elements in the coating interdiffused with the substrate to form zr-si, zr-al and other intermetallic compounds. The bonding strength between the coating and the substrate was significantly improved, and the coating had excellent anti-high temperature oxidation effect. In literature , silicon and chromium coatings were prepared on zirconium alloy surfaces to improve the high-temperature oxidation resistance and corrosion resistance of zircon coated tubes in nuclear reactor environment. SiO2, the glass form formed by silicon element in the coating at high temperature, fills the pores in the coating, increases the bonding strength between the zirconium alloy substrate and the coating, reduces the rate of oxygen and corrosion solution entering the coating, and greatly improves the corrosion resistance of the zirconium alloy.
The addition of a variety of elemental elements can significantly improve the performance of the alloy, which provides an idea for the preparation of composite coatings by adding a variety of elements with large differences in physical properties. The preparation of coatings containing some elemental elements on the surface of zirconium alloys and the in-situ reaction of the coatings is an important method to improve the corrosion resistance of zirconium alloys. Elemental elements are more likely than alloy elements to form stable new phase with zirconium alloy substrate in in-situ reaction. Coating a variety of elements under the condition of high temperature selective oxidation, some elements generate a layer of dense oxide film stop the destructive, oxygen, hydrogen and sulfur elements into the coating and substrate can effectively isolate zirconium alloy under the environment of water corrosion and hydrogen absorption, prolong the service life of the reactor cladding material, at the same time reduce the occurrence of serious accidents, to extend the life of the fuel, increase the security of the core is of great significance.
