Compared with traditional metal elements such as iron, copper and nickel, zirconium has a lower density and a smaller coefficient of thermal expansion. In addition, zirconium also has a low thermal neutron absorption cross-sectional area (only 0.18×10-28 m2) and good corrosion resistance, which makes zirconium and its alloys have a very wide range of application prospects in the nuclear industry, aerospace and other special fields. At present, zirconium and its alloys have been widely used as cladding materials in nuclear reactors. Compared with stainless steel, zirconium and its alloys effectively reflect neutrons back inside the reactor, greatly saving uranium fuel; The zirconium alloy has good corrosion resistance in 300~400 ℃ high temperature and high pressure water vapor, which also enables the reactor to have a long service life. Therefore, the metallic element zirconium is known as the first metal of the atomic age. With the continuous development of China's aerospace, navigation and chemical industry, alloy steel and other traditional materials are increasingly unable to adapt to the special environment such as space and ocean. In recent years, many scientists at home and abroad have turned to aluminum matrix composites and light metal materials such as titanium alloy and zirconium alloy.
At present, zirconium has been widely used as a corrosion resistant material in the chemical industry, and has been widely applied in the fields of heat exchange, dike washing tower, reactor, pump, valve and corrosive medium pipeline. For example, enrichment and hydrolysis tubes made from zirconium alloys have been successfully used in hydrogen peroxide production lines, while components such as zirconium pressure-reducing valves, agitators and flow meters are also used in fertilizer production, wastewater treatment and the dye industry. Corrosion resistance zirconium alloys are mainly Zr702, Zr704, Zr705 and Zr706 alloys. The composition of Zr702 alloy is close to pure zirconium, mainly adding a small amount of O, H and N elements, which has high corrosion resistance but low mechanical properties, and is used as a chemical pipeline in sulfuric acid medium containing FeCl3. Zr705 alloy is zirconium niobium alloy, and its mechanical properties are twice that of Zr702 alloy. Zr705 alloy is usually used as raw materials for chemical equipment with high requirements on strength and elongation, such as fence type heat exchanger.
Biomedical material is a new kind of high technology material in recent years. Biomedical alloy must have good compatibility with biological humoral environment and good corrosion resistance. Ti6Al4V alloy is a titanium alloy implanted in human hard tissue earlier, but its elastic modulus close to 110 GPa is far beyond the elastic modulus of 15~30 GPa of human natural skeleton. In the early 1990s, Smith & Nephew Richards developed an alloy called ZrTiNb, which not only has an elastic modulus similar to that of human bones, but also has an elastic modulus similar to that of human bones. Williams et al. also confirmed that the degradation degree of ZrTiNb alloy is significantly lower than that of Ti6Al4V alloy under the combined action of corrosion and friction and wear. Subsequently, a series of zirconium alloys for medical use were developed.
