China is the world's largest developing country, rich in water resources. The hydropower generation capacity is 380 million kw, and the annual generation capacity is 1.9 trillion kw.h, equivalent to 1.1 billion tons of raw coal.However, one of the characteristics of China's rivers is the large sediment content. There are 42 rivers with an average annual sediment content of more than 140,000 tons. Therefore, the problem of abrasion of turbine flow components, especially blade, is very prominent in China. It is estimated that in the hydropower station in operation, about 1/5 ~ 1/4 of the turbine blades suffer from different degrees of sediment damage, each year because the turbine flow components (mainly blades) abrasion damage and outage or maintenance caused by the power loss of about 2 ~ 3 billion kw.h, the annual consumption of inspection and maintenance costs and equipment update costs of up to 10 million yuan (Rodriguez Felix et al. 2017, Rodeiro-Guerra et al. 2017).
At present, the main types of turbine in hydropower station are: mixed flow turbine, axial flow turbine, tubular turbine and impact-water turbine. However, for large and medium-sized turbines, the majority is of mixed flow type (Preecha and Wianwiwat 2017, Navratil et al. 2017, Kongkapisuth et al. 2017). After running for a period of time, the runner, blade, lower crown and upper ring are mainly damaged by fish-scale pits, pinholes, pitting,honeycomb cavities, corrugated scratches and grooves, etc., which are often damaged differently in waters with different sediment contents (Nakajima et al. 2018, Suroglu 2018). For example, pinholes, pitting points and honeycomb cavities caused by cavitation and corrosion are often found in the Yangtze river and other waters with less sand. In the Yellow River with high sand content, ripples and grooves are often found (Crawford et al. 2018,Bhanja et al. 2018). The main hazards caused by sand abrasion can be divided into: (1) it reduces the unit efficiency of the power station and reduces the annual power generation; (2) shorten the overhaul interval and increase the cost of repair; (3) in the case of severe abrasion, if the maintenance is not timely, or even cause safety hazards, endangering the safety of the entire unit. Therefore, how to solve the problems of abrasion, cavitation and corrosion suffered by hydroturbine unit has become a key subject of safe and economic operation of hydropower in China.
Wei Han, Yong He, Chuanting Wang, Cheng Ji, Yuan He, Zhiping Guo published an article in the journal Ekoloji Issue 107, 2019, entitled: “Experimental Study on the Damage Ability of Reactive Fragments could Fabricated by Zr -- based Metallic Glass (An Environment Perspective)”.In this paper, quasi-sealed chamber test and multi-layer target test were used to evaluate the damage capacity of Zr funded glass fragments. The results showed that ZrCuNiAl metallic glass would have a violent chemical reaction after hitting the target material, releasing a large amount of chemical energy and causing obvious overpressure in the chamber. Impact velocity plays an important role in ZrCuNiAl reaction efficiency. BMG fragments cause more serious damage to the multilayered target than steel fragments. It demonstrates the potential of BMG for lightweight armor fragment applications. On the basis of this paper, the wear resistance of heterogeneous metallic materials was tested.
