Research On The Cavitation Erosion Behaviors Of Nano-SiO₂ And Glass Microballoon Filled UHMWPE Composites

Cavitation is an ancient and complex problem existed in hydraulic machinery. In southwest of China, The rivers flowing through karst topography with high velocity flow, generate many air bubbles. Cavitation erosion wear is serious when hydraulic machineries running on the region of the river. To resolve the problem, the principal way of doing that is through research and development of new cavitation resistance materials.In this paper, a kind of ultra-high molecular weight polyethylene (UHMWPE) composites filled with nano-SiO₂ and glass microballoon is designed. The composites synthesized by sintering and compaction. Some properties such as hardness, impact toughness, elastic and tribology are measured. The cavitation erosion and cavitation mechanism of composites are studied. Finally, the correlations of the cavitation erosion rate with composite properties are analyzed.The main conclusions are as follows.1. Modified nano-SiO₂ and glass microballoon have favorable dispersibility in the matrix of UHMWPE. It is found that the hardness increased and the high impact toughness and elastic properties remained with the composites filled with nano-SiO₂ and glass microballoon. The results also showed that this kind of composites has excellent wear resistance, the main wear mechanisms were adhesion and fatigue.2. Compared with pure UHMWPE, the composites have good cavitation resistance properties. The erosion rate of the composites filled with 4% nanometer SiO₂ and 6% glass microballoon is twice the pure UHMWPE. This may be attributed to the fact that the propagation of cavitation crack is stoped and dulled when it meet the fillers. And, the fillers can improve the thermal conductive capability of composites. Therefore, when some of the impact energy is converted into heat, maybe a great part of the heat is carried off by means of fillers.3. The cavitation mechanism of composites filled with nano-SiO₂ and glass microballoon is confirmed that the plastic deformation and cavitation pinholes are formed with the shock waves or micro-liquid jet produced by bubble collapse. The cavitation damage is the results of initiation and growth of fatigue cracks. 4. The cavitation erosion resistance of composites is closely related to their mechanical properties and concern into the index. By fitting, the index of hardness is between 1.2 and 2.3, the index of impact toughness is between 0.2 and 0.3, and the index of reciprocal of elastic modulus is between 1 and 2. In other words, the cavitation rate of compositesis is proportional to hardness, impact toughness, and the reciprocal of elastic modulus.