Study on carbon fiber surface treatment based on surface oxidation method
Surface conditions of carbon fibers severely effect on the bonding strength between the fibers and the matrix, even on the mechanical properties of the composites when carbon fibers were used as reinforcement on the preparation of ceramic matrix composites. Surface treatment of carbon fibers was carried out based on the air oxidation method and the liquid oxidation method with concentrated nitric acid (68%) as the oxidizing solution. It could remove impurities from the surface of carbon fibers and increase the degree of the surface concavoconvex, so the active surface area were increased and then improved the bonding strength between fibers and matrix. The surface topographies of carbon fibers after surface oxidation were characterized by SEM. The results illustrate that, impurities on the surface of carbon fibers are decreased and there are many longitudinal grooves evenly distributed on the surface in favor of increasing the bonding strength between the fibers and matrix.
Surface Treatment of Carbon Fiber for Composites
The carbon fiber and its composites have many excellent performances,such as the high specific strength,the high specific modulus,the heat endurance,anti-corrosion,anti-fatigue,anti-creep etc.It is very important to treat the surface of carbon fibre for making use of its performances.This thesis summarizes several approaches of surface treatment of carbon fibre,for example,gas oxidation,electrolysis oxidation,liquid oxidation, plasma oxidation,electro-polymerization,vapor deposition,electroplating,and compares the influences of different surface treatment methods on the fiber's structure and properties.The surface treatment of carbon fiber is an important measure that makes use of its performances.The surface treatment of carbon fiber is different for making use of requirement.By comparing several treatment approaches,it can be concluded that: ozone oxidation,anode electrolysis oxidation and plasma oxidation are widely used now.
Worn surface characteristics of Cu-based powder metallurgy bake materials for aircraft
Abstract Cu-based powder metallurgy brake materials are used for aircraft widely and successfully. The characteristics of worn surface of Cu-based powder metallurgy brake materials for aircraft after working under service condition were studied, and two main wear mechanisms were discussed. The results show that the main components of worn surface are graphite. SiO 2 , Fe, Cu and oxide of Fe (Fe 3 O 4 and FeO); the worn surface can be divided into three zones: severe wear zone, mild wear zone, and low wear zone; fatigue wear and grain wear are the main wear mechanisms of Cu-based materials. Some debris kept between brake discs reduce the wear rate to a certain extent by taking part in the regeneration of friction film.