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With the rapid development of modern aviation technology, the research of aircraft brake friction materials is more and more important. During the instantaneous brake,almost all the kinetic energy will transform into heat energy,and emited by the braking material,the temperature of the dics will reach 1000~1500℃. C/C composites is the latest aircraft friction material and their friction and wear properties are very important.Friction and wear properties of C/C composites from different techniques were studied and effects of braking speeds and pressure were also analyzed by most scholars.the optical microscopy,scanning electron microscopy,X-ray diffraction,laser Raman micro-spectroscopy are used to examine the morphology and structure of worn surfaces. Studies showed that C/C composites mainly with rough laminar pyrolytic carbon have small uniform wear debris…
Graphite is an allotrope of carbon, each carbon atom in the peripheral connecting also three carbon atoms (arrangement is multiple hexagon honeycomb) by covalent bonds with the covalent molecule is formed. Since each carbon atom emits an electron, the electrons can move freely, so that the graphite belongs to the conductor.. Graphite is one of the most soft minerals, and its use involves making pencil and lubricant.. Carbon is a non-metallic element, Latin Carbonium. Graphite and its products has high strength, acid resistance, corrosion resistance and high temperature resistant, 30 DEG C and resistance to low temperature - 204 DEG C and other excellent properties, is widely application in metallurgy, chemical industry, petroleum chemical industry, high energy physics, aerospace, electronics…
Low density carbon/graphite material has a good physical and chemical properties, in recent years,the study on the low density graphite material is very active.The expanded graphite block made of flexible graphite sheet,is also one kind of the low density graphite material. The method to make the expanded graphite block can be simply describe as below: Make the flexible graphite sheet dipped in the concentrated sulfuric acid and concentrated nitric acid,then,under the situation of 200℃～750℃ to make the expanded graphite block. The intercalator,dipping time,shape of the flexible graphite sheet and the operating temperature all have an influence on the density and shape integrity of the expanded graphite block. The density will be lower with the rise of operating temperature, but the…
