The density of carbon carbon composite material can be adjust between 1.3~2.0g/m3,and it can be widely used for any parts of the nozzle. According to the different ablation environment,the middle and high density carbon carbon composite material can be used for the throat part,the low density C/C composite material can be used for the back expansion part and the middle and low density material can be used for the front expansion part and the head. In addition,the screw,pin which are also made from the carbon carbon composite material can be used in the nozzle,and the function is connection.
The carbon carbon composite material nozzle and expansion part was widely used in the SRM since 1990s, multilevel SRM, strategic missile SRM,rocket booster SRM etc.all use the 3D,4D C/C throat.
Carbon carbon composite material is made from the reinforced carbon fiber and carbon matrix,the property of the carbon decides that it can not be made of normal inorganic materials and carbon fiber/ epoxy resin,it needs carbon precursor decomposition then form the matrix carbon to make it. The three basic steps of the technology include:carbon fiber precursor,matrix carbon densifying and high temperature treatment(graphitization). And there are two methods of the densifying,one is liquid phase impregnation(thermosetting resin or pitch),and another one is chemical vapor phase method(CVD with C,H element),and the two methods can also be used together. The technical route:selection of carbon fiber, forming,the densifying of the carbon perform,high temperature treatment and the machining.
The function of carbon fiber is increasing the toughness and bearing load,it decides the strength and the rigidity, the direction of the perform carbon fiber also has an important influence on the property of the carbon carbon composite,even the porosity and the distribution,and the structure of the matrix carbon can influence the velocity of densitying, all the influence can influence the strength property and ablation performance.
