Preparation Of Aramid Fiber Composite Materials And Lead-based Surface Metallization

The nuclear shielding material that is of structure and function is important guarantee of promoting the development of nuclear energy of our country.Lead has an excellent shielding ability because of strong absorption and scattering property for radioactive rays of α, β,γ,χ. However, the strength of the lead is so low that it cannot be used as the engineering structures material. So, in this paper,the kevlar fiber with high elastic modulus and toughness, high temperature resistant, acid and alkali resistant, low density and good thermal stability was used to change the property of lead,wich makes lead be of high toughness as well as high strength. Because Kevlar fiber is a molecular structure of high crystallization and orientation, its wetting quality is bad and surface lattice is compact with less active point, which leading to weak interface binding energy between kevlar fiber and metallic matrix. Therefore, the study on changing the property of kevlar fiber is necessary for increasing the bonding strength between the KF and matrix to realise the purpose that the property of lead is promoted.In this paper, the surface metallization of kevlar fiber is realized by means of chemical plating. The KF/Pb composites is prepared by pressure casting, and KF/Pb composites bar is obtained by extruding KF/Pb. Simultaneously, the pressure impregnation process and extrusion process are researched, and the hardness and three-point bending of KF/Pb composites material bar were tested. The study was showed that:1Plating Ni, Cu and Ni/Cu on kevlar fiber was done by chemical plating. The surface morphology, phase structure, content and binding force are researched.it is known that the character of coatings obtained by plating Ni on kevlar fiber is rather good.2The plating solution compositions and operating conditions of liquid needed in chemical plating process are analyzed by orthogonal test and single variable method, then getting the best formula of liquid needed in chemical plating and operating condition.3The casting blanks of the KF/Pb composite material were prepared by pressure impregnation. By analyzing the process condition, the best process parameters were acquired,which are listed as follow:impregnation pressure is0.60-0.65MPa, preheating temperature of mould and preform is110℃-120℃, temperature of lead liquid is about400℃, impregnation time is60s.4KF/Pb composites bar is obtained by the process of extrusion. The process also is analysed in detail. The results are shown that because of bearing extrusion and shear force leading to breakage and slippage in the process of extrusion, the fiber distribution is not uniform. In the tip of KF/Pb composites bar, the scoring and exfoliation of fiber is serious. Middle section of extrusion bar is complete relatively.5The anti-bending properties of extrusion bar are tested by three-point bending method. The results can be shown that the anti-bending properties of KF/Pb composite material with KF processed by chemical plating is much better than that with KF not processed by chemical plating. So, It can enhance the bonding force between Kevlar fiber and metal by surface metallization, leading to fine effect of strengthening and toughening.