| Since their first observation by Iijima in 1991, carbon nanotubes (CNTs) have been the focus of considerable research. Numerous investigators have reported remarkable physical, mechanical and electrochemical properties for them, such as unique electronic properties, high aspect ratio, outstanding thermal conductivity and strength et al. In the nature of things, CNTs are the perfect reinforce to composite materials, which offering tremendous opportunities for the development of mechanical and electronic industry. For the sake of making full use of their favorable properties, much work has been done and study on carbon nanotubes' preparation and application has being become the front-line of carbon nanotubes' research fields. This paper, basing on studying CNTs' preparation technology, researched the composition, morphology, structure and performance of Ni-P-CNTs composite electroless plating. The results show that,The optimum temperature range is from 700℃to 800℃, during the process of the preparations for nickel catalyst, by the reducing gas of ammonia and the raw material of nickel nitrate. While the optimum temperature range is from 600℃to 700℃, during the process of the preparations for nickel catalyst, by the reducing gas of hydrogen and the raw material of nickel nitrate, which is about 100℃lower than that of using the reducing gas of ammonia. The ammonia has double functions of carrier gas and reducing gas. CNTs can be synthesized with one-step method by using of ammonia and acetylene as source gas, which can simplify technology and equipment.The surface of Ni-P-carbon nanotubes (Ni-P-CNTs) electroless composite plating based on copper sheet consists of compact particles. With the increment of carbon nanotubes content in electroless plating solution, the grain size on the sample surface decreases, while the density of grains and the hardness for composite deposit increases. The presence of carbon nanotubes make phosphorous segregation in platings and improves the degree of crystallization for composite deposit helping the plating transform from amorphous state to nanocrystal state.The tensile test of Ni-P-CNTs composite electroless plating on the basis of copper sheet shows that, the maximum extensibility, the reduction of area and the crack density of the fracture side of Ni-P-CNTs composite electroless plating samples increase with the increment of CNTs content, while the tensile strength, the fracture strength and Young's modulus decrease. Adding carbon nanotubes to Ni-P alloys benefits the toughness of Ni-P-CNTs composite electroless to improve, while decreases the combining power between composite plating and copper sheet. The data show that the Young's modulus of Ni-P-CNTs composite electroless platings (Ec), the Young's modulus of Ni-P alloys (Em) and the content of CNTs (mn) fit the formula ofEc=Em(1-Kmn) K is a constant correlated with interface conditions in it. It's 3.3781 in this paper.It's thinked that interface conditions should be considered in the strength formula of composite materials. What's more, interface strength factor is put forward at the first time and the strength formula for composite materials consisting of three dimensional random distribution fibre and matrix is modified, asσc=1/4Kσf(1-Lc/2L)Vf+σm*Vm Lc≤Lσc=K1τL/4dVf+σmVm Lc＞L K and K1 are interface strength factors. If K or K1 is greater than zero, fibre can act as reinforcing materials. If K or K1 is less than zero, fibre cannot act as reinforcing materials and weaken the matrix strength.The stress and strain distribution under the condition of simple tension were analysed by finite element method. The results show that whenever the interface is under the condition of mechanical bonding or physical or chemical bonding, the biggest stress is at the end of CNTs and the biggest strain is in the martrix who connect with the end of CNTs among the cells. The placement azimuth, the length and the diameter of CNTs combining with the interface strength influence the stress and strain distribution. If the array CNTs is under the condition of simple tension, the ends of the outer CNTs and the matrix who connects with the CNTs ends have the biggest stress among the cells, while the biggest strain is in the interface or matrix, which connects with the CNTs ends. The external force influences the outer CNTs of array CNTs much more than the inner ones.The study of quantum chemistry method to the interface of Ni-P-CNTs electroless composite plating shows that, during the process of electroless plating, nickel and phosphorus can combine with carbon nanotubes, which makes the energy of whole system decrease, or to say there's some bonding power between nickel and carbon as well as phosphorus and carbon, and the energy decrease of nickel and carbon combining is bigger than that of phosphorus and carbon. It's easier for Phosphorus to enrich around carbon nanotubes than for nickel, resulting in Phosphorus segregation about carbon nanotubes. The bond energy of phosphorus and carbon is greater than that of nickel and carbon.In all models of particles and carbon nanotube what have been studied, the system energy decreases most while nickel and phosphorus combines with carbon nanotubes at the collapse indication, which is the strong bonding point at the interface of Ni-P alloy, and the corresponding bond energy is largest. The combination between the perfect parts of carbon nanotubes and nickel is weak, while that between the perfect ones and phosphorus is strong. It's obviously that the interface formed by Ni-P and carbon nanotubes is biatomic, one side of it are carbon atoms and the other side are nickel atoms or phosphorus atoms. The property of phosphorus carbon bonds is covalent bond, while some of the nickel carbon bonds represent van der waals bond property partly.
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