Study On Direct Selective Laser Sintering Of Ni-Based Metallic Powder And Key Technologies

Rapid Prototyping (RP) technology is a new subject that was developed in 1990s. It is a integration of CAD, CNC, Laser technology and the science of new materials. The most remarkable distinguish between RP and conventional manufacturing technology is its layer-wise manufacturing concept and its integrated design & producing fashion from the concept design, the prototyping to the forming of products. After ten years development, RP technology is changed from rapid prototyping to rapid production. Such change shows that RP technology is becoming more and more ripe.As an important branch of RP, Selective Laser Sintering (SLS) was cared greatly by many researchers of manufacturing for its'uses of metal, polyer, ceramic and other powder in the sintering. In this paper, a series of experiments are carried out with SLS for copper-nickel powder materials. Some creative works and conclusive remarks are as following:(1) Ni-based metal powder is directly sintered by powerful laser to form parts. Firstly, the characteristics of sintering process are discussed in details. Secondly, the sintering model is built. Lastly, a method of changing the shape of molten pool is presented to guarantee the required forming of parts. All those above lay the foundations for the forming metal parts by laser sintering metallic powder.(2) The characteristic of the solidification microstructure is studied. The nucleation mechanism and the feature of the morphology of microstructure are analyzed in details. By means of SEM with energy spectrum system, it is proved that sintering parts is composed of many layers, one on another. Each layer consists of a number of sintering line. And each sintering line is composed of two kinds of dendriter and equivalent dendriter.(3) Through a series of the sintering experiments of copper-nickel powder material, it is made clear that which process parameters affects the quality of sintering parts and how they affect. And some required-shape parts with certain mechanical strength are sintered successfully.(4) Because there are many problems in direct Ni-based powder laser sintering, the concept of developing the special SLS powder is put forward and Ni-based special SLS powder is developed. With some experiments, the phenomena of splashing, forming sphere and node is avoided. The same thickness and the same width of sintering line gotten are obtained successfully.