Research status of SPS Technology
Powder metallurgy technology has a series of advantages, such as short process, energy saving, low cost, less processing and so on. It can freely assemble the material structure and accurately control the material performance. It is an important development direction of green manufacturing technology. The spark plasma sintering technology has the advantages of high speed, low temperature, energy saving, environmental protection, simple operation and excellent product performance, which is widely used in metals, ceramics, cemented carbide, functionally gradient materials and other aspects, and is one of the most concerned new preparation technologies and processes.
SPS technology is a rapid prototyping preparation method, which is directly connected by pulse current between the mold and powder particles or bulk samples. It is a new rapid sintering technology which has been studied since 1990s. Compared to traditional hot pressing sintering technology, besides the official account of Joule heating and plastic deformation caused by pressure to promote sintering, the DC pulse voltage generated by special power is applied to compacted powder samples, which will produce a unique phenomenon of promoting sintering.
SPS device mainly includes pressure system, vacuum system, water cooling system, temperature measurement system, power supply and control system. Due to the unique technology and obvious process advantages of SPS, since the introduction of SPS equipment for research and development of new materials and industrial production in Japan in 1990, SPS technology and equipment have developed by leaps and bounds, opening up a new field of manufacturing industry.
The experimental equipment developed and produced by our company can process samples with a diameter of 300 mm, the pressure can reach 5t-400 T, and the maximum output current is 3000 a-48000 a. the equipment has strong versatility, and can meet the use requirements from R & D stage to product trial stage.
Figure 1. SPS spark plasma sintering equipment produced by Shanghai Haoyue Electric Furnace Technology Co., Ltd
Development trend of SPS Technology
Compared with the traditional sintering method, SPS technology has obvious advantages in saving energy and time, improving production efficiency, controllable product performance and many other aspects. At present, Japan has realized the industrial application of SPS, which is mainly used for the production of magnetic materials, cemented carbide, functionally gradient materials and so on. For example, Japan's Taida precision has achieved the SPS mass production of 100% WC superhard materials, and the products are provided to more than 40 manufacturers of motors, electronic parts, tools, molds, etc. at home and abroad. However, SPS technology is still in the stage of laboratory research in China, which is mostly used in the preparation of new materials and technology research.
2. The shape of sinter is various
Due to the limitation of sintering mechanism and graphite mold, the sample prepared by SPS is mainly simple cylinder, which is difficult to prepare complex shape workpiece and can not meet the needs of practical engineering.
Figure 2. Common graphite mold
3. Performance optimization of sintering die
Graphite has been used as a common mold material for SPS due to its high temperature resistance, excellent electrical and thermal conductivity, chemical stability, thermal shock resistance, good lubrication and wear resistance. However, graphite materials have low strength, short service life and are easy to pollute sintered materials. At present, cemented carbide mold, conductive ceramic mold, carbon fiber graphite mold and so on have been reported, but there are some problems such as high temperature deformation and high price. Therefore, in order to make better use of SPS technology, it is necessary to further develop new mold materials with higher strength, high reuse rate and no pollution.
4. Further development combined with finite element simulation
Due to the special working environment of SPS, the general methods can not accurately analyze the sintering process, forming mechanism, influencing factors and other aspects, and there are some errors in obtaining the temperature, displacement and other parameters in the sintering process, so the finite element simulation has become one of the new research methods of SPS. At present, it has been reported that through ABAQUS, MATLAB and MSC.MARC The temperature field and electric field distribution in the sintering process can be obtained by the simulation of the sintering process, and the specific influence of various sintering parameters on the sintering process can be analyzed, which is of great significance for the further study of SPS sintering mechanism, the early prediction of experimental results, and the theoretical guidance of production.
Since its appearance, spark plasma sintering technology has been developed rapidly because of its low temperature, short time and high efficiency. Important achievements have been made in the preparation of refractory metals, cemented carbide, ceramic materials, high thermal conductivity materials and other fields. However, the sintering mechanism of the intermediate process is still controversial, which needs a lot of experiments and theoretical research to improve, and needs further exploration in mold, technology and other aspects. Shanghai Haoyue Technology Co., Ltd. has been focusing on the four industries of semiconductor materials, carbon materials, advanced ceramics and composite materials and lithium battery materials. With rich industry experience and professional technology, we are dedicated to serving customers and providing perfect integrated industrial solutions.