| Lanthanum hexaboride (LaB6) is widely used in modern technology as an excellent thermionic electron emission source. In this paper, La and LaH2 nanopowder were prepared by hydrogen arc plasma method, and then La, LaH2 and B nanopowders were sintered by SPS (Spark Plasma Sintering) in situ, Oxygen free system, High pure LaB6 polycrystal crystal nano bulk with {100} fiber texture were fabricated by SPS, This LaB6 nano-bulk has an excellent property. The microstructure of nano bulk was investigated systematically. Many kinds of properties of the LaB6, such as mechanical, physical and emitting property etc were measured, the relationship between properties and microstructure were studied, furthmore, the precessing parameter of SPS were studied in order to get the best craft of SPS. Hydrogen arc plasma method was used to prepare La and LaH2 nanopowder, The productive rate of preparation of La and LaH2 nanopowder is 100 g/ h when the electric voltage was 30 volt and the current is or about 100 A. The particle sizes of La, LaH2 powders are about 20 nm. The DSC and vacuum annealing treating show that LaH2 particle will dehydrogenate at 796.4℃.The reactive eqution of preparation of LaB6 by SPS is that:①LaH2============ La+H2②La+6 B========= LaB6The best parameter using SPS to prepare LaB6 block has been got after systematic studying, by studying the mechanics of SPS preparating LaB6, it has been found that the sintering process can be divided into three parts. XRF, XRD, TEM, SEM and AFM were used to analysis microstructures of LaB6 nano blocks. The results show that blocks have high purity of 99.665%.The grains were equiax crystal, the average crystal sizes were from 60 to 200nm, and the crystal grains grew up with the increment of singtering temperature. It was find that, the main parameters which effect the phase components were sintering temperature and pressures of SPS. Two kinds of block which did not form pure LaB6 phase were studied and found that these transitions were caused by the uneven distribute of temperature or pressure in the sample and die.The relative densities of nano-bulk LaB6 reached 96.5%～99.2% , and the density increased 1300℃796.4℃ with the increment of sintering temperature. The hardness was 13.4-17.4 GPA, and it also increased with the increasing of temperature.The bend strength of the LaB6 were as high as around 219-245.6 MPa, very close to the theoretical value of single crastal which is 200-250 MPa.The electric resistance rate of the sample increased with the increasing of temperature. Electron emitting density of one sample which implied 2.5% extraneous component Cu was measured, the result is 1.03A/cm2, The existence of Cu reduced the electron emitting density of LaB6, but it is also very high compared with the comercial polycrystal LaB6 prepared by other sintering method. The electron emitting density of such polycrystal LaB6 block is or under about 1.5×10-1A/cm2. The LaB6 nano block cathode has been applied in a domestic electro-beam wekler machine of a business enterprise and got a good result. The contrast experiment in Ukraine shows that the properties have reached the foreign advanced level.Texture analysis reveals that the prepared LaB6 blocks have {100} < uvw> fiber texture which is benifical to develop its electron emitting property.In conclude, the LaB6 nano block prepared by SPS is better than the products prepareted by common sintering methods in many ways, such as relative density, pure degree, mechanics intensity and electronic emitting property. And it can be sintered at low tempereature and with short time and hence to save energy.
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