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(1) Kuchino Mo-Si powder, etc. in accordance with the atomic ratio of 1:2 were mixed, put into a graphite mold, graphite mold 6 Pa into the vacuum chamber, subjected to a mold pressure of 40 MPa, the powder is then fed to the pulse current to 0.17 ℃ / s temperature was raised to the maximum sintering temperature is 1 400 ℃, maintained in situ synthesis of 600 s 99% of the density of the material MoSi2, MoSi2 containing dense very small amount of SiO2. MoSi2 powder used as raw material, using the same technology is also synthesized material density of 99%, the synthetic material in the accelerated oxidation region (400 ~ 700 ℃) has good resistance to oxidation. 

 

(2) prepared by the SHS process Shimizu et a MoSi2 powder, and then at 1 254 ℃, under the pressure of 30 MPa for 10 min SPS sintering apparatus, the prepared density reaches 97.3%, the grain size is 7.5μm, Vickers hardness of 10.6 GPa, fracture toughness KIC of 4.5 MPa · m1 / 2, the bending strength of 560 MPa material. At 1 000 ℃, MoSi2 strength can be maintained at about 325 MPa. 

 

(3) Krakhmalev of raw materials such as high-energy ball milling the powder first, then use SPS sintering, were given a C40 structure Mo (Si0.75Al0.25) 2, Mo (Si0.75Al0.25) 2/SiC, Mo (Si0 .75 Al0.25) 2/0, 10,20,30% (volume fraction) Al2O3 and Mo (Si0.75Al0.25) 2/ZrO2 composites. Hardness Mo (Si0.75Al0.25) 2 as the base material 14 GPa, a fracture toughness of about indentation 1.84Mpa.m1 / 2, to cleavage fracture based materials. Add 20% did not improve the hardness of the SiC material, the fracture toughness can be increased to 2.48 MPa · m1 / 2, there intergranular fracture surface characteristics; When the Al2O3 content is less than 20%, the hardness of the material and the pressure marks not significantly improved fracture toughness and fracture of materials with cleavage-based, and the hardness of the composite material containing 30% Al2O3 decreases to 10.2 GPa, fracture toughness increased to 3.67 MPa · m1 / 2, the fracture surface showed significant intergranular characteristics. Found Mo, Mo5Si3, Al2O3 and Mo0.34Zr0.20Si0.46 in Mo (Si0.75Al0.25) 2/ZrO2 composite, i.e. Mo (Si, Zr) 2 phase, the material hardness is probably about 14 GPa, indentation fracture toughness of 2.69 ~ 2.94 MPa · m1 / 2, and Mo (Si0.75Al0.25) 2 compared to the fracture toughness increased by 50% in the synthesis may occur during the Zr substitution Mo (Si, Al) Al 2 reaction: 

AlMo (Si, Al) 2 + ZrO2 = ZrMo (Si, Zr) 2 + Al2O3 

 

Spark plasma sintering  is a relatively new technology, it can be seen from the above studies of this process can be obtained relatively dense matrix composite material and can be prepared, in this process has not yet been prepared MoSi2 widely Therefore, to improve the performance of the material is not very obvious. However, compared to other preparation methods, the performance of pure MoSi2 have relatively large increase. Because of its high density, low temperature can at least prevent MoSi2 "Pesting" phenomenon, so this process should be the next big development. 

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