The invention relates to a method for preparing nanometer tantalum carbide dispersion-strengthened tungsten bulk material, which is a method combining cold isostatic pressing and ultra-high pressure electrification sintering. In particular, the cold isostatic press-preforming is carried out before sintering, so that the billet has a higher forming density before sintering, and the ultra-high pressure electric-powered sintering also provides a higher sintering pressure, which is conducive to the preparation of high density tungsten block materials.
The preparation method has the characteristics of easy operation and simple process. The obtained tungsten block material has high density, high hardness and high bending strength. The corresponding performance test of the product, the density is determined by drainage method; The microhardness was measured by MH-6 microhardness tester. The bending strength was measured by three point bending method. The section morphology of sintered tungsten block was observed by SEM. Through the test, the highest relative density of the product can reach 99.48%, the highest hardness is 923.92HV0.1/10, and the highest bending strength is 892MPa.
Sintered tungsten bulk material with 0.5% nano-TAC content is prepared. In this embodiment, nano-TAC powder is prepared by liquid precursor method. The preparation process of nano-TAC is as follows: 1g of TaCl5 and 10mL of anhydrous ethanol were ultrasonically oscillated at 50℃ to produce tantalum ethanol, and then nano carbon powder was added and held in a vacuum atmosphere at 1300℃ for 30min to prepare nano TaC powder. Put 0.2g nano TaC and 39.8g tungsten powder into the ball mill tank, and then put 200g of φ8×10 pure tungsten rod as the grinding ball. The ball mill tank is placed on the horizontal ball mill for ball grinding mixture. The ball grinding process is as follows: the ball grinding speed is 150r/min, the ball material ratio is 5:1 (mass ratio), and the ball grinding time is 6 hours. The mixed powder was put into the PVC envelope, and the cold isostatic pressing was carried out at a pressure of 200MPa for 15min. The molded body is put into the graphite mold, and then the body and the graphite mold are put into the pyrophyllite envelope for ultra-high pressure electrification sintering. The process of ultra-high pressure electrification sintering is as follows: the sintering pressure is 1.2GPa, the electrification power is 1800W, and the sintering time is 20min.
The density, hardness, bending strength and SEM morphology of the tungsten block were tested. FIG. 1 (a) is the SEM image of the fracture morphology, from which it can be seen that there is almost no obturator in sintered tungsten. The measured density is 18.619g/cm3 and the relative density is 96.57%. The microhardness is 786.24HV0.1/10; The bending strength is 837.7MPa.
