Sintered hard metal tools based on tungsten carbide - where high impact resistance is combined with high wear resistance

摘要

Process for mfg. sintered hard metals based on tungsten carbide, by redn. of tungstic oxide in hydrogen to obtain metallic tungsten, which is then carburized at 1800-2400 degrees C to form tungsten carbide which is mixed and milled with a metal binder, then pressed and sintered. The novelty is that the WO3 is first reduced to 750-1300 degrees C. to obtain WO2 which is then reduced at 1000-1600 degrees C to obtain metallic tungsten. Used for mfg. upsetting-, cutting- and boring tools. The tungsten carbide produced by this process possesses high wear resistance combined with high resistance to impact loads, a combination hitherto unobtainable. The plastic deformation of fine and medium grained material (0.5-1.5 mu m and 2-3.5 mu m) is increased two to four times. The improved impact resistance is due to the formation of a complete crystal lattice structure with uniform, small grain size and without irregular inter growth.