Research of Co in high performance cemented carbide produced from In-situ synthesis WC-6Co composite powder

Put the in-situ synthesis WC-6Co composite powder into 300 L rolling ball mill with the rotation speed of 50 Hz to carry out wet milling. Add Co powder, grain size growth inhibitor, paraffin, alcohol, and perform wet milling for 48 h, discharge and sieve by mesh with diameter of 45 μm. After Using closed pressure type spray drying tower to produce WC-7Co to WC-15Co mixture powder and analyzing the morphology, grain size distribution, phase and constituent, it is found that when the Co in WC-Co mixture exceeds 10%, it has more powder agglomerate, and the agglomeration size is larger. With the increasing of Co powder, the oxygen also increase while the apparent density is decreasing. Then produce ultra-fine size YG7X to YG15X ultra-fine cemented carbide through adding forming agent to the prepared WC-7Co ~ WC-15Co mixture powder, pressing, low pressure sintering and etc. In the YG7X~YG15 Xultra-fine cemented carbide prepared by WC-6Co composite powder with different content of Co, research the influence of different Co content to the Metallographic, morphology, physic and mechanic properties. The results show that with the Co content increasing, the hardness and density of produced ultra-fine size cemented carbide are decreasing, while the bending strength and fracture toughness are increasing at first then decreasing. The ultra-fine size YG7 cemented carbide maximum HV30 hardness is 2 150, the minimum bending strength is 3 200 MPa. The ultra-fine size YG10 cemented carbide maximum bending strength is 4 950 MPa, and the maximum fracture toughness is 11.8 MPa·m^1/2.