Preparation And Wear Properties Of Diamond-WC-Co Mining Cemented Carbide

The complex,severe and changeable service environment of mining cemented carbide makes alloy tools produce various forms of wear,which puts forward more stringent requirements for the properties of WC-Co mining cemented carbide.Enhancing the toughness and wear resistance of mining cemented carbide is of great significance in improving mining efficiency and reducing resource cost waste.Due to its high hardness and low wear rate,diamond is a potential reinforcing phase for WC-Co alloys.This topic selects diamond reinforced WC-Co mining cemented carbide as the research object,and takes improving the fracture toughness and wear resistance of the alloy tools as the research goal.The diamond reinforced WC-Co mining cemented carbide was prepared by SPS sintering technology.The thermal stability of diamond becomes poor during the sintering process,and it is easy to transform into graphite,and Co will accelerate the process,which will deteriorate the properties of Diamond-WC-Co mining cemented carbide.Sintering temperature,Co content,type of diamond surface coating and diamond content are all influencing factors of diamond phase transformation.The relationship between the above factors on the microstructure,diamond graphitization transformation,hardness,fracture toughness and wear resistance of mining cemented carbide was systematically studied by means of XRD,Raman spectroscopy,SEM and wear testing machine.Provide the basis for the development of Diamond-WC-Co cemented carbide for mining.(1)Temperature is one of the key factors affecting the comprehensive properties of Diamond-WC-Co mining cemented carbide.When the sintering temperature is 1200?,the alloy is not sufficiently sintered,and the hardness and fracture toughness are poor.When the sintering temperature is 1300?,the diamond in the alloy undergoes partial graphitization transformation,which deteriorates the properties of the alloy.The properties of the samples prepared at 1250? were the best,and the wear coefficient was reduced by about 79%and 83%compared with 1200? and 1300?,respectively.(2)Co is used as the catalyst of diamond phase transformation and the binder of cemented carbide,and the change of its content has a great influence on the properties of cemented carbide.When the Co content increases in the range of 1.5-7.5 wt%,the densification degree of the alloy increases,and the hardness and wear resistance of the alloy decrease.The fracture toughness does not fluctuate significantly with the Co content,and the fracture toughness of HM-2.5Co is about 60%higher than that of the self-made WC-2.5Co alloy due to the impediment of crack propagation by diamond.(3)The coating acts as a transition layer to separate the diamond and Co phases during sintering while enhancing the bonding force of the two.Comparing the properties of WC-Co cemented carbides with different coating diamonds,it is found that when sintered at 1250?,the uncoated diamond bare leakage will partially undergo graphitization transformation in the alloy,and the diamond with Ti,W and Cr coatings can exist stably.The hardness and fracture toughness of HM-DTi and HM-DCr alloys are better than other alloys,and the wear resistance is about 3.34 times higher than that of HM-D0.(4)The diamond content of the enhanced phase changes the comprehensive properties of the alloy by affecting the interface distribution of diamond and WC-Co matrix.When the diamond content increases in the range of 0-15 vol%,the hardness and density of cemented carbides decrease.The increase of diamond content will also shorten the mean distance of diamonds,which is beneficial to improve the fracture of the alloy toughness.When the diamond content is 10 vol%,the wear resistance of cemented carbide is the best.