H_(2)对预烧结后的WC-11.2Co-0.3TaC硬质合金组织及性能的影响

Effects of H_(2) on Microstructure and Properties of Pre-sintered WC-11.2Co-0.3TaC Cemented Carbide

以二次烧结过程中是否通入H2的两组WC-11.2Co-0.3TaC硬质合金为研究对象,采用金相显微镜观察、物理化学性能检测等分析测试方法,研究了H_(2)对预烧结后的合金组织及性能的影响。结果表明:经850℃预烧结后试样的氧含量受放置时间的影响,放置时间越长,试样中的氧含量越高,当放置时间超过12 h后,氧含量基本稳定在0.22%左右。二次烧结过程中H_(2)的介入能较好地保护WC-11.2Co-0.3TaC硬质合金中的碳含量,使其相对磁饱和强度维持在94.9%左右,而较高的碳含量导致出现了较多欠匀的WC晶粒,同时也造成合金密度、硬度、矫顽磁力及抗弯强度下降,相比于未使用H2的二次烧结试样,抗弯强度降低了604 N/mm^(2)。

Taking the two groups of WC-11.2Co-0.3TaC cemented carbide with or without H2 during the process of secondary sintering as the research object,the influence of H2 on the microstructure and properties of the alloy after pre-sintering was studied by metalloscopic observation and physical and chemical properties testing.The results show that the oxygen content of the pre-sintered sample at 850℃ is affected by the storage time.With the prolongation of the storage time,the oxygen content of the sample gradually increases.After the storage time is more than 12 h,the oxygen content is basically stable at about 0.22%.H_(2) intervention during the secondary sintering can better protect the carbon content in WC-11.2CO-0.3TaC cemented carbide,so that its relative magnetic saturation strength is maintained at about 94.9%.The higher carbon content leads to more ununiform WC grains in the alloy,and at the same time leads to a decrease in density,hardness,coercive force and bending strength of the alloy.Compared with the secondariy sintered sample without H_(2),the flexural strength of the sample with H_(2) is reduced by 604 N/mm^(2).