硬质合金热处理和钴粘结相的转变温度

本工作证实WC-Co系硬质合金通过热处理可以提高其抗弯强度。所增加的抗弯强度决定于合金中钴的含量,钴含量越高的合金,其抗弯强度的增加重也就越多。主要是由于淬火热处理抑制了高温稳定的面心立方钴相转变成密排六方钴相。 本实验还采用差热分析仪测定了WC—Co系合金在加热过程中,密排六方钴相转变成面心立方钴相的相变温度。发现其相变温度随合金中钴含量的增加而升高,如YG8是742℃,YG15是770℃,YG20是821℃,这是由于高钴合金的粘结相在升温过程中有较高的钨含量。 本实验中还发现,烧结后低钴硬质合金要高于高钴硬质合金的粘结相中的钨含量,因为低钴硬质合金的烧结温度通常是高于高钴硬质合金,一般说来烧结温度越高,则粘结相中的钨含量也就越高,但当烧结态硬质合金再一次加热时,其钴结相中的钨含量要增加。所以淬火后高钴硬质合金的粘结相中的钨含量甚至比低钴硬质合金的粘结相中的还要高,这就是为什么钴粘结相由密度六方转变成面心立方的温度随硬质合金中钴含量的增加而提高。     

Development of new WC–Ni hardmetals for use in high pressure experiments

Ultrafine-grained (0.2–0.3?µm) WC–Ni hardmetals with a low Ni content (3–5?wt%) were developed using new production techniques based on adding an appropriate amount of VC and Cr₃C_2, combined with the strong mixing of raw materials. Their uniaxial compressibility was subsequently compared with that of existing WC–Ni and WC–Co hardmetals to assess their suitability for use as anvils in various high pressure experiments, particularly those associated with neutron or magnetic studies. The ultimate compressive strength of the newly developed hardmetals was over 7.7?GPa, which was higher by 1.2?GPa than that of the existing WC–Ni hardmetal ‘MF10’. When these hardmetals were used as anvils, a pressure of approximately 16?GPa was generated using a Paris-Edinburgh-type apparatus with φ8?mm culet, thereby proving that they can allow the physical properties of various materials to be measured at higher pressures than is possible with existing hardmetals.     

锌熔法回收硬质合金质量分析

系统分析了锌熔法回收硬质合金的生产工艺及锌熔粉末质量，查明了再生硬质合金质量不的原因及杂质来源，并提出了相应的改进措施。     

Heat Treatment of WC-Co Hardmetals and Transformation Temperature of Cobalt Phase

The Present work has found that the transverse rupture stren -gth of WC-Co hardmetals can be improved by queuching heat treatment. The increment of transverse rupture strength (4TRS) was dependent on the cobalt content of hardmetal. The higher the cobalt content of hardmetal is, the more the increment of transverse rupture strength is. The main reason is that the transformation of face centered cubic cobalt stabilized at high temperature to hexagonal close packed cobalt can be depressed by quenching. The transformation temperature of hexagonal close packed cobalt binder phase was determined by differential thermal analysis. It was found that the transformation temperature increases with increase of cobalt content of hardmetal. The reason is that the cobalt binder phase of high cobalt hardmetal contains higher tungsten content than that of low cobalt hardmetal after quenching.