DEVELOPMENT OF CRACK-RESISTING CEMENTED CARBIDE SLIDING MATERIALS

硬质合金被广泛用作摩擦材料。然而，它们有一个关键的缺陷，即在摩擦表面上偶尔会出现许多与滑动方向垂直的浅裂纹。本研究的目的是为抗裂硬质合金材料的发展制定设计指南。通过考虑热应力的热分析和弹塑性分析，研究了影响裂纹产生的因素对裂纹产生的影响。将7种硬质合金环(含和不含钴、镍粘结剂)、钨铬钴合金和钛合金环与一些陶瓷环配对进行了试验。研究了碳、铬对WC-Ni和WC-Ni-Cr硬质合金耐蚀性的影响，以及Ti-Mo合金的腐蚀行为。得到的主要结果如下：1.高接触应力和高切向力是基本的c…。在低接触压力和高滑动速度的条件下，裂纹主要是由摩擦热引起的热应力引起的残余拉应力产生的。另一方面，在高接触压力和低滑动速度的条件下，高摩擦源产生的拉应力会导致裂纹的产生。3.选择合适的形状和材料以减小接触压力和摩擦系数，以防止裂纹的产生。4.与相同成分的硬质合金材料相比，抗裂的临界载荷随着材料的抗热震断裂能力的提高而增加。5.滑动方向上存在的残余压应力抑制了裂纹的产生。7.WC-Ni-Cr硬质合金的耐蚀性随碳含量的降低和铬含量的增加而提高。8.钛钼合金的耐腐蚀性随钼含量的增加而提高。通过生产抗热震性高的硬质合金，在摩擦方向添加高的残余压应力，以及与热扩散率高、摩擦系数低的材料配合，可以防止硬质合金摩擦表面出现裂纹。较少

Cemented carbides have been widely used as rubbinng materials. They have, however, a critical defect that numerous shallow cracks, that run perpendicular to the direction of sliding, occasionally occur on the rubbing surface. The purpose of this study is to establish the design instruction for the development of crack-resisting cemented carbide materials. The effects of factors affecting the occurrence of these cracks were stdied by thermal and elastic-plastic analyzes taking into account the thermal stresses were conduced. The experiments were carried out by pairing 7 kinds of cemented carbide rings with and without Co or Ni binder, a stellite and Ti alloy rings with some ceramic rings. The effects of carbon and Cr on the corrosion resistance in WC-Ni and WC-Ni-Cr cemented carbides were also omvestigated, together with corrosion behavior of Ti-Mo alloys. The main results obtained are summarized as follows :1.A high contact stress together with a high tangential force is an essential c … More ondition for the occurrence of cracks and the direction of their propagation.2.Cracking is mainly produced bythe residual tensile stress due to thermal stresses induced by frictional heat under conditions of a low contact pressure and high sliding speed. On the other hand, cracking is induced by the tensile stress due to a high friction fource under conditions of a high contact pressure and low sliding speed.3.The selection of shape and material for reducing the contact pressure and friction coefficient are necessary to prevent cracking.4.Comparing among cemented carbide materials with the same composition, the critical load against cracking increases as the thermal shock fracture resistance of the material increases.5.The residual compressive stress existing in the direction of sliding suppresses the occurrence of cracks. 6.It is difficult for cracks to occur on the surface of cemented carbide surface paired with materials with a high thermal diffusivity.7.The corrosion resistance of WC-Ni-Cr cemented carbides is improved with decreasing of carbon content and with increasing of Cr content.8.The corrosion resistance of Ti-Mo alloy increases with an increase of Mo content.The occurrence of cracking on the frictional surface of cemented carbides can be prevented by producing cemented carbide with a high thermal shock fracture resistance, by adding a high residual compressive stress in the direction of the rubbing, and by mating with materials having a high thermal diffusivity and giving a low friction coefficient. Less