DEVELOPMENT OF CRACK-RESISTING CEMENTED CARBIDE SLIDING MATERIALS

硬质合金已被广泛用作摩擦材料。然而，它们有一个关键的缺陷，即在摩擦表面偶尔会出现许多垂直于滑动方向的浅裂纹。本研究的目的是为开发抗裂硬质合金材料提供设计指导。通过热分析和考虑热应力的弹塑性分析，研究了影响裂纹产生的各种因素的影响。将7种硬质合金环与不带Co或Ni粘结剂的环、一种钨铬钴合金环和一种钛合金环与一些陶瓷环配对进行了实验。研究了碳和Cr对WC-Ni和WC-Ni-Cr硬质合金耐腐蚀性能的影响，以及Ti-Mo合金的腐蚀行为。主要研究结果总结如下：1。高接触应力和高切向力是裂纹产生和扩展的必要条件。裂纹主要是在低接触压力和高滑动速度条件下，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条件下，由于高摩擦力而产生的拉应力引起开裂。减小接触压力和摩擦系数的形状和材料的选择是防止开裂的必要条件。与相同成分的硬质合金材料相比，随着材料抗热冲击断裂能力的增加，其抗开裂临界载荷也随之增加。滑移方向的残余压应力抑制了裂纹的产生。6.与热扩散系数高的材料配对，硬质合金表面不易产生裂纹。WC-Ni-Cr硬质合金的耐蚀性随碳含量的降低和Cr含量的增加而提高。随着Mo含量的增加，Ti-Mo合金的耐蚀性提高。通过生产具有高抗热冲击断裂性能的硬质合金，在摩擦方向上增加高残余压应力，以及与具有高热扩散率和低摩擦系数的材料配合，可以防止硬质合金摩擦表面发生裂纹。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