Evaluation of impact strength and reliability of ceramic bearing ball for next-generation airplanes

研制了摆锤冲击试验和落锤试验装置，用于评价冲击载荷作用下的环裂纹强度。在摆式冲击试验中，由于滚珠中心对中调整困难，容易产生斜向碰撞。虽然环裂纹萌生的碰撞载荷在理论上是可以计算的，但测量是非常困难的。另一方面，在落锤试验中，使用载荷传感器可以正确地测量环裂纹萌生的碰撞载荷。设备制造也相对容易。环状裂纹是由于粘结剂破坏了颗粒间的玻璃相、杂质等。从环状裂纹强度可以研究微观断口。在碰撞接触中，由于参与环裂纹萌生的裂纹长度比静态接触小，陶瓷球的强度提高，散布变小。

The equipments of pendulum impact test and weight-drop test were manufactured in order to evaluate the ring crack strength under impact load. In the pendulum impact test, a slanting collision is caused because alignment adjustment of balls center is difficult. The measurement is very difficult although collision load of ring crack initiation is theoretically computable. On the other hand, in weight-drop test, collision load of ring crack initiation is correctly measurable using a load cell. Equipment manufacture is also comparatively easy. The ring crack is attributed to binder destruction of the glassy phase between particles, impurities, etc. It is possible to investigate microscopic fracture from ring crack strength. In the collision contact, the strength of the ceramic ball rises and the scatter of them become small, because the crack length which participates in ring crack initiation is small compared with static contact.