| 摘要 |
PURPOSE:To predict exactly the defects and strength after calcination relate to ceramic degreasing bodies by immersing the degreasing bodies into a prescribed liquid and measuring the time until cracks arise in said bodies. CONSTITUTION:The degreasing bodies 2 are extracted for each of injection pressures an are gently sunk by hand into the preliminarily prepd. water 3 kept at about 23 deg.C. The surfaces of the bodies 2 are visually observed in this state and the positions where the cracks arise and the time when the cracks arise in the respective position are measured. The bodies 2 are extracted for each of the injection pressures in order to examine the non-defective percentage of calcination. The extracted bodies are calcined at about 1,750 deg.C in a gaseous nitrogen atmosphere of 1atm. and the generating ratios of defects in the calcined bodies, i.e., the crack in the key grooves 5, the crack 6 at the root of the tooth part and the crack 7 at the tip of the tooth part are examined. The bodies 4 of each injection pressure are meshed with a fixing jig 8 and torque is applied thereto by a rotating tank 9. The torque when the crack arises in the root of the tooth part is measured. As a result, the bodies 7 with which the time for generation of the crack owing to moisture absorption is longer has the less defects. The calcined bodies having high strength are thus obtd. |
