用ISOC型试样测试Ti(C,N)基金属陶瓷抗弯强度的不确定度评定

Evaluation of uncertainty in transverse rupture strength testing using ISO type C specimen of Ti(C, N)-based cermets

Ti(C,N)基金属陶瓷属于硬脆性材料,在实验研究及生产实践中一般用三点抗弯强度来表征其强度。由于金属陶瓷比WC基硬质合金脆性更大,在实际制样过程中,磨削加工容易导致试样开裂并出现边角崩缺,难以制备出符合要求的方条试样,其可能存在的显微崩缺及微裂纹会导致测试结果失真,散差增大。本文采用更容易制备的圆棒状试样测试抗弯强度(TRS),并对其测试结果的不确定度进行评定。结果表明:采用ISO C型试样测试金属陶瓷的抗弯强度的相对扩展不确定度小于5%。

As a kind of brittle material, transverse rupture strength（TRS） was adopted to evaluate the strength of Ti（C, N）-based cermets. Whereas, the brittleness of cermet is much higher than WC-based cemented carbide, it is hard to prepare eligible rectangular specimens because of cracking and chipping when grinding. Micro cracks and notches induced on specimens when grinding may bring big error into the results. So, ISO type-C specimens were used to test the TRS of Ti（C, N）-based cermets in the present paper, and the relative uncertainty of the measurement has also been evaluated. The results indicate that the result of type-C specimen is accurate and credible, and the relative expanded uncertainty is small than 5.0%.