金属基陶瓷涂层弹性模量和界面断裂韧度

对双面涂层三点弯曲试验方法进行了改进(两面涂层不必等厚度),基于该理论对一种铁基陶瓷涂层进行了试验研究,并与单面涂层的三点弯曲试验结果进行了比较.结果表明,随涂层厚度的增大,弹性模量增大.分析认为,一方面涂层越厚,测量精度越高;另一方面涂层厚度增大,孔隙率降低,使得弹性模量增大.研究发现涂层弹性模量与喷涂方向有关,呈现了各向异性的特性.文中还介绍了测量涂层/基体界面断裂韧度的研究进展,着重介绍了测量界面临界应变能量释放率的四点弯曲试验、改进的拉伸试验方法以及采用威布尔应力评价界面强度的局部法.

Young' s modulus and interface fracture toughness of metal-base ceramic coatings

The Young's modulus is a specially important material parameter, which is often used in the fracture mechanics study on coating/substitute interface strength. A new two-side coated specimen in 3-point bend test was proposed based on compound beam theory. The Young's modulus of metal-base ceramic coating was measured through the two-side coated specimen and through the single-side coated specimen. The test results show the Young's modulus increases with rise of coating thickness. On one hand, the thicker the coating is, the more accurate the result is. On the other hand, inctrase of coating thickness results in the reduction of porosity, which makes the Young's modulus increase. If was found that the spraying orientation has effect on Young's modulus of coating which takes on the anisotropic property. In addition, interface fracture toughness was also introduced, which mainly include the 4-point bend test to measure interface critical strain energy rate, improved tensile test and local approach based on Weibull criterion.