Evaluation of the elastic modulus and strength of unsymmetrical Al_2O_3 coating on Ti_3SiC_2 substrate by a modified relative methodology

摘要

Putting Ti_3SiC_2 in sandwich of Al_2O_3 will produce the hard-soft-hard sandwich composites of Al_2O_3/Ti_3SiC_2/Al_2O_3 with improved oxidation resistance and high hardness. The relative method has been established to evaluate the elastic modulus and strength of the symmetrical coating. However, it is difficult to make the thickness of the Al_2O_3 coatings on both sides exactly the same during the synthesis process and this results in deviation inevitably. It is significant to develop a modified relative method to suit for the unsymmetrical coated sandwich samples. In this work, the sandwich composites of Al_2O_3/Ti_3SiC_2/Al_2O_3 with strong interfaces were prepared by in situ hot pressing process and a modified relative method was derived for determining the elastic modulus and strength of the Al_2O_3 coating. Experimental results revealed that the modulus and strength of Al_2O_3 were 398.2 GPa and 313.2 MPa, respectively, which demonstrated the validity and convenience of the modified relative method. The mechanism for the strong interface between Ti_3SiC_2 and Al_2O_3 was also discussed.