Evaluation of the elastic modulus and strength of unsymmetrical Al2O3 coating on Ti3SiC2 substrate by a modified relative methodology

Putting Ti3SiC2 in sandwich of Al2O3 will produce the hard–soft–hard sandwich composites of Al2O3/Ti3SiC2/Al2O3 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 Al2O3 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 Al2O3/Ti3SiC2/Al2O3 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 Al2O3 coating. Experimental results revealed that the modulus and strength of Al2O3 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 Ti3SiC2 and Al2O3 was also discussed.