Mechanism of Fracture in Pre-Cracked Single-Edged Notched Bars With AI2O3-TiO2 and WC-CO Coatings

Experimental analysis is made to investigate the most significant fracture characterizing parameters in plasma sprayed substrate-coating composite. The experiments were conducted on the single edge notched bars (SENB) made with 7075 series aluminum alloy, with plasma sprayed Al2O3-TiO2 and WC-Co top coats. The pre-cracked bars were fractured in computerized universal testing machine in controlled conditions. The material has been tested under age-hardened and coated conditions also. The results have revealed that the age hardening and type of coating have a much influence on strain energy release rate. The experimental results have shown that WC-Co coated normal materials possess higher strength whereas uncoated normal materials possess lower strength. It is also found that Al2O3-TiO2 coated material possess better coating bond strength and moderate load bearing capacity. The SEM fractographic analysis has been made to analyze the fracture behavior as a function of coating type and the material conditions.