Microstructures and mechanical properties of interface between porcelain and Ni–Cr alloy

Microstructures and mechanical properties of interface between porcelain and Ni–Cr alloy have been investigated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analyzer (XRD) and electronic universal testing machine. Experimental results show that there exists a reaction layer in the Ni–Cr/porcelain bond interface and the thickness of the reaction layer increases with the increase of firing temperature and firing time. The interdiffusion of atoms occurred during firing, Al, Si, Sn and O diffusing from porcelain material into Ni–Cr alloy, and Ni and Cr diffusing into the porcelain material. The phase composition of Ni–Cr/porcelain interface is complicated and mainly contains SnO2, AlNi3, SnCr0.14Ox and KAlSi2O6 compounds. Firing temperature and firing time have obvious effect on the shear bond strength of Ni–Cr/porcelain interface relative to the different reaction layer structures. The maximum shear bond strength reached 43.8 MPa at firing temperatures of 990 °C for firing time of 2.5 min.