Characterization of glass-infiltrated alumina-based ceramics

Characterize the microstructure, composition, and important properties of glass-infiltrated alumina-based ceramics similar to the In-Ceram system.

Materials used were: IA, In-Ceram Alumina (Vita); IAE, IA electrophoretically deposited (Vita); AEM, IA using a vacuum driven method (Vita); VC, Vitro-Ceram (Angelus); TC, Turkom-Cera (Turkom-Ceramic); CC, Ceramcap (Foto-Ceram); and AG, Alglass (EDG). Ceramic specimens were fabricated following manufacturers' instructions and ISO6872 standard and polished successively through 1 microm alumina abrasive. Semi-quantitative and qualitative analyses were performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and stereology (Vv). The elastic modulus (E) and Poisson's ratio (nu) were determined using time-of-flight data measured in an ultrasonic pulser/receiver and the density (rho) was determined using a helium pycnometer. Vicker's indentation was used to calculate hardness (H). Bar specimens (25 mm x 4 mm x 1.2 mm) were loaded in three-point bending to fracture using a universal testing machine with cross-head speed of 1mm/min. Flexural strength (sigma(3P)) was calculated and statistically analyzed using ANOVA, Tukey (alpha = 0.05) and Weibull (m = modulus, sigma(0) = characteristic strength).

SEM and EDS analyses revealed similar microstructure for all-ceramics, except for a lead-based matrix in CC and a zirconia phase in VC. TC, AG and CC showed significantly lower mean sigma(3P) values than the other ceramics (p< or =0.05). AEM showed the greatest m (16).

Despite few differences in microstructure and composition, the IA, IAE, AEM and VC ceramics have similar properties.

The glass-infiltrated alumina-based ceramics from different manufacturers presented distinct characteristics. It is necessary to characterize new commercially available materials to understand their properties.