Characterization of Glass-infiltrated Alumina-based Ceramics

Objective: to characterize the microstructure, composition, and some properties of glass-infiltrated alumina-based ceramics similar to the In-Ceram system (Vita, Germany). Methods:  Materials used were: IA- In-Ceram Alumina (Vita); IAE- In-Ceram Alumina electrophoretically deposited (Vita); AEM- alumina-based ceramic experimental method (Vita); VC- Vitro-Ceram (Angelus, Brazil); TC- Turkom-Cera (Turkom-Ceramic, Malaysia); AG- Alglass (EDG, Brazil); and CC- Ceramcap (Foto-Ceram, Brazil). Ceramic specimens were fabricated following manufacturers' instructions and ISO6872 standard and polished through 1µm alumina abrasive. Semi-quantitative and qualitative analyses were performed using scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), and stereology principles for volume fraction (Vv). The elastic modulus (E) and Poisson's ratio (v) were determined using ultrasonic-time-of-flight data measured in an ultrasonic pulser/receiver, and the density (r) using a helium pycnometer. Vicker's indenter was used to calculate hardness (H). Bar specimens were loaded in three-point bending to fracture using a universal testing machine with cross-head speed of 1mm/min. Flexural strength (s_3P) was calculated and statistically analyzed using ANOVA, Tukey (a=0.05)* and Weibull (m= modulus)†. Results:

	s3P (MPa)*	m†	E (GPa)	v	H (GPa)*	r (g/cm3)	Vv (%Al2O3)
IA	489±62a	9.4±4.7	280±1	0.25	12.1±1.1ab	3.8±0.01	74±3
IAE	485±63a	7.0±2.2	277±3	0.26	12.9±1.1a	3.8±0.01	75±3
AEM	517±37a	16.4±5.5	300±4	0.25	11.3±0.5b	4.0±0.01	70±3
VC	529±67a	8.8±2.9	284±5	0.24	12.4±0.4ab	3.8±0.01	62±3
TC	332±44b	8.9±2.0	245±3	0.25	9.3±0.7c	4.2±0.02	63±3
AG	233±26c	11.6±3.5	239±2	0.25	8.5±0.8c	3.6±0.02	57±2
CC	258±28c	9.0±2.0	167±1	0.23	7.4±0.5d	4.2±0.02	42±2

Similar letters* show no statistical difference (p>0.05). SEM, XRD and EDS analyses revealed similar microstructure for all ceramics, but a lead-based matrix for CC and a zirconia phase for VC. TC, AG and CC showed significantly lower mean s_3P value than the other ceramics (p≤0.05). AEM showed the greatest m (16.4). Conclusion: IA, IAE, AEM and VC ceramics seemed to have similar properties.

CNPq-Brasil:300748/2006-0