PURPOSE To investigate the reliability of titanium abutments veneered with indirect composites for implant-supported crowns and the possibility to trace back the fracture origin by qualitative fractographic analysis. MATERIALS AND METHODS Large base (LB) (6.4-mm diameter base, with a 4-mm high cone in the center for composite retention), small base (SB-4) (5.2-mm base, 4-mm high cone), and sm...

The effects of Zr additive on the microstructure, mechanical properties, and fracture behavior of Al-Si alloy were systematically investigated. The additive of Zr obviously reduced the size of Si particles and changed its morphology. Grain size refinement was promoted by the reaction between Al and Zr forming Al3Zr and ZrSi2 compounds. Compared to a Zr-free alloy, the additive enhanced the tens...

X-ray methods were used to measure the residual stress near a fracture surface of a sintered composite system of A&03/ Sic. A specimen bent at three points with different notch radii was used to measure h-acture toughness. Effects of the notch radii on the stress intensity factor Kp were measured during the initiation of the crack. Experimental results agreed with fracture mechanics theory.

Gallium arsenide (GaAs) is used in the most demanding semiconductor applications, including medical, aerospace and communication industries, where significant mechanical stresses are experienced during operation. Mechanical from thermal expansion loading can result fracture of GaAs crystals, a leading cause device failure. Unfortunately, underlying mechanisms III-V semiconductors currently not ...