High-voltage screening on titania ceramics with differently finished surfaces

Effects of high-voltage screening were examined on titania rectangular bars whose top and bottom surfaces were differently finished. A screening field, at or below which 30% of titania samples break electrically, was applied to the samples. After high-voltage screening, the survived samples were fractured by a three-point bending strength test with their rough face placed on the tensile or compressive side. And the resultant strength distribution was compared to the distribution before high voltage screening. For the specimens with rough face on the tensile side, the strength distribution in Weibull plot becomes a convex curve with keeping the high strength region before screening. This indicate that low strength samples were selectively eliminated by high-voltage screening. On the other hand, the effect of screening process on the samples tested with their rough surface in compression was very small.