The Effect of Hydrogen on the Fracture Properties of 0.8(Na1/2Bi1/2)TiO3-0.2(K1/2Bi1/2)TiO3 Ferroelectric Ceramics

Abstract

The effect of hydrogen on the fracture properties of lead-free ferroelectric ceramics has been studied. For hydrogen precharged samples, the fracture toughness decreased linearly with both increasing hydrogen concentration and the logarithm of dwell time of indenting. Hydrogen-induced delayed propagation of unloaded indentation cracks can occur, and the threshold stress intensity factor of hydrogen-induced cracking induced by residual stress decreases linearly with increasing hydrogen concentration.

Hydrogen in Ferroelectrics

“…The fracture toughness for hydrogenated sample K IC (H) can also be obtained. The experiments indicated that both K IH /K IC and K IC (H)/K IC decreased linearly with the increasing C H , as shown in Figure 13 (Zhang et al, 2008). Fig.…”

“…Therefore, the cracks can also grow with the prolongation of dwell time during indentation test in a precharged sample since the hydrogen concentration will increase at the indentation crack tips by stress-induced diffusion. The experimental results indicate that the longer the indentation load hold, the larger the indentation crack length is, and the smaller fracture toughness, K IC (H,t) measures, as shown in Figure 14 (Zhang et al, 2008). Under a constant load, the HIDC can occur by the stress-induced hydrogen diffusion and enrichment.…”

“…13. Hydrogen concentration dependence of the relative fracture toughness of charged samples, K IH /K IC , and of the normalized threshold stress intensity factor of hydrogeninduced cracking induced by residual stress, K IC (H)/K IC (Zhang et al, 2008) The crack length increased with increasing hydrogen concentration in the samples. Therefore, the cracks can also grow with the prolongation of dwell time during indentation test in a precharged sample since the hydrogen concentration will increase at the indentation crack tips by stress-induced diffusion.…”

“…14. The normalized fracture toughness K IC (H,t)/K IC versus the logarithm of the dwell time during the indentation test for the charged sample (Zhang et al, 2008) …”

“…The mechanical property is another important property to sure ferroelectric devices could be used reliably. Hydrogen fissure (Peng et al, 2004) and hydrogen-induced delayed fracture (Huang et al, 2005;Zhang et al, 2008;Wang et al, 2003aWang et al, , 2003b could occur in some conditions. This chapter reviews the effects of hydrogen on the properties of ferroelectric materials.…”