Ys. Cheong et al., Improved oxidation resistance of silicon nitride by aluminum implantation:II, analysis and optimization, J AM CERAM, 83(1), 2000, pp. 161-165
In the preceding paper, it was shown that aluminum ion implantation signifi
cantly improves the oxidation resistance of Si3N4 ceramics under the influe
nce of sodium. Not only is the oxidation rate reduced by up to an order of
magnitude, the phase and morphological characteristics of the oxides grown
on aluminum-implanted samples are improved as well. The role of aluminum in
negating the detrimental effect of sodium on the oxidation resistance of S
i3N4 ceramics can be interpreted on the basis of network modification of th
e oxide layers by sodium and aluminum cations. The degree of improvement in
the oxidation resistance does not, however, necessarily increase with the
aluminum concentration. A simple quantitative analysis is presented which c
orrelates the optimum aluminum implant concentration and the sodium content
in the gas phase for the optimization of the oxidation resistance of Si3N4
ceramics.