We extend the formalism presented in our recent calculations of dust ejecta from the Thermally Pulsing Asymptotic Giant Branch ( TP-AGB ) phase , to the case of super-solar metallicity stars .
The TP-AGB evolutionary models are computed with the colibri code .
We adopt our preferred scheme for dust growth .
For M-giants , we neglect chemisputtering by H _ { 2 } molecules and , for C-stars we assume a homogeneous growth scheme which is primarily controlled by the carbon over oxygen excess .

At super-solar metallicities , dust forms more efficiently and silicates tend to condense significantly closer to the photosphere ( r \sim 1.5 R _ { * } ) – and thus at higher temperatures and densities – than at solar and sub-solar metallicities ( r \sim 2 - 3 R _ { * } ) .

In such conditions , the hypothesis of thermal decoupling between gas and dust becomes questionable , while dust heating due to collisions plays an important role .
The heating mechanism delays dust condensation to slightly outer regions in the circumstellar envelope .
We find that the same mechanism is not significant at solar and sub-solar metallicities .

The main dust products at super-solar metallicities are silicates .
We calculate the total dust ejecta and dust-to-gas ejecta , for various values of the stellar initial masses and initial metallicities Z = 0.04 , 0.06 .

Merging these new calculations with those for lower metallicities it turns out that , contrary to what often assumed , the total dust-to-gas ejecta of intermediate-mass stars exhibit only a weak dependence on the initial metal content .