Annealing and coagulation timescales for Al-Ca-Ti oxide particles of different sizes in the disc midplane as a function of r for an age of the solar nebula of 0.1 Myr. The silicates have sublimated inside of about 0.45 au. Inside of about 0.2 au, only Al₂O₃ and ZrO₂ remain, whereas outside of 0.2 au, Ca₂Al₂SiO₇ and CaTiO₃ are present as well, which creates another small step in the dust-to-gas ratio and hence in the coagulation timescales.