  Collisions between sintered icy dust aggregates are numerically simulated. If
the temperature of an icy aggregate is sufficiently high, sintering promotes
molecular transport and a neck between adjacent grains grows. This growth
changes the mechanical responses of the neck. We included this effect to a
simulation code, and conducted collisional simulations. For porous aggregates,
the critical velocity for growth, below which the mass of an aggregate
increases, decreased from 50\,m\,s$^{-1}$ for the non-sintered case to
20\,m\,s$^{-1}$. For compacted aggregates, the main collisional outcome is
bouncing. These results come from the fact that the strength of the neck is
increased by sintering. The numerical results suggest that the collisional
growth of icy grain aggregates is strongly affected by sintering.
