Methods for preparing a silicon bonded PCD material involving a one step, double sweep process and drilling cutters made by such processes are disclosed. The PCD material includes thermally stable phases in the interstitial spaces between the sintered diamond grains. The method sweeps a diamond powder with a binder to form sintered PCD, reacts said molten binder with a temporary barrier separating said binder and said diamond from a silicon (Si) source, and sweeps said sintered PCD with said Si source to form SiC bonded PCD.