Opposite words for friction:
accord, concurrence, peace, concord, harmony, agreement, concordance, cooperation.
Usage samples:
  1. The wheels of routine began to turn again, slowly and with a little friction at first, then smoothly and swiftly as if they had never stopped.
    "The Blue Flower, and Others", Henry van Dyke.
  2. Some friction and some gossip is presumably inevitable wherever women herd together in an unnatural segregation from men and children.
    "Home Life in Germany", Mrs. Alfred Sidgwick.
  3. By varying the friction the following curves were obtained.
    "Response in the Living and Non-Living", Jagadis Chunder Bose.
  4. Why should there be any more friction between them at all?
    "Delia Blanchflower", Mrs. Humphry Ward.