Wear resistance and anti-friction of expansion cone with hard coating

To improve wear resistance of expansion cone and decrease the friction between cone and tube, an expansion cone covered by hard coating was prepared and applied in the field. The carbide-based hard coatings were fabricated on the expansion cone surface by using high-velocity oxygen fuel thermal spraying technology, and the coating improved surface hardness of the cone by nearly 60%. The wear tests indicate that: the hard coating reduces friction coefficient of expansion cone sample by over 30% and wear loss by 33% with lithium grease lubricating; the hard coating reduces friction coefficient of expansion cone sample by about 25% with water lubricating; the hard coating reduces the wear and friction between expansion cone and tube significantly, and extends the cone life. Field tests indicate that: the expansion cones with hard coating have excellent wear resistance; the coating bound well with the expansion cone substrate after application for four wells, and no evident abrasion happens on the cone surface; the cone is successfully applied in the field to repair the damaged casings.