Study on Surface Hardening Technology of Metal Composite Ceramic Alloying Plating for Active Drill Pipe Joint
TiO2 powders are placed in NaCl-MgCl2 molten salt with tiny amount of Ag and Cu powders at 500-800 ℃ for 16 hours to prepare the gradient nitride ceramic phase on the surface of active drill pipe joint,therefore to improve the adhesion re-sistance,wear resistance and mechanical properties of the joint.The hardness,microstructure,phase and wear resistance of the strengthened joint are tested and analyzed.It is found out that strengthening phases of TiN and FexTi(Ag,Cu)are formed in the infiltration layer.The surface hardness increases to 1 710HV0.05,the specific wear rate decreases to 0.027 0 mm3/(N·m),and the wear resistance is 1.8 times higher than that of the ordinary nitrided joint,and 6.8 times higher than that of the matrix material.Compared with the common surface nitriding process,the composite cermet infiltration process forms a multi-gradient infiltration coating structure on surface of the joint,which has the effects of reducing wear,cooling and self-lubrication,and can greatly improve the surface hardness and wear resistance of the active drill pipe joint.
active drill pipe jointcomposite cermet infiltration platingsurface hardnesswear rate
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