Tribological Study Of Bearing Material In Oil Well Condition

In petroleum/gas drilling processes,down hole tools work under special environment with slurries composing of water and abrasive sands.Bearings in such mechanical systems suffer from high loads and high shear in addition to the extreme environment.Friction and wear causes damage of the bearings,leading to the failure of the whole system.Therefore,it is significant to study the tribological characteristics of bearing materials in the special environment with slurries composing of water and abrasive sands,which has important significance in improving the stability and life of the bearing components and reducing the cost of oil well.In this paper,the sliding friction and wear characteristics of 9Cr18,GCr15,Cr4Mo4 V and G20 CrNi Mo in water base drilling fluid are studied.The research result shows that the coefficients of friction of GCr15,G20 CrNiMo and Cr4Mo4 V stay steady with increasing loads while they reduce with increasing rotation speed.For 9Cr18,however,a remarkable increase of coefficient of friction with load and speed is observed.The primary wear forms of G20 CrNi Mo and GCr15 are corrosion wear and abrasive wear.The primary wear forms of Cr4Mo4 V are corrosion wear,fatigue wear and abrasive wear.When the rotational speed and load reach 40 N and 100r/min,the wear form of 9Cr18 changes from abrasive wear to adhesive wear.Then the sliding friction and wear characteristics of GCr15 in water base drilling fluid containing polyether additives are studied.The research result shows that the coefficient of friction of GCr15 increases in turn in PPG200,PPG400,PPG600 and PPG1000.In the four kinds of water base drilling fluid containing polyether additives the wear scar diameter decreases and then increases slightly as the polyether concentration increases.In PPG200,PPG400 and PPG600,the coefficient of friction decreases and then increases slightly as the polyether concentration increases.The primary wear forms of GCr15 are abrasive wear corrosion wear and fatigue wear.At last the sliding friction and wear characteristics of GCr15 and 12Cr17Mn6Ni5 N in water base drilling fluid with different pH value are studied.The research result shows that both the coefficient of friction and the wear scar diameter of GCr15 and 12Cr17Mn6Ni5 N increase as the pH value increases.The primary wear forms of GCr15 are corrosion wear,abrasive wear and fatigue wear.The primary wear forms of 12Cr17Mn6Ni5 N are corrosion wear and abrasive wear.