Strengthening And Toughening On Ends Of Ceramic-lined Pipe And The Wear Properties Of Pump Friction Pair Materials

Among the most important energy resources, petroleum as a vital lifeline of national economy development has been the strategical resources chased by each nation for a long time. Petroleum products is involved in all aspects of our lives, there is an irreplaceable role in our lives. China's oil production has developed more than 30 years, it made an indelible contribution to the economic development. However, many oil field exploitation has entered the middle or late in our country. The water and sediment concentration in the oil well increases, and the liquid has so strong erosion that, the pump and pumping pipeline corrosion, wear increases. The oil cost also increases. Ceramic lined pipes can effectively reduce pipeline corrosion and wear, but the ceramic layer is so brittle that need to improve. Pump failure was mainly pump barrel - plunger wearing serious. Finding the pump cylinder - plunger friction material which has good wear properties is great significance for petroleum exploration.The yttria-doped ZrO₂ powder contains 32.1% of m-ZrO₂,the other constituent is t-ZrO₂.Only t-ZrO₂ was detected by XRD in the resultant ZrO₂ ceramic layer in the composite tube. The ZrO₂ particles of 1mm diameter are distributed on the boundary of theα-Al₂O₃ dendrites. The ZrO₂ has a grain refining effect; the average width of theα-Al₂O₃ is 7.7μm, decreases by 31.9% as compared with the width of 11.3μm for the conventional ceramic layer. The addition of ZrO₂ can effectively improve the fracture toughness of the ceramic layer,for instance, the fracture toughness is 0.88 MPam1/2 under addition of 2 wt.% ZrO₂, then significantly increases to 5.92 MPam1/2 with more ZrO₂ addition until 6 wt.%. Further addition results in a decrease in fracture toughness due to the low fluidity, difficulty in evacuation of gas and the increases in pore ratio at high temperature.Using induction heating to the ends of ceramic-lined pipe heats to about 830℃, keeping 400 s, and then air-cooled, water-jet 4 s, 6 s, 8 s and 10 s. before the spraying time 6s, Steel matrix microstructure is pearlite and sorbite. When water-cooling time was 8 s, the microstructure is troostite. When water-cooling time was 10 s, the microstructure is upper bainite. Processing into thread end and then put up to the tensile test, with water-cooling time increased, the tensile strength of thread increases. The maximum tensile strength is water-cooling 10 s which reached 704 KN. It have been able to meet the requirements. Water-cooling time under 4 s the thread failure form is thread release. When water-cooling time is more than 6 s, the screw thread failure form is complete rupture.Nickel base alloy has mainly FeNi3 as matrix phase, Cr5B3, Ni31Si12, Fe3C. The last three phases haves high hardness, good corrosion resistance. They strengthened the nickel-based alloy matrix. Toughened Ceramics has mainly a-Al₂O₃ and t-ZrO₂ phase. In dry friction experiments, the nickel base alloy friction coefficient decreases as the load increases. The wear rate increases slowly at low load. When the load was increased to 40 N, the wear rate increases rapidly, reaching to 20.7x10-4 mm3m-1, and then with the load increasing the wear rate has stabilized. In less than 20N load The wear mechanism is micro-cutting when the load is under 20N. When the load is more than 40N, the wear mechanism is adhesive wear. In the water lubrication wearing experiment, the nickel-based alloy friction coefficient decreases as the load increasing. The wear rate is low as the load of 10 N. When the load is up to 20 N, the wear rate increases rapidly, from 1.09x10-4 mm3m-1 increasing to 5.46x10-4 mm3m-1. With the load increasing, the wear rate stabilized. The wear mechanism is adhesive wear in water lubrication. In the abrasive wear experiment, the wear rate increases with the load increasing. The wear rate reaches to 118.77x10-3 mm3m-1 when the load is 60 N.The wear mechanism is micro-plowing. The furrow is deeper as the load increasing.In dry friction experiments, the toughened ceramic friction coefficient decreases as the load increase, the wear rate decreased with the increase of load. The wear rate is 3.04x10-4 mm3m-1 when the load is 60 N. The wear mechanism is micro-fracture and micro-grain cut as the load under 20 N. The wear mechanism is adhesive wear as the load more than 40 N. In the water lubrication experiment, the friction coefficient decreases as the load increase. When the load is 60 N, the friction coefficient decreased to 0.56. When the load is 10 N,the wear rate is high, reaching to 8.05x10-4 mm3m-1, but the wear rate decreases rapidly as the load increase. In less than 20 N load the wear mechanism is micro-fracture and grain cutting. The wear mechanism is micro-fracture and Al₂O₃ hydrolysis as the load more than 40 N. In the abrasive wear test, the wear rate of toughening ceramics has been in a low level. Wear mechanism of ceramic is micro-fracture and micro-grain cutting.