Application of Plasma Spraying Technology in Practical Engineering

       (1) The oil coring bit is sprayed with a wear-resistant coating. Coring bits are a key tool in oilfield exploitation. In deep wells with complex geology and hard rock formations, imported synthetic diamond drill bits are used to drill below 2700m to the ground, due to the wear of the matrix, resulting in the diamond particles falling off. Using the plasma spraying process, the nickel-coated aluminum and cobalt-coated tungsten carbide composite coatings are sprayed on the core bit, which not only increases the bonding strength of the synthetic diamond particles on the bit, but also improves the anti-wear performance of the bit matrix, making the diamond particles more effective. to play a role, thus saving a lot of synthetic diamonds.



   (2) Repair of machine tool guide rail wear. The wear resistance and dimensional accuracy of machine tool guide rails are one of the main factors that affect the life and accuracy of machine tools. General machine tool guides are made of cast iron, which has low hardness and wear resistance. Therefore, in the repair workload of machine tools, the repair of guide rails accounts for 50%~90~. Plasma spraying technology can not only effectively repair the local wear parts of the guide rail, but also apply it on the production guide rail to improve its wear resistance and prolong the service life of the machine tool. The guide rail of the large lathe of Harbin Electric Machinery Factory was worn by 0.3mm. The plasma spraying process was used to spray Ni/Al plus iron-based alloy coating. After grinding, the use effect was good.

    (3) Corrosion-resistant coating is sprayed on the water-passing surface of the large shaft of the 6105kW steam turbine generator. The water-passing surface of the large shaft of the generator is corroded by 80-degree hot water at a speed of 7/s. It is necessary to spray a waterproof and erosion-resistant coating to ensure that the shaft does not corrode and the coating does not fall off during the long-term operation of more than 2 years. At the same time, it can ensure the water quality of the water cooling system is clean, and will not cause failures such as cooling effect decline or blockage. This is one of the key issues of the 6105kW turbo-generator set. Two kinds of Harbin Electric Machinery and Harbin Electric Machinery Research Institute conducted material selection tests under simulated working conditions on 48 kinds of waterproof erosion coating materials (including paint, electroplating, plastic, enamel, rubber, thermal spray coating, etc.). The test results show that the plasma sprayed Ni/Al anti-corrosion coating is used. The performance and safety meet the requirements, and the waterproof erosion is ideal.

     (4) The blast furnace slag mouth is sprayed with heat-resistant coating. The slag port is an important device for blast furnace slag discharge. During the blast furnace smelting process, the amount of slag is large and the slag discharge is frequent. The slag mouth is composed of a copper water cooling jacket. When the slag is discharged, the slag port is eroded, corroded and washed by high temperature alkaline slag, molten iron and blast furnace gas entrained in the slag. Broken easily. Therefore, the life of blast furnace slag mouth is one of the key issues in blast furnace smelting. Using the plasma spraying process, the heat-resistant composite coating (metal + cermet + ceramic) is sprayed on the front end of the easily damaged slag mouth within 30mm in the axial direction. The economic effect is very significant.

     (5) The polysilicon reduction furnace is sprayed with anti-diffusion and heat-resistant coating. The inner wall of the polysilicon reduction furnace is made of heat-resistant stainless steel plate. At the polysilicon reduction temperature, due to the trace pollution of the elements contained in the stainless steel, the yield of silicon crystals and the quality of silicon components are affected. In foreign countries, expensive crystal clocks are used to protect polysilicon crystals for restoration, and the value is as high as hundreds of thousands of dollars. The cooperation between Shanghai Spraying Machinery Factory and Shanghai Electronic Equipment Co., Ltd. uses plasma spraying pure silicon coating on the inner wall of stainless steel, which effectively prevents the diffusion pollution of elements contained in stainless steel, and improves the purity of polysilicon products by an order of magnitude.

     (6) Xiangjiang Machinery Factory used plasma spraying 50% Ni-Cr-B-Si, 50% TiC, 0.1mm thick coating on the turbine blade crowns of I, II and III special engines. After producing about 60,000 blades for 20 engines and flying with good results, the factory has officially stipulated the use of this coating on the design drawings.

     The inner wall of the pressure combustion chamber is primed with Ni/Al, and the surface is sprayed with Al2O3, which has a good thermal insulation effect. The aircraft tail cover adopts plasma spraying Al2O3 to prevent the tail cover from cracking caused by high temperature airflow.