APPLICATION OF TIN ON MECHANICAL SEALS

At present, with the development of industry, mechanical seals have gradually replaced packing seals due to their advantages of good sealing performance, low frictional resistance and slow wear on contact surfaces. In the turbine compressors used in petroleum, chemical and petrochemical departments, the quality of the shaft elastomer bellow seal directly affects the operation of the machine.

For the entire mechanical sealing device, the key parts that affect the spring sealing performance are the moving ring and the static ring. Therefore, materials with good heat resistance and high mechanical strength should be selected. Generally, the moving ring is tungsten diamond cemented carbide, and the static ring is impregnated with phenolic graphite. For the mechanical seal, the one with good thermal conductivity and low thermal expansion coefficient material should be selected. At present, the ideal friction material is YG6 hard alloy for the moving ring, and epoxy resin graphite is used for the static ring. The moving ring is inlaid structure, and the grinding surface is cemented carbide ring inlay and grinded to reach the use state.

The essence of TiN is an energy activation technology. It not only contains ions to transfer energy and electric charge, but also generates high-energy neutral particles during ion collision. Therefore, TiN technology is different from other coating technologies such as electroplating, hot-dip plating, etc. In fact, it not only does not produce a dissociated coating, but on the contrary, it even changes the chemical composition of the secondary surface. TiN technology is a mature technology in the aerospace and aircraft industry to improve the durability of rolling and sliding parts that are subject to friction, wear and corrosion. It is reported that in order to prevent failure caused by frictional contact, anti-friction coatings made by TiN, such as soft metal lubricating films, and hard wear-resistant films are extremely effective.

According to the characteristics of TiN, we tried to coat the mechanical dense parts. The general mechanical pump seal moving ring material is cemented carbide, and its microhardness is 1200kg / mm², while the microhardness of TiN is 2000kg / mm². Multi-arc TiN has a good binding force and fully meets the requirements for use. At present, the price of the moving ring made of cemented carbide on the market is 148 yuan, and after we use TiN, the price can be reduced by 20%, and the economic effect is remarkable.

From the perspective of the needs of mechanical seals, China's mainframe demands are 2.2 million sets per year, and the output of mechanical seals produced by large and small factories in the country is 1.3 million sets / year, which means that 700,000 sets of seals are imported every year, and the import price is 10 times higher than the domestic price, so the supply of mechanical seals in the domestic market is in short supply. The technical level of domestic carbide seals lags behind the international market, and there is an urgent need for technical improvements. We can vigorously promote TiN technology on mechanical seals to meet market demand.