Silicon nitride riser tube has many excellent characteristics, such as corrosion resistance, low thermal-expansion coefficient and long service life .It is the ideal materials of the metallurgy industry because of the excellent oxidation resistance, heat-shock stability and no reaction with the metal solution.

The thermal-expansion coefficient of the silicon nitride is 1.0×10－6/ deg ,the flexural strength is 80～90mpa .After using ,not only can improve the quality of the casting products but also can reduce the cost. The service life of the silicon nitride lift tube is 5-20 times longer than the traditional lift tube, so the replacement of the lift tube is reduced and the continuous of the production is ensured. Now the silicon nitride lift tube is widely used in the aluminum smelting industry,petroleum chemical industry, ceramic industry and electronics industry.