Silicon nitride riser tube is the key part of the low pressure casting machine for aluminum casting (especially the products of the automobile and the motorcycle ).When the casting machine works, the silicon nitride riser tube is put in the insulation furnace under 700’deg. Every 3-5 minutes, the casting machine fulfill some pressure to the liquid aluminum so as to lift the liquid aluminum to the mould . .In the process of aluminum casting, the pressure can reach 0.8～1㎏/㎝2,so request that the riser tube should have excellent heat-shock resistance, corrosion ,strength and good tightness.

Silicon nitride riser tube is the ideal materials of the metallurgy industry because of excellent characteristics, such as corrosion resistance, low thermal-expansion coefficient . 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 riser tube is 5-20 times longer than the traditional riser tube, so the replacement of the riser tube is reduced and the continuous of the production is ensured. Now the silicon nitride riser tube is widely used in the aluminum smelting industry , petroleum chemical industry, ceramic industry and electronics industry.