Material to making nozzles
The material to making nozzles is required to have preferable mechanical strength and good heat conductivity. For other material like inorganic mineral filler, reinforced glass fiber or material mixed with fire retardant, the material of the nozzle should have the capability of abrasion resistance and chemical resistance. The most used is heat resistant steel,include German DIN1.2343, X38CrMoV5-1, which are belong to hardening steel, equivalent to American H11, with HRC 44, heat conductivity 25W/(m.K). They are used to the case of nozzle and other components.
For valve gate nozzle , it has high requirement on heat resistance. Some use beryllium copper to make valve gate nozzle, with heat conductivity 200W/(m.K); Some other use Beryllium cooper cobalt alloy to valve gate nozzle,with heat conductivity 225W/(m.K), with heating with working temperature 280 °But need to smear some Ni on the surface to prevent the decrease of mechanical energy because of the high temperature.Valve gate normally use beryllium copper, which do not need nozzle body around the surface. Copper alloy has heat conductivity over 350W/(m.K), Aluminum alloy has heat conductivity arrange from 130 to 170 W/(m.K). Both of them are used to make the sleeve of nozzle heater and rolled bend.
The supporting pad, bearing ring and other heat insulation elements are all of stainless steel, but they are poor in bear high pressure. So, most of them are used of titanium alloy such as TiA1V4 with 7W/(m.K) heat conductivity. The best material is fired ceramic, with 2W/(m.K) heat conductivity, and good pressure resistance, with very low expansion factor.
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