粉末冶金TiAl基合金排气阀的制备及性能

Manufacture and properties of powder metallurgy TiAl based valves

研究了粉末冶金TiAl基合金柴油机排气阀的近型成形技术 ,其要点为 :采用元素粉末冶金方法 ,以元素Ti,Al粉末为主要原料 ,首先在刚模中冷压成排气阀菌部 ;然后在真空热压炉中 ,通过准等静压工艺 ,同时实现TiAl基合金的反应合成与近型成形 ;最后通过真空扩散联接工艺 ,使粉末冶金TiAl基合金菌部与铸态TiAl基合金杆部联接成完整的排气阀零件。通过发动机台架的初步试验表明 ,所制备的粉末冶金TiAl基合金排气阀表现出良好的服役性能。

The manufacturing method and properties of P/M TiAl based exhaust valves were investigated. The P/M TiAl based exhaust valves were prepared through elemental powder metallurgy (EPM), i.e. elemental Ti, Al powders were used as raw material. Firstly, the mixed elemental powders were cold pressed into a mushroomed head of the valve. Then the compacts were pseudo HIPed, in which both the material synthesis and near net shaping were realized at one step. Finally, the P/M TiAl based mushroomed valve heads were connected with the as cast TiAl based valve stems through diffusion joining technique. The primary results in diesel stand test using those valves prepared above showed that the diesel properties have met the requirements for practical application.