Natural gravel is rich natural resources and also better stable compacting roadbed material in the river courses of mountain areas.
天然砂砾料是山区河道中丰富的自然资源，也是压实后稳定性良好的路基填筑材料。
2
Material compoSition, compacting method and die structure of P/M bush with step and prismatic surface on cylinder were outlined.
介绍带台阶并在圆柱体上有三棱面的粉末冶金村套的材料配方、压制方法和模具结构。
3
The compacting density, bending strength, fracture toughness and rigidity value of the synthesis can be prepared to be applicable gradient material structure under suitable pressure and temperature.