材料期刊网

以Ti粉为原料,高速压制内.外径分别为30和60 mm的圆环状及直径为20 mm的圆柱状两种试样,探讨冲击能量,装粉量等对压坯密度的影响,并寻求高速压制过程的合适表征方式.结果表明:对于内,外径分别为30和60 mm的圆环试样,当冲击能量为3.804 kJ时,可成形的压坯密度最大,为4.00 g/cm~3,致密度为88.9%;对于直径为20 mm的圆柱试样,当冲击能量为1.217 kJ时,可成形的压坯密度最大,为4.38 g/cm~3,致密度为97.4%.对于同种试样,压坯密度随冲击能量的增加而增大,随装粉量的增加而减小.质量能量密度能全面地表征试样大小,冲击能量和装粉量等不同参数下的压坯密度.

High velocity compaction (HVC) is a recently developed technology for forming high density metallic parts with high efficiency, whose densification is realized through the strong impact wave generated by liquid-pressure controlled by heavy hamper. This technology is thought to have an excellent balance between properties and cost and has several advantages over other existingforming technologies, including high and homogeneous green density, low cost, low springback and high precision. It is extremely competitive to prepare powder metallurgy parts with high density, high strength, high precision and low cost. With a high hardening rate, Ti powder is difficult to be formed through traditional pressing methods, although advanced forming methods are effective for increasing its density, such as hot-pressing and isothermal-statistic pressing, they are very expensive. HVC would thus be highly attractive to solve these problems of low density and high cost in forming Ti powder. In this paper, the process of HVC forming Ti powder was studied. Two kinds of samples, the rings with 60 mm outer and 30 mm inner diameters and the cylindricals with 20 mm diameter were prepared through HVC, respectively. The influences of impact energy and filling weight on the green density were investigated. The results show that, for the ring samples, the maximum of green density is 4.00 g/cm~3and its relative density is 88.9% at an impact energy of 3.804 kj. However, for the cylindrical samples,the maximum of green density is 4.38 g/cm~3 and its relative density is 97.4% at an impact energy of 1.217 Kj. For the both kinds of samples, the green density increases with increasing impact energy while decreases with increasing filling weight. Impact energy per weight is helpful to characterize the green density obtained at different dimension, impact energy and filling weight.