Iron-based powder mixtures were prepared by dry and wet mixing method. The friction properties during compaction were tested by measuring the internal and external friction coefficient. The test results showed that the wet mixing process could realise the homogeneity of lubricant and improve the processing properties of the powder mixtures. With 0.6 wt-% lubricants, wet mixing powder mixtures have a flow rate of 29.6 s/50 g, an apparent density of 3.18 g cm–3, a repose angle of 35.5°, and the friction coefficient during the compaction is 0.223. An equation to calculate the total (both internal and external) friction forces during the compaction process is proposed, and then the factors influencing the friction coefficient during compaction were quantitatively analysed.
Highly uniform oxide dispersion-strengthened materials W–1 wt % Nd2O3 and W–1 wt % CeO2 were successfully fabricated via a novel wet chemical method followed by hydrogen reduction. The powders were consolidated by spark plasma sintering at 1700 °C to suppress grain growth. The samples were characterized by performing field emission scanning electron microscopy and transmission electron microscopy analyses, Vickers microhardness measurements, thermal conductivity, and tensile testing. The oxide particles were dispersed at the tungsten grain boundaries and within the grains. The thermal conductivity of the samples at room temperature exceeded 140 W/m·K. The tensile tests indicated that W–1 wt % CeO2 exhibited a ductile–brittle transition temperature between 500 °C and 550 °C, which was a lower range than that for W–1 wt % Nd2O3. Surface topography and Vickers microhardness analyses were conducted before and after irradiations with 50 eV He ions at a fluence of 1 × 1022 m−2 for 1 h in the large-powder material irradiation experiment system. The grain boundaries of the irradiated area became more evident than that of the unirradiated area for both samples. Irradiation hardening was recognized for the W–1 wt % Nd2O3 and W–1 wt % CeO2 samples.
1 June 2018 in Transactions of Nonferrous Metals Society of China