Oxidation And Friction Wear Properties Of Hydrogenated TC4 Powdre Prepared By Magnetic Pulse Compaction And Sintering

Titanium alloys have excellent combination of attractive properties, including small density, high specific strength, high specific stiffness, etc. But it has terrible frictional behavior which is due to its proper properties. In this article, hydrogenated Ti6Al4V alloy powder was compacted by magnetic pulse compaction. Then, sintering and vacuum annealing was investigated. In order to provide theory directs for the use of vacuum annealed samples, it was investigated by sliding contact conditions. Thermal oxidation process and thermal oxidation (TO) +oxygen diffusion (OD) have been investigated to improve the wear-resistance of samples. Then the sliding frictional properties of the two kinds of surface treatments were investigated.The results show that the relative density of compacts didn't increase by the addition of hydrogen. Compaction temperature enhances the relative density and reduces the relative density differences of compacts with different hydrogen content. Compaction temperature can increase the hardness of compacts. Hydrogen has good effects on the improvement of the relative density during sintering process. Compaction temperature improves the hardness of vacuum annealed samples and reduces the difference between different hydrogen content.The coating formed by thermal oxidation is compact and insulated, its thickness increase as the temperature and time increase, but the coating may break off when it is too thick. The main substance of the coating is Al₂O₃ which is at the surface of the coating and TiO₂ at the inside. On the inner side of the coating, there is a strengthened layer penetrated by oxygen, its thickness can be 80⁹0μm. The surface oxides of TO+OD treated samples are small and tiny and it contains TiO. The strengthened layer of this samples can be 200μm, with basically no difference between different TO treat times. The effects of hydrogen on the wear-resistance of vacuum annealed samples are as the same of relative density. The main wear mechanism of vacuum annealed samples is fatigue wear with a certain extent of abrasive wear. The extent of abrasive wear was lightened as hydrogen extent increased.The wear rate of thermal oxidation treated samples is smaller than that of vacuum annealed samples by two orders. And its wear mechanism is the brittle cracking of thermal oxidation coating. The abrasive dusts are tiny, so they have the effects of polish. The wear rate of TO+OD treated samples is also smaller than that of vacuum annealed samples by two orders. When the TO treated time is appreciated, the wear rate of TO+OD treated samples is smaller than that of thermal oxidation treats samples. The tiny oxides of its surface have the effects of reducing wear.