Influence of mechanical milling on the hydrogen absorption properties of TiCrV – based alloys

Abstract

The hydrogen economy is a concept focused on this element as a carrier of clean and cheap energy, one of the keys is the storage of this gas safely. In this sense, TiCrV-based alloys have great capacity to store hydrogen. In the present working studied the influence of the process of mechanical milling of high energy in the storage capacity of hydrogen of TiCr1.1 V0.9 alloy. The alloy was synthesized by arc fusion and manually crushed. The effects of mechanical milling were studied for periods of time of 1 hour and 3 hours at 300 revolutions per minute with a weight/weight ratio of the sample 10: 1. The x-ray diffraction analyzes revealed solid phase formation of body center cubic phase, characteristic of TiCrV base alloys, and formation of TiCr1.8H5.3 hydrides and TiH2 hydrides with orthorhombic structure and body center cubic, respectively. The hydrogen storage capacity of the TiCr1.1 V0.9 alloy decreased with the increase in grinding time. The reasons for the drop in hydrogen storage capacity are mainly two: contamination of the surface of the alloy powder and changes in the microstructure generated by the plastic deformation in the grinding process. However, an increase in absorption kinetics was observed at longer milling times because the surface area increases since the crystallite size decreases. This phenomenon can be explained by the catalytic effect produced by the decrease in the particle size of the samples. The differential scanning calorimetry analysis was able to determine that the TiCr1.8H5.3 hydride stored a greater amount of hydrogen and has a lower desorption temperature compared to the TiH2 hydride.