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Why study the reaction between titanium alloy plates and water vapor? |
[ Information dissemination:This station | Release Time:2018-04-16 | Number of views:451 ] |
| The test was carried out in a vacuum microbalance device with a quartz spring. The accuracy of the readings is 4 x 10 g / cm sample surface. Use a Mercury manometer connected to the reaction chamber to determine the pressure in the system. Titanium iodide as sample. The deformable titanium rod is cold rolled into a 0.7 mm thick strip. The samples of 9 x 25 mm size are then cut from the strip. In order to remove the surface dirt, the sample was ground with fine sandpaper and eroded in 7 % HF HNO3 solution. A test tube filled with distilled water and connected to the device by a vacuum cock is used as the source of water vapor. Keep the water under the stars for some time in order to remove the dissolved gasification. After the sample is heated to a specified temperature in vacuum, the water-filled tube is connected to the system and the water vapor pressure at room temperature is established. When the system is full, the water tube is truncated to the system and tested in closed volume. The reaction of titanium alloy plates with water vapor was tested at 800, 850, 900 and 950 ℃ and 14 mm Mercury column water vapour pressure. The kinetic curves of these experiments show that the reaction between titanium alloy plate and water vapor is subservient to the parabolic law at the beginning of the reaction. In order to determine the effect of pressure on the reaction speed, two experiments were carried out at 4 mm Mercury column pressure. The reaction process between titanium alloy plate and water vapor, like any process of metal and gas, is composed of many continuous stages, the main ones being: 1) the interaction between gas molecules and metal, 2) the adsorption of gas molecules on metal surface, 3) the separation of gas molecules, 4) the diffusion of the reagent through the surface film of the reaction product, and 5) the chemical reaction. The speed of the whole reaction process depends on the speed of the most rapid phase. Since the rate of reaction between manganese and water vapor remains constant at a 5 / 7 pressure reduction, it should be recognized that the rate of reaction depends on the diffusion of the reagent through the surface membrane, which is the only stage at which the rate is independent of the gas pressure. |