Temperature dependence of (a) the solubility of hydrogen in titanium and (b) the equilibrium pressure of hydrogen dissolved from titanium hydride , when the surrounding pressure of hydrogen gas is . The solubility is expressed using the ratio of the number of H atoms to the number of Ti atoms. It can be seen that full occlusion/dissociation of hydrogen in/from titanium happens at . This means that prior to hydrogen occlusion, titanium washers must be heated up at least above for degassing and then cooled down in an atmosphere of hydrogen.
A schematic diagram of the instrument for hydrogen occlusion. It operates in controlled high-temperature furnace with ultrahigh vacuum condition. The instrument consists of mainly four parts: (A) the cylindrical electric furnace for heating, (B) the container tube made of quartz, (C) the gas reservoir, and (D) the vacuum generator.
A schematic drawing of the cylindrical electric furnace. A SiC heater is used as a heating element which can generate as the maximum temperature.
Time histories of temperature for each set of titanium washers listed in Table I. At first, rises gradually to in . After reaching , is maintained for for degasification. Subsequently, decreases programmatically. When gas is introduced at , is retained at the temperature for [for cases of (1)—(5)] and [for the case of (6)].
Values of (a) the ratio of to and (b) the product of and for each set of titanium washers listed in Table I. Here, and are the change in weight of titanium washers before and after occlusion of hydrogen and the amount of hydrogen prereserved in the gas reservoir, respectively. Also, is the temperature at the time when gas begins to be introduced and is the duration of maintained at the temperature.
The dependence of solubility on along with pressure in the quartz tube. At , (black circles) ranges approximately from 0.2 to 0.4. As drops, increases and finally reaches its prescribed value at . Simultaneously, is seen to approach zero at the temperature. This means that at all hydrogen are completely absorbed and blocked in titanium washers, suggesting that no occlusion of hydrogen can appear at .
A typical time history of the compression pressure imposed on the loaded titanium washer and the dependence of the maximum tolerable pressure on . As increases, decreases significantly. Data suggest that the appropriate value of is less than unity for the application to the Ti gun.
Values of temperature when gas begins to be introduced and the filling pressure of hydrogen in the gas reservoir for six sets of titanium washers.
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